Test commit

Merge branch 'rc/1.54.3' into release
Revert "reenable the SimplificationPass in spirv-opt"
2024-09-16 12:09:26 -07:00 · 2024-09-10 12:26:56 -07:00 · 2024-09-09 10:37:11 -07:00 · 2024-09-04 18:55:59 +00:00 · 2024-09-04 18:55:59 +00:00 · 2024-09-04 17:07:51 +00:00
245 changed files with 6087 additions and 10949 deletions
@@ -1,9 +0,0 @@
-name: 'ubuntu apt add deb-src'
-runs:
-  using: "composite"
-  steps:
-    - name: "ubuntu apt add deb-src"
-      run: |
-          echo "deb-src http://archive.ubuntu.com/ubuntu jammy main restricted universe" | sudo tee /etc/apt/sources.list.d/my.list
-          sudo apt-get update
-      shell: bash
@@ -8,15 +8,35 @@ on:
      - rc/**

 jobs:
-  build-android:
-    name: build-android
-    # We intentially use a larger runner here to enable larger disk space
-    # (standard linux runner will fail on disk space and faster build time).
-    runs-on: ubuntu-22.04-32core
+  build-android-armv7:
+    name: build-android-armv7
+    runs-on: macos-14

    steps:
      - uses: actions/checkout@v4.1.6
      - name: Run Android Continuous
        uses: ./.github/actions/android-continuous
        with:
-          build-abi: armeabi-v7a,arm64-v8a,x86_64
+          build-abi: armeabi-v7a
+
+  build-android-armv8a:
+    name: build-android-armv8a
+    runs-on: macos-14
+
+    steps:
+      - uses: actions/checkout@v4.1.6
+      - name: Run Android Continuous
+        uses: ./.github/actions/android-continuous
+        with:
+          build-abi: arm64-v8a
+
+  build-android-x86_64:
+    name: build-android-x86_64
+    runs-on: macos-14
+
+    steps:
+      - uses: actions/checkout@v4.1.6
+      - name: Run Android Continuous
+        uses: ./.github/actions/android-continuous
+        with:
+          build-abi: x86_64
@@ -10,14 +10,14 @@ on:
 jobs:
  build-ios:
    name: build-ios
-    runs-on: macos-14-xlarge
+    runs-on: macos-14

    steps:
      - uses: actions/checkout@v4.1.6
      - name: Run build script
        run: |
          cd build/ios && printf "y" | ./build.sh continuous
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v1.0.0
        with:
          name: filament-ios
          path: out/filament-release-ios.tgz
@@ -10,14 +10,14 @@ on:
 jobs:
  build-linux:
    name: build-linux
-    runs-on: ubuntu-22.04-16core
+    runs-on: ubuntu-22.04

    steps:
      - uses: actions/checkout@v4.1.6
      - name: Run build script
        run: |
          cd build/linux && printf "y" | ./build.sh continuous
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v1.0.0
        with:
          name: filament-linux
          path: out/filament-release-linux.tgz
@@ -10,14 +10,14 @@ on:
 jobs:
  build-mac:
    name: build-mac
-    runs-on: macos-14-xlarge
+    runs-on: macos-14

    steps:
      - uses: actions/checkout@v4.1.6
      - name: Run build script
        run: |
          cd build/mac && printf "y" | ./build.sh continuous
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v1.0.0
        with:
          name: filament-mac
          path: out/filament-release-darwin.tgz
@@ -15,7 +15,7 @@ jobs:

    strategy:
      matrix:
-        os: [macos-14-xlarge, ubuntu-22.04-16core]
+        os: [macos-14, ubuntu-22.04]

    steps:
      - uses: actions/checkout@v4.1.6
@@ -29,7 +29,7 @@ jobs:

  build-windows:
    name: build-windows
-    runs-on: win-2019-16core
+    runs-on: windows-2019

    steps:
      - uses: actions/checkout@v4.1.6
@@ -40,7 +40,7 @@ jobs:

  build-android:
    name: build-android
-    runs-on: ubuntu-22.04-16core
+    runs-on: macos-14

    steps:
      - uses: actions/checkout@v4.1.6
@@ -56,7 +56,7 @@ jobs:

  build-ios:
    name: build-iOS
-    runs-on: macos-14-xlarge
+    runs-on: macos-14

    steps:
      - uses: actions/checkout@v4.1.6
@@ -69,25 +69,10 @@ jobs:

  build-web:
    name: build-web
-    runs-on: ubuntu-22.04-16core
+    runs-on: macos-14

    steps:
      - uses: actions/checkout@v4.1.6
      - name: Run build script
        run: |
          cd build/web && printf "y" | ./build.sh presubmit
-
-  test-renderdiff:
-    name: test-renderdiff
-    runs-on: ubuntu-22.04-32core
-
-    steps:
-      - uses: actions/checkout@v4.1.6
-      - uses: ./.github/actions/ubuntu-apt-add-src
-      - name: Run script
-        run: |
-          source ./build/linux/ci-common.sh && bash test/renderdiff_tests.sh
-      - uses: actions/upload-artifact@v4
-        with:
-          name: presubmit-renderdiff-result
-          path: ./out/renderdiff_tests
@@ -31,7 +31,7 @@ jobs:

    strategy:
      matrix:
-        os: [macos-14-xlarge, ubuntu-22.04-32core]
+        os: [macos-14, ubuntu-22.04]

    steps:
      - name: Decide Git ref
@@ -65,7 +65,7 @@ jobs:

  build-web:
    name: build-web
-    runs-on: ubuntu-22.04-16core
+    runs-on: macos-14
    if: github.event_name == 'release' || github.event.inputs.platform == 'web'

    steps:
@@ -98,7 +98,7 @@ jobs:

  build-android:
    name: build-android
-    runs-on: ubuntu-22.04-16core
+    runs-on: macos-14
    if: github.event_name == 'release' || github.event.inputs.platform == 'android'

    steps:
@@ -152,7 +152,7 @@ jobs:

  build-ios:
    name: build-ios
-    runs-on: macos-14-xlarge
+    runs-on: macos-14
    if: github.event_name == 'release' || github.event.inputs.platform == 'ios'

    steps:
@@ -185,7 +185,7 @@ jobs:

  build-windows:
    name: build-windows
-    runs-on: windows-2019-32core
+    runs-on: windows-2019
    if: github.event_name == 'release' || github.event.inputs.platform == 'windows'

    steps:
@@ -205,7 +205,6 @@ jobs:
          TAG: ${{ steps.git_ref.outputs.tag }}
        run: |
          build\windows\build-github.bat release
-          echo on
          move out\filament-windows.tgz out\filament-%TAG%-windows.tgz
        shell: cmd
      - uses: actions/github-script@v6
@@ -10,14 +10,14 @@ on:
 jobs:
  build-web:
    name: build-web
-    runs-on: ubuntu-22.04-16core
+    runs-on: macos-14

    steps:
      - uses: actions/checkout@v4.1.6
      - name: Run build script
        run: |
          cd build/web && printf "y" | ./build.sh continuous
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v1.0.0
        with:
          name: filament-web
          path: out/filament-release-web.tgz
@@ -10,7 +10,7 @@ on:
 jobs:
  build-windows:
    name: build-windows
-    runs-on: windows-2019-32core
+    runs-on: windows-2019

    steps:
      - uses: actions/checkout@v4.1.6
@@ -18,7 +18,7 @@ jobs:
        run: |
          build\windows\build-github.bat continuous
        shell: cmd
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v1.0.0
        with:
          name: filament-windows
          path: out/filament-windows.tgz
@@ -45,8 +45,6 @@ option(FILAMENT_ENABLE_FEATURE_LEVEL_0 "Enable Feature Level 0" ON)

 option(FILAMENT_ENABLE_MULTIVIEW "Enable multiview for Filament" OFF)

-option(FILAMENT_SUPPORTS_OSMESA "Enable OSMesa (headless GL context) for Filament" OFF)
-
 set(FILAMENT_NDK_VERSION "" CACHE STRING
    "Android NDK version or version prefix to be used when building for Android."
 )
@@ -75,10 +73,6 @@ set(FILAMENT_BACKEND_DEBUG_FLAG "" CACHE STRING
    "A debug flag meant for enabling/disabling backend debugging paths"
 )

-set(FILAMENT_OSMESA_PATH "" CACHE STRING
-    "Path to the OSMesa header and lib"
-)
-
 # Enable exceptions by default in spirv-cross.
 set(SPIRV_CROSS_EXCEPTIONS_TO_ASSERTIONS OFF)

@@ -138,22 +132,12 @@ else()
 endif()

 if (LINUX)
-    if (NOT FILAMENT_OSMESA_PATH STREQUAL "")
-        if (NOT EXISTS ${FILAMENT_OSMESA_PATH}/)
-            message(FATAL_ERROR "Cannot find specified OSMesa build directory: ${FILAMENT_OSMESA_PATH}")
-        endif()
-        set(FILAMENT_SUPPORTS_OSMESA TRUE)
-    endif()
-
    if (FILAMENT_SUPPORTS_WAYLAND)
        add_definitions(-DFILAMENT_SUPPORTS_WAYLAND)
        set(FILAMENT_SUPPORTS_X11 FALSE)
    elseif (FILAMENT_SUPPORTS_EGL_ON_LINUX)
        add_definitions(-DFILAMENT_SUPPORTS_EGL_ON_LINUX)
        set(FILAMENT_SUPPORTS_X11 FALSE)
-    elseif (FILAMENT_SUPPORTS_OSMESA)
-        set(FILAMENT_SUPPORTS_X11 FALSE)
-        add_definitions(-DFILAMENT_SUPPORTS_OSMESA)
    else ()
        if (FILAMENT_SUPPORTS_XCB)
            add_definitions(-DFILAMENT_SUPPORTS_XCB)
@@ -31,7 +31,7 @@ repositories {
 }

 dependencies {
-    implementation 'com.google.android.filament:filament-android:1.55.1'
+    implementation 'com.google.android.filament:filament-android:1.54.3'
 }
 ```

@@ -51,7 +51,7 @@ Here are all the libraries available in the group `com.google.android.filament`:
 iOS projects can use CocoaPods to install the latest release:

 ```shell
-pod 'Filament', '~> 1.55.1'
+pod 'Filament', '~> 1.54.3'
 ```

 ## Documentation
@@ -7,19 +7,6 @@ A new header is inserted each time a *tag* is created.
 Instead, if you are authoring a PR for the main branch, add your release note to
 [NEW_RELEASE_NOTES.md](./NEW_RELEASE_NOTES.md).

-## v1.55.1
-
-
-## v1.55.0
- Add descriptor sets to describe shader resources. [⚠️ **New Material Version**]
-
-## v1.54.5
-
-
-## v1.54.4
-
- Add support for multi-layered render target with array textures.
-
 ## v1.54.3


@@ -520,12 +520,13 @@ extern "C" JNIEXPORT void JNICALL Java_com_google_android_filament_Engine_nSetBu
 extern "C" JNIEXPORT void JNICALL Java_com_google_android_filament_Engine_nSetBuilderConfig(JNIEnv*,
        jclass, jlong nativeBuilder, jlong commandBufferSizeMB, jlong perRenderPassArenaSizeMB,
        jlong driverHandleArenaSizeMB, jlong minCommandBufferSizeMB, jlong perFrameCommandsSizeMB,
-        jlong jobSystemThreadCount, jboolean disableParallelShaderCompile,
+        jlong jobSystemThreadCount,
+        jlong textureUseAfterFreePoolSize, jboolean disableParallelShaderCompile,
        jint stereoscopicType, jlong stereoscopicEyeCount,
        jlong resourceAllocatorCacheSizeMB, jlong resourceAllocatorCacheMaxAge,
        jboolean disableHandleUseAfterFreeCheck,
        jint preferredShaderLanguage,
-        jboolean forceGLES2Context, jboolean assertNativeWindowIsValid) {
+        jboolean forceGLES2Context) {
    Engine::Builder* builder = (Engine::Builder*) nativeBuilder;
    Engine::Config config = {
            .commandBufferSizeMB = (uint32_t) commandBufferSizeMB,
@@ -534,6 +535,7 @@ extern "C" JNIEXPORT void JNICALL Java_com_google_android_filament_Engine_nSetBu
            .minCommandBufferSizeMB = (uint32_t) minCommandBufferSizeMB,
            .perFrameCommandsSizeMB = (uint32_t) perFrameCommandsSizeMB,
            .jobSystemThreadCount = (uint32_t) jobSystemThreadCount,
+            .textureUseAfterFreePoolSize = (uint32_t) textureUseAfterFreePoolSize,
            .disableParallelShaderCompile = (bool) disableParallelShaderCompile,
            .stereoscopicType = (Engine::StereoscopicType) stereoscopicType,
            .stereoscopicEyeCount = (uint8_t) stereoscopicEyeCount,
@@ -542,7 +544,6 @@ extern "C" JNIEXPORT void JNICALL Java_com_google_android_filament_Engine_nSetBu
            .disableHandleUseAfterFreeCheck = (bool) disableHandleUseAfterFreeCheck,
            .preferredShaderLanguage = (Engine::Config::ShaderLanguage) preferredShaderLanguage,
            .forceGLES2Context = (bool) forceGLES2Context,
-            .assertNativeWindowIsValid = (bool) assertNativeWindowIsValid,
    };
    builder->config(&config);
 }
@@ -224,12 +224,13 @@ public class Engine {
            nSetBuilderConfig(mNativeBuilder, config.commandBufferSizeMB,
                    config.perRenderPassArenaSizeMB, config.driverHandleArenaSizeMB,
                    config.minCommandBufferSizeMB, config.perFrameCommandsSizeMB,
-                    config.jobSystemThreadCount, config.disableParallelShaderCompile,
+                    config.jobSystemThreadCount,
+                    config.textureUseAfterFreePoolSize, config.disableParallelShaderCompile,
                    config.stereoscopicType.ordinal(), config.stereoscopicEyeCount,
                    config.resourceAllocatorCacheSizeMB, config.resourceAllocatorCacheMaxAge,
                    config.disableHandleUseAfterFreeCheck,
                    config.preferredShaderLanguage.ordinal(),
-                    config.forceGLES2Context, config.assertNativeWindowIsValid);
+                    config.forceGLES2Context);
            return this;
        }

@@ -418,12 +419,12 @@ public class Engine {
         */
        public long stereoscopicEyeCount = 2;

-        /**
+        /*
         * @Deprecated This value is no longer used.
         */
        public long resourceAllocatorCacheSizeMB = 64;

-        /**
+        /*
         * This value determines how many frames texture entries are kept for in the cache. This
         * is a soft limit, meaning some texture older than this are allowed to stay in the cache.
         * Typically only one texture is evicted per frame.
@@ -431,12 +432,12 @@ public class Engine {
         */
        public long resourceAllocatorCacheMaxAge = 1;

-        /**
+        /*
         * Disable backend handles use-after-free checks.
         */
        public boolean disableHandleUseAfterFreeCheck = false;

-        /**
+        /*
         * Sets a preferred shader language for Filament to use.
         *
         * The Metal backend supports two shader languages: MSL (Metal Shading Language) and
@@ -458,19 +459,12 @@ public class Engine {
        };
        public ShaderLanguage preferredShaderLanguage = ShaderLanguage.DEFAULT;

-        /**
+        /*
         * When the OpenGL ES backend is used, setting this value to true will force a GLES2.0
         * context if supported by the Platform, or if not, will have the backend pretend
         * it's a GLES2 context. Ignored on other backends.
         */
        public boolean forceGLES2Context = false;
-
-        /**
-         * Assert the native window associated to a SwapChain is valid when calling makeCurrent().
-         * This is only supported for:
-         *      - PlatformEGLAndroid
-         */
-        public boolean assertNativeWindowIsValid = false;
    }

    private Engine(long nativeEngine, Config config) {
@@ -1412,11 +1406,12 @@ public class Engine {
    private static native void nSetBuilderConfig(long nativeBuilder, long commandBufferSizeMB,
            long perRenderPassArenaSizeMB, long driverHandleArenaSizeMB,
            long minCommandBufferSizeMB, long perFrameCommandsSizeMB, long jobSystemThreadCount,
-            boolean disableParallelShaderCompile, int stereoscopicType, long stereoscopicEyeCount,
+            long textureUseAfterFreePoolSize, boolean disableParallelShaderCompile,
+            int stereoscopicType, long stereoscopicEyeCount,
            long resourceAllocatorCacheSizeMB, long resourceAllocatorCacheMaxAge,
            boolean disableHandleUseAfterFreeCheck,
            int preferredShaderLanguage,
-            boolean forceGLES2Context, boolean assertNativeWindowIsValid);
+            boolean forceGLES2Context);
    private static native void nSetBuilderFeatureLevel(long nativeBuilder, int ordinal);
    private static native void nSetBuilderSharedContext(long nativeBuilder, long sharedContext);
    private static native void nSetBuilderPaused(long nativeBuilder, boolean paused);
@@ -1,5 +1,5 @@
 GROUP=com.google.android.filament
-VERSION_NAME=1.55.1
+VERSION_NAME=1.54.3

 POM_DESCRIPTION=Real-time physically based rendering engine for Android.

@@ -64,9 +64,6 @@ function print_help {
    echo "        enabling debug paths in the backend from the build script. For example, make a"
    echo "        systrace-enabled build without directly changing #defines. Remember to add -f when"
    echo "        changing this option."
-    echo "    -X osmesa_path"
-    echo "        Indicates a path to a completed OSMesa build. OSMesa is used to create an offscreen GL"
-    echo "        context for software rasterization"
    echo "    -S type"
    echo "        Enable stereoscopic rendering where type is one of [instanced|multiview]. This is only"
    echo "        meant for building the samples."
@@ -183,8 +180,6 @@ BACKEND_DEBUG_FLAG_OPTION=""

 STEREOSCOPIC_OPTION=""

-OSMESA_OPTION=""
-
 IOS_BUILD_SIMULATOR=false
 BUILD_UNIVERSAL_LIBRARIES=false

@@ -245,7 +240,6 @@ function build_desktop_target {
            ${ASAN_UBSAN_OPTION} \
            ${BACKEND_DEBUG_FLAG_OPTION} \
            ${STEREOSCOPIC_OPTION} \
-            ${OSMESA_OPTION} \
            ${architectures} \
            ../..
        ln -sf "out/cmake-${lc_target}/compile_commands.json" \
@@ -802,7 +796,7 @@ function check_debug_release_build {

 pushd "$(dirname "$0")" > /dev/null

-while getopts ":hacCfgijmp:q:uvslwedk:bx:S:X:" opt; do
+while getopts ":hacCfgijmp:q:uvslwedk:bx:S:" opt; do
    case ${opt} in
        h)
            print_help
@@ -956,8 +950,6 @@ while getopts ":hacCfgijmp:q:uvslwedk:bx:S:X:" opt; do
                    exit 1
            esac
            ;;
-        X)  OSMESA_OPTION="-DFILAMENT_OSMESA_PATH=${OPTARG}"
-            ;;
        \?)
            echo "Invalid option: -${OPTARG}" >&2
            echo ""
@@ -1,6 +1,7 @@
 #!/bin/bash
 if [ `uname` == "Linux" ];then
-    source `dirname $0`/../linux/ci-common.sh
+    curl -OL https://github.com/ninja-build/ninja/releases/download/v1.10.2/ninja-linux.zip
+    unzip -q ninja-linux.zip
 elif [ `uname` == "Darwin" ];then
    curl -OL https://github.com/ninja-build/ninja/releases/download/v1.10.2/ninja-mac.zip
    unzip -q ninja-mac.zip
@@ -12,6 +13,9 @@ fi
 chmod +x ninja
 export PATH="$PWD:$PATH"

+# FIXME: kokoro machines have node and npm but currently they are symlinked to non-existent files
+# npm install -g typescript
+
 # Install emscripten.
 curl -L https://github.com/emscripten-core/emsdk/archive/refs/tags/3.1.15.zip > emsdk.zip
 unzip emsdk.zip ; mv emsdk-* emsdk ; cd emsdk
@@ -115,23 +115,17 @@ cmake ..\.. ^
    -DFILAMENT_SUPPORTS_VULKAN=ON ^
    || exit /b

-set build_flags=-j %NUMBER_OF_PROCESSORS%
-
-@echo on
-
-:: we've upgraded the windows machines, so the following are no longer accurate as of 09/19/24, but
-:: keeping around the comment for record.
-
 :: Attempt to fix "error C1060: compiler is out of heap space" seen on CI.
 :: Some resource libraries require significant heap space to compile, so first compile them serially.
-:: cmake --build . --target filagui --config %config% %build_flags% || exit /b
-:: cmake --build . --target uberarchive --config %config% %build_flags% || exit /b
-:: cmake --build . --target gltf-demo-resources --config %config% %build_flags% || exit /b
-:: cmake --build . --target filamentapp-resources --config %config% %build_flags% || exit /b
-:: cmake --build . --target sample-resources --config %config% %build_flags% || exit /b
-:: cmake --build . --target suzanne-resources --config %config% %build_flags% || exit /b
+@echo on
+cmake --build . --target filagui --config %config% || exit /b
+cmake --build . --target uberarchive --config %config% || exit /b
+cmake --build . --target gltf-demo-resources --config %config% || exit /b
+cmake --build . --target filamentapp-resources --config %config% || exit /b
+cmake --build . --target sample-resources --config %config% || exit /b
+cmake --build . --target suzanne-resources --config %config% || exit /b

-cmake --build . %INSTALL% --config %config% %build_flags% -- /m || exit /b
+cmake --build . %INSTALL% --config %config% -- /m || exit /b
@echo off

 echo Disk info after building variant: %variant%
@@ -66,7 +66,6 @@ set(SRCS
        src/FrameSkipper.cpp
        src/Froxelizer.cpp
        src/Frustum.cpp
-        src/HwDescriptorSetLayoutFactory.cpp
        src/HwRenderPrimitiveFactory.cpp
        src/HwVertexBufferInfoFactory.cpp
        src/IndexBuffer.cpp
@@ -77,6 +76,8 @@ set(SRCS
        src/MaterialInstance.cpp
        src/MaterialParser.cpp
        src/MorphTargetBuffer.cpp
+        src/PerViewUniforms.cpp
+        src/PerShadowMapUniforms.cpp
        src/PostProcessManager.cpp
        src/RenderPass.cpp
        src/RenderPrimitive.cpp
@@ -125,12 +126,6 @@ set(SRCS
        src/details/Texture.cpp
        src/details/VertexBuffer.cpp
        src/details/View.cpp
-        src/ds/ColorPassDescriptorSet.cpp
-        src/ds/DescriptorSet.cpp
-        src/ds/DescriptorSetLayout.cpp
-        src/ds/PostProcessDescriptorSet.cpp
-        src/ds/ShadowMapDescriptorSet.cpp
-        src/ds/SsrPassDescriptorSet.cpp
        src/fg/Blackboard.cpp
        src/fg/DependencyGraph.cpp
        src/fg/FrameGraph.cpp
@@ -154,21 +149,23 @@ set(PRIVATE_HDRS
        src/FrameInfo.h
        src/FrameSkipper.h
        src/Froxelizer.h
-        src/HwDescriptorSetLayoutFactory.h
        src/HwRenderPrimitiveFactory.h
        src/HwVertexBufferInfoFactory.h
        src/Intersections.h
        src/MaterialParser.h
+        src/PerViewUniforms.h
+        src/PerShadowMapUniforms.h
        src/PIDController.h
        src/PostProcessManager.h
+        src/RendererUtils.h
        src/RenderPass.h
        src/RenderPrimitive.h
-        src/RendererUtils.h
        src/ResourceAllocator.h
        src/ResourceList.h
        src/ShadowMap.h
        src/ShadowMapManager.h
        src/SharedHandle.h
+        src/TypedUniformBuffer.h
        src/UniformBuffer.h
        src/components/CameraManager.h
        src/components/LightManager.h
@@ -196,14 +193,6 @@ set(PRIVATE_HDRS
        src/details/Texture.h
        src/details/VertexBuffer.h
        src/details/View.h
-        src/downcast.h
-        src/ds/ColorPassDescriptorSet.h
-        src/ds/DescriptorSetLayout.h
-        src/ds/PostProcessDescriptorSet.h
-        src/ds/ShadowMapDescriptorSet.h
-        src/ds/SsrPassDescriptorSet.h
-        src/ds/TypedBuffer.h
-        src/ds/TypedUniformBuffer.h
        src/fg/Blackboard.h
        src/fg/FrameGraph.h
        src/fg/FrameGraphId.h
@@ -221,6 +210,7 @@ set(PRIVATE_HDRS
        src/materials/fsr/ffx_a.h
        src/materials/fsr/ffx_fsr1.h
        src/materials/fsr/ffx_fsr1_mobile.fs
+        src/downcast.h
 )

 set(MATERIAL_SRCS
@@ -12,7 +12,6 @@ set(PUBLIC_HDRS
        include/backend/AcquiredImage.h
        include/backend/BufferDescriptor.h
        include/backend/CallbackHandler.h
-        include/backend/DescriptorSetOffsetArray.h
        include/backend/DriverApiForward.h
        include/backend/DriverEnums.h
        include/backend/Handle.h
@@ -70,13 +69,9 @@ set(PRIVATE_HDRS
 if (FILAMENT_SUPPORTS_OPENGL AND NOT FILAMENT_USE_EXTERNAL_GLES3)
    list(APPEND SRCS
            include/backend/platforms/OpenGLPlatform.h
-            src/opengl/BindingMap.h
            src/opengl/gl_headers.cpp
            src/opengl/gl_headers.h
            src/opengl/GLBufferObject.h
-            src/opengl/GLDescriptorSet.cpp
-            src/opengl/GLDescriptorSet.h
-            src/opengl/GLDescriptorSetLayout.h
            src/opengl/GLTexture.h
            src/opengl/GLUtils.cpp
            src/opengl/GLUtils.h
@@ -119,8 +114,6 @@ if (FILAMENT_SUPPORTS_OPENGL AND NOT FILAMENT_USE_EXTERNAL_GLES3)
            list(APPEND SRCS src/opengl/platforms/PlatformGLX.cpp)
        elseif (FILAMENT_SUPPORTS_EGL_ON_LINUX)
            list(APPEND SRCS src/opengl/platforms/PlatformEGLHeadless.cpp)
-        elseif (FILAMENT_SUPPORTS_OSMESA)
-            list(APPEND SRCS src/opengl/platforms/PlatformOSMesa.cpp)
        endif()
    elseif (WIN32)
        list(APPEND SRCS src/opengl/platforms/PlatformWGL.cpp)
@@ -368,11 +361,6 @@ set(LINUX_LINKER_OPTIMIZATION_FLAGS
        -Wl,--exclude-libs,bluegl
 )

-if (LINUX AND FILAMENT_SUPPORTS_OSMESA)
-    set(OSMESA_COMPILE_FLAGS
-        -I${FILAMENT_OSMESA_PATH}/include/GL)
-endif()
-
 if (MSVC)
    set(FILAMENT_WARNINGS /W3)
 else()
@@ -393,7 +381,6 @@ endif()

 target_compile_options(${TARGET} PRIVATE
        ${FILAMENT_WARNINGS}
-        ${OSMESA_COMPILE_FLAGS}
        $<$<CONFIG:Release>:${OPTIMIZATION_FLAGS}>
        $<$<AND:$<PLATFORM_ID:Darwin>,$<CONFIG:Release>>:${DARWIN_OPTIMIZATION_FLAGS}>
 )
@@ -403,7 +390,6 @@ if (FILAMENT_SUPPORTS_METAL)
 endif()

 target_link_libraries(${TARGET} PRIVATE
-        ${OSMESA_LINKER_FLAGS}
        $<$<AND:$<PLATFORM_ID:Linux>,$<CONFIG:Release>>:${LINUX_LINKER_OPTIMIZATION_FLAGS}>
 )

@@ -438,7 +424,6 @@ if (APPLE OR LINUX)
        test/test_StencilBuffer.cpp
        test/test_Scissor.cpp
        test/test_MipLevels.cpp
-        test/test_Handles.cpp
    )
    set(BACKEND_TEST_LIBS
        backend
@@ -510,40 +495,21 @@ endif()

 # ==================================================================================================
 # Compute tests
-#
-#if (NOT IOS AND NOT WEBGL)
-#
-#add_executable(compute_test
-#        test/ComputeTest.cpp
-#        test/Arguments.cpp
-#        test/test_ComputeBasic.cpp
-#        )
-#
-#target_link_libraries(compute_test PRIVATE
-#        backend
-#        getopt
-#        gtest
-#        )
-#
-#set_target_properties(compute_test PROPERTIES FOLDER Tests)
-#
-#endif()

-# ==================================================================================================
-# Metal utils tests
+if (NOT IOS AND NOT WEBGL)

-if (APPLE AND NOT IOS)
+add_executable(compute_test
+        test/ComputeTest.cpp
+        test/Arguments.cpp
+        test/test_ComputeBasic.cpp
+        )

-add_executable(metal_utils_test test/MetalTest.mm)
-
-target_compile_options(metal_utils_test PRIVATE "-fobjc-arc")
-
-target_link_libraries(metal_utils_test PRIVATE
+target_link_libraries(compute_test PRIVATE
        backend
        getopt
        gtest
        )

-set_target_properties(metal_utils_test PROPERTIES FOLDER Tests)
+set_target_properties(compute_test PROPERTIES FOLDER Tests)

 endif()
@@ -1,101 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_COMMANDSTREAMVECTOR_H
-#define TNT_FILAMENT_BACKEND_COMMANDSTREAMVECTOR_H
-
-#include <backend/DriverApiForward.h>
-
-#include <initializer_list>
-#include <memory>
-
-#include <stddef.h>
-#include <stdint.h>
-
-
-namespace filament::backend {
-
-void* allocateFromCommandStream(DriverApi& driver, size_t size, size_t alignment) noexcept;
-
-class DescriptorSetOffsetArray {
-public:
-    using value_type = uint32_t;
-    using reference = value_type&;
-    using const_reference = value_type const&;
-    using size_type = uint32_t;
-    using difference_type = int32_t;
-    using pointer = value_type*;
-    using const_pointer = value_type const*;
-    using iterator = pointer;
-    using const_iterator = const_pointer;
-
-    DescriptorSetOffsetArray() noexcept = default;
-
-    ~DescriptorSetOffsetArray() noexcept = default;
-
-    DescriptorSetOffsetArray(size_type size, DriverApi& driver) noexcept {
-        mOffsets = (value_type *)allocateFromCommandStream(driver,
-                size * sizeof(value_type), alignof(value_type));
-        std::uninitialized_fill_n(mOffsets, size, 0);
-    }
-
-    DescriptorSetOffsetArray(std::initializer_list<uint32_t> list, DriverApi& driver) noexcept {
-        mOffsets = (value_type *)allocateFromCommandStream(driver,
-                list.size() * sizeof(value_type), alignof(value_type));
-        std::uninitialized_copy(list.begin(), list.end(), mOffsets);
-    }
-
-    DescriptorSetOffsetArray(DescriptorSetOffsetArray const&) = delete;
-    DescriptorSetOffsetArray& operator=(DescriptorSetOffsetArray const&) = delete;
-
-    DescriptorSetOffsetArray(DescriptorSetOffsetArray&& rhs) noexcept
-            : mOffsets(rhs.mOffsets) {
-        rhs.mOffsets = nullptr;
-    }
-
-    DescriptorSetOffsetArray& operator=(DescriptorSetOffsetArray&& rhs) noexcept {
-        if (this != &rhs) {
-            mOffsets = rhs.mOffsets;
-            rhs.mOffsets = nullptr;
-        }
-        return *this;
-    }
-
-    bool empty() const noexcept { return mOffsets == nullptr; }
-
-    value_type* data() noexcept { return mOffsets; }
-    const value_type* data() const noexcept { return mOffsets; }
-
-
-    reference operator[](size_type n) noexcept {
-        return *(data() + n);
-    }
-
-    const_reference operator[](size_type n) const noexcept {
-        return *(data() + n);
-    }
-
-    void clear() noexcept {
-        mOffsets = nullptr;
-    }
-
-private:
-    value_type *mOffsets = nullptr;
-};
-
-} // namespace filament::backend
-
-#endif //TNT_FILAMENT_BACKEND_COMMANDSTREAMVECTOR_H
@@ -19,16 +19,13 @@
 #ifndef TNT_FILAMENT_BACKEND_DRIVERENUMS_H
 #define TNT_FILAMENT_BACKEND_DRIVERENUMS_H

+#include <utils/BitmaskEnum.h>
 #include <utils/unwindows.h> // Because we define ERROR in the FenceStatus enum.

 #include <backend/Platform.h>
 #include <backend/PresentCallable.h>

-#include <utils/BitmaskEnum.h>
-#include <utils/FixedCapacityVector.h>
 #include <utils/Invocable.h>
-#include <utils/compiler.h>
-#include <utils/debug.h>
 #include <utils/ostream.h>

 #include <math/vec4.h>
@@ -100,8 +97,6 @@ static constexpr size_t MAX_VERTEX_ATTRIBUTE_COUNT  = 16;   // This is guarantee
 static constexpr size_t MAX_SAMPLER_COUNT           = 62;   // Maximum needed at feature level 3.
 static constexpr size_t MAX_VERTEX_BUFFER_COUNT     = 16;   // Max number of bound buffer objects.
 static constexpr size_t MAX_SSBO_COUNT              = 4;    // This is guaranteed by OpenGL ES.
-static constexpr size_t MAX_DESCRIPTOR_SET_COUNT    = 4;    // This is guaranteed by Vulkan.
-static constexpr size_t MAX_DESCRIPTOR_COUNT        = 64;   // per set

 static constexpr size_t MAX_PUSH_CONSTANT_COUNT     = 32;   // Vulkan 1.1 spec allows for 128-byte
                                                            // of push constant (we assume 4-byte
@@ -196,70 +191,6 @@ static constexpr const char* shaderLanguageToString(ShaderLanguage shaderLanguag
    }
 }

-enum class ShaderStage : uint8_t {
-    VERTEX = 0,
-    FRAGMENT = 1,
-    COMPUTE = 2
-};
-
-static constexpr size_t PIPELINE_STAGE_COUNT = 2;
-enum class ShaderStageFlags : uint8_t {
-    NONE        =    0,
-    VERTEX      =    0x1,
-    FRAGMENT    =    0x2,
-    COMPUTE     =    0x4,
-    ALL_SHADER_STAGE_FLAGS = VERTEX | FRAGMENT | COMPUTE
-};
-
-static inline constexpr bool hasShaderType(ShaderStageFlags flags, ShaderStage type) noexcept {
-    switch (type) {
-        case ShaderStage::VERTEX:
-            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::VERTEX));
-        case ShaderStage::FRAGMENT:
-            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::FRAGMENT));
-        case ShaderStage::COMPUTE:
-            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::COMPUTE));
-    }
-}
-
-enum class DescriptorType : uint8_t {
-    UNIFORM_BUFFER,
-    SHADER_STORAGE_BUFFER,
-    SAMPLER,
-    INPUT_ATTACHMENT,
-};
-
-enum class DescriptorFlags : uint8_t {
-    NONE = 0x00,
-    DYNAMIC_OFFSET = 0x01
-};
-
-using descriptor_set_t = uint8_t;
-
-using descriptor_binding_t = uint8_t;
-
-struct DescriptorSetLayoutBinding {
-    DescriptorType type;
-    ShaderStageFlags stageFlags;
-    descriptor_binding_t binding;
-    DescriptorFlags flags = DescriptorFlags::NONE;
-    uint16_t count = 0;
-
-    friend inline bool operator==(
-            DescriptorSetLayoutBinding const& lhs,
-            DescriptorSetLayoutBinding const& rhs) noexcept {
-        return lhs.type == rhs.type &&
-               lhs.flags == rhs.flags &&
-               lhs.count == rhs.count &&
-               lhs.stageFlags == rhs.stageFlags;
-    }
-};
-
-struct DescriptorSetLayout {
-    utils::FixedCapacityVector<DescriptorSetLayoutBinding> bindings;
-};
-
-
 /**
 * Bitmask for selecting render buffers
 */
@@ -339,6 +270,15 @@ enum class FenceStatus : int8_t {
    TIMEOUT_EXPIRED = 1,        //!< wait()'s timeout expired. The Fence condition is not satisfied.
 };

+/**
+ * Status codes for sync objects
+ */
+enum class SyncStatus : int8_t {
+    ERROR = -1,          //!< An error occurred. The Sync is not signaled.
+    SIGNALED = 0,        //!< The Sync is signaled.
+    NOT_SIGNALED = 1,    //!< The Sync is not signaled yet
+};
+
 static constexpr uint64_t FENCE_WAIT_FOR_EVER = uint64_t(-1);

 /**
@@ -428,18 +368,6 @@ enum class SamplerType : uint8_t {
    SAMPLER_CUBEMAP_ARRAY,  //!< Cube map array texture (feature level 2)
 };

-inline const char* stringify(SamplerType samplerType) {
-    switch (samplerType) {
-        case SamplerType::SAMPLER_2D: return "SAMPLER_2D";
-        case SamplerType::SAMPLER_2D_ARRAY: return "SAMPLER_2D_ARRAY";
-        case SamplerType::SAMPLER_CUBEMAP: return "SAMPLER_CUBEMAP";
-        case SamplerType::SAMPLER_EXTERNAL: return "SAMPLER_EXTERNAL";
-        case SamplerType::SAMPLER_3D: return "SAMPLER_3D";
-        case SamplerType::SAMPLER_CUBEMAP_ARRAY: return "SAMPLER_CUBEMAP_ARRAY";
-    }
-    return "UNKNOWN";
-}
-
 //! Subpass type
 enum class SubpassType : uint8_t {
    SUBPASS_INPUT
@@ -765,27 +693,9 @@ enum class TextureUsage : uint16_t {
    BLIT_SRC            = 0x0040,            //!< Texture can be used the source of a blit()
    BLIT_DST            = 0x0080,            //!< Texture can be used the destination of a blit()
    PROTECTED           = 0x0100,            //!< Texture can be used for protected content
-    DEFAULT             = UPLOADABLE | SAMPLEABLE,   //!< Default texture usage
-    ALL_ATTACHMENTS     = COLOR_ATTACHMENT | DEPTH_ATTACHMENT | STENCIL_ATTACHMENT | SUBPASS_INPUT,   //!< Mask of all attachments
+    DEFAULT             = UPLOADABLE | SAMPLEABLE   //!< Default texture usage
 };

-inline const char* stringify(TextureUsage usage) {
-    switch (usage) {
-        case TextureUsage::NONE: return "NONE";
-        case TextureUsage::COLOR_ATTACHMENT: return "COLOR_ATTACHMENT";
-        case TextureUsage::DEPTH_ATTACHMENT: return "DEPTH_ATTACHMENT";
-        case TextureUsage::STENCIL_ATTACHMENT: return "STENCIL_ATTACHMENT";
-        case TextureUsage::UPLOADABLE: return "UPLOADABLE";
-        case TextureUsage::SAMPLEABLE: return "SAMPLEABLE";
-        case TextureUsage::SUBPASS_INPUT: return "SUBPASS_INPUT";
-        case TextureUsage::BLIT_SRC: return "BLIT_SRC";
-        case TextureUsage::BLIT_DST: return "BLIT_DST";
-        case TextureUsage::PROTECTED: return "PROTECTED";
-        case TextureUsage::DEFAULT: return "DEFAULT";
-        default: return "UNKNOWN";
-    }
-}
-
 //! Texture swizzle
 enum class TextureSwizzle : uint8_t {
    SUBSTITUTE_ZERO,
@@ -977,9 +887,6 @@ struct SamplerParams { // NOLINT

    struct EqualTo {
        bool operator()(SamplerParams lhs, SamplerParams rhs) const noexcept {
-            assert_invariant(lhs.padding0 == 0);
-            assert_invariant(lhs.padding1 == 0);
-            assert_invariant(lhs.padding2 == 0);
            auto* pLhs = reinterpret_cast<uint32_t const*>(reinterpret_cast<char const*>(&lhs));
            auto* pRhs = reinterpret_cast<uint32_t const*>(reinterpret_cast<char const*>(&rhs));
            return *pLhs == *pRhs;
@@ -988,9 +895,6 @@ struct SamplerParams { // NOLINT

    struct LessThan {
        bool operator()(SamplerParams lhs, SamplerParams rhs) const noexcept {
-            assert_invariant(lhs.padding0 == 0);
-            assert_invariant(lhs.padding1 == 0);
-            assert_invariant(lhs.padding2 == 0);
            auto* pLhs = reinterpret_cast<uint32_t const*>(reinterpret_cast<char const*>(&lhs));
            auto* pRhs = reinterpret_cast<uint32_t const*>(reinterpret_cast<char const*>(&rhs));
            return *pLhs == *pRhs;
@@ -998,12 +902,6 @@ struct SamplerParams { // NOLINT
    };

 private:
-    friend inline bool operator == (SamplerParams lhs, SamplerParams rhs) noexcept {
-        return SamplerParams::EqualTo{}(lhs, rhs);
-    }
-    friend inline bool operator != (SamplerParams lhs, SamplerParams rhs) noexcept {
-        return  !SamplerParams::EqualTo{}(lhs, rhs);
-    }
    friend inline bool operator < (SamplerParams lhs, SamplerParams rhs) noexcept {
        return SamplerParams::LessThan{}(lhs, rhs);
    }
@@ -1171,6 +1069,32 @@ struct RasterState {
 * \privatesection
 */

+enum class ShaderStage : uint8_t {
+    VERTEX = 0,
+    FRAGMENT = 1,
+    COMPUTE = 2
+};
+
+static constexpr size_t PIPELINE_STAGE_COUNT = 2;
+enum class ShaderStageFlags : uint8_t {
+    NONE        =    0,
+    VERTEX      =    0x1,
+    FRAGMENT    =    0x2,
+    COMPUTE     =    0x4,
+    ALL_SHADER_STAGE_FLAGS = VERTEX | FRAGMENT | COMPUTE
+};
+
+static inline constexpr bool hasShaderType(ShaderStageFlags flags, ShaderStage type) noexcept {
+    switch (type) {
+        case ShaderStage::VERTEX:
+            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::VERTEX));
+        case ShaderStage::FRAGMENT:
+            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::FRAGMENT));
+        case ShaderStage::COMPUTE:
+            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::COMPUTE));
+    }
+}
+
 /**
 * Selects which buffers to clear at the beginning of the render pass, as well as which buffers
 * can be discarded at the beginning and end of the render pass.
@@ -1335,8 +1259,6 @@ template<> struct utils::EnableBitMaskOperators<filament::backend::ShaderStageFl
        : public std::true_type {};
 template<> struct utils::EnableBitMaskOperators<filament::backend::TargetBufferFlags>
        : public std::true_type {};
-template<> struct utils::EnableBitMaskOperators<filament::backend::DescriptorFlags>
-        : public std::true_type {};
 template<> struct utils::EnableBitMaskOperators<filament::backend::TextureUsage>
        : public std::true_type {};
 template<> struct utils::EnableBitMaskOperators<filament::backend::StencilFace>
@@ -23,7 +23,6 @@
 #include <utils/debug.h>

 #include <type_traits> // FIXME: STL headers are not allowed in public headers
-#include <utility>

 #include <stdint.h>

@@ -42,8 +41,6 @@ struct HwTexture;
 struct HwTimerQuery;
 struct HwVertexBufferInfo;
 struct HwVertexBuffer;
-struct HwDescriptorSetLayout;
-struct HwDescriptorSet;

 /*
 * A handle to a backend resource. HandleBase is for internal use only.
@@ -107,18 +104,8 @@ struct Handle : public HandleBase {
    Handle(Handle const& rhs) noexcept = default;
    Handle(Handle&& rhs) noexcept = default;

-    // Explicitly redefine copy/move assignment operators rather than just using default here.
-    // Because it doesn't make a call to the parent's method automatically during the std::move
-    // function call(https://en.cppreference.com/w/cpp/algorithm/move) in certain compilers like
-    // NDK 25.1.8937393 and below (see b/371980551)
-    Handle& operator=(Handle const& rhs) noexcept {
-        HandleBase::operator=(rhs);
-        return *this;
-    }
-    Handle& operator=(Handle&& rhs) noexcept {
-        HandleBase::operator=(std::move(rhs));
-        return *this;
-    }
+    Handle& operator=(Handle const& rhs) noexcept = default;
+    Handle& operator=(Handle&& rhs) noexcept = default;

    explicit Handle(HandleId id) noexcept : HandleBase(id) { }

@@ -143,21 +130,19 @@ private:

 // Types used by the command stream
 // (we use this renaming because the macro-system doesn't deal well with "<" and ">")
-using BufferObjectHandle        = Handle<HwBufferObject>;
-using FenceHandle               = Handle<HwFence>;
-using IndexBufferHandle         = Handle<HwIndexBuffer>;
-using ProgramHandle             = Handle<HwProgram>;
-using RenderPrimitiveHandle     = Handle<HwRenderPrimitive>;
-using RenderTargetHandle        = Handle<HwRenderTarget>;
-using SamplerGroupHandle        = Handle<HwSamplerGroup>;
-using StreamHandle              = Handle<HwStream>;
-using SwapChainHandle           = Handle<HwSwapChain>;
-using TextureHandle             = Handle<HwTexture>;
-using TimerQueryHandle          = Handle<HwTimerQuery>;
-using VertexBufferHandle        = Handle<HwVertexBuffer>;
-using VertexBufferInfoHandle    = Handle<HwVertexBufferInfo>;
-using DescriptorSetLayoutHandle = Handle<HwDescriptorSetLayout>;
-using DescriptorSetHandle       = Handle<HwDescriptorSet>;
+using BufferObjectHandle     = Handle<HwBufferObject>;
+using FenceHandle            = Handle<HwFence>;
+using IndexBufferHandle      = Handle<HwIndexBuffer>;
+using ProgramHandle          = Handle<HwProgram>;
+using RenderPrimitiveHandle  = Handle<HwRenderPrimitive>;
+using RenderTargetHandle     = Handle<HwRenderTarget>;
+using SamplerGroupHandle     = Handle<HwSamplerGroup>;
+using StreamHandle           = Handle<HwStream>;
+using SwapChainHandle        = Handle<HwSwapChain>;
+using TextureHandle          = Handle<HwTexture>;
+using TimerQueryHandle       = Handle<HwTimerQuery>;
+using VertexBufferHandle     = Handle<HwVertexBuffer>;
+using VertexBufferInfoHandle = Handle<HwVertexBufferInfo>;

 } // namespace filament::backend

@@ -22,23 +22,15 @@

 #include <utils/ostream.h>

-#include <array>
-
 #include <stdint.h>

 namespace filament::backend {

 //! \privatesection

-struct PipelineLayout {
-    using SetLayout = std::array<Handle<HwDescriptorSetLayout>, MAX_DESCRIPTOR_SET_COUNT>;
-    SetLayout setLayout;      // 16
-};
-
 struct PipelineState {
    Handle<HwProgram> program;                                              //  4
    Handle<HwVertexBufferInfo> vertexBufferInfo;                            //  4
-    PipelineLayout pipelineLayout;                                          // 16
    RasterState rasterState;                                                //  4
    StencilState stencilState;                                              // 12
    PolygonOffset polygonOffset;                                            //  8
@@ -68,6 +68,13 @@ public:
         */
        size_t handleArenaSize = 0;

+        /**
+         * This number of most-recently destroyed textures will be tracked for use-after-free.
+         * Throws an exception when a texture is freed but still bound to a SamplerGroup and used in
+         * a draw call. 0 disables completely. Currently only respected by the Metal backend.
+         */
+        size_t textureUseAfterFreePoolSize = 0;
+
        size_t metalUploadBufferSizeBytes = 512 * 1024;

        /**
@@ -91,13 +98,6 @@ public:
         * Sets the technique for stereoscopic rendering.
         */
        StereoscopicType stereoscopicType = StereoscopicType::NONE;
-
-        /**
-         * Assert the native window associated to a SwapChain is valid when calling makeCurrent().
-         * This is only supported for:
-         *      - PlatformEGLAndroid
-         */
-        bool assertNativeWindowIsValid = false;
    };

    Platform() noexcept;
@@ -24,11 +24,9 @@

 #include <backend/DriverEnums.h>

-#include <array>
-#include <unordered_map>
-#include <tuple>
-#include <utility>
-#include <variant>
+#include <array>    // FIXME: STL headers are not allowed in public headers
+#include <utility>  // FIXME: STL headers are not allowed in public headers
+#include <variant>  // FIXME: STL headers are not allowed in public headers

 #include <stddef.h>
 #include <stdint.h>
@@ -42,36 +40,29 @@ public:
    static constexpr size_t UNIFORM_BINDING_COUNT = CONFIG_UNIFORM_BINDING_COUNT;
    static constexpr size_t SAMPLER_BINDING_COUNT = CONFIG_SAMPLER_BINDING_COUNT;

-    struct Descriptor {
-        utils::CString name;
-        backend::DescriptorType type;
-        backend::descriptor_binding_t binding;
+    struct Sampler {
+        utils::CString name = {};   // name of the sampler in the shader
+        uint32_t binding = 0;       // binding point of the sampler in the shader
    };

-    struct SpecializationConstant {
-        using Type = std::variant<int32_t, float, bool>;
-        uint32_t id;    // id set in glsl
-        Type value;     // value and type
+    struct SamplerGroupData {
+        utils::FixedCapacityVector<Sampler> samplers;
+        ShaderStageFlags stageFlags = ShaderStageFlags::ALL_SHADER_STAGE_FLAGS;
    };

-    struct Uniform { // For ES2 support
+    struct Uniform {
        utils::CString name;    // full qualified name of the uniform field
        uint16_t offset;        // offset in 'uint32_t' into the uniform buffer
        uint8_t size;           // >1 for arrays
        UniformType type;       // uniform type
    };

-    using DescriptorBindingsInfo = utils::FixedCapacityVector<Descriptor>;
-    using DescriptorSetInfo = std::array<DescriptorBindingsInfo, MAX_DESCRIPTOR_SET_COUNT>;
-    using SpecializationConstantsInfo = utils::FixedCapacityVector<SpecializationConstant>;
+    using UniformBlockInfo = std::array<utils::CString, UNIFORM_BINDING_COUNT>;
+    using UniformInfo = utils::FixedCapacityVector<Uniform>;
+    using SamplerGroupInfo = std::array<SamplerGroupData, SAMPLER_BINDING_COUNT>;
    using ShaderBlob = utils::FixedCapacityVector<uint8_t>;
    using ShaderSource = std::array<ShaderBlob, SHADER_TYPE_COUNT>;

-    using AttributesInfo = utils::FixedCapacityVector<std::pair<utils::CString, uint8_t>>;
-    using UniformInfo = utils::FixedCapacityVector<Uniform>;
-    using BindingUniformsInfo = utils::FixedCapacityVector<
-            std::tuple<uint8_t, utils::CString, Program::UniformInfo>>;
-
    Program() noexcept;

    Program(const Program& rhs) = delete;
@@ -88,19 +79,43 @@ public:
    Program& diagnostics(utils::CString const& name,
            utils::Invocable<utils::io::ostream&(utils::io::ostream& out)>&& logger);

-    // Sets one of the program's shader (e.g. vertex, fragment)
+    // sets one of the program's shader (e.g. vertex, fragment)
    // string-based shaders are null terminated, consequently the size parameter must include the
    // null terminating character.
    Program& shader(ShaderStage shader, void const* data, size_t size);

-    // Sets the language of the shader sources provided with shader() (defaults to ESSL3)
+    // sets the language of the shader sources provided with shader() (defaults to ESSL3)
    Program& shaderLanguage(ShaderLanguage shaderLanguage);

-    // Descriptor binding (set, binding, type -> shader name) info
-    Program& descriptorBindings(backend::descriptor_set_t set,
-            DescriptorBindingsInfo descriptorBindings) noexcept;
+    // Note: This is only needed for GLES3.0 backends, because the layout(binding=) syntax is
+    //       not permitted in glsl. The backend needs a way to associate a uniform block
+    //       to a binding point.
+    Program& uniformBlockBindings(
+            utils::FixedCapacityVector<std::pair<utils::CString, uint8_t>> const& uniformBlockBindings) noexcept;

-    Program& specializationConstants(SpecializationConstantsInfo specConstants) noexcept;
+    // Note: This is only needed for GLES2.0, this is used to emulate UBO. This function tells
+    // the program everything it needs to know about the uniforms at a given binding
+    Program& uniforms(uint32_t index, UniformInfo const& uniforms) noexcept;
+
+    // Note: This is only needed for GLES2.0.
+    Program& attributes(
+            utils::FixedCapacityVector<std::pair<utils::CString, uint8_t>> attributes) noexcept;
+
+    // sets the 'bindingPoint' sampler group descriptor for this program.
+    // 'samplers' can be destroyed after this call.
+    // This effectively associates a set of (BindingPoints, index) to a texture unit in the shader.
+    // Or more precisely, what layout(binding=) is set to in GLSL.
+    Program& setSamplerGroup(size_t bindingPoint, ShaderStageFlags stageFlags,
+            Sampler const* samplers, size_t count) noexcept;
+
+    struct SpecializationConstant {
+        using Type = std::variant<int32_t, float, bool>;
+        uint32_t id;                                // id set in glsl
+        Type value;                                 // value and type
+    };
+
+    Program& specializationConstants(
+            utils::FixedCapacityVector<SpecializationConstant> specConstants) noexcept;

    struct PushConstant {
        utils::CString name;
@@ -114,40 +129,33 @@ public:

    Program& multiview(bool multiview) noexcept;

-    // For ES2 support only...
-    Program& uniforms(uint32_t index, utils::CString name, UniformInfo uniforms) noexcept;
-    Program& attributes(AttributesInfo attributes) noexcept;
-
-    //
-    // Getters for program construction...
-    //
-
    ShaderSource const& getShadersSource() const noexcept { return mShadersSource; }
    ShaderSource& getShadersSource() noexcept { return mShadersSource; }

+    UniformBlockInfo const& getUniformBlockBindings() const noexcept { return mUniformBlocks; }
+    UniformBlockInfo& getUniformBlockBindings() noexcept { return mUniformBlocks; }
+
+    SamplerGroupInfo const& getSamplerGroupInfo() const { return mSamplerGroups; }
+    SamplerGroupInfo& getSamplerGroupInfo() { return mSamplerGroups; }
+
+    auto const& getBindingUniformInfo() const { return mBindingUniformInfo; }
+    auto& getBindingUniformInfo() { return mBindingUniformInfo; }
+
+    auto const& getAttributes() const { return mAttributes; }
+    auto& getAttributes() { return mAttributes; }
+
    utils::CString const& getName() const noexcept { return mName; }
    utils::CString& getName() noexcept { return mName; }

    auto const& getShaderLanguage() const { return mShaderLanguage; }

-    uint64_t getCacheId() const noexcept { return mCacheId; }
-
-    bool isMultiview() const noexcept { return mMultiview; }
-
-    CompilerPriorityQueue getPriorityQueue() const noexcept { return mPriorityQueue; }
-
-    SpecializationConstantsInfo const& getSpecializationConstants() const noexcept {
+    utils::FixedCapacityVector<SpecializationConstant> const& getSpecializationConstants() const noexcept {
        return mSpecializationConstants;
    }
-
-    SpecializationConstantsInfo& getSpecializationConstants() noexcept {
+    utils::FixedCapacityVector<SpecializationConstant>& getSpecializationConstants() noexcept {
        return mSpecializationConstants;
    }

-    DescriptorSetInfo& getDescriptorBindings() noexcept {
-        return mDescriptorBindings;
-    }
-
    utils::FixedCapacityVector<PushConstant> const& getPushConstants(
            ShaderStage stage) const noexcept {
        return mPushConstants[static_cast<uint8_t>(stage)];
@@ -157,29 +165,27 @@ public:
        return mPushConstants[static_cast<uint8_t>(stage)];
    }

-    auto const& getBindingUniformInfo() const { return mBindingUniformsInfo; }
-    auto& getBindingUniformInfo() { return mBindingUniformsInfo; }
+    uint64_t getCacheId() const noexcept { return mCacheId; }

-    auto const& getAttributes() const { return mAttributes; }
-    auto& getAttributes() { return mAttributes; }
+    bool isMultiview() const noexcept { return mMultiview; }
+
+    CompilerPriorityQueue getPriorityQueue() const noexcept { return mPriorityQueue; }

 private:
    friend utils::io::ostream& operator<<(utils::io::ostream& out, const Program& builder);

+    UniformBlockInfo mUniformBlocks = {};
+    SamplerGroupInfo mSamplerGroups = {};
    ShaderSource mShadersSource;
    ShaderLanguage mShaderLanguage = ShaderLanguage::ESSL3;
    utils::CString mName;
    uint64_t mCacheId{};
-    CompilerPriorityQueue mPriorityQueue = CompilerPriorityQueue::HIGH;
    utils::Invocable<utils::io::ostream&(utils::io::ostream& out)> mLogger;
-    SpecializationConstantsInfo mSpecializationConstants;
+    utils::FixedCapacityVector<SpecializationConstant> mSpecializationConstants;
    std::array<utils::FixedCapacityVector<PushConstant>, SHADER_TYPE_COUNT> mPushConstants;
-    DescriptorSetInfo mDescriptorBindings;
-
-    // For ES2 support only
-    AttributesInfo mAttributes;
-    BindingUniformsInfo mBindingUniformsInfo;
-
+    utils::FixedCapacityVector<std::pair<utils::CString, uint8_t>> mAttributes;
+    std::array<UniformInfo, Program::UNIFORM_BINDING_COUNT> mBindingUniformInfo;
+    CompilerPriorityQueue mPriorityQueue = CompilerPriorityQueue::HIGH;
    // Indicates the current engine was initialized with multiview stereo, and the variant for this
    // program contains STE flag. This will be referred later for the OpenGL shader compiler to
    // determine whether shader code replacement for the num_views should be performed.
@@ -30,6 +30,10 @@ namespace filament::backend {

 struct TargetBufferInfo {
    // note: the parameters of this constructor are not in the order of this structure's fields
+    TargetBufferInfo(Handle<HwTexture> handle, uint8_t level, uint16_t layer, uint8_t baseViewIndex) noexcept
+        : handle(handle), baseViewIndex(baseViewIndex), level(level), layer(layer) {
+    }
+
    TargetBufferInfo(Handle<HwTexture> handle, uint8_t level, uint16_t layer) noexcept
            : handle(handle), level(level), layer(layer) {
    }
@@ -47,15 +51,14 @@ struct TargetBufferInfo {
    // texture to be used as render target
    Handle<HwTexture> handle;

+    // Starting layer index for multiview. This value is only used when the `layerCount` for the
+    // render target is greater than 1.
+    uint8_t baseViewIndex = 0;
+
    // level to be used
    uint8_t level = 0;

-    // - For cubemap textures, this indicates the face of the cubemap. See TextureCubemapFace for
-    //   the face->layer mapping)
-    // - For 2d array, cubemap array, and 3d textures, this indicates an index of a single layer of
-    //   them.
-    // - For multiview textures (i.e., layerCount for the RenderTarget is greater than 1), this
-    //   indicates a starting layer index of the current 2d array texture for multiview.
+    // For cubemaps and 3D textures. See TextureCubemapFace for the face->layer mapping
    uint16_t layer = 0;
 };

@@ -100,7 +103,7 @@ public:

    // this is here for backward compatibility
    MRT(Handle<HwTexture> handle, uint8_t level, uint16_t layer) noexcept
-            : mInfos{{ handle, level, layer }} {
+            : mInfos{{ handle, level, layer, 0 }} {
    }
 };

@@ -89,11 +89,6 @@ protected:
     */
    AcquiredImage transformAcquiredImage(AcquiredImage source) noexcept override;

-protected:
-    bool makeCurrent(ContextType type,
-            SwapChain* drawSwapChain,
-            SwapChain* readSwapChain) noexcept override;
-
 private:
    struct InitializeJvmForPerformanceManagerIfNeeded {
        InitializeJvmForPerformanceManagerIfNeeded();
@@ -107,10 +102,6 @@ private:

    using clock = std::chrono::high_resolution_clock;
    clock::time_point mStartTimeOfActualWork;
-
-    void* mNativeWindowLib = nullptr;
-    int32_t (*ANativeWindow_getBuffersDefaultDataSpace)(ANativeWindow* window) = nullptr;
-    bool mAssertNativeWindowIsValid = false;
 };

 } // namespace filament::backend
@@ -1,64 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_OPENGL_OPENGL_PLATFORM_OSMESA_H
-#define TNT_FILAMENT_BACKEND_OPENGL_OPENGL_PLATFORM_OSMESA_H
-
-#include <stdint.h>
-
-#include "bluegl/BlueGL.h"
-
-#include <osmesa.h>
-
-#include <backend/platforms/OpenGLPlatform.h>
-#include <backend/DriverEnums.h>
-
-namespace filament::backend {
-
-/**
- * A concrete implementation of OpenGLPlatform that uses OSMesa, which is an offscreen
- * context that can be used in conjunction with Mesa for software rasterization.
- * See https://docs.mesa3d.org/osmesa.html for more information.
- */
-class PlatformOSMesa : public OpenGLPlatform {
-protected:
-    // --------------------------------------------------------------------------------------------
-    // Platform Interface
-
-    Driver* createDriver(void* sharedGLContext, const DriverConfig& driverConfig) noexcept override;
-
-    int getOSVersion() const noexcept final override { return 0; }
-
-    // --------------------------------------------------------------------------------------------
-    // OpenGLPlatform Interface
-
-    void terminate() noexcept override;
-
-    SwapChain* createSwapChain(void* nativewindow, uint64_t flags) noexcept override;
-    SwapChain* createSwapChain(uint32_t width, uint32_t height, uint64_t flags) noexcept override;
-    void destroySwapChain(SwapChain* swapChain) noexcept override;
-    bool makeCurrent(ContextType type, SwapChain* drawSwapChain,
-            SwapChain* readSwapChain) noexcept override;
-    void commit(SwapChain* swapChain) noexcept override;
-
-private:
-    OSMesaContext mContext;
-    void* mOsMesaApi = nullptr;
-};
-
-} // namespace filament::backend
-
-#endif // TNT_FILAMENT_BACKEND_OPENGL_OPENGL_PLATFORM_OSMESA_H
@@ -18,7 +18,6 @@
 #define TNT_FILAMENT_BACKEND_PRIVATE_DRIVER_H

 #include <backend/CallbackHandler.h>
-#include <backend/DescriptorSetOffsetArray.h>
 #include <backend/DriverApiForward.h>
 #include <backend/DriverEnums.h>
 #include <backend/Handle.h>
@@ -139,8 +139,7 @@ DECL_DRIVER_API_N(beginFrame,
 DECL_DRIVER_API_N(setFrameScheduledCallback,
        backend::SwapChainHandle, sch,
        backend::CallbackHandler*, handler,
-        backend::FrameScheduledCallback&&, callback,
-        uint64_t, flags)
+        backend::FrameScheduledCallback&&, callback)

 DECL_DRIVER_API_N(setFrameCompletedCallback,
        backend::SwapChainHandle, sch,
@@ -201,33 +200,20 @@ DECL_DRIVER_API_R_N(backend::TextureHandle, createTexture,
        uint32_t, depth,
        backend::TextureUsage, usage)

-DECL_DRIVER_API_R_N(backend::TextureHandle, createTextureView,
-        backend::TextureHandle, texture,
-        uint8_t, baseLevel,
-        uint8_t, levelCount)
-
-DECL_DRIVER_API_R_N(backend::TextureHandle, createTextureViewSwizzle,
-        backend::TextureHandle, texture,
+DECL_DRIVER_API_R_N(backend::TextureHandle, createTextureSwizzled,
+        backend::SamplerType, target,
+        uint8_t, levels,
+        backend::TextureFormat, format,
+        uint8_t, samples,
+        uint32_t, width,
+        uint32_t, height,
+        uint32_t, depth,
+        backend::TextureUsage, usage,
        backend::TextureSwizzle, r,
        backend::TextureSwizzle, g,
        backend::TextureSwizzle, b,
        backend::TextureSwizzle, a)

-DECL_DRIVER_API_R_N(backend::TextureHandle, createTextureExternalImage,
-        backend::TextureFormat, format,
-        uint32_t, width,
-        uint32_t, height,
-        backend::TextureUsage, usage,
-        void*, image)
-
-DECL_DRIVER_API_R_N(backend::TextureHandle, createTextureExternalImagePlane,
-        backend::TextureFormat, format,
-        uint32_t, width,
-        uint32_t, height,
-        backend::TextureUsage, usage,
-        void*, image,
-        uint32_t, plane)
-
 DECL_DRIVER_API_R_N(backend::TextureHandle, importTexture,
        intptr_t, id,
        backend::SamplerType, target,
@@ -239,6 +225,9 @@ DECL_DRIVER_API_R_N(backend::TextureHandle, importTexture,
        uint32_t, depth,
        backend::TextureUsage, usage)

+DECL_DRIVER_API_R_N(backend::SamplerGroupHandle, createSamplerGroup,
+        uint32_t, size, utils::FixedSizeString<32>, debugName)
+
 DECL_DRIVER_API_R_N(backend::RenderPrimitiveHandle, createRenderPrimitive,
        backend::VertexBufferHandle, vbh,
        backend::IndexBufferHandle, ibh,
@@ -272,53 +261,25 @@ DECL_DRIVER_API_R_N(backend::SwapChainHandle, createSwapChainHeadless,

 DECL_DRIVER_API_R_0(backend::TimerQueryHandle, createTimerQuery)

-DECL_DRIVER_API_R_N(backend::DescriptorSetLayoutHandle, createDescriptorSetLayout,
-        backend::DescriptorSetLayout&&, info)
-
-DECL_DRIVER_API_R_N(backend::DescriptorSetHandle, createDescriptorSet,
-        backend::DescriptorSetLayoutHandle, dslh)
-
-DECL_DRIVER_API_N(updateDescriptorSetBuffer,
-        backend::DescriptorSetHandle, dsh,
-        backend::descriptor_binding_t, binding,
-        backend::BufferObjectHandle, boh,
-        uint32_t, offset,
-        uint32_t, size
-)
-
-DECL_DRIVER_API_N(updateDescriptorSetTexture,
-        backend::DescriptorSetHandle, dsh,
-        backend::descriptor_binding_t, binding,
-        backend::TextureHandle, th,
-        SamplerParams, params
-)
-
-DECL_DRIVER_API_N(bindDescriptorSet,
-        backend::DescriptorSetHandle, dsh,
-        backend::descriptor_set_t, set,
-        backend::DescriptorSetOffsetArray&&, offsets
-)
-

 /*
 * Destroying driver objects
 * -------------------------
 */

-DECL_DRIVER_API_N(destroyVertexBuffer,          backend::VertexBufferHandle, vbh)
-DECL_DRIVER_API_N(destroyVertexBufferInfo,      backend::VertexBufferInfoHandle, vbih)
-DECL_DRIVER_API_N(destroyIndexBuffer,           backend::IndexBufferHandle, ibh)
-DECL_DRIVER_API_N(destroyBufferObject,          backend::BufferObjectHandle, ibh)
-DECL_DRIVER_API_N(destroyRenderPrimitive,       backend::RenderPrimitiveHandle, rph)
-DECL_DRIVER_API_N(destroyProgram,               backend::ProgramHandle, ph)
-DECL_DRIVER_API_N(destroyTexture,               backend::TextureHandle, th)
-DECL_DRIVER_API_N(destroyRenderTarget,          backend::RenderTargetHandle, rth)
-DECL_DRIVER_API_N(destroySwapChain,             backend::SwapChainHandle, sch)
-DECL_DRIVER_API_N(destroyStream,                backend::StreamHandle, sh)
-DECL_DRIVER_API_N(destroyTimerQuery,            backend::TimerQueryHandle, sh)
-DECL_DRIVER_API_N(destroyFence,                 backend::FenceHandle, fh)
-DECL_DRIVER_API_N(destroyDescriptorSetLayout,   backend::DescriptorSetLayoutHandle, dslh)
-DECL_DRIVER_API_N(destroyDescriptorSet,         backend::DescriptorSetHandle, dsh)
+DECL_DRIVER_API_N(destroyVertexBuffer,    backend::VertexBufferHandle, vbh)
+DECL_DRIVER_API_N(destroyVertexBufferInfo,backend::VertexBufferInfoHandle, vbih)
+DECL_DRIVER_API_N(destroyIndexBuffer,     backend::IndexBufferHandle, ibh)
+DECL_DRIVER_API_N(destroyBufferObject,    backend::BufferObjectHandle, ibh)
+DECL_DRIVER_API_N(destroyRenderPrimitive, backend::RenderPrimitiveHandle, rph)
+DECL_DRIVER_API_N(destroyProgram,         backend::ProgramHandle, ph)
+DECL_DRIVER_API_N(destroySamplerGroup,    backend::SamplerGroupHandle, sbh)
+DECL_DRIVER_API_N(destroyTexture,         backend::TextureHandle, th)
+DECL_DRIVER_API_N(destroyRenderTarget,    backend::RenderTargetHandle, rth)
+DECL_DRIVER_API_N(destroySwapChain,       backend::SwapChainHandle, sch)
+DECL_DRIVER_API_N(destroyStream,          backend::StreamHandle, sh)
+DECL_DRIVER_API_N(destroyTimerQuery,      backend::TimerQueryHandle, sh)
+DECL_DRIVER_API_N(destroyFence,           backend::FenceHandle, fh)

 /*
 * Synchronous APIs
@@ -385,6 +346,15 @@ DECL_DRIVER_API_N(updateBufferObjectUnsynchronized,
 DECL_DRIVER_API_N(resetBufferObject,
        backend::BufferObjectHandle, ibh)

+DECL_DRIVER_API_N(updateSamplerGroup,
+        backend::SamplerGroupHandle, ubh,
+        backend::BufferDescriptor&&, data)
+
+DECL_DRIVER_API_N(setMinMaxLevels,
+        backend::TextureHandle, th,
+        uint32_t, minLevel,
+        uint32_t, maxLevel)
+
 DECL_DRIVER_API_N(update3DImage,
        backend::TextureHandle, th,
        uint32_t, level,
@@ -399,12 +369,10 @@ DECL_DRIVER_API_N(update3DImage,
 DECL_DRIVER_API_N(generateMipmaps,
        backend::TextureHandle, th)

-// Deprecated
 DECL_DRIVER_API_N(setExternalImage,
        backend::TextureHandle, th,
        void*, image)

-// Deprecated
 DECL_DRIVER_API_N(setExternalImagePlane,
        backend::TextureHandle, th,
        void*, image,
@@ -451,6 +419,25 @@ DECL_DRIVER_API_N(commit,
 * -----------------------
 */

+DECL_DRIVER_API_N(bindUniformBuffer,
+        uint32_t, index,
+        backend::BufferObjectHandle, ubh)
+
+DECL_DRIVER_API_N(bindBufferRange,
+        BufferObjectBinding, bindingType,
+        uint32_t, index,
+        backend::BufferObjectHandle, ubh,
+        uint32_t, offset,
+        uint32_t, size)
+
+DECL_DRIVER_API_N(unbindBuffer,
+        BufferObjectBinding, bindingType,
+        uint32_t, index)
+
+DECL_DRIVER_API_N(bindSamplers,
+        uint32_t, index,
+        backend::SamplerGroupHandle, sbh)
+
 DECL_DRIVER_API_N(setPushConstant,
        backend::ShaderStage, stage,
        uint8_t, index,
@@ -18,17 +18,6 @@
 #define TNT_FILAMENT_BACKEND_PRIVATE_DRIVERAPI_H

 #include "backend/DriverApiForward.h"
-
 #include "private/backend/CommandStream.h"

-#include <stddef.h>
-
-namespace filament::backend {
-
-inline void* allocateFromCommandStream(DriverApi& driver, size_t size, size_t alignment) noexcept {
-    return driver.allocate(size, alignment);
-}
-
-} // namespace filament::backend
-
 #endif // TNT_FILAMENT_BACKEND_PRIVATE_DRIVERAPI_H
@@ -38,7 +38,7 @@
 #include <stddef.h>
 #include <stdint.h>

-#define HandleAllocatorGL  HandleAllocator<32,  96, 136>    // ~4520 / pool / MiB
+#define HandleAllocatorGL  HandleAllocator<32,  64, 136>    // ~4520 / pool / MiB
 #define HandleAllocatorVK  HandleAllocator<64, 160, 312>    // ~1820 / pool / MiB
 #define HandleAllocatorMTL HandleAllocator<32,  64, 552>    // ~1660 / pool / MiB

@@ -169,7 +169,7 @@ public:
        auto [p, tag] = handleToPointer(handle.getId());

        if (isPoolHandle(handle.getId())) {
-            // check for pool handle use-after-free
+            // check for use after free
            if (UTILS_UNLIKELY(!mUseAfterFreeCheckDisabled)) {
                uint8_t const age = (tag & HANDLE_AGE_MASK) >> HANDLE_AGE_SHIFT;
                auto const pNode = static_cast<typename Allocator::Node*>(p);
@@ -179,22 +179,6 @@ public:
                        << "use-after-free of Handle with id=" << handle.getId()
                        << ", tag=" << getHandleTag(handle.getId()).c_str_safe();
            }
-        } else {
-            // check for heap handle use-after-free
-            if (UTILS_UNLIKELY(!mUseAfterFreeCheckDisabled)) {
-                uint8_t const index = (handle.getId() & HANDLE_INDEX_MASK);
-                // if we've already handed out this handle index before, it's definitely a
-                // use-after-free, otherwise it's probably just a corrupted handle
-                if (index < mId) {
-                    FILAMENT_CHECK_POSTCONDITION(p != nullptr)
-                            << "use-after-free of heap Handle with id=" << handle.getId()
-                            << ", tag=" << getHandleTag(handle.getId()).c_str_safe();
-                } else {
-                    FILAMENT_CHECK_POSTCONDITION(p != nullptr)
-                            << "corrupted heap Handle with id=" << handle.getId()
-                            << ", tag=" << getHandleTag(handle.getId()).c_str_safe();
-                }
-            }
        }

        return static_cast<Dp>(p);
@@ -202,18 +186,14 @@ public:

    template<typename B>
    bool is_valid(Handle<B>& handle) {
-        if (!handle) {
-            // null handles are invalid
-            return false;
-        }
-        auto [p, tag] = handleToPointer(handle.getId());
-        if (isPoolHandle(handle.getId())) {
+        if (handle && isPoolHandle(handle.getId())) {
+            auto [p, tag] = handleToPointer(handle.getId());
            uint8_t const age = (tag & HANDLE_AGE_MASK) >> HANDLE_AGE_SHIFT;
            auto const pNode = static_cast<typename Allocator::Node*>(p);
            uint8_t const expectedAge = pNode[-1].age;
            return expectedAge == age;
        }
-        return p != nullptr;
+        return true;
    }

    template<typename Dp, typename B>
@@ -20,16 +20,11 @@
 #include <utils/CallStack.h>
 #endif

-#include <utils/compiler.h>
 #include <utils/Log.h>
-#include <utils/ostream.h>
 #include <utils/Profiler.h>
 #include <utils/Systrace.h>

-#include <cstddef>
 #include <functional>
-#include <string>
-#include <utility>

 #ifdef __ANDROID__
 #include <sys/system_properties.h>
@@ -79,8 +74,8 @@ CommandStream::CommandStream(Driver& driver, CircularBuffer& buffer) noexcept
 }

 void CommandStream::execute(void* buffer) {
-    // NOTE: we can't use SYSTRACE_CALL() or similar here because, execute() below, also
-    // uses systrace BEGIN/END and the END is not guaranteed to be happening in this scope.
+    SYSTRACE_CALL();
+    SYSTRACE_CONTEXT();

    Profiler profiler;

@@ -105,7 +100,6 @@ void CommandStream::execute(void* buffer) {
            // we want to remove all this when tracing is completely disabled
            profiler.stop();
            UTILS_UNUSED Profiler::Counters const counters = profiler.readCounters();
-            SYSTRACE_CONTEXT();
            SYSTRACE_VALUE32("GLThread (I)", counters.getInstructions());
            SYSTRACE_VALUE32("GLThread (C)", counters.getCpuCycles());
            SYSTRACE_VALUE32("GLThread (CPI x10)", counters.getCPI() * 10);
@@ -101,14 +101,6 @@ struct HwProgram : public HwBase {
    HwProgram() noexcept = default;
 };

-struct HwDescriptorSetLayout : public HwBase {
-    HwDescriptorSetLayout() noexcept = default;
-};
-
-struct HwDescriptorSet : public HwBase {
-    HwDescriptorSet() noexcept = default;
-};
-
 struct HwSamplerGroup : public HwBase {
    HwSamplerGroup() noexcept = default;
 };
@@ -41,10 +41,6 @@
        #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3)
            #include "backend/platforms/PlatformEGLHeadless.h"
        #endif
-    #elif defined(FILAMENT_SUPPORTS_OSMESA)
-        #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3)
-            #include "backend/platforms/PlatformOSMesa.h"
-        #endif
    #endif
 #elif defined(WIN32)
    #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3)
@@ -128,8 +124,6 @@ Platform* PlatformFactory::create(Backend* backend) noexcept {
                return new PlatformGLX();
            #elif defined(FILAMENT_SUPPORTS_EGL_ON_LINUX)
                return new PlatformEGLHeadless();
-            #elif defined(FILAMENT_SUPPORTS_OSMESA)
-                return new PlatformOSMesa();
            #else
                return nullptr;
            #endif
@@ -14,18 +14,7 @@
 * limitations under the License.
 */

-#include <backend/Program.h>
-#include <backend/DriverEnums.h>
-
-#include <utils/debug.h>
-#include <utils/CString.h>
-#include <utils/ostream.h>
-#include <utils/Invocable.h>
-
-#include <utility>
-
-#include <stddef.h>
-#include <stdint.h>
+#include "backend/Program.h"

 namespace filament::backend {

@@ -63,24 +52,41 @@ Program& Program::shaderLanguage(ShaderLanguage shaderLanguage) {
    return *this;
 }

-Program& Program::descriptorBindings(backend::descriptor_set_t set,
-        DescriptorBindingsInfo descriptorBindings) noexcept {
-    mDescriptorBindings[set] = std::move(descriptorBindings);
+Program& Program::uniformBlockBindings(
+        FixedCapacityVector<std::pair<utils::CString, uint8_t>> const& uniformBlockBindings) noexcept {
+    for (auto const& item : uniformBlockBindings) {
+        assert_invariant(item.second < UNIFORM_BINDING_COUNT);
+        mUniformBlocks[item.second] = item.first;
+    }
    return *this;
 }

-Program& Program::uniforms(uint32_t index, utils::CString name, UniformInfo uniforms) noexcept {
-    mBindingUniformsInfo.reserve(mBindingUniformsInfo.capacity() + 1);
-    mBindingUniformsInfo.emplace_back(index, std::move(name), std::move(uniforms));
+Program& Program::uniforms(uint32_t index, UniformInfo const& uniforms) noexcept {
+    assert_invariant(index < UNIFORM_BINDING_COUNT);
+    mBindingUniformInfo[index] = uniforms;
    return *this;
 }

-Program& Program::attributes(AttributesInfo attributes) noexcept {
+
+Program& Program::attributes(
+        utils::FixedCapacityVector<std::pair<utils::CString, uint8_t>> attributes) noexcept {
    mAttributes = std::move(attributes);
    return *this;
 }

-Program& Program::specializationConstants(SpecializationConstantsInfo specConstants) noexcept {
+Program& Program::setSamplerGroup(size_t bindingPoint, ShaderStageFlags stageFlags,
+        const Program::Sampler* samplers, size_t count) noexcept {
+    auto& groupData = mSamplerGroups[bindingPoint];
+    groupData.stageFlags = stageFlags;
+    auto& samplerList = groupData.samplers;
+    samplerList.reserve(count);
+    samplerList.resize(count);
+    std::copy_n(samplers, count, samplerList.data());
+    return *this;
+}
+
+Program& Program::specializationConstants(
+        FixedCapacityVector<SpecializationConstant> specConstants) noexcept {
    mSpecializationConstants = std::move(specConstants);
    return *this;
 }
@@ -73,11 +73,10 @@ public:
    enum class Type {
        NONE = 0,
        GENERIC = 1,
-        RING = 2,       // deprecated
+        RING = 2,
        STAGING = 3,
-        DESCRIPTOR_SET = 4,
    };
-    static constexpr size_t TypeCount = 4;
+    static constexpr size_t TypeCount = 3;

    static constexpr auto toIndex(Type t) {
        assert_invariant(t != Type::NONE);
@@ -89,8 +88,6 @@ public:
                return 1;
            case Type::STAGING:
                return 2;
-            case Type::DESCRIPTOR_SET:
-                return 3;
        }
    }

@@ -174,10 +171,8 @@ public:
     * Update the buffer with data inside src. Potentially allocates a new buffer allocation to hold
     * the bytes which will be released when the current frame is finished.
     */
-    using TagResolver = utils::Invocable<const char*(void)>;
-    void copyIntoBuffer(void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag);
-    void copyIntoBufferUnsynchronized(
-            void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag);
+    void copyIntoBuffer(void* src, size_t size, size_t byteOffset);
+    void copyIntoBufferUnsynchronized(void* src, size_t size, size_t byteOffset);

    /**
     * Denotes that this buffer is used for a draw call ensuring that its allocation remains valid
@@ -187,7 +182,7 @@ public:
     * is no device allocation.
     *
     */
-    id<MTLBuffer> getGpuBufferForDraw() noexcept;
+    id<MTLBuffer> getGpuBufferForDraw(id<MTLCommandBuffer> cmdBuffer) noexcept;

    void* getCpuBuffer() const noexcept { return mCpuBuffer; }

@@ -216,10 +211,8 @@ private:
        BUMP_ALLOCATOR,
    };

-    void uploadWithPoolBuffer(
-            void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag) const;
-    void uploadWithBumpAllocator(
-            void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag) const;
+    void uploadWithPoolBuffer(void* src, size_t size, size_t byteOffset) const;
+    void uploadWithBumpAllocator(void* src, size_t size, size_t byteOffset) const;

    UploadStrategy mUploadStrategy;
    TrackedMetalBuffer mBuffer;
@@ -40,15 +40,12 @@ MetalBuffer::MetalBuffer(MetalContext& context, BufferObjectBinding bindingType,
    // If the buffer is less than 4K in size and is updated frequently, we don't use an explicit
    // buffer. Instead, we use immediate command encoder methods like setVertexBytes:length:atIndex:.
    // This won't work for SSBOs, since they are read/write.
-
-    /*
    if (size <= 4 * 1024 && bindingType != BufferObjectBinding::SHADER_STORAGE &&
            usage == BufferUsage::DYNAMIC && !forceGpuBuffer) {
        mBuffer = nil;
        mCpuBuffer = malloc(size);
        return;
    }
-    */

    // Otherwise, we allocate a private GPU buffer.
    {
@@ -66,20 +63,15 @@ MetalBuffer::~MetalBuffer() {
    }
 }

-void MetalBuffer::copyIntoBuffer(
-        void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag) {
+void MetalBuffer::copyIntoBuffer(void* src, size_t size, size_t byteOffset) {
    if (size <= 0) {
        return;
    }
-
-    FILAMENT_CHECK_PRECONDITION(src)
-            << "copyIntoBuffer called with a null src, tag=" << getHandleTag();
    FILAMENT_CHECK_PRECONDITION(size + byteOffset <= mBufferSize)
            << "Attempting to copy " << size << " bytes into a buffer of size " << mBufferSize
-            << " at offset " << byteOffset << ", tag=" << getHandleTag();
+            << " at offset " << byteOffset;
    // The copy blit requires that byteOffset be a multiple of 4.
-    FILAMENT_CHECK_PRECONDITION(!(byteOffset & 0x3))
-            << "byteOffset must be a multiple of 4, tag=" << getHandleTag();
+    FILAMENT_CHECK_PRECONDITION(!(byteOffset & 0x3)) << "byteOffset must be a multiple of 4";

    // If we have a cpu buffer, we can directly copy into it.
    if (mCpuBuffer) {
@@ -89,21 +81,20 @@ void MetalBuffer::copyIntoBuffer(

    switch (mUploadStrategy) {
        case UploadStrategy::BUMP_ALLOCATOR:
-            uploadWithBumpAllocator(src, size, byteOffset, std::move(getHandleTag));
+            uploadWithBumpAllocator(src, size, byteOffset);
            break;
        case UploadStrategy::POOL:
-            uploadWithPoolBuffer(src, size, byteOffset, std::move(getHandleTag));
+            uploadWithPoolBuffer(src, size, byteOffset);
            break;
    }
 }

-void MetalBuffer::copyIntoBufferUnsynchronized(
-        void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag) {
+void MetalBuffer::copyIntoBufferUnsynchronized(void* src, size_t size, size_t byteOffset) {
    // TODO: implement the unsynchronized version
-    copyIntoBuffer(src, size, byteOffset, std::move(getHandleTag));
+    copyIntoBuffer(src, size, byteOffset);
 }

-id<MTLBuffer> MetalBuffer::getGpuBufferForDraw() noexcept {
+id<MTLBuffer> MetalBuffer::getGpuBufferForDraw(id<MTLCommandBuffer> cmdBuffer) noexcept {
    // If there's a CPU buffer, then we return nil here, as the CPU-side buffer will be bound
    // separately.
    if (mCpuBuffer) {
@@ -146,7 +137,7 @@ void MetalBuffer::bindBuffers(id<MTLCommandBuffer> cmdBuffer, id<MTLCommandEncod
        }
        // getGpuBufferForDraw() might return nil, which means there isn't a device allocation for
        // this buffer. In this case, we'll bind the buffer below with the CPU-side memory.
-        id<MTLBuffer> gpuBuffer = buffer->getGpuBufferForDraw();
+        id<MTLBuffer> gpuBuffer = buffer->getGpuBufferForDraw(cmdBuffer);
        if (!gpuBuffer) {
            continue;
        }
@@ -206,13 +197,9 @@ void MetalBuffer::bindBuffers(id<MTLCommandBuffer> cmdBuffer, id<MTLCommandEncod
    }
 }

-void MetalBuffer::uploadWithPoolBuffer(
-        void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag) const {
+void MetalBuffer::uploadWithPoolBuffer(void* src, size_t size, size_t byteOffset) const {
    MetalBufferPool* bufferPool = mContext.bufferPool;
    const MetalBufferPoolEntry* const staging = bufferPool->acquireBuffer(size);
-    FILAMENT_CHECK_POSTCONDITION(staging)
-            << "uploadWithPoolbuffer unable to acquire staging buffer of size " << size
-            << ", tag=" << getHandleTag();
    memcpy(staging->buffer.get().contents, src, size);

    // Encode a blit from the staging buffer into the private GPU buffer.
@@ -230,18 +217,10 @@ void MetalBuffer::uploadWithPoolBuffer(
    }];
 }

-void MetalBuffer::uploadWithBumpAllocator(
-        void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag) const {
+void MetalBuffer::uploadWithBumpAllocator(void* src, size_t size, size_t byteOffset) const {
    MetalBumpAllocator& allocator = *mContext.bumpAllocator;
    auto [buffer, offset] = allocator.allocateStagingArea(size);
-    FILAMENT_CHECK_POSTCONDITION(buffer)
-            << "uploadWithBumpAllocator unable to acquire staging area of size " << size
-            << ", tag=" << getHandleTag();
-    void* const contents = buffer.contents;
-    FILAMENT_CHECK_POSTCONDITION(contents)
-            << "uploadWithBumpAllocator unable to acquire pointer to staging area, size " << size
-            << ", tag=" << getHandleTag();
-    memcpy(static_cast<char*>(contents) + offset, src, size);
+    memcpy(static_cast<char*>(buffer.contents) + offset, src, size);

    // Encode a blit from the staging buffer into the private GPU buffer.
    id<MTLCommandBuffer> cmdBuffer = getPendingCommandBuffer(&mContext);
@@ -21,8 +21,6 @@
 #include "MetalShaderCompiler.h"
 #include "MetalState.h"

-#include <backend/DriverEnums.h>
-
 #include <CoreVideo/CVMetalTextureCache.h>
 #include <Metal/Metal.h>
 #include <QuartzCore/QuartzCore.h>
@@ -48,13 +46,13 @@ class MetalBlitter;
 class MetalBufferPool;
 class MetalBumpAllocator;
 class MetalRenderTarget;
+class MetalSamplerGroup;
 class MetalSwapChain;
 class MetalTexture;
 class MetalTimerQueryInterface;
 struct MetalUniformBuffer;
 struct MetalIndexBuffer;
 struct MetalVertexBuffer;
-struct MetalDescriptorSet;

 constexpr static uint8_t MAX_SAMPLE_COUNT = 8;  // Metal devices support at most 8 MSAA samples

@@ -70,64 +68,16 @@ private:
    bool mDirty = false;
 };

-class MetalDynamicOffsets {
-public:
-    void setOffsets(uint32_t set, const uint32_t* offsets, uint32_t count) {
-        assert(set < MAX_DESCRIPTOR_SET_COUNT);
-
-        auto getStartIndexForSet = [&](uint32_t s) {
-            uint32_t startIndex = 0;
-            for (uint32_t i = 0; i < s; i++) {
-                startIndex += mCounts[i];
-            }
-            return startIndex;
-        };
-
-        const bool resizeNecessary = mCounts[set] != count;
-        if (UTILS_UNLIKELY(resizeNecessary)) {
-            int delta = count - mCounts[set];
-
-            auto thisSetStart = mOffsets.begin() + getStartIndexForSet(set);
-            if (delta > 0) {
-                mOffsets.insert(thisSetStart, delta, 0);
-            } else {
-                mOffsets.erase(thisSetStart, thisSetStart - delta);
-            }
-
-            mCounts[set] = count;
-        }
-
-        if (resizeNecessary ||
-                !std::equal(
-                        offsets, offsets + count, mOffsets.begin() + getStartIndexForSet(set))) {
-            std::copy(offsets, offsets + count, mOffsets.begin() + getStartIndexForSet(set));
-            mDirty = true;
-        }
-    }
-    bool isDirty() const { return mDirty; }
-    void setDirty(bool dirty) { mDirty = dirty; }
-
-    std::pair<uint32_t, const uint32_t*> getOffsets() const {
-        return { mOffsets.size(), mOffsets.data() };
-    }
-
-private:
-    std::array<uint32_t, MAX_DESCRIPTOR_SET_COUNT> mCounts = { 0 };
-    std::vector<uint32_t> mOffsets;
-    bool mDirty = false;
-};
-
 struct MetalContext {
+    explicit MetalContext(size_t metalFreedTextureListSize)
+        : texturesToDestroy(metalFreedTextureListSize) {}
+
    MetalDriver* driver;
    id<MTLDevice> device = nullptr;
    id<MTLCommandQueue> commandQueue = nullptr;

-    // The ID of pendingCommandBuffer (or the next command buffer, if pendingCommandBuffer is nil).
-    uint64_t pendingCommandBufferId = 1;
-    // read from driver thread, set from completion handlers
-    std::atomic<uint64_t> latestCompletedCommandBufferId = 0;
-    id<MTLCommandBuffer> pendingCommandBuffer = nil;
-    id<MTLRenderCommandEncoder> currentRenderPassEncoder = nil;
+    id<MTLCommandBuffer> pendingCommandBuffer = nullptr;
+    id<MTLRenderCommandEncoder> currentRenderPassEncoder = nullptr;

    std::atomic<bool> memorylessLimitsReached = false;

@@ -158,6 +108,8 @@ struct MetalContext {
    // State trackers.
    PipelineStateTracker pipelineState;
    DepthStencilStateTracker depthStencilState;
+    std::array<BufferState, Program::UNIFORM_BINDING_COUNT> uniformState;
+    std::array<BufferState, MAX_SSBO_COUNT> ssboState;
    CullModeStateTracker cullModeState;
    WindingStateTracker windingState;
    DepthClampStateTracker depthClampState;
@@ -173,17 +125,23 @@ struct MetalContext {

    std::array<MetalPushConstantBuffer, Program::SHADER_TYPE_COUNT> currentPushConstants;

-    // Keeps track of descriptor sets we've finalized for the current render pass.
-    tsl::robin_set<MetalDescriptorSet*> finalizedDescriptorSets;
-    std::array<MetalDescriptorSet*, MAX_DESCRIPTOR_SET_COUNT> currentDescriptorSets = {};
-    MetalBufferBindings<MAX_DESCRIPTOR_SET_COUNT, ShaderStage::VERTEX> vertexDescriptorBindings;
-    MetalBufferBindings<MAX_DESCRIPTOR_SET_COUNT, ShaderStage::FRAGMENT> fragmentDescriptorBindings;
-    MetalBufferBindings<MAX_DESCRIPTOR_SET_COUNT, ShaderStage::COMPUTE> computeDescriptorBindings;
-    MetalDynamicOffsets dynamicOffsets;
+    MetalSamplerGroup* samplerBindings[Program::SAMPLER_BINDING_COUNT] = {};

-    // Keeps track of all alive textures.
+    // Keeps track of sampler groups we've finalized for the current render pass.
+    tsl::robin_set<MetalSamplerGroup*> finalizedSamplerGroups;
+
+    // Keeps track of all alive sampler groups, textures.
+    tsl::robin_set<MetalSamplerGroup*> samplerGroups;
    tsl::robin_set<MetalTexture*> textures;

+    // This circular buffer implements delayed destruction for Metal texture handles. It keeps a
+    // handle to a fixed number of the most recently destroyed texture handles. When we're asked to
+    // destroy a texture handle, we free its texture memory, but keep the MetalTexture object alive,
+    // marking it as "terminated". If we later are asked to use that texture, we can check its
+    // terminated status and throw an Objective-C error instead of crashing, which is helpful for
+    // debugging use-after-free issues in release builds.
+    utils::FixedCircularBuffer<Handle<HwTexture>> texturesToDestroy;
+
    MetalBufferPool* bufferPool;
    MetalBumpAllocator* bumpAllocator;

@@ -196,7 +154,6 @@ struct MetalContext {

    // Empty texture used to prevent GPU errors when a sampler has been bound without a texture.
    id<MTLTexture> emptyTexture = nil;
-    id<MTLBuffer> emptyBuffer = nil;

    MetalBlitter* blitter = nullptr;

@@ -101,14 +101,9 @@ id<MTLCommandBuffer> getPendingCommandBuffer(MetalContext* context) {
    context->pendingCommandBuffer = [context->commandQueue commandBuffer];
    // It's safe for this block to capture the context variable. MetalDriver::terminate will ensure
    // all frames and their completion handlers finish before context is deallocated.
-    uint64_t thisCommandBufferId = context->pendingCommandBufferId;
    [context->pendingCommandBuffer addCompletedHandler:^(id <MTLCommandBuffer> buffer) {
        context->resourceTracker.clearResources((__bridge void*) buffer);
-
-        // Command buffers should complete in order, so latestCompletedCommandBufferId will only
-        // ever increase.
-        context->latestCompletedCommandBufferId = thisCommandBufferId;
-
+        
        auto errorCode = (MTLCommandBufferError)buffer.error.code;
        if (@available(macOS 11.0, *)) {
            if (errorCode == MTLCommandBufferErrorMemoryless) {
@@ -130,7 +125,6 @@ void submitPendingCommands(MetalContext* context) {
    assert_invariant(context->pendingCommandBuffer.status != MTLCommandBufferStatusCommitted);
    [context->pendingCommandBuffer commit];
    context->pendingCommandBuffer = nil;
-    context->pendingCommandBufferId++;
 }

 id<MTLTexture> getOrCreateEmptyTexture(MetalContext* context) {
@@ -173,6 +167,7 @@ void MetalPushConstantBuffer::setPushConstant(PushConstantVariant value, uint8_t

 void MetalPushConstantBuffer::setBytes(id<MTLCommandEncoder> encoder, ShaderStage stage) {
    constexpr size_t PUSH_CONSTANT_SIZE_BYTES = 4;
+    constexpr size_t PUSH_CONSTANT_BUFFER_INDEX = 26;

    static char buffer[MAX_PUSH_CONSTANT_COUNT * PUSH_CONSTANT_SIZE_BYTES];
    assert_invariant(mPushConstants.size() <= MAX_PUSH_CONSTANT_COUNT);
@@ -32,7 +32,6 @@
 #include <functional>
 #include <mutex>
 #include <vector>
-#include <deque>

 namespace filament {
 namespace backend {
@@ -62,7 +61,6 @@ public:
 private:

    friend class MetalSwapChain;
-    friend struct MetalDescriptorSet;

    MetalPlatform& mPlatform;
    MetalContext* mContext;
@@ -81,17 +79,6 @@ private:
    void executeTickOps() noexcept;
    std::vector<std::function<void()>> mTickOps;

-    // Tasks regularly executed on the driver thread after a command buffer has completed
-    struct DeferredTask {
-        DeferredTask(uint64_t commandBufferId, utils::Invocable<void()>&& fn) noexcept
-            : commandBufferId(commandBufferId), fn(std::move(fn)) {}
-        uint64_t commandBufferId;     // after this command buffer completes
-        utils::Invocable<void()> fn;  // execute this task
-    };
-    void executeAfterCurrentCommandBufferCompletes(utils::Invocable<void()>&& fn) noexcept;
-    void executeDeferredOps() noexcept;
-    std::deque<DeferredTask> mDeferredTasks;
-
    /*
     * Driver interface
     */
@@ -151,6 +138,7 @@ private:
    inline void setRenderPrimitiveBuffer(Handle<HwRenderPrimitive> rph, PrimitiveType pt,
            Handle<HwVertexBuffer> vbh, Handle<HwIndexBuffer> ibh);

+    void finalizeSamplerGroup(MetalSamplerGroup* sg);
    void enumerateBoundBuffers(BufferObjectBinding bindingType,
            const std::function<void(const BufferState&, MetalBuffer*, uint32_t)>& f);

@@ -32,75 +32,100 @@ struct MetalContext;
 * texture.
 */
 class MetalExternalImage {
+
 public:
-    MetalExternalImage() = default;

-    MetalExternalImage(MetalExternalImage&&);
-    MetalExternalImage& operator=(MetalExternalImage&&);
-    ~MetalExternalImage() noexcept;
-
-    MetalExternalImage(const MetalExternalImage&) = delete;
-    MetalExternalImage& operator=(const MetalExternalImage&) = delete;
+    MetalExternalImage(MetalContext& context,
+            TextureSwizzle r = TextureSwizzle::CHANNEL_0,
+            TextureSwizzle g = TextureSwizzle::CHANNEL_1,
+            TextureSwizzle b = TextureSwizzle::CHANNEL_2,
+            TextureSwizzle a = TextureSwizzle::CHANNEL_3) noexcept;

    /**
-     * While the texture is used for rendering, this MetalExternalImage must be kept alive.
+     * @return true, if this MetalExternalImage is holding a live external image. Returns false
+     * until set has been called with a valid CVPixelBuffer. The image can be cleared via
+     * set(nullptr), and isValid will return false again.
     */
-    id<MTLTexture> getMtlTexture() const noexcept;
-
-    bool isValid() const noexcept {
-        return mImage != nil || mRgbTexture != nullptr;
-    }
-
-    NSUInteger getWidth() const noexcept;
-    NSUInteger getHeight() const noexcept;
+    bool isValid() const noexcept;

    /**
-     * Create an external image with the passed-in CVPixelBuffer.
+     * Set this external image to the passed-in CVPixelBuffer. Future calls to
+     * getMetalTextureForDraw will return a texture backed by this CVPixelBuffer. Previous
+     * CVPixelBuffers and related resources will be released when all GPU work using them has
+     * finished.
     *
-     * Ownership is taken of the CVPixelBuffer, which will be released when the returned
-     * MetalExternalImage is destroyed (or, in the case of a YCbCr image, after the conversion has
-     * completed).
-     *
-     * Calling set with a YCbCr image will encode a compute pass to convert the image from
-     * YCbCr to RGB.
+     * Calling set with a YCbCr image will encode a compute pass to convert the image from YCbCr to
+     * RGB.
     */
-    static MetalExternalImage createFromImage(MetalContext& context, CVPixelBufferRef image);
+    void set(CVPixelBufferRef image) noexcept;

    /**
-     * Create an external image with a specific plane of the passed-in CVPixelBuffer.
-     *
-     * Ownership is taken of the CVPixelBuffer, which will be released when the returned
-     * MetalExternalImage is destroyed.
+     * Set this external image to a specific plane of the passed-in CVPixelBuffer. Future calls to
+     * getMetalTextureForDraw will return a texture backed by a single plane of this CVPixelBuffer.
+     * Previous CVPixelBuffers and related resources will be released when all GPU work using them
+     * has finished.
     */
-    static MetalExternalImage createFromImagePlane(
-            MetalContext& context, CVPixelBufferRef image, uint32_t plane);
+    void set(CVPixelBufferRef image, size_t plane) noexcept;

-    static void assertWritableImage(CVPixelBufferRef image);
+    /**
+     * Returns the width of the external image, or 0 if one is not set. For YCbCr images, returns
+     * the width of the luminance plane.
+     */
+    size_t getWidth() const noexcept { return mWidth; }
+
+    /**
+     * Returns the height of the external image, or 0 if one is not set. For YCbCr images, returns
+     * the height of the luminance plane.
+     */
+    size_t getHeight() const noexcept { return mHeight; }
+
+    /**
+     * Get a Metal texture used to draw this image and denote that it is used for the current frame.
+     * For future frames that use this external image, getMetalTextureForDraw must be called again.
+     */
+    id<MTLTexture> getMetalTextureForDraw() const noexcept;

    /**
     * Free resources. Should be called at least once when no further calls to set will occur.
     */
    static void shutdown(MetalContext& context) noexcept;

-private:
-    MetalExternalImage(CVPixelBufferRef image, CVMetalTextureRef texture) noexcept
-        : mImage(image), mTexture(texture) {}
-    explicit MetalExternalImage(id<MTLTexture> texture) noexcept : mRgbTexture(texture) {}
+    static void assertWritableImage(CVPixelBufferRef image);

-    static id<MTLTexture> createRgbTexture(id<MTLDevice> device, size_t width, size_t height);
-    static CVMetalTextureRef createTextureFromImage(CVMetalTextureCacheRef textureCache,
-            CVPixelBufferRef image, MTLPixelFormat format, size_t plane);
-    static void ensureComputePipelineState(MetalContext& context);
-    static id<MTLCommandBuffer> encodeColorConversionPass(MetalContext& context,
-            id<MTLTexture> inYPlane, id<MTLTexture> inCbCrTexture, id<MTLTexture> outTexture);
+private:
+
+    void unset();
+
+    CVMetalTextureRef createTextureFromImage(CVPixelBufferRef image, MTLPixelFormat format,
+            size_t plane);
+    id<MTLTexture> createRgbTexture(size_t width, size_t height);
+    id<MTLTexture> createSwizzledTextureView(id<MTLTexture> texture) const;
+    id<MTLTexture> createSwizzledTextureView(CVMetalTextureRef texture) const;
+    void ensureComputePipelineState();
+    id<MTLCommandBuffer> encodeColorConversionPass(id<MTLTexture> inYPlane, id<MTLTexture>
+            inCbCrTexture, id<MTLTexture> outTexture);

    static constexpr size_t Y_PLANE = 0;
    static constexpr size_t CBCR_PLANE = 1;

-    // TODO: this could probably be a union.
+    MetalContext& mContext;
+
+    // If the external image has a single plane, mImage and mTexture hold references to the image
+    // and created Metal texture, respectively.
+    // mTextureView is a view of mTexture with any swizzling applied.
    CVPixelBufferRef mImage = nullptr;
    CVMetalTextureRef mTexture = nullptr;
+    id<MTLTexture> mTextureView = nullptr;
+    size_t mWidth = 0;
+    size_t mHeight = 0;
+
+    // If the external image is in the YCbCr format, this holds the result of the converted RGB
+    // texture.
    id<MTLTexture> mRgbTexture = nil;
+
+    struct {
+        TextureSwizzle r, g, b, a;
+    } mSwizzle;
 };

 } // namespace backend
@@ -34,6 +34,10 @@
 namespace filament {
 namespace backend {

+static const auto cvBufferDeleter = [](const void* buffer) {
+    CVBufferRelease((CVMetalTextureRef) buffer);
+};
+
 static const char* kernel = R"(
 #include <metal_stdlib>
 #include <simd/simd.h>
@@ -67,30 +71,18 @@ ycbcrToRgb(texture2d<half, access::read>  inYTexture    [[texture(0)]],
 }
 )";

-NSUInteger MetalExternalImage::getWidth() const noexcept {
-    if (mImage) {
-        return CVPixelBufferGetWidth(mImage);
-    }
-    if (mRgbTexture) {
-        return mRgbTexture.width;
-    }
-    return 0;
+MetalExternalImage::MetalExternalImage(MetalContext& context, TextureSwizzle r, TextureSwizzle g,
+        TextureSwizzle b, TextureSwizzle a) noexcept : mContext(context), mSwizzle{r, g, b, a} { }
+
+bool MetalExternalImage::isValid() const noexcept {
+    return mRgbTexture != nil || mImage != nullptr;
 }

-NSUInteger MetalExternalImage::getHeight() const noexcept {
-    if (mImage) {
-        return CVPixelBufferGetHeight(mImage);
-    }
-    if (mRgbTexture) {
-        return mRgbTexture.height;
-    }
-    return 0;
-}
+void MetalExternalImage::set(CVPixelBufferRef image) noexcept {
+    unset();

-MetalExternalImage MetalExternalImage::createFromImage(
-        MetalContext& context, CVPixelBufferRef image) {
    if (!image) {
-        return {};
+        return;
    }

    OSType formatType = CVPixelBufferGetPixelFormatType(image);
@@ -104,29 +96,30 @@ MetalExternalImage MetalExternalImage::createFromImage(
            << ".";

    if (planeCount == 0) {
-        CVMetalTextureRef texture =
-                createTextureFromImage(context.textureCache, image, MTLPixelFormatBGRA8Unorm, 0);
-        return { CVPixelBufferRetain(image), texture };
+        mImage = image;
+        mTexture = createTextureFromImage(image, MTLPixelFormatBGRA8Unorm, 0);
+        mTextureView = createSwizzledTextureView(mTexture);
+        mWidth = CVPixelBufferGetWidth(image);
+        mHeight = CVPixelBufferGetHeight(image);
    }

    if (planeCount == 2) {
-        CVPixelBufferRetain(image);
-
-        CVMetalTextureRef yPlane =
-                createTextureFromImage(context.textureCache, image, MTLPixelFormatR8Unorm, Y_PLANE);
-        CVMetalTextureRef cbcrPlane =
-                createTextureFromImage(context.textureCache, image, MTLPixelFormatRG8Unorm, CBCR_PLANE);
+        CVMetalTextureRef yPlane = createTextureFromImage(image, MTLPixelFormatR8Unorm, Y_PLANE);
+        CVMetalTextureRef cbcrPlane = createTextureFromImage(image, MTLPixelFormatRG8Unorm,
+                CBCR_PLANE);

        // Get the size of luminance plane.
-        NSUInteger width = CVPixelBufferGetWidthOfPlane(image, Y_PLANE);
-        NSUInteger height = CVPixelBufferGetHeightOfPlane(image, Y_PLANE);
+        mWidth = CVPixelBufferGetWidthOfPlane(image, Y_PLANE);
+        mHeight = CVPixelBufferGetHeightOfPlane(image, Y_PLANE);

-        id<MTLTexture> rgbTexture = createRgbTexture(context.device, width, height);
-        id<MTLCommandBuffer> commandBuffer = encodeColorConversionPass(context,
+        id<MTLTexture> rgbTexture = createRgbTexture(mWidth, mHeight);
+        id<MTLCommandBuffer> commandBuffer = encodeColorConversionPass(
                CVMetalTextureGetTexture(yPlane),
                CVMetalTextureGetTexture(cbcrPlane),
                rgbTexture);

+        mRgbTexture = createSwizzledTextureView(rgbTexture);
+
        [commandBuffer addCompletedHandler:^(id <MTLCommandBuffer> o) {
            CVBufferRelease(yPlane);
            CVBufferRelease(cbcrPlane);
@@ -134,83 +127,70 @@ MetalExternalImage MetalExternalImage::createFromImage(
        }];

        [commandBuffer commit];
-        return MetalExternalImage { rgbTexture };
    }
-
-    return {};
 }

-MetalExternalImage MetalExternalImage::createFromImagePlane(
-        MetalContext& context, CVPixelBufferRef image, uint32_t plane) {
+void MetalExternalImage::set(CVPixelBufferRef image, size_t plane) noexcept {
+    unset();
+
    if (!image) {
-        return {};
+        return;
    }

    const OSType formatType = CVPixelBufferGetPixelFormatType(image);
    FILAMENT_CHECK_POSTCONDITION(formatType == kCVPixelFormatType_420YpCbCr8BiPlanarFullRange)
            << "Metal planar external images must be in the 420f format.";
-    FILAMENT_CHECK_POSTCONDITION(plane == 0 || plane == 1)
-            << "Metal planar external images must be created from planes 0 or 1.";

-    auto getPlaneFormat = [](size_t plane) {
-        // Right now Metal only supports kCVPixelFormatType_420YpCbCr8BiPlanarFullRange planar
-        // external images, so we can make the following assumptions about the format of each plane.
-        if (plane == 0) {
-            return MTLPixelFormatR8Unorm;  // luminance
-        }
-        if (plane == 1) {
-            return MTLPixelFormatRG8Unorm;  // CbCr
-        }
-        return MTLPixelFormatInvalid;
+    mImage = image;
+
+    auto getPlaneFormat = [] (size_t plane) {
+      // Right now Metal only supports kCVPixelFormatType_420YpCbCr8BiPlanarFullRange planar
+      // external images, so we can make the following assumptions about the format of each plane.
+      if (plane == 0) {
+        return MTLPixelFormatR8Unorm; // luminance
+      }
+      if (plane == 1) {
+        // CbCr
+        return MTLPixelFormatRG8Unorm; // CbCr
+      }
+      return MTLPixelFormatInvalid;
    };

    const MTLPixelFormat format = getPlaneFormat(plane);
    assert_invariant(format != MTLPixelFormatInvalid);
-    CVMetalTextureRef mTexture = createTextureFromImage(context.textureCache, image, format, plane);
-    return { CVPixelBufferRetain(image), mTexture };
+    mTexture = createTextureFromImage(image, format, plane);
+    mTextureView = createSwizzledTextureView(mTexture);
 }

-MetalExternalImage::MetalExternalImage(MetalExternalImage&& rhs) {
-    std::swap(mImage, rhs.mImage);
-    std::swap(mTexture, rhs.mTexture);
-    std::swap(mRgbTexture, rhs.mRgbTexture);
-}
-
-MetalExternalImage& MetalExternalImage::operator=(MetalExternalImage&& rhs) {
-    CVPixelBufferRelease(mImage);
-    CVBufferRelease(mTexture);
-    mImage = nullptr;
-    mTexture = nullptr;
-    mRgbTexture = nullptr;
-    std::swap(mImage, rhs.mImage);
-    std::swap(mTexture, rhs.mTexture);
-    std::swap(mRgbTexture, rhs.mRgbTexture);
-    return *this;
-}
-
-MetalExternalImage::~MetalExternalImage() noexcept {
-    CVPixelBufferRelease(mImage);
-    CVBufferRelease(mTexture);
-}
-
-id<MTLTexture> MetalExternalImage::getMtlTexture() const noexcept {
+id<MTLTexture> MetalExternalImage::getMetalTextureForDraw() const noexcept {
    if (mRgbTexture) {
        return mRgbTexture;
    }
-    if (mTexture) {
-        return CVMetalTextureGetTexture(mTexture);
+
+    // Retain the image and Metal texture until the GPU has finished with this frame. This does
+    // not need to be done for the RGB texture, because it is an Objective-C object whose
+    // lifetime is automatically managed by Metal.
+    auto& tracker = mContext.resourceTracker;
+    auto commandBuffer = getPendingCommandBuffer(&mContext);
+    if (tracker.trackResource((__bridge void*) commandBuffer, mImage, cvBufferDeleter)) {
+        CVPixelBufferRetain(mImage);
    }
-    return nil;
+    if (tracker.trackResource((__bridge void*) commandBuffer, mTexture, cvBufferDeleter)) {
+        CVBufferRetain(mTexture);
+    }
+
+    assert_invariant(mTextureView);
+    return mTextureView;
 }

-CVMetalTextureRef MetalExternalImage::createTextureFromImage(CVMetalTextureCacheRef textureCache,
-        CVPixelBufferRef image, MTLPixelFormat format, size_t plane) {
+CVMetalTextureRef MetalExternalImage::createTextureFromImage(CVPixelBufferRef image,
+        MTLPixelFormat format, size_t plane) {
    const size_t width = CVPixelBufferGetWidthOfPlane(image, plane);
    const size_t height = CVPixelBufferGetHeightOfPlane(image, plane);

    CVMetalTextureRef texture;
-    CVReturn result = CVMetalTextureCacheCreateTextureFromImage(kCFAllocatorDefault, textureCache,
-            image, nullptr, format, width, height, plane, &texture);
+    CVReturn result = CVMetalTextureCacheCreateTextureFromImage(kCFAllocatorDefault,
+            mContext.textureCache, image, nullptr, format, width, height, plane, &texture);
    FILAMENT_CHECK_POSTCONDITION(result == kCVReturnSuccess)
            << "Could not create a CVMetalTexture from CVPixelBuffer.";

@@ -221,19 +201,58 @@ void MetalExternalImage::shutdown(MetalContext& context) noexcept {
    context.externalImageComputePipelineState = nil;
 }

-id<MTLTexture> MetalExternalImage::createRgbTexture(
-        id<MTLDevice> device, size_t width, size_t height) {
+void MetalExternalImage::assertWritableImage(CVPixelBufferRef image) {
+    OSType formatType = CVPixelBufferGetPixelFormatType(image);
+    FILAMENT_CHECK_PRECONDITION(formatType == kCVPixelFormatType_32BGRA)
+            << "Metal SwapChain images must be in the 32BGRA format.";
+}
+
+void MetalExternalImage::unset() {
+    CVPixelBufferRelease(mImage);
+    CVBufferRelease(mTexture);
+
+    mImage = nullptr;
+    mTexture = nullptr;
+    mTextureView = nil;
+    mRgbTexture = nil;
+    mWidth = 0;
+    mHeight = 0;
+}
+
+id<MTLTexture> MetalExternalImage::createRgbTexture(size_t width, size_t height) {
    MTLTextureDescriptor *descriptor =
            [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatRGBA8Unorm
                                                               width:width
                                                              height:height
                                                           mipmapped:NO];
    descriptor.usage = MTLTextureUsageShaderWrite | MTLTextureUsageShaderRead;
-    return [device newTextureWithDescriptor:descriptor];
+    return [mContext.device newTextureWithDescriptor:descriptor];
 }

-void MetalExternalImage::ensureComputePipelineState(MetalContext& context) {
-    if (context.externalImageComputePipelineState != nil) {
+id<MTLTexture> MetalExternalImage::createSwizzledTextureView(id<MTLTexture> texture) const {
+    const bool isDefaultSwizzle =
+            mSwizzle.r == TextureSwizzle::CHANNEL_0 &&
+            mSwizzle.g == TextureSwizzle::CHANNEL_1 &&
+            mSwizzle.b == TextureSwizzle::CHANNEL_2 &&
+            mSwizzle.a == TextureSwizzle::CHANNEL_3;
+    if (!isDefaultSwizzle && mContext.supportsTextureSwizzling) {
+        // Even though we've already checked supportsTextureSwizzling, we still need to guard these
+        // calls with @availability, otherwise the API usage will generate compiler warnings.
+        if (@available(iOS 13, *)) {
+            texture = createTextureViewWithSwizzle(texture,
+                    getSwizzleChannels(mSwizzle.r, mSwizzle.g, mSwizzle.b, mSwizzle.a));
+        }
+    }
+    return texture;
+}
+
+id<MTLTexture> MetalExternalImage::createSwizzledTextureView(CVMetalTextureRef ref) const {
+    id<MTLTexture> texture = CVMetalTextureGetTexture(ref);
+    return createSwizzledTextureView(texture);
+}
+
+void MetalExternalImage::ensureComputePipelineState() {
+    if (mContext.externalImageComputePipelineState != nil) {
        return;
    }

@@ -241,28 +260,29 @@ void MetalExternalImage::ensureComputePipelineState(MetalContext& context) {

    NSString* objcSource = [NSString stringWithCString:kernel
                                              encoding:NSUTF8StringEncoding];
-    id<MTLLibrary> library = [context.device newLibraryWithSource:objcSource
-                                                          options:nil
-                                                            error:&error];
+    id<MTLLibrary> library = [mContext.device newLibraryWithSource:objcSource
+                                                            options:nil
+                                                              error:&error];
    NSERROR_CHECK("Unable to compile Metal shading library.");

    id<MTLFunction> kernelFunction = [library newFunctionWithName:@"ycbcrToRgb"];

-    context.externalImageComputePipelineState =
-            [context.device newComputePipelineStateWithFunction:kernelFunction error:&error];
+    mContext.externalImageComputePipelineState =
+            [mContext.device newComputePipelineStateWithFunction:kernelFunction
+                                                           error:&error];
    NSERROR_CHECK("Unable to create Metal compute pipeline state.");
 }

-id<MTLCommandBuffer> MetalExternalImage::encodeColorConversionPass(MetalContext& context,
-        id<MTLTexture> inYPlane, id<MTLTexture> inCbCrTexture, id<MTLTexture> outTexture) {
-    ensureComputePipelineState(context);
+id<MTLCommandBuffer> MetalExternalImage::encodeColorConversionPass(id<MTLTexture> inYPlane,
+        id<MTLTexture> inCbCrTexture, id<MTLTexture> outTexture) {
+    ensureComputePipelineState();

-    id<MTLCommandBuffer> commandBuffer = [context.commandQueue commandBuffer];
+    id<MTLCommandBuffer> commandBuffer = [mContext.commandQueue commandBuffer];
    commandBuffer.label = @"YCbCr to RGB conversion";

    id<MTLComputeCommandEncoder> computeEncoder = [commandBuffer computeCommandEncoder];

-    [computeEncoder setComputePipelineState:context.externalImageComputePipelineState];
+    [computeEncoder setComputePipelineState:mContext.externalImageComputePipelineState];
    [computeEncoder setTexture:inYPlane atIndex:0];
    [computeEncoder setTexture:inCbCrTexture atIndex:1];
    [computeEncoder setTexture:outTexture atIndex:2];
@@ -280,11 +300,5 @@ id<MTLCommandBuffer> MetalExternalImage::encodeColorConversionPass(MetalContext&
    return commandBuffer;
 }

-void MetalExternalImage::assertWritableImage(CVPixelBufferRef image) {
-    OSType formatType = CVPixelBufferGetPixelFormatType(image);
-    FILAMENT_CHECK_PRECONDITION(formatType == kCVPixelFormatType_32BGRA)
-            << "Metal SwapChain images must be in the 32BGRA format.";
-}
-
 } // namespace backend
 } // namespace filament
@@ -44,7 +44,6 @@
 #include <condition_variable>
 #include <memory>
 #include <type_traits>
-#include <vector>

 namespace filament {
 namespace backend {
@@ -74,8 +73,7 @@ public:

    void releaseDrawable();

-    void setFrameScheduledCallback(
-            CallbackHandler* handler, FrameScheduledCallback&& callback, uint64_t flags);
+    void setFrameScheduledCallback(CallbackHandler* handler, FrameScheduledCallback&& callback);
    void setFrameCompletedCallback(
            CallbackHandler* handler, utils::Invocable<void(void)>&& callback);

@@ -86,8 +84,6 @@ public:
    NSUInteger getSurfaceWidth() const;
    NSUInteger getSurfaceHeight() const;

-    bool isPixelBuffer() const { return type == SwapChainType::CVPIXELBUFFERREF; }
-
 private:

    enum class SwapChainType {
@@ -97,6 +93,7 @@ private:
    };
    bool isCaMetalLayer() const { return type == SwapChainType::CAMETALLAYER; }
    bool isHeadless() const { return type == SwapChainType::HEADLESS; }
+    bool isPixelBuffer() const { return type == SwapChainType::CVPIXELBUFFERREF; }

    void scheduleFrameScheduledCallback();
    void scheduleFrameCompletedCallback();
@@ -124,7 +121,6 @@ private:
    struct {
        CallbackHandler* handler = nullptr;
        std::shared_ptr<FrameScheduledCallback> callback = nullptr;
-        uint64_t flags = 0;
    } frameScheduled;

    struct {
@@ -135,17 +131,19 @@ private:

 class MetalBufferObject : public HwBufferObject {
 public:
-
-    using TagResolver = MetalBuffer::TagResolver;
-
    MetalBufferObject(MetalContext& context, BufferObjectBinding bindingType, BufferUsage usage,
         uint32_t byteCount);

-    void updateBuffer(void* data, size_t size, uint32_t byteOffset, TagResolver&& getHandleTag);
-    void updateBufferUnsynchronized(
-            void* data, size_t size, uint32_t byteOffset, TagResolver&& getHandleTag);
+    void updateBuffer(void* data, size_t size, uint32_t byteOffset);
+    void updateBufferUnsynchronized(void* data, size_t size, uint32_t byteOffset);
    MetalBuffer* getBuffer() { return &buffer; }

+    // Tracks which uniform/ssbo buffers this buffer object is bound into.
+    static_assert(Program::UNIFORM_BINDING_COUNT <= 32);
+    static_assert(MAX_SSBO_COUNT <= 32);
+    utils::bitset32 boundUniformBuffers;
+    utils::bitset32 boundSsbos;
+
 private:
    MetalBuffer buffer;
 };
@@ -202,10 +200,12 @@ public:
    MetalProgram(MetalContext& context, Program&& program) noexcept;

    const MetalShaderCompiler::MetalFunctionBundle& getFunctions();
+    const Program::SamplerGroupInfo& getSamplerGroupInfo() { return samplerGroupInfo; }

 private:
    void initialize();

+    Program::SamplerGroupInfo samplerGroupInfo;
    MetalContext& mContext;
    MetalShaderCompiler::MetalFunctionBundle mFunctionBundle;
    MetalShaderCompiler::program_token_t mToken;
@@ -227,42 +227,43 @@ struct PixelBufferShape {
 class MetalTexture : public HwTexture {
 public:
    MetalTexture(MetalContext& context, SamplerType target, uint8_t levels, TextureFormat format,
-            uint8_t samples, uint32_t width, uint32_t height, uint32_t depth,
-            TextureUsage usage) noexcept;
-
-    // constructors for creating texture views
-    MetalTexture(MetalContext& context, MetalTexture const* src, uint8_t baseLevel,
-            uint8_t levelCount) noexcept;
-    MetalTexture(MetalContext& context, MetalTexture const* src, TextureSwizzle r, TextureSwizzle g,
-            TextureSwizzle b, TextureSwizzle a) noexcept;
+            uint8_t samples, uint32_t width, uint32_t height, uint32_t depth, TextureUsage usage,
+            TextureSwizzle r, TextureSwizzle g, TextureSwizzle b, TextureSwizzle a)
+            noexcept;

    // Constructor for importing an id<MTLTexture> outside of Filament.
    MetalTexture(MetalContext& context, SamplerType target, uint8_t levels, TextureFormat format,
            uint8_t samples, uint32_t width, uint32_t height, uint32_t depth, TextureUsage usage,
            id<MTLTexture> texture) noexcept;

-    // Constructors for importing external images.
-    MetalTexture(MetalContext& context, TextureFormat format, uint32_t width, uint32_t height,
-            TextureUsage usage, CVPixelBufferRef image) noexcept;
-    MetalTexture(MetalContext& context, TextureFormat format, uint32_t width, uint32_t height,
-            TextureUsage usage, CVPixelBufferRef image, uint32_t plane) noexcept;
+    ~MetalTexture();

-    // Returns an id<MTLTexture> suitable for reading in a shader, taking into account swizzle.
-    id<MTLTexture> getMtlTextureForRead() const noexcept;
+    // Returns an id<MTLTexture> suitable for reading in a shader, taking into account swizzle and
+    // LOD clamping.
+    id<MTLTexture> getMtlTextureForRead() noexcept;

    // Returns the id<MTLTexture> for attaching to a render pass.
-    id<MTLTexture> getMtlTextureForWrite() const noexcept {
+    id<MTLTexture> getMtlTextureForWrite() noexcept {
        return texture;
    }

-    std::shared_ptr<MetalExternalImage> getExternalImage() const noexcept { return externalImage; }
-
    void loadImage(uint32_t level, MTLRegion region, PixelBufferDescriptor& p) noexcept;
    void generateMipmaps() noexcept;

+    // A texture starts out with none of its mip levels (also referred to as LODs) available for
+    // reading. 4 actions update the range of LODs available:
+    // - calling loadImage
+    // - calling generateMipmaps
+    // - using the texture as a render target attachment
+    // - calling setMinMaxLevels
+    // A texture's available mips are consistent throughout a render pass.
+    void setLodRange(uint16_t minLevel, uint16_t maxLevel);
+    void extendLodRangeTo(uint16_t level);
+
    static MTLPixelFormat decidePixelFormat(MetalContext* context, TextureFormat format);

    MetalContext& context;
+    MetalExternalImage externalImage;

    // A "sidecar" texture used to implement automatic MSAA resolve.
    // This is created by MetalRenderTarget and stored here so it can be used with multiple
@@ -271,6 +272,26 @@ public:

    MTLPixelFormat devicePixelFormat;

+    // Frees memory associated with this texture and marks it as "terminated".
+    // Used to track "use after free" scenario.
+    void terminate() noexcept;
+    bool isTerminated() const noexcept { return terminated; }
+    inline void checkUseAfterFree(const char* samplerGroupDebugName, size_t textureIndex) const {
+        if (UTILS_LIKELY(!isTerminated())) {
+            return;
+        }
+        NSString* reason =
+                [NSString stringWithFormat:
+                                  @"Filament Metal texture use after free, sampler group = "
+                                  @"%s, texture index = %zu",
+                          samplerGroupDebugName, textureIndex];
+        NSException* useAfterFreeException =
+                [NSException exceptionWithName:@"MetalTextureUseAfterFree"
+                                        reason:reason
+                                      userInfo:nil];
+        [useAfterFreeException raise];
+    }
+
 private:
    void loadSlice(uint32_t level, MTLRegion region, uint32_t byteOffset, uint32_t slice,
            PixelBufferDescriptor const& data) noexcept;
@@ -281,12 +302,95 @@ private:

    id<MTLTexture> texture = nil;

-    std::shared_ptr<MetalExternalImage> externalImage;
-
    // If non-nil, a swizzled texture view to use instead of "texture".
    // Filament swizzling only affects texture reads, so this should not be used when the texture is
    // bound as a render target attachment.
    id<MTLTexture> swizzledTextureView = nil;
+    id<MTLTexture> lodTextureView = nil;
+
+    uint16_t minLod = std::numeric_limits<uint16_t>::max();
+    uint16_t maxLod = 0;
+
+    bool terminated = false;
+};
+
+class MetalSamplerGroup : public HwSamplerGroup {
+public:
+    explicit MetalSamplerGroup(size_t size, utils::FixedSizeString<32> name) noexcept
+        : size(size),
+          debugName(name),
+          textureHandles(size, Handle<HwTexture>()),
+          textures(size, nil),
+          samplers(size, nil) {}
+
+    inline void setTextureHandle(size_t index, Handle<HwTexture> th) {
+        assert_invariant(!finalized);
+        textureHandles[index] = th;
+    }
+
+    // This method is only used for debugging, to ensure all texture handles are alive.
+    const auto& getTextureHandles() const {
+        return textureHandles;
+    }
+
+    // Encode a MTLTexture into this SamplerGroup at the given index.
+    inline void setFinalizedTexture(size_t index, id<MTLTexture> t) {
+        assert_invariant(!finalized);
+        textures[index] = t;
+    }
+
+    // Encode a MTLSamplerState into this SamplerGroup at the given index.
+    inline void setFinalizedSampler(size_t index, id<MTLSamplerState> s) {
+        assert_invariant(!finalized);
+        samplers[index] = s;
+    }
+
+    // A SamplerGroup is "finalized" when all of its textures have been set and is ready for use in
+    // a draw call.
+    // Once a SamplerGroup is finalized, it must be reset or mutated to be written into again.
+    void finalize();
+    bool isFinalized() const noexcept { return finalized; }
+
+    // Both of these methods "unfinalize" a SamplerGroup, allowing it to be updated via calls to
+    // setFinalizedTexture or setFinalizedSampler. The difference is that when reset is called, all
+    // the samplers/textures must be rebound. The MTLArgumentEncoder must be specified, in case
+    // the texture types have changed.
+    // Mutate re-encodes the current set of samplers/textures into the new argument
+    // buffer.
+    void reset(id<MTLCommandBuffer> cmdBuffer, id<MTLArgumentEncoder> e, id<MTLDevice> device);
+    void mutate(id<MTLCommandBuffer> cmdBuffer);
+
+    id<MTLBuffer> getArgumentBuffer() const {
+        assert_invariant(finalized);
+        return argBuffer->getCurrentAllocation().first;
+    }
+
+    NSUInteger getArgumentBufferOffset() const {
+        return argBuffer->getCurrentAllocation().second;
+    }
+
+    inline std::pair<Handle<HwTexture>, id<MTLTexture>> getFinalizedTexture(size_t index) {
+        return {textureHandles[index], textures[index]};
+    }
+
+    // Calls the Metal useResource:usage:stages: method for all the textures in this SamplerGroup.
+    void useResources(id<MTLRenderCommandEncoder> renderPassEncoder);
+
+    size_t size;
+    utils::FixedSizeString<32> debugName;
+
+public:
+
+    // These vectors are kept in sync with one another.
+    utils::FixedCapacityVector<Handle<HwTexture>> textureHandles;
+    utils::FixedCapacityVector<id<MTLTexture>> textures;
+    utils::FixedCapacityVector<id<MTLSamplerState>> samplers;
+
+    id<MTLArgumentEncoder> encoder;
+
+    std::unique_ptr<MetalRingBuffer> argBuffer = nullptr;
+
+    bool finalized = false;
 };

 class MetalRenderTarget : public HwRenderTarget {
@@ -443,61 +547,6 @@ struct MetalTimerQuery : public HwTimerQuery {
    std::shared_ptr<Status> status;
 };

-class MetalDescriptorSetLayout : public HwDescriptorSetLayout {
-public:
-    MetalDescriptorSetLayout(DescriptorSetLayout&& layout) noexcept;
-
-    const auto& getBindings() const noexcept { return mLayout.bindings; }
-
-    size_t getDynamicOffsetCount() const noexcept { return mDynamicOffsetCount; }
-
-    /**
-     * Get an argument encoder for this descriptor set and shader stage.
-     * textureTypes should only include the textures present in the corresponding shader stage.
-     */
-    id<MTLArgumentEncoder> getArgumentEncoder(id<MTLDevice> device, ShaderStage stage,
-            utils::FixedCapacityVector<MTLTextureType> const& textureTypes);
-
-private:
-    id<MTLArgumentEncoder> getArgumentEncoderSlow(id<MTLDevice> device, ShaderStage stage,
-            utils::FixedCapacityVector<MTLTextureType> const& textureTypes);
-
-    DescriptorSetLayout mLayout;
-    size_t mDynamicOffsetCount = 0;
-    std::array<id<MTLArgumentEncoder>, Program::SHADER_TYPE_COUNT> mCachedArgumentEncoder = { nil };
-    std::array<utils::FixedCapacityVector<MTLTextureType>, Program::SHADER_TYPE_COUNT>
-            mCachedTextureTypes;
-};
-
-struct MetalDescriptorSet : public HwDescriptorSet {
-    MetalDescriptorSet(MetalDescriptorSetLayout* layout) noexcept;
-
-    void finalize(MetalDriver* driver);
-
-    id<MTLBuffer> finalizeAndGetBuffer(MetalDriver* driver, ShaderStage stage);
-
-    MetalDescriptorSetLayout* layout;
-
-    struct BufferBinding {
-        id<MTLBuffer> buffer;
-        uint32_t offset;
-        uint32_t size;
-    };
-    struct TextureBinding {
-        id<MTLTexture> texture;
-        SamplerParams sampler;
-    };
-    tsl::robin_map<descriptor_binding_t, BufferBinding> buffers;
-    tsl::robin_map<descriptor_binding_t, TextureBinding> textures;
-
-    std::vector<id<MTLResource>> vertexResources;
-    std::vector<id<MTLResource>> fragmentResources;
-
-    std::vector<std::shared_ptr<MetalExternalImage>> externalImages;
-
-    std::array<TrackedMetalBuffer, Program::SHADER_TYPE_COUNT> cachedBuffer = { nil };
-};
-
 } // namespace backend
 } // namespace filament

@@ -74,6 +74,7 @@ MetalSwapChain::MetalSwapChain(MetalContext& context, CAMetalLayer* nativeWindow
      depthStencilFormat(decideDepthStencilFormat(flags)),
      layer(nativeWindow),
      layerDrawableMutex(std::make_shared<std::mutex>()),
+      externalImage(context),
      type(SwapChainType::CAMETALLAYER) {

    if (!(flags & SwapChain::CONFIG_TRANSPARENT) && !nativeWindow.opaque) {
@@ -99,15 +100,17 @@ MetalSwapChain::MetalSwapChain(MetalContext& context, int32_t width, int32_t hei
      depthStencilFormat(decideDepthStencilFormat(flags)),
      headlessWidth(width),
      headlessHeight(height),
+      externalImage(context),
      type(SwapChainType::HEADLESS) {}

 MetalSwapChain::MetalSwapChain(MetalContext& context, CVPixelBufferRef pixelBuffer, uint64_t flags)
    : context(context),
      depthStencilFormat(decideDepthStencilFormat(flags)),
-      externalImage(MetalExternalImage::createFromImage(context, pixelBuffer)),
+      externalImage(context),
      type(SwapChainType::CVPIXELBUFFERREF) {
    assert_invariant(flags & SWAP_CHAIN_CONFIG_APPLE_CVPIXELBUFFER);
    MetalExternalImage::assertWritableImage(pixelBuffer);
+    externalImage.set(pixelBuffer);
    assert_invariant(externalImage.isValid());
 }

@@ -118,6 +121,7 @@ MTLPixelFormat MetalSwapChain::decideDepthStencilFormat(uint64_t flags) {
 }

 MetalSwapChain::~MetalSwapChain() {
+    externalImage.set(nullptr);
 }

 NSUInteger MetalSwapChain::getSurfaceWidth() const {
@@ -167,7 +171,7 @@ id<MTLTexture> MetalSwapChain::acquireDrawable() {
    }

    if (isPixelBuffer()) {
-        return externalImage.getMtlTexture();
+        return externalImage.getMetalTextureForDraw();
    }

    assert_invariant(isCaMetalLayer());
@@ -229,10 +233,9 @@ void MetalSwapChain::ensureDepthStencilTexture() {
 }

 void MetalSwapChain::setFrameScheduledCallback(
-        CallbackHandler* handler, FrameScheduledCallback&& callback, uint64_t flags) {
+        CallbackHandler* handler, FrameScheduledCallback&& callback) {
    frameScheduled.handler = handler;
    frameScheduled.callback = std::make_shared<FrameScheduledCallback>(std::move(callback));
-    frameScheduled.flags = flags;
 }

 void MetalSwapChain::setFrameCompletedCallback(
@@ -261,10 +264,10 @@ public:
    PresentDrawableData& operator=(const PresentDrawableData&) = delete;

    static PresentDrawableData* create(id<CAMetalDrawable> drawable,
-            std::shared_ptr<std::mutex> drawableMutex, MetalDriver* driver, uint64_t flags) {
+            std::shared_ptr<std::mutex> drawableMutex, MetalDriver* driver) {
        assert_invariant(drawableMutex);
        assert_invariant(driver);
-        return new PresentDrawableData(drawable, drawableMutex, driver, flags);
+        return new PresentDrawableData(drawable, drawableMutex, driver);
    }

    static void maybePresentAndDestroyAsync(PresentDrawableData* that, bool shouldPresent) {
@@ -272,23 +275,16 @@ public:
           [that->mDrawable present];
        }

-        if (that->mFlags & SwapChain::CALLBACK_DEFAULT_USE_METAL_COMPLETION_HANDLER) {
-            cleanupAndDestroy(that);
-        } else {
-            // mDrawable is acquired on the driver thread. Typically, we would release this object
-            // on the same thread, but after receiving consistent crash reports from within
-            // [CAMetalDrawable dealloc], we suspect this object requires releasing on the main
-            // thread.
-            dispatch_async(dispatch_get_main_queue(), ^{
-                cleanupAndDestroy(that);
-            });
-        }
+        // mDrawable is acquired on the driver thread. Typically, we would release this object on
+        // the same thread, but after receiving consistent crash reports from within
+        // [CAMetalDrawable dealloc], we suspect this object requires releasing on the main thread.
+        dispatch_async(dispatch_get_main_queue(), ^{ cleanupAndDestroy(that); });
    }

 private:
    PresentDrawableData(id<CAMetalDrawable> drawable, std::shared_ptr<std::mutex> drawableMutex,
-            MetalDriver* driver, uint64_t flags)
-        : mDrawable(drawable), mDrawableMutex(drawableMutex), mDriver(driver), mFlags(flags) {}
+            MetalDriver* driver)
+        : mDrawable(drawable), mDrawableMutex(drawableMutex), mDriver(driver) {}

    static void cleanupAndDestroy(PresentDrawableData *that) {
        if (that->mDrawable) {
@@ -303,7 +299,6 @@ private:
    id<CAMetalDrawable> mDrawable;
    std::shared_ptr<std::mutex> mDrawableMutex;
    MetalDriver* mDriver = nullptr;
-    uint64_t mFlags = 0;
 };

 void presentDrawable(bool presentFrame, void* user) {
@@ -320,8 +315,8 @@ void MetalSwapChain::scheduleFrameScheduledCallback() {

    struct Callback {
        Callback(std::shared_ptr<FrameScheduledCallback> callback, id<CAMetalDrawable> drawable,
-                 std::shared_ptr<std::mutex> drawableMutex, MetalDriver* driver, uint64_t flags)
-            : f(callback), data(PresentDrawableData::create(drawable, drawableMutex, driver, flags)) {}
+                 std::shared_ptr<std::mutex> drawableMutex, MetalDriver* driver)
+            : f(callback), data(PresentDrawableData::create(drawable, drawableMutex, driver)) {}
        std::shared_ptr<FrameScheduledCallback> f;
        // PresentDrawableData* is destroyed by maybePresentAndDestroyAsync() later.
        std::unique_ptr<PresentDrawableData> data;
@@ -336,19 +331,14 @@ void MetalSwapChain::scheduleFrameScheduledCallback() {

    // This callback pointer will be captured by the block. Even if the scheduled handler is never
    // called, the unique_ptr will still ensure we don't leak memory.
-    uint64_t const flags = frameScheduled.flags;
    __block auto callback = std::make_unique<Callback>(
-            frameScheduled.callback, drawable, layerDrawableMutex, context.driver, flags);
+        frameScheduled.callback, drawable, layerDrawableMutex, context.driver);

    backend::CallbackHandler* handler = frameScheduled.handler;
    MetalDriver* driver = context.driver;
    [getPendingCommandBuffer(&context) addScheduledHandler:^(id<MTLCommandBuffer> cb) {
        Callback* user = callback.release();
-        if (flags & SwapChain::CALLBACK_DEFAULT_USE_METAL_COMPLETION_HANDLER) {
-            Callback::func(user);
-        } else {
-            driver->scheduleCallback(handler, user, &Callback::func);
-        }
+        driver->scheduleCallback(handler, user, &Callback::func);
    }];
 }

@@ -383,14 +373,12 @@ MetalBufferObject::MetalBufferObject(MetalContext& context, BufferObjectBinding
        BufferUsage usage, uint32_t byteCount)
        : HwBufferObject(byteCount), buffer(context, bindingType, usage, byteCount) {}

-void MetalBufferObject::updateBuffer(
-        void* data, size_t size, uint32_t byteOffset, TagResolver&& getHandleTag) {
-    buffer.copyIntoBuffer(data, size, byteOffset, std::move(getHandleTag));
+void MetalBufferObject::updateBuffer(void* data, size_t size, uint32_t byteOffset) {
+    buffer.copyIntoBuffer(data, size, byteOffset);
 }

-void MetalBufferObject::updateBufferUnsynchronized(
-        void* data, size_t size, uint32_t byteOffset, TagResolver&& getHandleTag) {
-    buffer.copyIntoBufferUnsynchronized(data, size, byteOffset, std::move(getHandleTag));
+void MetalBufferObject::updateBufferUnsynchronized(void* data, size_t size, uint32_t byteOffset) {
+    buffer.copyIntoBufferUnsynchronized(data, size, byteOffset);
 }

 MetalVertexBufferInfo::MetalVertexBufferInfo(MetalContext& context, uint8_t bufferCount,
@@ -486,6 +474,11 @@ void MetalRenderPrimitive::setBuffers(MetalVertexBufferInfo const* const vbi,

 MetalProgram::MetalProgram(MetalContext& context, Program&& program) noexcept
    : HwProgram(program.getName()), mContext(context) {
+
+    // Save this program's SamplerGroupInfo, it's used during draw calls to bind sampler groups to
+    // the appropriate stage(s).
+    samplerGroupInfo = program.getSamplerGroupInfo();
+
    mToken = context.shaderCompiler->createProgram(program.getName(), std::move(program));
    assert_invariant(mToken);
 }
@@ -505,9 +498,10 @@ void MetalProgram::initialize() {

 MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t levels,
        TextureFormat format, uint8_t samples, uint32_t width, uint32_t height, uint32_t depth,
-        TextureUsage usage) noexcept
-    : HwTexture(target, levels, samples, width, height, depth, format, usage), context(context) {
-    assert_invariant(target != SamplerType::SAMPLER_EXTERNAL);
+        TextureUsage usage, TextureSwizzle r, TextureSwizzle g, TextureSwizzle b,
+        TextureSwizzle a) noexcept
+    : HwTexture(target, levels, samples, width, height, depth, format, usage), context(context),
+        externalImage(context, r, g, b, a) {

    devicePixelFormat = decidePixelFormat(&context, format);
    FILAMENT_CHECK_POSTCONDITION(devicePixelFormat != MTLPixelFormatInvalid)
@@ -593,28 +587,16 @@ MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t le
            << ", levels = " << int(levels) << ", MTLPixelFormat = " << int(devicePixelFormat)
            << ", width = " << width << ", height = " << height << ", depth = " << depth
            << "). Out of memory?";
-}

-MetalTexture::MetalTexture(MetalContext& context, MetalTexture const* src, uint8_t baseLevel,
-        uint8_t levelCount) noexcept
-    : HwTexture(src->target, src->levels, src->samples, src->width, src->height, src->depth,
-              src->format, src->usage),
-      context(context),
-      devicePixelFormat(src->devicePixelFormat),
-      externalImage(src->externalImage) {
-    texture = createTextureViewWithLodRange(
-            src->getMtlTextureForRead(), baseLevel, baseLevel + levelCount - 1);
-}
-
-MetalTexture::MetalTexture(MetalContext& context, MetalTexture const* src, TextureSwizzle r,
-        TextureSwizzle g, TextureSwizzle b, TextureSwizzle a) noexcept
-    : HwTexture(src->target, src->levels, src->samples, src->width, src->height, src->depth,
-              src->format, src->usage),
-      context(context),
-      devicePixelFormat(src->devicePixelFormat),
-      externalImage(src->externalImage) {
-    texture = src->getMtlTextureForRead();
-    if (context.supportsTextureSwizzling) {
+    // If swizzling is set, set up a swizzled texture view that we'll use when sampling this texture.
+    const bool isDefaultSwizzle =
+            r == TextureSwizzle::CHANNEL_0 &&
+            g == TextureSwizzle::CHANNEL_1 &&
+            b == TextureSwizzle::CHANNEL_2 &&
+            a == TextureSwizzle::CHANNEL_3;
+    // If texture is nil, then it must be a SAMPLER_EXTERNAL texture.
+    // Swizzling for external textures is handled inside MetalExternalImage.
+    if (!isDefaultSwizzle && texture && context.supportsTextureSwizzling) {
        // Even though we've already checked context.supportsTextureSwizzling, we still need to
        // guard these calls with @availability, otherwise the API usage will generate compiler
        // warnings.
@@ -628,30 +610,44 @@ MetalTexture::MetalTexture(MetalContext& context, MetalTexture const* src, Textu
 MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t levels, TextureFormat format,
        uint8_t samples, uint32_t width, uint32_t height, uint32_t depth, TextureUsage usage,
        id<MTLTexture> metalTexture) noexcept
-    : HwTexture(target, levels, samples, width, height, depth, format, usage), context(context) {
+    : HwTexture(target, levels, samples, width, height, depth, format, usage), context(context),
+        externalImage(context) {
    texture = metalTexture;
+    setLodRange(0, levels - 1);
 }

-MetalTexture::MetalTexture(MetalContext& context, TextureFormat format, uint32_t width,
-        uint32_t height, TextureUsage usage, CVPixelBufferRef image) noexcept
-    : HwTexture(SamplerType::SAMPLER_EXTERNAL, 1, 1, width, height, 1, format, usage),
-      context(context),
-      externalImage(std::make_shared<MetalExternalImage>(
-              MetalExternalImage::createFromImage(context, image))) {
-    texture = externalImage->getMtlTexture();
+void MetalTexture::terminate() noexcept {
+    texture = nil;
+    swizzledTextureView = nil;
+    lodTextureView = nil;
+    msaaSidecar = nil;
+    externalImage.set(nullptr);
+    terminated = true;
 }

-MetalTexture::MetalTexture(MetalContext& context, TextureFormat format, uint32_t width,
-        uint32_t height, TextureUsage usage, CVPixelBufferRef image, uint32_t plane) noexcept
-    : HwTexture(SamplerType::SAMPLER_EXTERNAL, 1, 1, width, height, 1, format, usage),
-      context(context),
-      externalImage(std::make_shared<MetalExternalImage>(
-              MetalExternalImage::createFromImagePlane(context, image, plane))) {
-    texture = externalImage->getMtlTexture();
+MetalTexture::~MetalTexture() {
+    externalImage.set(nullptr);
 }

-id<MTLTexture> MetalTexture::getMtlTextureForRead() const noexcept {
-    return swizzledTextureView ? swizzledTextureView : texture;
+id<MTLTexture> MetalTexture::getMtlTextureForRead() noexcept {
+    if (lodTextureView) {
+        return lodTextureView;
+    }
+    // The texture's swizzle remains constant throughout its lifetime, however its LOD range can
+    // change. We'll cache the LOD view, and set lodTextureView to nil if minLod or maxLod is
+    // updated.
+    id<MTLTexture> t = swizzledTextureView ? swizzledTextureView : texture;
+    if (!t) {
+        return nil;
+    }
+    if (UTILS_UNLIKELY(minLod > maxLod)) {
+        // If the texture does not have any available LODs, provide a view of only level 0.
+        // Filament should prevent this from ever occurring.
+        lodTextureView = createTextureViewWithLodRange(t, 0, 0);
+        return lodTextureView;
+    }
+    lodTextureView = createTextureViewWithLodRange(t, minLod, maxLod);
+    return lodTextureView;
 }

 MTLPixelFormat MetalTexture::decidePixelFormat(MetalContext* context, TextureFormat format) {
@@ -770,12 +766,15 @@ void MetalTexture::loadImage(uint32_t level, MTLRegion region, PixelBufferDescri
            assert_invariant(false);
        }
    }
+
+    extendLodRangeTo(level);
 }

 void MetalTexture::generateMipmaps() noexcept {
    id <MTLBlitCommandEncoder> blitEncoder = [getPendingCommandBuffer(&context) blitCommandEncoder];
    [blitEncoder generateMipmapsForTexture:texture];
    [blitEncoder endEncoding];
+    setLodRange(0, texture.mipmapLevelCount - 1);
 }

 void MetalTexture::loadSlice(uint32_t level, MTLRegion region, uint32_t byteOffset, uint32_t slice,
@@ -899,6 +898,98 @@ void MetalTexture::loadWithBlit(uint32_t level, uint32_t slice, MTLRegion region
    context.blitter->blit(getPendingCommandBuffer(&context), args, "Texture upload blit");
 }

+void MetalTexture::extendLodRangeTo(uint16_t level) {
+    assert_invariant(!isInRenderPass(&context));
+    minLod = std::min(minLod, level);
+    maxLod = std::max(maxLod, level);
+    lodTextureView = nil;
+}
+
+void MetalTexture::setLodRange(uint16_t min, uint16_t max) {
+    assert_invariant(!isInRenderPass(&context));
+    assert_invariant(min <= max);
+    minLod = min;
+    maxLod = max;
+    lodTextureView = nil;
+}
+
+void MetalSamplerGroup::finalize() {
+    assert_invariant(encoder);
+    // TODO: we should be able to encode textures and samplers inside setFinalizedTexture and
+    // setFinalizedSampler as they become available, but Metal doesn't seem to like this; the arg
+    // buffer gets encoded incorrectly. This warrants more investigation.
+
+    auto [buffer, offset] = argBuffer->getCurrentAllocation();
+    [encoder setArgumentBuffer:buffer offset:offset];
+
+    // Encode all textures and samplers.
+    for (size_t s = 0; s < size; s++) {
+        [encoder setTexture:textures[s] atIndex:(s * 2 + 0)];
+        [encoder setSamplerState:samplers[s] atIndex:(s * 2 + 1)];
+    }
+
+    finalized = true;
+}
+
+void MetalSamplerGroup::reset(id<MTLCommandBuffer> cmdBuffer, id<MTLArgumentEncoder> e,
+        id<MTLDevice> device) {
+    encoder = e;
+
+    // The number of slots in the ring buffer we use to manage argument buffer allocations.
+    // This number was chosen to avoid running out of slots and having to allocate a "fallback"
+    // buffer when SamplerGroups are updated multiple times a frame. This value can reduced after
+    // auditing Filament's calls to updateSamplerGroup, which should be as few times as possible.
+    // For example, the bloom downsample pass should be refactored to maintain two separate
+    // MaterialInstances instead of "ping ponging" between two texture bindings, which causes a
+    // single SamplerGroup to be updated many times a frame.
+    static constexpr auto METAL_ARGUMENT_BUFFER_SLOTS = 32;
+
+    MTLSizeAndAlign argBufferLayout;
+    argBufferLayout.size = encoder.encodedLength;
+    argBufferLayout.align = encoder.alignment;
+    // Chances are, even though the MTLArgumentEncoder might change, the required size and alignment
+    // probably won't. So we can re-use the previous ring buffer.
+    if (UTILS_UNLIKELY(!argBuffer || !argBuffer->canAccomodateLayout(argBufferLayout))) {
+        argBuffer = std::make_unique<MetalRingBuffer>(device, MTLResourceStorageModeShared,
+                argBufferLayout, METAL_ARGUMENT_BUFFER_SLOTS);
+    } else {
+        argBuffer->createNewAllocation(cmdBuffer);
+    }
+
+    // Clear all textures and samplers.
+    assert_invariant(textureHandles.size() == textures.size());
+    assert_invariant(textures.size() == samplers.size());
+    for (size_t s = 0; s < textureHandles.size(); s++) {
+        textureHandles[s] = {};
+        textures[s] = nil;
+        samplers[s] = nil;
+    }
+
+    finalized = false;
+}
+
+void MetalSamplerGroup::mutate(id<MTLCommandBuffer> cmdBuffer) {
+    assert_invariant(finalized);    // only makes sense to mutate if this sampler group is finalized
+    assert_invariant(argBuffer);
+    argBuffer->createNewAllocation(cmdBuffer);
+    finalized = false;
+}
+
+void MetalSamplerGroup::useResources(id<MTLRenderCommandEncoder> renderPassEncoder) {
+    assert_invariant(finalized);
+    if (@available(iOS 13, *)) {
+        // TODO: pass only the appropriate stages to useResources.
+        [renderPassEncoder useResources:textures.data()
+                                  count:textures.size()
+                                  usage:MTLResourceUsageRead | MTLResourceUsageSample
+                                 stages:MTLRenderStageFragment | MTLRenderStageVertex];
+    } else {
+        [renderPassEncoder useResources:textures.data()
+                                  count:textures.size()
+                                  usage:MTLResourceUsageRead | MTLResourceUsageSample];
+    }
+}
+
 MetalRenderTarget::MetalRenderTarget(MetalContext* context, uint32_t width, uint32_t height,
        uint8_t samples, Attachment colorAttachments[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT],
        Attachment depthAttachment, Attachment stencilAttachment) :
@@ -1244,193 +1335,5 @@ FenceStatus MetalFence::wait(uint64_t timeoutNs) {
    return FenceStatus::ERROR;
 }

-MetalDescriptorSetLayout::MetalDescriptorSetLayout(DescriptorSetLayout&& l) noexcept
-    : mLayout(std::move(l)) {
-    size_t dynamicBindings = 0;
-    for (const auto& binding : mLayout.bindings) {
-        if (any(binding.flags & DescriptorFlags::DYNAMIC_OFFSET)) {
-            dynamicBindings++;
-        }
-    }
-    mDynamicOffsetCount = dynamicBindings;
-}
-
-id<MTLArgumentEncoder> MetalDescriptorSetLayout::getArgumentEncoder(id<MTLDevice> device, ShaderStage stage,
-        utils::FixedCapacityVector<MTLTextureType> const& textureTypes) {
-    auto const index = static_cast<size_t>(stage);
-    assert_invariant(index < mCachedArgumentEncoder.size());
-    if (mCachedArgumentEncoder[index] &&
-            std::equal(
-                    textureTypes.begin(), textureTypes.end(), mCachedTextureTypes[index].begin())) {
-        return mCachedArgumentEncoder[index];
-    }
-    mCachedArgumentEncoder[index] = getArgumentEncoderSlow(device, stage, textureTypes);
-    mCachedTextureTypes[index] = textureTypes;
-    return mCachedArgumentEncoder[index];
-}
-
-id<MTLArgumentEncoder> MetalDescriptorSetLayout::getArgumentEncoderSlow(id<MTLDevice> device,
-        ShaderStage stage, utils::FixedCapacityVector<MTLTextureType> const& textureTypes) {
-    auto const& bindings = getBindings();
-    NSMutableArray<MTLArgumentDescriptor*>* arguments = [NSMutableArray new];
-    // Important! The bindings must be sorted by binding number. This has already been done inside
-    // createDescriptorSetLayout.
-    size_t textureIndex = 0;
-    for (auto const& binding : bindings) {
-        if (!hasShaderType(binding.stageFlags, stage)) {
-            continue;
-        }
-        switch (binding.type) {
-            case DescriptorType::UNIFORM_BUFFER:
-            case DescriptorType::SHADER_STORAGE_BUFFER: {
-                MTLArgumentDescriptor* bufferArgument = [MTLArgumentDescriptor argumentDescriptor];
-                bufferArgument.index = binding.binding * 2;
-                bufferArgument.dataType = MTLDataTypePointer;
-                bufferArgument.access = MTLArgumentAccessReadOnly;
-                [arguments addObject:bufferArgument];
-                break;
-            }
-            case DescriptorType::SAMPLER: {
-                MTLArgumentDescriptor* textureArgument = [MTLArgumentDescriptor argumentDescriptor];
-                textureArgument.index = binding.binding * 2;
-                textureArgument.dataType = MTLDataTypeTexture;
-                MTLTextureType textureType = MTLTextureType2D;
-                if (textureIndex < textureTypes.size()) {
-                    textureType = textureTypes[textureIndex++];
-                }
-                textureArgument.textureType = textureType;
-                textureArgument.access = MTLArgumentAccessReadOnly;
-                [arguments addObject:textureArgument];
-
-                MTLArgumentDescriptor* samplerArgument = [MTLArgumentDescriptor argumentDescriptor];
-                samplerArgument.index = binding.binding * 2 + 1;
-                samplerArgument.dataType = MTLDataTypeSampler;
-                textureArgument.access = MTLArgumentAccessReadOnly;
-                [arguments addObject:samplerArgument];
-                break;
-            }
-            case DescriptorType::INPUT_ATTACHMENT:
-                // TODO: support INPUT_ATTACHMENT
-                assert_invariant(false);
-                break;
-        }
-    }
-    return [device newArgumentEncoderWithArguments:arguments];
-}
-
-MetalDescriptorSet::MetalDescriptorSet(MetalDescriptorSetLayout* layout) noexcept
-    : layout(layout) {}
-
-void MetalDescriptorSet::finalize(MetalDriver* driver) {
-    [driver->mContext->currentRenderPassEncoder useResource:driver->mContext->emptyBuffer
-                                                      usage:MTLResourceUsageRead];
-    [driver->mContext->currentRenderPassEncoder
-            useResource:getOrCreateEmptyTexture(driver->mContext)
-                  usage:MTLResourceUsageRead];
-
-    if (@available(iOS 13.0, *)) {
-        [driver->mContext->currentRenderPassEncoder useResources:vertexResources.data()
-                                                           count:vertexResources.size()
-                                                           usage:MTLResourceUsageRead
-                                                          stages:MTLRenderStageVertex];
-        [driver->mContext->currentRenderPassEncoder useResources:fragmentResources.data()
-                                                           count:fragmentResources.size()
-                                                           usage:MTLResourceUsageRead
-                                                          stages:MTLRenderStageFragment];
-    } else {
-        [driver->mContext->currentRenderPassEncoder useResources:vertexResources.data()
-                                                           count:vertexResources.size()
-                                                           usage:MTLResourceUsageRead];
-        [driver->mContext->currentRenderPassEncoder useResources:fragmentResources.data()
-                                                           count:fragmentResources.size()
-                                                           usage:MTLResourceUsageRead];
-    }
-}
-
-id<MTLBuffer> MetalDescriptorSet::finalizeAndGetBuffer(MetalDriver* driver, ShaderStage stage) {
-    auto const index = static_cast<size_t>(stage);
-    assert_invariant(index < cachedBuffer.size());
-    auto& buffer = cachedBuffer[index];
-
-    if (buffer) {
-        return buffer.get();
-    }
-
-    // Map all the texture bindings to their respective texture types.
-    auto const& bindings = layout->getBindings();
-    auto textureTypes = utils::FixedCapacityVector<MTLTextureType>::with_capacity(bindings.size());
-    for (auto const& binding : bindings) {
-        if (!hasShaderType(binding.stageFlags, stage)) {
-            continue;
-        }
-        MTLTextureType textureType = MTLTextureType2D;
-        if (auto found = textures.find(binding.binding); found != textures.end()) {
-            auto const& textureBinding = textures[binding.binding];
-            textureType = textureBinding.texture.textureType;
-        }
-        textureTypes.push_back(textureType);
-    }
-
-    MetalContext const& context = *driver->mContext;
-
-    id<MTLArgumentEncoder> encoder =
-            layout->getArgumentEncoder(context.device, stage, textureTypes);
-
-    {
-        ScopedAllocationTimer timer("descriptor_set");
-        buffer = { [context.device newBufferWithLength:encoder.encodedLength
-                                               options:MTLResourceStorageModeShared],
-            TrackedMetalBuffer::Type::DESCRIPTOR_SET };
-    }
-    [encoder setArgumentBuffer:buffer.get() offset:0];
-
-    for (auto const& binding : bindings) {
-        if (!hasShaderType(binding.stageFlags, stage)) {
-            continue;
-        }
-        switch (binding.type) {
-            case DescriptorType::UNIFORM_BUFFER:
-            case DescriptorType::SHADER_STORAGE_BUFFER: {
-                auto found = buffers.find(binding.binding);
-                if (found == buffers.end()) {
-                    [encoder setBuffer:driver->mContext->emptyBuffer
-                                offset:0
-                               atIndex:binding.binding * 2];
-                    continue;
-                }
-
-                auto const& bufferBinding = buffers[binding.binding];
-                [encoder setBuffer:bufferBinding.buffer
-                            offset:bufferBinding.offset
-                           atIndex:binding.binding * 2];
-                break;
-            }
-            case DescriptorType::SAMPLER: {
-                auto found = textures.find(binding.binding);
-                if (found == textures.end()) {
-                    [encoder setTexture:driver->mContext->emptyTexture atIndex:binding.binding * 2];
-                    id<MTLSamplerState> sampler =
-                            driver->mContext->samplerStateCache.getOrCreateState({});
-                    [encoder setSamplerState:sampler atIndex:binding.binding * 2 + 1];
-                    continue;
-                }
-
-                auto const& textureBinding = textures[binding.binding];
-                [encoder setTexture:textureBinding.texture atIndex:binding.binding * 2];
-                SamplerState samplerState { .samplerParams = textureBinding.sampler };
-                id<MTLSamplerState> sampler =
-                        driver->mContext->samplerStateCache.getOrCreateState(samplerState);
-                [encoder setSamplerState:sampler atIndex:binding.binding * 2 + 1];
-                break;
-            }
-            case DescriptorType::INPUT_ATTACHMENT:
-                assert_invariant(false);
-                break;
-        }
-    }
-
-    return buffer.get();
-}
-
 } // namespace backend
 } // namespace filament
@@ -33,28 +33,32 @@
 namespace filament {
 namespace backend {

+inline bool operator==(const SamplerParams& lhs, const SamplerParams& rhs) {
+    return SamplerParams::EqualTo{}(lhs, rhs);
+}
+
 //   Rasterization Bindings
 //   ----------------------
 //   Bindings    Buffer name                          Count
 //   ------------------------------------------------------
 //   0           Zero buffer (placeholder vertex buffer)  1
 //   1-16        Filament vertex buffers                 16   limited by MAX_VERTEX_BUFFER_COUNT
-//   20          Push constants                           1
-//   21-24       Descriptor sets (argument buffers)       4   limited by MAX_DESCRIPTOR_SET_COUNT
-//   25          Dynamic offset buffer                    1
+//   17-25       Uniform buffers                          9   Program::UNIFORM_BINDING_COUNT
+//   26          Push constants                           1
+//   27-30       Sampler groups (argument buffers)        4   Program::SAMPLER_BINDING_COUNT
 //
-//   Total                                               23
+//   Total                                               31

 //   Compute Bindings
 //   ----------------------
 //   Bindings    Buffer name                          Count
 //   ------------------------------------------------------
 //   0-3         SSBO buffers                             4   MAX_SSBO_COUNT
-//   20          Push constants                           1
-//   21-24       Descriptor sets (argument buffers)       4   limited by MAX_DESCRIPTOR_SET_COUNT
-//   25          Dynamic offset buffer                    1
+//   17-25       Uniform buffers                          9   Program::UNIFORM_BINDING_COUNT
+//   26          Push constants                           1
+//   27-30       Sampler groups (argument buffers)        4   Program::SAMPLER_BINDING_COUNT
 //
-//   Total                                               10
+//   Total                                               18

 // The total number of vertex buffer "slots" that the Metal backend can bind.
 // + 1 to account for the zero buffer, a placeholder buffer used internally by the Metal backend.
@@ -67,11 +71,10 @@ static constexpr uint32_t ZERO_VERTEX_BUFFER_BINDING = 0u;

 static constexpr uint32_t USER_VERTEX_BUFFER_BINDING_START = 1u;

-
 // These constants must match the equivalent in CodeGenerator.h.
-static constexpr uint32_t PUSH_CONSTANT_BUFFER_INDEX = 20u;
-static constexpr uint32_t DESCRIPTOR_SET_BINDING_START = 21u;
-static constexpr uint32_t DYNAMIC_OFFSET_BINDING = 25u;
+static constexpr uint32_t UNIFORM_BUFFER_BINDING_START = 17u;
+static constexpr uint32_t SSBO_BINDING_START = 0u;
+static constexpr uint32_t SAMPLER_GROUP_BINDING_START = 27u;

 // Forward declarations necessary here, definitions at end of file.
 inline bool operator==(const MTLViewport& lhs, const MTLViewport& rhs);
@@ -384,17 +387,14 @@ using DepthClampStateTracker = StateTracker<MTLDepthClipMode>;
 // Argument encoder

 struct ArgumentEncoderState {
-    NSUInteger bufferCount;
    utils::FixedCapacityVector<MTLTextureType> textureTypes;

-    explicit ArgumentEncoderState(
-            NSUInteger bufferCount, utils::FixedCapacityVector<MTLTextureType>&& types)
-        : bufferCount(bufferCount), textureTypes(std::move(types)) {}
+    explicit ArgumentEncoderState(utils::FixedCapacityVector<MTLTextureType>&& types)
+        : textureTypes(std::move(types)) {}

    bool operator==(const ArgumentEncoderState& rhs) const noexcept {
        return std::equal(textureTypes.begin(), textureTypes.end(), rhs.textureTypes.begin(),
-                       rhs.textureTypes.end()) &&
-                bufferCount == rhs.bufferCount;
+                rhs.textureTypes.end());
    }

    bool operator!=(const ArgumentEncoderState& rhs) const noexcept {
@@ -416,30 +416,6 @@ struct ArgumentEncoderCreator {
 using ArgumentEncoderCache = StateCache<ArgumentEncoderState, id<MTLArgumentEncoder>,
        ArgumentEncoderCreator, ArgumentEncoderHasher>;

-template <NSUInteger N, ShaderStage stage>
-class MetalBufferBindings {
-public:
-    MetalBufferBindings() { invalidate(); }
-
-    void invalidate() {
-        mDirtyBuffers.reset();
-        mDirtyOffsets.reset();
-        for (int i = 0; i < int(N); i++) {
-            mDirtyBuffers.set(i, true);
-            mDirtyOffsets.set(i, true);
-        }
-    }
-    void setBuffer(const id<MTLBuffer> buffer, NSUInteger offset, NSUInteger index);
-    void bindBuffers(id<MTLCommandEncoder> encoder, NSUInteger startIndex);
-
-private:
-    static_assert(N <= 8);
-    std::array<__weak id<MTLBuffer>, N> mBuffers = { nil };
-    std::array<NSUInteger, N> mOffsets = { 0 };
-    utils::bitset8 mDirtyBuffers;
-    utils::bitset8 mDirtyOffsets;
-};
-
 } // namespace backend
 } // namespace filament

@@ -166,40 +166,28 @@ id<MTLSamplerState> SamplerStateCreator::operator()(id<MTLDevice> device,
 id<MTLArgumentEncoder> ArgumentEncoderCreator::operator()(id<MTLDevice> device,
        const ArgumentEncoderState &state) noexcept {
    const auto& textureTypes = state.textureTypes;
-    const auto& textureCount = textureTypes.size();
-    const auto& bufferCount = state.bufferCount;
-    assert_invariant(textureCount > 0);
+    const auto& count = textureTypes.size();
+    assert_invariant(count > 0);

    // Metal has separate data types for textures versus samplers, so the argument buffer layout
    // alternates between texture and sampler, i.e.:
-    // buffer0
-    // buffer1
    // textureA
    // samplerA
    // textureB
    // samplerB
    // etc
    NSMutableArray<MTLArgumentDescriptor*>* arguments =
-            [NSMutableArray arrayWithCapacity:(bufferCount + textureCount * 2)];
-    size_t i = 0;
-    for (size_t j = 0; j < bufferCount; j++) {
-        MTLArgumentDescriptor* bufferArgument = [MTLArgumentDescriptor argumentDescriptor];
-        bufferArgument.index = i++;
-        bufferArgument.dataType = MTLDataTypePointer;
-        bufferArgument.access = MTLArgumentAccessReadOnly;
-        [arguments addObject:bufferArgument];
-    }
-
-    for (size_t j = 0; j < textureCount; j++) {
+            [NSMutableArray arrayWithCapacity:(count * 2)];
+    for (size_t i = 0; i < count; i++) {
        MTLArgumentDescriptor* textureArgument = [MTLArgumentDescriptor argumentDescriptor];
-        textureArgument.index = i++;
+        textureArgument.index = i * 2 + 0;
        textureArgument.dataType = MTLDataTypeTexture;
        textureArgument.textureType = textureTypes[i];
        textureArgument.access = MTLArgumentAccessReadOnly;
        [arguments addObject:textureArgument];

        MTLArgumentDescriptor* samplerArgument = [MTLArgumentDescriptor argumentDescriptor];
-        samplerArgument.index = i++;
+        samplerArgument.index = i * 2 + 1;
        samplerArgument.dataType = MTLDataTypeSampler;
        textureArgument.access = MTLArgumentAccessReadOnly;
        [arguments addObject:samplerArgument];
@@ -208,64 +196,5 @@ id<MTLArgumentEncoder> ArgumentEncoderCreator::operator()(id<MTLDevice> device,
    return [device newArgumentEncoderWithArguments:arguments];
 }

-template <NSUInteger N, ShaderStage stage>
-void MetalBufferBindings<N, stage>::setBuffer(const id<MTLBuffer> buffer, NSUInteger offset, NSUInteger index) {
-    assert_invariant(offset + 1 <= N);
-
-    if (mBuffers[index] != buffer) {
-        mBuffers[index] = buffer;
-        mDirtyBuffers.set(index);
-    }
-
-    if (mOffsets[index] != offset) {
-        mOffsets[index] = offset;
-        mDirtyOffsets.set(index);
-    }
-}
-
-template <NSUInteger N, ShaderStage stage>
-void MetalBufferBindings<N, stage>::bindBuffers(
-        id<MTLCommandEncoder> encoder, NSUInteger startIndex) {
-    if (mDirtyBuffers.none() && mDirtyOffsets.none()) {
-        return;
-    }
-
-    utils::bitset8 onlyOffsetDirty = mDirtyOffsets & ~mDirtyBuffers;
-    onlyOffsetDirty.forEachSetBit([&](size_t i) {
-        if constexpr (stage == ShaderStage::VERTEX) {
-            [(id<MTLRenderCommandEncoder>)encoder setVertexBufferOffset:mOffsets[i]
-                                                                atIndex:i + startIndex];
-        } else if constexpr (stage == ShaderStage::FRAGMENT) {
-            [(id<MTLRenderCommandEncoder>)encoder setFragmentBufferOffset:mOffsets[i]
-                                                                  atIndex:i + startIndex];
-        } else if constexpr (stage == ShaderStage::COMPUTE) {
-            [(id<MTLComputeCommandEncoder>)encoder setBufferOffset:mOffsets[i]
-                                                           atIndex:i + startIndex];
-        }
-    });
-    mDirtyOffsets.reset();
-
-    mDirtyBuffers.forEachSetBit([&](size_t i) {
-        if constexpr (stage == ShaderStage::VERTEX) {
-            [(id<MTLRenderCommandEncoder>)encoder setVertexBuffer:mBuffers[i]
-                                                           offset:mOffsets[i]
-                                                          atIndex:i + startIndex];
-        } else if constexpr (stage == ShaderStage::FRAGMENT) {
-            [(id<MTLRenderCommandEncoder>)encoder setFragmentBuffer:mBuffers[i]
-                                                             offset:mOffsets[i]
-                                                            atIndex:i + startIndex];
-        } else if constexpr (stage == ShaderStage::COMPUTE) {
-            [(id<MTLComputeCommandEncoder>)encoder setBuffer:mBuffers[i]
-                                                      offset:mOffsets[i]
-                                                     atIndex:i + startIndex];
-        }
-    });
-    mDirtyBuffers.reset();
-}
-
-template class MetalBufferBindings<MAX_DESCRIPTOR_SET_COUNT, ShaderStage::VERTEX>;
-template class MetalBufferBindings<MAX_DESCRIPTOR_SET_COUNT, ShaderStage::FRAGMENT>;
-template class MetalBufferBindings<MAX_DESCRIPTOR_SET_COUNT, ShaderStage::COMPUTE>;
-
 } // namespace backend
 } // namespace filament
@@ -54,7 +54,7 @@ void NoopDriver::beginFrame(int64_t monotonic_clock_ns,
 }

 void NoopDriver::setFrameScheduledCallback(Handle<HwSwapChain> sch,
-        CallbackHandler* handler, FrameScheduledCallback&& callback, uint64_t flags) {
+        CallbackHandler* handler, FrameScheduledCallback&& callback) {

 }

@@ -99,6 +99,9 @@ void NoopDriver::destroyProgram(Handle<HwProgram> ph) {
 void NoopDriver::destroyRenderTarget(Handle<HwRenderTarget> rth) {
 }

+void NoopDriver::destroySamplerGroup(Handle<HwSamplerGroup> sbh) {
+}
+
 void NoopDriver::destroySwapChain(Handle<HwSwapChain> sch) {
 }

@@ -108,12 +111,6 @@ void NoopDriver::destroyStream(Handle<HwStream> sh) {
 void NoopDriver::destroyTimerQuery(Handle<HwTimerQuery> tqh) {
 }

-void NoopDriver::destroyDescriptorSetLayout(Handle<HwDescriptorSetLayout> tqh) {
-}
-
-void NoopDriver::destroyDescriptorSet(Handle<HwDescriptorSet> tqh) {
-}
-
 Handle<HwStream> NoopDriver::createStreamNative(void* nativeStream) {
    return {};
 }
@@ -251,6 +248,9 @@ void NoopDriver::setVertexBufferObject(Handle<HwVertexBuffer> vbh, uint32_t inde
        Handle<HwBufferObject> boh) {
 }

+void NoopDriver::setMinMaxLevels(Handle<HwTexture> th, uint32_t minLevel, uint32_t maxLevel) {
+}
+
 void NoopDriver::update3DImage(Handle<HwTexture> th,
        uint32_t level, uint32_t xoffset, uint32_t yoffset, uint32_t zoffset,
        uint32_t width, uint32_t height, uint32_t depth,
@@ -276,6 +276,11 @@ void NoopDriver::setExternalStream(Handle<HwTexture> th, Handle<HwStream> sh) {

 void NoopDriver::generateMipmaps(Handle<HwTexture> th) { }

+void NoopDriver::updateSamplerGroup(Handle<HwSamplerGroup> sbh,
+        BufferDescriptor&& data) {
+    scheduleDestroy(std::move(data));
+}
+
 void NoopDriver::compilePrograms(CompilerPriorityQueue priority,
        CallbackHandler* handler, CallbackHandler::Callback callback, void* user) {
    if (callback) {
@@ -298,6 +303,19 @@ void NoopDriver::makeCurrent(Handle<HwSwapChain> drawSch, Handle<HwSwapChain> re
 void NoopDriver::commit(Handle<HwSwapChain> sch) {
 }

+void NoopDriver::bindUniformBuffer(uint32_t index, Handle<HwBufferObject> ubh) {
+}
+
+void NoopDriver::bindBufferRange(BufferObjectBinding bindingType, uint32_t index,
+        Handle<HwBufferObject> ubh, uint32_t offset, uint32_t size) {
+}
+
+void NoopDriver::unbindBuffer(BufferObjectBinding bindingType, uint32_t index) {
+}
+
+void NoopDriver::bindSamplers(uint32_t index, Handle<HwSamplerGroup> sbh) {
+}
+
 void NoopDriver::setPushConstant(backend::ShaderStage stage, uint8_t index,
        backend::PushConstantVariant value) {
 }
@@ -374,27 +392,6 @@ void NoopDriver::endTimerQuery(Handle<HwTimerQuery> tqh) {
 void NoopDriver::resetState(int) {
 }

-void NoopDriver::updateDescriptorSetBuffer(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_binding_t binding,
-        backend::BufferObjectHandle boh,
-        uint32_t offset,
-        uint32_t size) {
-}
-
-void NoopDriver::updateDescriptorSetTexture(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_binding_t binding,
-        backend::TextureHandle th,
-        SamplerParams params) {
-}
-
-void NoopDriver::bindDescriptorSet(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_set_t set,
-        backend::DescriptorSetOffsetArray&& offsets) {
-}
-
 void NoopDriver::setDebugTag(HandleBase::HandleId handleId, utils::CString tag) {
 }

@@ -1,89 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_OPENGL_BINDINGMAP_H
-#define TNT_FILAMENT_BACKEND_OPENGL_BINDINGMAP_H
-
-#include <backend/DriverEnums.h>
-
-#include "gl_headers.h"
-
-#include <utils/bitset.h>
-#include <utils/debug.h>
-
-#include <new>
-
-#include <stddef.h>
-#include <stdint.h>
-#include <string.h>
-
-namespace filament::backend {
-
-class BindingMap {
-    struct CompressedBinding {
-        // this is in fact a GLuint, but we only want 8-bits
-        uint8_t binding : 7;
-        uint8_t sampler : 1;
-    };
-
-    CompressedBinding (*mStorage)[MAX_DESCRIPTOR_COUNT];
-
-    utils::bitset64 mActiveDescriptors[MAX_DESCRIPTOR_SET_COUNT];
-
-public:
-    BindingMap() noexcept
-            : mStorage(new (std::nothrow) CompressedBinding[MAX_DESCRIPTOR_SET_COUNT][MAX_DESCRIPTOR_COUNT]) {
-#ifndef NDEBUG
-        memset(mStorage, 0xFF, sizeof(CompressedBinding[MAX_DESCRIPTOR_SET_COUNT][MAX_DESCRIPTOR_COUNT]));
-#endif
-    }
-
-    ~BindingMap() noexcept {
-        delete [] mStorage;
-    }
-
-    BindingMap(BindingMap const&) noexcept = delete;
-    BindingMap(BindingMap&&) noexcept = delete;
-    BindingMap& operator=(BindingMap const&) noexcept = delete;
-    BindingMap& operator=(BindingMap&&) noexcept = delete;
-
-    struct Binding {
-        GLuint binding;
-        DescriptorType type;
-    };
-
-    void insert(descriptor_set_t set, descriptor_binding_t binding, Binding entry) noexcept {
-        assert_invariant(set < MAX_DESCRIPTOR_SET_COUNT);
-        assert_invariant(binding < MAX_DESCRIPTOR_COUNT);
-        assert_invariant(entry.binding < 128); // we reserve 1 bit for the type right now
-        mStorage[set][binding] = { (uint8_t)entry.binding, entry.type == DescriptorType::SAMPLER };
-        mActiveDescriptors[set].set(binding);
-    }
-
-    GLuint get(descriptor_set_t set, descriptor_binding_t binding) const noexcept {
-        assert_invariant(set < MAX_DESCRIPTOR_SET_COUNT);
-        assert_invariant(binding < MAX_DESCRIPTOR_COUNT);
-        return mStorage[set][binding].binding;
-    }
-
-    utils::bitset64 getActiveDescriptors(descriptor_set_t set) const noexcept {
-        return mActiveDescriptors[set];
-    }
-};
-
-} // namespace filament::backend
-
-#endif //TNT_FILAMENT_BACKEND_OPENGL_BINDINGMAP_H
@@ -1,363 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "GLDescriptorSet.h"
-
-#include "GLBufferObject.h"
-#include "GLDescriptorSetLayout.h"
-#include "GLTexture.h"
-#include "GLUtils.h"
-#include "OpenGLDriver.h"
-#include "OpenGLContext.h"
-#include "OpenGLProgram.h"
-
-#include "gl_headers.h"
-
-#include <private/backend/HandleAllocator.h>
-
-#include <backend/DriverEnums.h>
-#include <backend/Handle.h>
-
-#include <utils/BitmaskEnum.h>
-#include <utils/Log.h>
-#include <utils/Panic.h>
-#include <utils/bitset.h>
-#include <utils/compiler.h>
-#include <utils/debug.h>
-#include <algorithm>
-
-#include <type_traits>
-#include <utility>
-#include <variant>
-
-#include <stddef.h>
-#include <stdint.h>
-
-namespace filament::backend {
-
-GLDescriptorSet::GLDescriptorSet(OpenGLContext& gl, DescriptorSetLayoutHandle dslh,
-        GLDescriptorSetLayout const* layout) noexcept
-        : descriptors(layout->maxDescriptorBinding + 1),
-          dslh(std::move(dslh)) {
-
-    // We have allocated enough storage for all descriptors. Now allocate the empty descriptor
-    // themselves.
-    for (auto const& entry : layout->bindings) {
-        size_t const index = entry.binding;
-
-        // now we'll initialize the alternative for each way we can handle this descriptor.
-        auto& desc = descriptors[index].desc;
-        switch (entry.type) {
-            case DescriptorType::UNIFORM_BUFFER: {
-                // A uniform buffer can have dynamic offsets or not and have special handling for
-                // ES2 (where we need to emulate it). That's four alternatives.
-                bool const dynamicOffset = any(entry.flags & DescriptorFlags::DYNAMIC_OFFSET);
-                dynamicBuffers.set(index, dynamicOffset);
-                if (UTILS_UNLIKELY(gl.isES2())) {
-                    if (dynamicOffset) {
-                        dynamicBufferCount++;
-                    }
-                    desc.emplace<BufferGLES2>(dynamicOffset);
-                } else {
-                    auto const type = GLUtils::getBufferBindingType(BufferObjectBinding::UNIFORM);
-                    if (dynamicOffset) {
-                        dynamicBufferCount++;
-                        desc.emplace<DynamicBuffer>(type);
-                    } else {
-                        desc.emplace<Buffer>(type);
-                    }
-                }
-                break;
-            }
-            case DescriptorType::SHADER_STORAGE_BUFFER: {
-                // shader storage buffers are not supported on ES2, So that's two alternatives.
-                bool const dynamicOffset = any(entry.flags & DescriptorFlags::DYNAMIC_OFFSET);
-                dynamicBuffers.set(index, dynamicOffset);
-                auto const type = GLUtils::getBufferBindingType(BufferObjectBinding::SHADER_STORAGE);
-                if (dynamicOffset) {
-                    dynamicBufferCount++;
-                    desc.emplace<DynamicBuffer>(type);
-                } else {
-                    desc.emplace<Buffer>(type);
-                }
-                break;
-            }
-            case DescriptorType::SAMPLER:
-                if (UTILS_UNLIKELY(gl.isES2())) {
-                    desc.emplace<SamplerGLES2>();
-                } else {
-                    const bool anisotropyWorkaround =
-                            gl.ext.EXT_texture_filter_anisotropic &&
-                            gl.bugs.texture_filter_anisotropic_broken_on_sampler;
-                    if (anisotropyWorkaround) {
-                        desc.emplace<SamplerWithAnisotropyWorkaround>();
-                    } else {
-                        desc.emplace<Sampler>();
-                    }
-                }
-                break;
-            case DescriptorType::INPUT_ATTACHMENT:
-                break;
-        }
-    }
-}
-
-void GLDescriptorSet::update(OpenGLContext&,
-        descriptor_binding_t binding, GLBufferObject* bo, size_t offset, size_t size) noexcept {
-    assert_invariant(binding < descriptors.size());
-    std::visit([=](auto&& arg) {
-        using T = std::decay_t<decltype(arg)>;
-        if constexpr (std::is_same_v<T, Buffer> || std::is_same_v<T, DynamicBuffer>) {
-            assert_invariant(arg.target != 0);
-            arg.id = bo ? bo->gl.id : 0;
-            arg.offset = uint32_t(offset);
-            arg.size = uint32_t(size);
-            assert_invariant(arg.id || (!arg.size && !offset));
-        } else if constexpr (std::is_same_v<T, BufferGLES2>) {
-            arg.bo = bo;
-            arg.offset = uint32_t(offset);
-        } else {
-            // API usage error. User asked to update the wrong type of descriptor.
-            PANIC_PRECONDITION("descriptor %d is not a buffer", +binding);
-        }
-    }, descriptors[binding].desc);
-}
-
-void GLDescriptorSet::update(OpenGLContext& gl,
-        descriptor_binding_t binding, GLTexture* t, SamplerParams params) noexcept {
-    assert_invariant(binding < descriptors.size());
-    std::visit([=, &gl](auto&& arg) mutable {
-        using T = std::decay_t<decltype(arg)>;
-        if constexpr (std::is_same_v<T, Sampler> ||
-                      std::is_same_v<T, SamplerWithAnisotropyWorkaround> ||
-                      std::is_same_v<T, SamplerGLES2>) {
-            if (UTILS_UNLIKELY(t && t->target == SamplerType::SAMPLER_EXTERNAL)) {
-                // From OES_EGL_image_external spec:
-                // "The default s and t wrap modes are CLAMP_TO_EDGE, and it is an INVALID_ENUM
-                //  error to set the wrap mode to any other value."
-                params.wrapS = SamplerWrapMode::CLAMP_TO_EDGE;
-                params.wrapT = SamplerWrapMode::CLAMP_TO_EDGE;
-                params.wrapR = SamplerWrapMode::CLAMP_TO_EDGE;
-            }
-            // GLES3.x specification forbids depth textures to be filtered.
-            if (t && isDepthFormat(t->format)
-                    && params.compareMode == SamplerCompareMode::NONE) {
-                params.filterMag = SamplerMagFilter::NEAREST;
-                switch (params.filterMin) {
-                    case SamplerMinFilter::LINEAR:
-                        params.filterMin = SamplerMinFilter::NEAREST;
-                        break;
-                    case SamplerMinFilter::LINEAR_MIPMAP_NEAREST:
-                    case SamplerMinFilter::NEAREST_MIPMAP_LINEAR:
-                    case SamplerMinFilter::LINEAR_MIPMAP_LINEAR:
-                        params.filterMin = SamplerMinFilter::NEAREST_MIPMAP_NEAREST;
-                        break;
-                    default:
-                        break;
-                }
-            }
-
-            arg.target = t ? t->gl.target : 0;
-            arg.id = t ? t->gl.id : 0;
-            if constexpr (std::is_same_v<T, Sampler> ||
-                          std::is_same_v<T, SamplerWithAnisotropyWorkaround>) {
-                if constexpr (std::is_same_v<T, SamplerWithAnisotropyWorkaround>) {
-                    arg.anisotropy = float(1u << params.anisotropyLog2);
-                }
-                if (t) {
-                    arg.ref = t->ref;
-                    arg.baseLevel = t->gl.baseLevel;
-                    arg.maxLevel = t->gl.maxLevel;
-                    arg.swizzle = t->gl.swizzle;
-                }
-#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
-                arg.sampler = gl.getSampler(params);
-#else
-                (void)gl;
-#endif
-            } else {
-                arg.params = params;
-            }
-        } else {
-            // API usage error. User asked to update the wrong type of descriptor.
-            PANIC_PRECONDITION("descriptor %d is not a texture", +binding);
-        }
-    }, descriptors[binding].desc);
-}
-
-template<typename T>
-void GLDescriptorSet::updateTextureView(OpenGLContext& gl,
-        HandleAllocatorGL& handleAllocator, GLuint unit, T const& desc) noexcept {
-    // The common case is that we don't have a ref handle (we only have one if
-    // the texture ever had a View on it).
-    assert_invariant(desc.ref);
-    GLTextureRef* const ref = handleAllocator.handle_cast<GLTextureRef*>(desc.ref);
-    if (UTILS_UNLIKELY((desc.baseLevel != ref->baseLevel || desc.maxLevel != ref->maxLevel))) {
-        // If we have views, then it's still uncommon that we'll switch often
-        // handle the case where we reset to the original texture
-        GLint baseLevel = GLint(desc.baseLevel); // NOLINT(*-signed-char-misuse)
-        GLint maxLevel = GLint(desc.maxLevel); // NOLINT(*-signed-char-misuse)
-        if (baseLevel > maxLevel) {
-            baseLevel = 0;
-            maxLevel = 1000; // per OpenGL spec
-        }
-        // that is very unfortunate that we have to call activeTexture here
-        gl.activeTexture(unit);
-        glTexParameteri(desc.target, GL_TEXTURE_BASE_LEVEL, baseLevel);
-        glTexParameteri(desc.target, GL_TEXTURE_MAX_LEVEL,  maxLevel);
-        ref->baseLevel = desc.baseLevel;
-        ref->maxLevel = desc.maxLevel;
-    }
-    if (UTILS_UNLIKELY(desc.swizzle != ref->swizzle)) {
-        using namespace GLUtils;
-        gl.activeTexture(unit);
-#if !defined(__EMSCRIPTEN__)  && !defined(FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2)
-        glTexParameteri(desc.target, GL_TEXTURE_SWIZZLE_R, (GLint)getSwizzleChannel(desc.swizzle[0]));
-        glTexParameteri(desc.target, GL_TEXTURE_SWIZZLE_G, (GLint)getSwizzleChannel(desc.swizzle[1]));
-        glTexParameteri(desc.target, GL_TEXTURE_SWIZZLE_B, (GLint)getSwizzleChannel(desc.swizzle[2]));
-        glTexParameteri(desc.target, GL_TEXTURE_SWIZZLE_A, (GLint)getSwizzleChannel(desc.swizzle[3]));
-#endif
-        ref->swizzle = desc.swizzle;
-    }
-}
-
-void GLDescriptorSet::bind(
-        OpenGLContext& gl,
-        HandleAllocatorGL& handleAllocator,
-        OpenGLProgram const& p,
-        descriptor_set_t set, uint32_t const* offsets, bool offsetsOnly) const noexcept {
-    // TODO: check that offsets is sized correctly
-    size_t dynamicOffsetIndex = 0;
-
-    utils::bitset64 activeDescriptorBindings = p.getActiveDescriptors(set);
-    if (offsetsOnly) {
-        activeDescriptorBindings &= dynamicBuffers;
-    }
-
-    // loop only over the active indices for this program
-    activeDescriptorBindings.forEachSetBit(
-            [this,&gl, &handleAllocator, &p, set, offsets, &dynamicOffsetIndex]
-            (size_t binding) {
-
-        // This would fail here if we're trying to set a descriptor that doesn't exist in the
-        // program. In other words, a mismatch between the program's layout and this descriptor-set.
-        assert_invariant(binding < descriptors.size());
-
-        auto const& entry = descriptors[binding];
-        std::visit(
-                [&gl, &handleAllocator, &p, &dynamicOffsetIndex, set, binding, offsets]
-                (auto&& arg) {
-            using T = std::decay_t<decltype(arg)>;
-            if constexpr (std::is_same_v<T, Buffer>) {
-                GLuint const bindingPoint = p.getBufferBinding(set, binding);
-                GLintptr const offset = arg.offset;
-                assert_invariant(arg.id || (!arg.size && !offset));
-                gl.bindBufferRange(arg.target, bindingPoint, arg.id, offset, arg.size);
-            } else if constexpr (std::is_same_v<T, DynamicBuffer>) {
-                GLuint const bindingPoint = p.getBufferBinding(set, binding);
-                GLintptr const offset = arg.offset + offsets[dynamicOffsetIndex++];
-                assert_invariant(arg.id || (!arg.size && !offset));
-                gl.bindBufferRange(arg.target, bindingPoint, arg.id, offset, arg.size);
-            } else if constexpr (std::is_same_v<T, BufferGLES2>) {
-                GLuint const bindingPoint = p.getBufferBinding(set, binding);
-                GLintptr offset = arg.offset;
-                if (arg.dynamicOffset) {
-                    offset += offsets[dynamicOffsetIndex++];
-                }
-                if (arg.bo) {
-                    auto buffer = static_cast<char const*>(arg.bo->gl.buffer) + offset;
-                    p.updateUniforms(bindingPoint, arg.bo->gl.id, buffer, arg.bo->age);
-                }
-            } else if constexpr (std::is_same_v<T, Sampler>) {
-                GLuint const unit = p.getTextureUnit(set, binding);
-                if (arg.target) {
-                    gl.bindTexture(unit, arg.target, arg.id);
-                    gl.bindSampler(unit, arg.sampler);
-                    if (UTILS_UNLIKELY(arg.ref)) {
-                        updateTextureView(gl, handleAllocator, unit, arg);
-                    }
-                } else {
-                    gl.unbindTextureUnit(unit);
-                }
-            } else if constexpr (std::is_same_v<T, SamplerWithAnisotropyWorkaround>) {
-                GLuint const unit = p.getTextureUnit(set, binding);
-                if (arg.target) {
-                    gl.bindTexture(unit, arg.target, arg.id);
-                    gl.bindSampler(unit, arg.sampler);
-                    if (UTILS_UNLIKELY(arg.ref)) {
-                        updateTextureView(gl, handleAllocator, unit, arg);
-                    }
-#if defined(GL_EXT_texture_filter_anisotropic)
-                    // Driver claims to support anisotropic filtering, but it fails when set on
-                    // the sampler, we have to set it on the texture instead.
-                    glTexParameterf(arg.target, GL_TEXTURE_MAX_ANISOTROPY_EXT,
-                            std::min(gl.gets.max_anisotropy, float(arg.anisotropy)));
-#endif
-                } else {
-                    gl.unbindTextureUnit(unit);
-                }
-            } else if constexpr (std::is_same_v<T, SamplerGLES2>) {
-                // in ES2 the sampler parameters need to be set on the texture itself
-                GLuint const unit = p.getTextureUnit(set, binding);
-                if (arg.target) {
-                    gl.bindTexture(unit, arg.target, arg.id);
-                    SamplerParams const params = arg.params;
-                    glTexParameteri(arg.target, GL_TEXTURE_MIN_FILTER,
-                            (GLint)GLUtils::getTextureFilter(params.filterMin));
-                    glTexParameteri(arg.target, GL_TEXTURE_MAG_FILTER,
-                            (GLint)GLUtils::getTextureFilter(params.filterMag));
-                    glTexParameteri(arg.target, GL_TEXTURE_WRAP_S,
-                            (GLint)GLUtils::getWrapMode(params.wrapS));
-                    glTexParameteri(arg.target, GL_TEXTURE_WRAP_T,
-                            (GLint)GLUtils::getWrapMode(params.wrapT));
-#if defined(GL_EXT_texture_filter_anisotropic)
-                    glTexParameterf(arg.target, GL_TEXTURE_MAX_ANISOTROPY_EXT,
-                            std::min(gl.gets.max_anisotropy, arg.anisotropy));
-#endif
-                } else {
-                    gl.unbindTextureUnit(unit);
-                }
-            }
-        }, entry.desc);
-    });
-    CHECK_GL_ERROR(utils::slog.e)
-}
-
-void GLDescriptorSet::validate(HandleAllocatorGL& allocator,
-        DescriptorSetLayoutHandle pipelineLayout) const {
-
-    if (UTILS_UNLIKELY(dslh != pipelineLayout)) {
-        auto* const dsl = allocator.handle_cast < GLDescriptorSetLayout const * > (dslh);
-        auto* const cur = allocator.handle_cast < GLDescriptorSetLayout const * > (pipelineLayout);
-
-        UTILS_UNUSED_IN_RELEASE
-        bool const pipelineLayoutMatchesDescriptorSetLayout = std::equal(
-                dsl->bindings.begin(), dsl->bindings.end(),
-                cur->bindings.begin(),
-                [](DescriptorSetLayoutBinding const& lhs,
-                        DescriptorSetLayoutBinding const& rhs) {
-                    return lhs.type == rhs.type &&
-                           lhs.stageFlags == rhs.stageFlags &&
-                           lhs.binding == rhs.binding &&
-                           lhs.flags == rhs.flags &&
-                           lhs.count == rhs.count;
-                });
-
-        assert_invariant(pipelineLayoutMatchesDescriptorSetLayout);
-    }
-}
-
-} // namespace filament::backend
@@ -1,175 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSET_H
-#define TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSET_H
-
-#include "DriverBase.h"
-
-#include "gl_headers.h"
-
-#include <private/backend/HandleAllocator.h>
-
-#include <backend/DriverEnums.h>
-#include <backend/Handle.h>
-
-#include <utils/bitset.h>
-#include <utils/FixedCapacityVector.h>
-
-#include <math/half.h>
-
-#include <array>
-#include <variant>
-
-#include <stddef.h>
-#include <stdint.h>
-
-namespace filament::backend {
-
-struct GLBufferObject;
-struct GLTexture;
-struct GLTextureRef;
-struct GLDescriptorSetLayout;
-class OpenGLProgram;
-class OpenGLContext;
-class OpenGLDriver;
-
-struct GLDescriptorSet : public HwDescriptorSet {
-
-    using HwDescriptorSet::HwDescriptorSet;
-
-    GLDescriptorSet(OpenGLContext& gl, DescriptorSetLayoutHandle dslh,
-            GLDescriptorSetLayout const* layout) noexcept;
-
-    // update a buffer descriptor in the set
-    void update(OpenGLContext& gl,
-            descriptor_binding_t binding, GLBufferObject* bo, size_t offset, size_t size) noexcept;
-
-    // update a sampler descriptor in the set
-    void update(OpenGLContext& gl,
-            descriptor_binding_t binding, GLTexture* t, SamplerParams params) noexcept;
-
-    // conceptually bind the set to the command buffer
-    void bind(
-            OpenGLContext& gl,
-            HandleAllocatorGL& handleAllocator,
-            OpenGLProgram const& p,
-            descriptor_set_t set, uint32_t const* offsets, bool offsetsOnly) const noexcept;
-
-    uint32_t getDynamicBufferCount() const noexcept {
-        return dynamicBufferCount;
-    }
-
-    void validate(HandleAllocatorGL& allocator, DescriptorSetLayoutHandle pipelineLayout) const;
-
-private:
-    // a Buffer Descriptor such as SSBO or UBO with static offset
-    struct Buffer {
-        // Workaround: we cannot define the following as Buffer() = default because one of our
-        // clients has their compiler set up where such declaration (possibly coupled with explicit)
-        // will be considered a deleted constructor.
-        Buffer() {}
-
-        explicit Buffer(GLenum target) noexcept : target(target) {}
-        GLenum target;                          // 4
-        GLuint id = 0;                          // 4
-        uint32_t offset = 0;                    // 4
-        uint32_t size = 0;                      // 4
-    };
-
-    // a Buffer Descriptor such as SSBO or UBO with dynamic offset
-    struct DynamicBuffer {
-        DynamicBuffer() = default;
-        explicit DynamicBuffer(GLenum target) noexcept : target(target) { }
-        GLenum target;                          // 4
-        GLuint id = 0;                          // 4
-        uint32_t offset = 0;                    // 4
-        uint32_t size = 0;                      // 4
-    };
-
-    // a UBO descriptor for ES2
-    struct BufferGLES2 {
-        BufferGLES2() = default;
-        explicit BufferGLES2(bool dynamicOffset) noexcept : dynamicOffset(dynamicOffset) { }
-        GLBufferObject const* bo = nullptr;     // 8
-        uint32_t offset = 0;                    // 4
-        bool dynamicOffset = false;             // 4
-    };
-
-    // A sampler descriptor
-    struct Sampler {
-        GLenum target = 0;                      // 4
-        GLuint id = 0;                          // 4
-        GLuint sampler = 0;                     // 4
-        Handle<GLTextureRef> ref;               // 4
-        int8_t baseLevel = 0x7f;                // 1
-        int8_t maxLevel = -1;                   // 1
-        std::array<TextureSwizzle, 4> swizzle{  // 4
-                TextureSwizzle::CHANNEL_0,
-                TextureSwizzle::CHANNEL_1,
-                TextureSwizzle::CHANNEL_2,
-                TextureSwizzle::CHANNEL_3
-        };
-    };
-
-    struct SamplerWithAnisotropyWorkaround {
-        GLenum target = 0;                      // 4
-        GLuint id = 0;                          // 4
-        GLuint sampler = 0;                     // 4
-        Handle<GLTextureRef> ref;               // 4
-        math::half anisotropy = 1.0f;           // 2
-        int8_t baseLevel = 0x7f;                // 1
-        int8_t maxLevel = -1;                   // 1
-        std::array<TextureSwizzle, 4> swizzle{  // 4
-                TextureSwizzle::CHANNEL_0,
-                TextureSwizzle::CHANNEL_1,
-                TextureSwizzle::CHANNEL_2,
-                TextureSwizzle::CHANNEL_3
-        };
-    };
-
-    // A sampler descriptor for ES2
-    struct SamplerGLES2 {
-        GLenum target = 0;                      // 4
-        GLuint id = 0;                          // 4
-        SamplerParams params{};                 // 4
-        float anisotropy = 1.0f;                // 4
-    };
-    struct Descriptor {
-        std::variant<
-                Buffer,
-                DynamicBuffer,
-                BufferGLES2,
-                Sampler,
-                SamplerWithAnisotropyWorkaround,
-                SamplerGLES2> desc;
-    };
-    static_assert(sizeof(Descriptor) <= 32);
-
-    template<typename T>
-    static void updateTextureView(OpenGLContext& gl,
-            HandleAllocatorGL& handleAllocator, GLuint unit, T const& desc) noexcept;
-
-    utils::FixedCapacityVector<Descriptor> descriptors;     // 16
-    utils::bitset64 dynamicBuffers;                         // 8
-    DescriptorSetLayoutHandle dslh;                         // 4
-    uint8_t dynamicBufferCount = 0;                         // 1
-};
-static_assert(sizeof(GLDescriptorSet) <= 32);
-
-} // namespace filament::backend
-
-#endif //TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSET_H
@@ -1,52 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSETLAYOUT_H
-#define TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSETLAYOUT_H
-
-#include "DriverBase.h"
-
-#include <backend/DriverEnums.h>
-
-#include <algorithm>
-#include <utility>
-
-#include <stdint.h>
-
-namespace filament::backend {
-
-struct GLDescriptorSetLayout : public HwDescriptorSetLayout, public DescriptorSetLayout {
-    using HwDescriptorSetLayout::HwDescriptorSetLayout;
-    explicit GLDescriptorSetLayout(DescriptorSetLayout&& layout) noexcept
-            : DescriptorSetLayout(std::move(layout)) {
-
-        std::sort(bindings.begin(), bindings.end(),
-                [](auto&& lhs, auto&& rhs){
-            return lhs.binding < rhs.binding;
-        });
-
-        auto p = std::max_element(bindings.cbegin(), bindings.cend(),
-                [](auto const& lhs, auto const& rhs) {
-            return lhs.binding < rhs.binding;
-        });
-        maxDescriptorBinding = p->binding;
-    }
-    uint8_t maxDescriptorBinding = 0;
-};
-
-} // namespace filament::backend
-
-#endif //TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSETLAYOUT_H
@@ -21,32 +21,12 @@

 #include "gl_headers.h"

-#include <backend/Handle.h>
-#include <backend/DriverEnums.h>
 #include <backend/platforms/OpenGLPlatform.h>

-#include <array>
-
 #include <stdint.h>

 namespace filament::backend {

-struct GLTextureRef {
-    GLTextureRef() = default;
-    // view reference counter
-    uint16_t count = 1;
-    // current per-view values of the texture (in GL we can only have a single View active at
-    // a time, and this tracks that state). It's used to avoid unnecessarily change state.
-    int8_t baseLevel = 127;
-    int8_t maxLevel = -1;
-    std::array<TextureSwizzle, 4> swizzle{
-            TextureSwizzle::CHANNEL_0,
-            TextureSwizzle::CHANNEL_1,
-            TextureSwizzle::CHANNEL_2,
-            TextureSwizzle::CHANNEL_3
-    };
-};
-
 struct GLTexture : public HwTexture {
    using HwTexture::HwTexture;
    struct GL {
@@ -64,14 +44,8 @@ struct GLTexture : public HwTexture {
        bool imported           : 1;
        uint8_t sidecarSamples  : 4;
        uint8_t reserved1       : 3;
-        std::array<TextureSwizzle, 4> swizzle{
-                TextureSwizzle::CHANNEL_0,
-                TextureSwizzle::CHANNEL_1,
-                TextureSwizzle::CHANNEL_2,
-                TextureSwizzle::CHANNEL_3
-        };
    } gl;
-    mutable Handle<GLTextureRef> ref;
+
    OpenGLPlatform::ExternalTexture* externalTexture = nullptr;
 };

@@ -552,14 +552,6 @@ void OpenGLContext::initBugs(Bugs* bugs, Extensions const& exts,
        } else if (strstr(renderer, "AMD") ||
                   strstr(renderer, "ATI")) {
            // AMD/ATI GPU
-        } else if (strstr(vendor, "Mesa")) {
-            // Seen on
-            //  [Mesa],
-            //  [llvmpipe (LLVM 17.0.6, 256 bits)],
-            //  [4.5 (Core Profile) Mesa 24.0.6-1],
-            //  [4.50]
-            // not known which version are affected
-            bugs->rebind_buffer_after_deletion = true;
        } else if (strstr(renderer, "Mozilla")) {
            bugs->disable_invalidate_framebuffer = true;
        }
@@ -937,19 +929,15 @@ void OpenGLContext::unbindSampler(GLuint sampler) noexcept {
    }
 }

-void OpenGLContext::deleteBuffer(GLuint buffer, GLenum target) noexcept {
-    glDeleteBuffers(1, &buffer);
-
+void OpenGLContext::deleteBuffers(GLsizei n, const GLuint* buffers, GLenum target) noexcept {
+    glDeleteBuffers(n, buffers);
    // bindings of bound buffers are reset to 0
-    size_t const targetIndex = getIndexForBufferTarget(target);
-    auto& genericBinding = state.buffers.genericBinding[targetIndex];
-    if (genericBinding == buffer) {
-        genericBinding = 0;
-    }
-
-    if (UTILS_UNLIKELY(bugs.rebind_buffer_after_deletion)) {
-        if (genericBinding) {
-            glBindBuffer(target, genericBinding);
+    const size_t targetIndex = getIndexForBufferTarget(target);
+    auto& genericBuffer = state.buffers.genericBinding[targetIndex];
+    UTILS_NOUNROLL
+    for (GLsizei i = 0; i < n; ++i) {
+        if (genericBuffer == buffers[i]) {
+            genericBuffer = 0;
        }
    }

@@ -958,13 +946,16 @@ void OpenGLContext::deleteBuffer(GLuint buffer, GLenum target) noexcept {
            (target != GL_UNIFORM_BUFFER && target != GL_TRANSFORM_FEEDBACK_BUFFER));

    if (target == GL_UNIFORM_BUFFER || target == GL_TRANSFORM_FEEDBACK_BUFFER) {
-        auto& indexedBinding = state.buffers.targets[targetIndex];
-        UTILS_NOUNROLL
-        for (auto& entry: indexedBinding.buffers) {
-            if (entry.name == buffer) {
-                entry.name = 0;
-                entry.offset = 0;
-                entry.size = 0;
+        auto& indexedBuffer = state.buffers.targets[targetIndex];
+        UTILS_NOUNROLL // clang generates >1 KiB of code!!
+        for (GLsizei i = 0; i < n; ++i) {
+            UTILS_NOUNROLL
+            for (auto& buffer : indexedBuffer.buffers) {
+                if (buffer.name == buffers[i]) {
+                    buffer.name = 0;
+                    buffer.offset = 0;
+                    buffer.size = 0;
+                }
            }
        }
    }
@@ -60,19 +60,10 @@ public:
    struct RenderPrimitive {
        static_assert(MAX_VERTEX_ATTRIBUTE_COUNT <= 16);

-        GLuint vao[2] = {};                                     // 8
+        GLuint vao[2] = {};                                     // 4
        GLuint elementArray = 0;                                // 4
-        GLenum indicesType = 0;                                 // 4
-
-        // The optional 32-bit handle to a GLVertexBuffer is necessary only if the referenced
-        // VertexBuffer supports buffer objects. If this is zero, then the VBO handles array is
-        // immutable.
-        Handle<HwVertexBuffer> vertexBufferWithObjects;         // 4
-
        mutable utils::bitset<uint16_t> vertexAttribArray;      // 2

-        uint8_t reserved[2] = {};                               // 2
-
        // if this differs from vertexBufferWithObjects->bufferObjectsVersion, this VAO needs to
        // be updated (see OpenGLDriver::updateVertexArrayObject())
        uint8_t vertexBufferVersion = 0;                        // 1
@@ -85,11 +76,16 @@ public:
        // See OpenGLContext::bindVertexArray()
        uint8_t nameVersion = 0;                                // 1

-        // Size in bytes of indices in the index buffer (1 or 2)
-        uint8_t indicesShift = 0;                                // 1
+        // Size in bytes of indices in the index buffer
+        uint8_t indicesSize = 0;                                // 1
+
+        // The optional 32-bit handle to a GLVertexBuffer is necessary only if the referenced
+        // VertexBuffer supports buffer objects. If this is zero, then the VBO handles array is
+        // immutable.
+        Handle<HwVertexBuffer> vertexBufferWithObjects;         // 4

        GLenum getIndicesType() const noexcept {
-            return indicesType;
+            return indicesSize == 4 ? GL_UNSIGNED_INT : GL_UNSIGNED_SHORT;
        }
    } gl;

@@ -190,7 +186,7 @@ public:
    inline void viewport(GLint left, GLint bottom, GLsizei width, GLsizei height) noexcept;
    inline void depthRange(GLclampf near, GLclampf far) noexcept;

-    void deleteBuffer(GLuint buffer, GLenum target) noexcept;
+    void deleteBuffers(GLsizei n, const GLuint* buffers, GLenum target) noexcept;
    void deleteVertexArray(GLuint vao) noexcept;

    void destroyWithContext(size_t index, std::function<void(OpenGLContext&)> const& closure) noexcept;
@@ -316,15 +312,10 @@ public:
        // a glFinish. So we must delay the destruction until we know the GPU is finished.
        bool delay_fbo_destruction;

-        // Mesa sometimes clears the generic buffer binding when *another* buffer is destroyed,
-        // if that other buffer is bound on an *indexed* buffer binding.
-        bool rebind_buffer_after_deletion;
-
        // Force feature level 0. Typically used for low end ES3 devices with significant driver
        // bugs or performance issues.
        bool force_feature_level0;

-
    } bugs = {};

    // state getters -- as needed.
@@ -483,6 +474,12 @@ public:

    void unbindEverything() noexcept;
    void synchronizeStateAndCache(size_t index) noexcept;
+    void setEs2UniformBinding(size_t index, GLuint id, void const* data, uint16_t age) noexcept {
+        mUniformBindings[index] = { id, data, age };
+    }
+    auto getEs2UniformBinding(size_t index) const noexcept {
+        return mUniformBindings[index];
+    }

 #ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
    GLuint getSamplerSlow(SamplerParams sp) const noexcept;
@@ -509,6 +506,9 @@ private:
    std::vector<std::function<void(OpenGLContext&)>> mDestroyWithNormalContext;
    RenderPrimitive mDefaultVAO;
    std::optional<GLuint> mDefaultFbo[2];
+    std::array<
+            std::tuple<GLuint, void const*, uint16_t>,
+            CONFIG_UNIFORM_BINDING_COUNT> mUniformBindings = {};
    mutable tsl::robin_map<SamplerParams, GLuint,
            SamplerParams::Hasher, SamplerParams::EqualTo> mSamplerMap;

@@ -559,9 +559,6 @@ private:
            {   bugs.delay_fbo_destruction,
                    "delay_fbo_destruction",
                    ""},
-            {   bugs.rebind_buffer_after_deletion,
-                    "rebind_buffer_after_deletion",
-                    ""},
            {   bugs.force_feature_level0,
                    "force_feature_level0",
                    ""},
@@ -17,7 +17,6 @@
 #include "OpenGLDriver.h"

 #include "CommandStreamDispatcher.h"
-#include "GLTexture.h"
 #include "GLUtils.h"
 #include "OpenGLContext.h"
 #include "OpenGLDriverFactory.h"
@@ -29,21 +28,19 @@

 #include <backend/BufferDescriptor.h>
 #include <backend/CallbackHandler.h>
-#include <backend/DescriptorSetOffsetArray.h>
 #include <backend/DriverApiForward.h>
 #include <backend/DriverEnums.h>
 #include <backend/Handle.h>
 #include <backend/PipelineState.h>
 #include <backend/Platform.h>
 #include <backend/Program.h>
+#include <backend/SamplerDescriptor.h>
 #include <backend/TargetBufferInfo.h>

 #include "private/backend/Dispatcher.h"
 #include "private/backend/DriverApi.h"

-#include <type_traits>
 #include <utils/BitmaskEnum.h>
-#include <utils/FixedCapacityVector.h>
 #include <utils/CString.h>
 #include <utils/Log.h>
 #include <utils/Panic.h>
@@ -62,9 +59,7 @@
 #include <memory>
 #include <mutex>
 #include <new>
-#include <type_traits>
 #include <utility>
-#include <variant>

 #include <stdint.h>
 #include <stdlib.h>
@@ -137,16 +132,17 @@ Driver* OpenGLDriver::create(OpenGLPlatform* const platform,
    // this is useful for development, but too verbose even for debug builds
    // For reference on a 64-bits machine in Release mode:
    //    GLIndexBuffer             :   8       moderate
+    //    GLSamplerGroup            :  16       few
    //    GLSwapChain               :  16       few
    //    GLTimerQuery              :  16       few
    //    GLFence                   :  24       few
    //    GLRenderPrimitive         :  32       many
    //    GLBufferObject            :  32       many
    // -- less than or equal 32 bytes
+    //    OpenGLProgram             :  56       moderate
    //    GLTexture                 :  64       moderate
+    // -- less than or equal 64 bytes
    //    GLVertexBuffer            :  76       moderate
-    //    OpenGLProgram             :  96       moderate
-    // -- less than or equal 96 bytes
    //    GLStream                  : 104       few
    //    GLRenderTarget            : 112       few
    //    GLVertexBufferInfo        : 132       moderate
@@ -158,6 +154,7 @@ Driver* OpenGLDriver::create(OpenGLPlatform* const platform,
           << "\nGLVertexBuffer: " << sizeof(GLVertexBuffer)
           << "\nGLVertexBufferInfo: " << sizeof(GLVertexBufferInfo)
           << "\nGLIndexBuffer: " << sizeof(GLIndexBuffer)
+           << "\nGLSamplerGroup: " << sizeof(GLSamplerGroup)
           << "\nGLRenderPrimitive: " << sizeof(GLRenderPrimitive)
           << "\nGLTexture: " << sizeof(GLTexture)
           << "\nGLTimerQuery: " << sizeof(GLTimerQuery)
@@ -252,6 +249,8 @@ OpenGLDriver::OpenGLDriver(OpenGLPlatform* platform, const Platform::DriverConfi
          mDriverConfig(driverConfig),
          mCurrentPushConstants(new(std::nothrow) PushConstantBundle{}) {

+    std::fill(mSamplerBindings.begin(), mSamplerBindings.end(), nullptr);
+
    // set a reasonable default value for our stream array
    mTexturesWithStreamsAttached.reserve(8);
    mStreamsWithPendingAcquiredImage.reserve(8);
@@ -382,28 +381,18 @@ void OpenGLDriver::bindTexture(GLuint unit, GLTexture const* t) noexcept {
 }

 bool OpenGLDriver::useProgram(OpenGLProgram* p) noexcept {
-    if (UTILS_UNLIKELY(mBoundProgram == p)) {
-        // program didn't change, don't do anything.
-        return true;
-    }
-
-    // compile/link the program if needed and call glUseProgram
+    // set-up textures and samplers in the proper TMUs (as specified in setSamplers)
    bool const success = p->use(this, mContext);
    assert_invariant(success == p->isValid());
-  
-    if (success) {
-        // TODO: we could even improve this if the program could tell us which of the descriptors
-        //       bindings actually changed. In practice, it is likely that set 0 or 1 might not
-        //       change often.
-        decltype(mInvalidDescriptorSetBindings) changed;
-        changed.setValue((1 << MAX_DESCRIPTOR_SET_COUNT) - 1);
-        mInvalidDescriptorSetBindings |= changed;
-
-        mBoundProgram = p;
-    }

    if (UTILS_UNLIKELY(mContext.isES2() && success)) {
-        // Set the output colorspace for this program (linear or rec709). This is only relevant
+        for (uint32_t i = 0; i < Program::UNIFORM_BINDING_COUNT; i++) {
+            auto [id, buffer, age] = mContext.getEs2UniformBinding(i);
+            if (buffer) {
+                p->updateUniforms(i, id, buffer, age);
+            }
+        }
+        // Set the output colorspace for this program (linear or rec709). This in only relevant
        // when mPlatform.isSRGBSwapChainSupported() is false (no need to check though).
        p->setRec709ColorSpace(mRec709OutputColorspace);
    }
@@ -543,23 +532,15 @@ Handle<HwProgram> OpenGLDriver::createProgramS() noexcept {
    return initHandle<OpenGLProgram>();
 }

+Handle<HwSamplerGroup> OpenGLDriver::createSamplerGroupS() noexcept {
+    return initHandle<GLSamplerGroup>();
+}
+
 Handle<HwTexture> OpenGLDriver::createTextureS() noexcept {
    return initHandle<GLTexture>();
 }

-Handle<HwTexture> OpenGLDriver::createTextureViewS() noexcept {
-    return initHandle<GLTexture>();
-}
-
-Handle<HwTexture> OpenGLDriver::createTextureViewSwizzleS() noexcept {
-    return initHandle<GLTexture>();
-}
-
-Handle<HwTexture> OpenGLDriver::createTextureExternalImageS() noexcept {
-    return initHandle<GLTexture>();
-}
-
-Handle<HwTexture> OpenGLDriver::createTextureExternalImagePlaneS() noexcept {
+Handle<HwTexture> OpenGLDriver::createTextureSwizzledS() noexcept {
    return initHandle<GLTexture>();
 }

@@ -591,14 +572,6 @@ Handle<HwTimerQuery> OpenGLDriver::createTimerQueryS() noexcept {
    return initHandle<GLTimerQuery>();
 }

-Handle<HwDescriptorSetLayout> OpenGLDriver::createDescriptorSetLayoutS() noexcept {
-    return initHandle<GLDescriptorSetLayout>();
-}
-
-Handle<HwDescriptorSet> OpenGLDriver::createDescriptorSetS() noexcept {
-    return initHandle<GLDescriptorSet>();
-}
-
 void OpenGLDriver::createVertexBufferInfoR(
        Handle<HwVertexBufferInfo> vbih,
        uint8_t bufferCount,
@@ -671,8 +644,7 @@ void OpenGLDriver::createRenderPrimitiveR(Handle<HwRenderPrimitive> rph,

    GLVertexBuffer* const vb = handle_cast<GLVertexBuffer*>(vbh);
    GLRenderPrimitive* const rp = handle_cast<GLRenderPrimitive*>(rph);
-    rp->gl.indicesShift = (ib->elementSize == 4u) ? 2u : 1u;
-    rp->gl.indicesType  = (ib->elementSize == 4u) ? GL_UNSIGNED_INT : GL_UNSIGNED_SHORT;
+    rp->gl.indicesSize = (ib->elementSize == 4u) ? 4u : 2u;
    rp->gl.vertexBufferWithObjects = vbh;
    rp->type = pt;
    rp->vbih = vb->vbih;
@@ -726,6 +698,13 @@ void OpenGLDriver::createProgramR(Handle<HwProgram> ph, Program&& program) {
    CHECK_GL_ERROR(utils::slog.e)
 }

+void OpenGLDriver::createSamplerGroupR(Handle<HwSamplerGroup> sbh, uint32_t size,
+        utils::FixedSizeString<32> debugName) {
+    DEBUG_MARKER()
+
+    construct<GLSamplerGroup>(sbh, size);
+}
+
 UTILS_NOINLINE
 void OpenGLDriver::textureStorage(OpenGLDriver::GLTexture* t,
        uint32_t width, uint32_t height, uint32_t depth, bool useProtectedMemory) noexcept {
@@ -921,129 +900,32 @@ void OpenGLDriver::createTextureR(Handle<HwTexture> th, SamplerType target, uint
    CHECK_GL_ERROR(utils::slog.e)
 }

-void OpenGLDriver::createTextureViewR(Handle<HwTexture> th,
-        Handle<HwTexture> srch, uint8_t baseLevel, uint8_t levelCount) {
+void OpenGLDriver::createTextureSwizzledR(Handle<HwTexture> th,
+        SamplerType target, uint8_t levels, TextureFormat format, uint8_t samples,
+        uint32_t w, uint32_t h, uint32_t depth, TextureUsage usage,
+        TextureSwizzle r, TextureSwizzle g, TextureSwizzle b, TextureSwizzle a) {
    DEBUG_MARKER()
-    GLTexture const* const src = handle_cast<GLTexture const*>(srch);

-    FILAMENT_CHECK_PRECONDITION(any(src->usage & TextureUsage::SAMPLEABLE))
-            << "TextureView can only be created on a SAMPLEABLE texture";
+    assert_invariant(uint8_t(usage) & uint8_t(TextureUsage::SAMPLEABLE));

-    FILAMENT_CHECK_PRECONDITION(!src->gl.imported)
-            << "TextureView can't be created on imported textures";
+    createTextureR(th, target, levels, format, samples, w, h, depth, usage);

-    if (!src->ref) {
-        // lazily create the ref handle, because most textures will never get a texture view
-        src->ref = initHandle<GLTextureRef>();
+    // WebGL does not support swizzling. We assert for this in the Texture builder,
+    // so it is probably fine to silently ignore the swizzle state here.
+#if !defined(__EMSCRIPTEN__)  && !defined(FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2)
+    if (!mContext.isES2()) {
+        // the texture is still bound and active from createTextureR
+        GLTexture* t = handle_cast<GLTexture*>(th);
+        glTexParameteri(t->gl.target, GL_TEXTURE_SWIZZLE_R, (GLint)getSwizzleChannel(r));
+        glTexParameteri(t->gl.target, GL_TEXTURE_SWIZZLE_G, (GLint)getSwizzleChannel(g));
+        glTexParameteri(t->gl.target, GL_TEXTURE_SWIZZLE_B, (GLint)getSwizzleChannel(b));
+        glTexParameteri(t->gl.target, GL_TEXTURE_SWIZZLE_A, (GLint)getSwizzleChannel(a));
    }
-
-    GLTexture* t = construct<GLTexture>(th,
-            src->target,
-            src->levels,
-            src->samples,
-            src->width, src->height, src->depth,
-            src->format,
-            src->usage);
-
-    t->gl = src->gl;
-    t->gl.sidecarRenderBufferMS = 0;
-    t->gl.sidecarSamples = 1;
-
-    auto srcBaseLevel = src->gl.baseLevel;
-    auto srcMaxLevel = src->gl.maxLevel;
-    if (srcBaseLevel > srcMaxLevel) {
-        srcBaseLevel = 0;
-        srcMaxLevel = 127;
-    }
-    t->gl.baseLevel = (int8_t)std::min(127, srcBaseLevel + baseLevel);
-    t->gl.maxLevel  = (int8_t)std::min(127, srcBaseLevel + baseLevel + levelCount - 1);
-
-    // increase reference count to this texture handle
-    t->ref = src->ref;
-    GLTextureRef* ref = handle_cast<GLTextureRef*>(t->ref);
-    assert_invariant(ref);
-    ref->count++;
+#endif

    CHECK_GL_ERROR(utils::slog.e)
 }

-void OpenGLDriver::createTextureViewSwizzleR(Handle<HwTexture> th, Handle<HwTexture> srch,
-        backend::TextureSwizzle r, backend::TextureSwizzle g, backend::TextureSwizzle b,
-        backend::TextureSwizzle a) {
-
-    DEBUG_MARKER()
-    GLTexture const* const src = handle_cast<GLTexture const*>(srch);
-
-    FILAMENT_CHECK_PRECONDITION(any(src->usage & TextureUsage::SAMPLEABLE))
-                    << "TextureView can only be created on a SAMPLEABLE texture";
-
-    FILAMENT_CHECK_PRECONDITION(!src->gl.imported)
-                    << "TextureView can't be created on imported textures";
-
-    if (!src->ref) {
-        // lazily create the ref handle, because most textures will never get a texture view
-        src->ref = initHandle<GLTextureRef>();
-    }
-
-    GLTexture* t = construct<GLTexture>(th,
-            src->target,
-            src->levels,
-            src->samples,
-            src->width, src->height, src->depth,
-            src->format,
-            src->usage);
-
-    t->gl = src->gl;
-    t->gl.baseLevel = src->gl.baseLevel;
-    t->gl.maxLevel = src->gl.maxLevel;
-    t->gl.sidecarRenderBufferMS = 0;
-    t->gl.sidecarSamples = 1;
-
-    auto getChannel = [&swizzle = src->gl.swizzle](TextureSwizzle ch) {
-        switch (ch) {
-            case TextureSwizzle::SUBSTITUTE_ZERO:
-            case TextureSwizzle::SUBSTITUTE_ONE:
-                return ch;
-            case TextureSwizzle::CHANNEL_0:
-                return swizzle[0];
-            case TextureSwizzle::CHANNEL_1:
-                return swizzle[1];
-            case TextureSwizzle::CHANNEL_2:
-                return swizzle[2];
-            case TextureSwizzle::CHANNEL_3:
-                return swizzle[3];
-        }
-    };
-
-    t->gl.swizzle = {
-            getChannel(r),
-            getChannel(g),
-            getChannel(b),
-            getChannel(a),
-    };
-
-    // increase reference count to this texture handle
-    t->ref = src->ref;
-    GLTextureRef* ref = handle_cast<GLTextureRef*>(t->ref);
-    assert_invariant(ref);
-    ref->count++;
-
-    CHECK_GL_ERROR(utils::slog.e)
-}
-
-void OpenGLDriver::createTextureExternalImageR(Handle<HwTexture> th, backend::TextureFormat format,
-        uint32_t width, uint32_t height, backend::TextureUsage usage, void* image) {
-    createTextureR(th, SamplerType::SAMPLER_EXTERNAL, 1, format, 1, width, height, 1, usage);
-    setExternalImage(th, image);
-}
-
-void OpenGLDriver::createTextureExternalImagePlaneR(Handle<HwTexture> th,
-        backend::TextureFormat format, uint32_t width, uint32_t height, backend::TextureUsage usage,
-        void* image, uint32_t plane) {
-    createTextureR(th, SamplerType::SAMPLER_EXTERNAL, 1, format, 1, width, height, 1, usage);
-    setExternalImagePlane(th, image, plane);
-}
-
 void OpenGLDriver::importTextureR(Handle<HwTexture> th, intptr_t id,
        SamplerType target, uint8_t levels, TextureFormat format, uint8_t samples,
        uint32_t w, uint32_t h, uint32_t depth, TextureUsage usage) {
@@ -1266,7 +1148,6 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,
    if (any(t->usage & TextureUsage::SAMPLEABLE)) {
        switch (t->target) {
            case SamplerType::SAMPLER_2D:
-            case SamplerType::SAMPLER_3D:
            case SamplerType::SAMPLER_2D_ARRAY:
            case SamplerType::SAMPLER_CUBEMAP_ARRAY:
                // this could be GL_TEXTURE_2D_MULTISAMPLE or GL_TEXTURE_2D_ARRAY
@@ -1277,9 +1158,7 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,
                target = getCubemapTarget(binfo.layer);
                // note: cubemaps can't be multi-sampled
                break;
-            case SamplerType::SAMPLER_EXTERNAL:
-                // This is an error. We have asserted in debug build.
-                target = t->gl.target;
+            default:
                break;
        }
    }
@@ -1297,7 +1176,7 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,

    if (rt->gl.samples <= 1 ||
        (rt->gl.samples > 1 && t->samples > 1 && gl.features.multisample_texture)) {
-        // On GL3.2 / GLES3.1 and above multisample is handled when creating the texture.
+        // on GL3.2 / GLES3.1 and above multisample is handled when creating the texture.
        // If multisampled textures are not supported and we end-up here, things should
        // still work, albeit without MSAA.
        gl.bindFramebuffer(GL_FRAMEBUFFER, rt->gl.fbo);
@@ -1321,7 +1200,6 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,
                            GL_RENDERBUFFER, t->gl.id);
                }
                break;
-            case GL_TEXTURE_3D:
            case GL_TEXTURE_2D_ARRAY:
            case GL_TEXTURE_CUBE_MAP_ARRAY:
 #ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
@@ -1331,7 +1209,7 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,
                if (layerCount > 1) {
                    // if layerCount > 1, it means we use the multiview extension.
                    glFramebufferTextureMultiviewOVR(GL_FRAMEBUFFER, attachment,
-                        t->gl.id, 0, binfo.layer, layerCount);
+                        t->gl.id, 0, binfo.baseViewIndex, layerCount);
                } else
 #endif // !defined(__EMSCRIPTEN__) && !defined(IOS)
                {
@@ -1435,7 +1313,6 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,
                            GL_RENDERBUFFER, t->gl.id);
                }
                break;
-            case GL_TEXTURE_3D:
            case GL_TEXTURE_2D_ARRAY:
            case GL_TEXTURE_CUBE_MAP_ARRAY:
 #ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
@@ -1453,6 +1330,14 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,

    rt->gl.resolve |= resolveFlags;

+    if (any(t->usage & TextureUsage::SAMPLEABLE)) {
+        // In a sense, drawing to a texture level is similar to calling setTextureData on it; in
+        // both cases, we update the base/max LOD to give shaders access to levels as they become
+        // available.  Note that this can only expand the LOD range (never shrink it), and that
+        // users can override this range by calling setMinMaxLevels().
+        updateTextureLodRange(t, (int8_t)binfo.level);
+    }
+
    CHECK_GL_ERROR(utils::slog.e)
    CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_FRAMEBUFFER)
 }
@@ -1693,19 +1578,6 @@ void OpenGLDriver::createTimerQueryR(Handle<HwTimerQuery> tqh, int) {
    mContext.createTimerQuery(tq);
 }

-void OpenGLDriver::createDescriptorSetLayoutR(Handle<HwDescriptorSetLayout> dslh,
-        DescriptorSetLayout&& info) {
-    DEBUG_MARKER()
-    construct<GLDescriptorSetLayout>(dslh, std::move(info));
-}
-
-void OpenGLDriver::createDescriptorSetR(Handle<HwDescriptorSet> dsh,
-        Handle<HwDescriptorSetLayout> dslh) {
-    DEBUG_MARKER()
-    GLDescriptorSetLayout const* dsl = handle_cast<GLDescriptorSetLayout*>(dslh);
-    construct<GLDescriptorSet>(dsh, mContext, dslh, dsl);
-}
-
 // ------------------------------------------------------------------------------------------------
 // Destroying driver objects
 // ------------------------------------------------------------------------------------------------
@@ -1732,7 +1604,7 @@ void OpenGLDriver::destroyIndexBuffer(Handle<HwIndexBuffer> ibh) {
    if (ibh) {
        auto& gl = mContext;
        GLIndexBuffer const* ib = handle_cast<const GLIndexBuffer*>(ibh);
-        gl.deleteBuffer(ib->gl.buffer, GL_ELEMENT_ARRAY_BUFFER);
+        gl.deleteBuffers(1, &ib->gl.buffer, GL_ELEMENT_ARRAY_BUFFER);
        destruct(ibh, ib);
    }
 }
@@ -1745,7 +1617,7 @@ void OpenGLDriver::destroyBufferObject(Handle<HwBufferObject> boh) {
        if (UTILS_UNLIKELY(bo->bindingType == BufferObjectBinding::UNIFORM && gl.isES2())) {
            free(bo->gl.buffer);
        } else {
-            gl.deleteBuffer(bo->gl.id, bo->gl.binding);
+            gl.deleteBuffers(1, &bo->gl.id, bo->gl.binding);
        }
        destruct(boh, bo);
    }
@@ -1783,41 +1655,35 @@ void OpenGLDriver::destroyProgram(Handle<HwProgram> ph) {
    }
 }

+void OpenGLDriver::destroySamplerGroup(Handle<HwSamplerGroup> sbh) {
+    DEBUG_MARKER()
+    if (sbh) {
+        GLSamplerGroup* sb = handle_cast<GLSamplerGroup*>(sbh);
+        for (auto& binding : mSamplerBindings) {
+            if (binding == sb) {
+                binding = nullptr;
+            }
+        }
+        destruct(sbh, sb);
+    }
+}
+
 void OpenGLDriver::destroyTexture(Handle<HwTexture> th) {
    DEBUG_MARKER()

    if (th) {
        auto& gl = mContext;
        GLTexture* t = handle_cast<GLTexture*>(th);
-
        if (UTILS_LIKELY(!t->gl.imported)) {
            if (UTILS_LIKELY(t->usage & TextureUsage::SAMPLEABLE)) {
-                // drop a reference
-                uint16_t count = 0;
-                if (UTILS_UNLIKELY(t->ref)) {
-                    // the common case is that we don't have a ref handle
-                    GLTextureRef* const ref = handle_cast<GLTextureRef*>(t->ref);
-                    count = --(ref->count);
-                    if (count == 0) {
-                        destruct(t->ref, ref);
-                    }
+                gl.unbindTexture(t->gl.target, t->gl.id);
+                if (UTILS_UNLIKELY(t->hwStream)) {
+                    detachStream(t);
                }
-                if (count == 0) {
-                    // if this was the last reference, we destroy the refcount as well as
-                    // the GL texture name itself.
-                    gl.unbindTexture(t->gl.target, t->gl.id);
-                    if (UTILS_UNLIKELY(t->hwStream)) {
-                        detachStream(t);
-                    }
-                    if (UTILS_UNLIKELY(t->target == SamplerType::SAMPLER_EXTERNAL)) {
-                        mPlatform.destroyExternalImage(t->externalTexture);
-                    } else {
-                        glDeleteTextures(1, &t->gl.id);
-                    }
+                if (UTILS_UNLIKELY(t->target == SamplerType::SAMPLER_EXTERNAL)) {
+                    mPlatform.destroyExternalImage(t->externalTexture);
                } else {
-                    // The Handle<HwTexture> is always destroyed. For extra precaution we also
-                    // check that the GLTexture has a trivial destructor.
-                    static_assert(std::is_trivially_destructible_v<GLTexture>);
+                    glDeleteTextures(1, &t->gl.id);
                }
            } else {
                assert_invariant(t->gl.target == GL_RENDERBUFFER);
@@ -1922,28 +1788,6 @@ void OpenGLDriver::destroyTimerQuery(Handle<HwTimerQuery> tqh) {
    }
 }

-void OpenGLDriver::destroyDescriptorSetLayout(Handle<HwDescriptorSetLayout> dslh) {
-    DEBUG_MARKER()
-    if (dslh) {
-        GLDescriptorSetLayout* dsl = handle_cast<GLDescriptorSetLayout*>(dslh);
-        destruct(dslh, dsl);
-    }
-}
-
-void OpenGLDriver::destroyDescriptorSet(Handle<HwDescriptorSet> dsh) {
-    DEBUG_MARKER()
-    if (dsh) {
-        // unbind the descriptor-set, to avoid use-after-free
-        for (auto& bound : mBoundDescriptorSets) {
-            if (bound.dsh == dsh) {
-                bound = {};
-            }
-        }
-        GLDescriptorSet* ds = handle_cast<GLDescriptorSet*>(dsh);
-        destruct(dsh, ds);
-    }
-}
-
 // ------------------------------------------------------------------------------------------------
 // Synchronous APIs
 // These are called on the application's thread
@@ -2520,6 +2364,122 @@ void OpenGLDriver::resetBufferObject(Handle<HwBufferObject> boh) {
    }
 }

+void OpenGLDriver::updateSamplerGroup(Handle<HwSamplerGroup> sbh,
+        BufferDescriptor&& data) {
+    DEBUG_MARKER()
+
+    OpenGLContext const& context = getContext();
+
+#if defined(GL_EXT_texture_filter_anisotropic)
+    const bool anisotropyWorkaround =
+            context.ext.EXT_texture_filter_anisotropic &&
+            context.bugs.texture_filter_anisotropic_broken_on_sampler;
+#endif
+
+    GLSamplerGroup* const sb = handle_cast<GLSamplerGroup *>(sbh);
+    assert_invariant(sb->textureUnitEntries.size() == data.size / sizeof(SamplerDescriptor));
+
+#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
+    bool const es2 = context.isES2();
+#endif
+
+    auto const* const pSamplers = (SamplerDescriptor const*)data.buffer;
+    for (size_t i = 0, c = sb->textureUnitEntries.size(); i < c; i++) {
+        GLuint samplerId = 0u;
+        Handle<HwTexture> th = pSamplers[i].t;
+        if (UTILS_LIKELY(th)) {
+            GLTexture const* const t = handle_cast<const GLTexture*>(th);
+            assert_invariant(t);
+
+            if (UTILS_UNLIKELY(es2)
+#if defined(GL_EXT_texture_filter_anisotropic)
+                    || UTILS_UNLIKELY(anisotropyWorkaround)
+ #endif
+                    ) {
+                // We must set texture parameters on the texture itself.
+                bindTexture(OpenGLContext::DUMMY_TEXTURE_BINDING, t);
+            }
+
+            SamplerParams params = pSamplers[i].s;
+            if (UTILS_UNLIKELY(t->target == SamplerType::SAMPLER_EXTERNAL)) {
+                // From OES_EGL_image_external spec:
+                // "The default s and t wrap modes are CLAMP_TO_EDGE, and it is an INVALID_ENUM
+                //  error to set the wrap mode to any other value."
+                params.wrapS = SamplerWrapMode::CLAMP_TO_EDGE;
+                params.wrapT = SamplerWrapMode::CLAMP_TO_EDGE;
+                params.wrapR = SamplerWrapMode::CLAMP_TO_EDGE;
+            }
+            // GLES3.x specification forbids depth textures to be filtered.
+            if (UTILS_UNLIKELY(isDepthFormat(t->format)
+                               && params.compareMode == SamplerCompareMode::NONE
+                               && params.filterMag != SamplerMagFilter::NEAREST
+                               && params.filterMin != SamplerMinFilter::NEAREST
+                               && params.filterMin != SamplerMinFilter::NEAREST_MIPMAP_NEAREST)) {
+                params.filterMag = SamplerMagFilter::NEAREST;
+                params.filterMin = SamplerMinFilter::NEAREST;
+#ifndef NDEBUG
+                slog.w << "HwSamplerGroup specifies a filtered depth texture, which is not allowed."
+                       << io::endl;
+#endif
+            }
+#if defined(GL_EXT_texture_filter_anisotropic)
+            if (UTILS_UNLIKELY(anisotropyWorkaround)) {
+                // Driver claims to support anisotropic filtering, but it fails when set on
+                // the sampler, we have to set it on the texture instead.
+                // The texture is already bound here.
+                GLfloat const anisotropy = float(1u << params.anisotropyLog2);
+                glTexParameterf(t->gl.target, GL_TEXTURE_MAX_ANISOTROPY_EXT,
+                        std::min(context.gets.max_anisotropy, anisotropy));
+            }
+#endif
+#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
+            if (UTILS_LIKELY(!es2)) {
+                samplerId = mContext.getSampler(params);
+            } else
+#endif
+            {
+                // in ES2 the sampler parameters need to be set on the texture itself
+                glTexParameteri(t->gl.target, GL_TEXTURE_MIN_FILTER,
+                        (GLint)getTextureFilter(params.filterMin));
+                glTexParameteri(t->gl.target, GL_TEXTURE_MAG_FILTER,
+                        (GLint)getTextureFilter(params.filterMag));
+                glTexParameteri(t->gl.target, GL_TEXTURE_WRAP_S,
+                        (GLint)getWrapMode(params.wrapS));
+                glTexParameteri(t->gl.target, GL_TEXTURE_WRAP_T,
+                        (GLint)getWrapMode(params.wrapT));
+            }
+        } else {
+            // this happens if the program doesn't use all samplers of a sampler group,
+            // which is not an error.
+        }
+
+        sb->textureUnitEntries[i] = { th, samplerId };
+    }
+    scheduleDestroy(std::move(data));
+}
+
+void OpenGLDriver::setMinMaxLevels(Handle<HwTexture> th, uint32_t minLevel, uint32_t maxLevel) {
+    DEBUG_MARKER()
+
+#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
+    auto& gl = mContext;
+    if (!gl.isES2()) {
+        GLTexture* t = handle_cast<GLTexture*>(th);
+        bindTexture(OpenGLContext::DUMMY_TEXTURE_BINDING, t);
+        gl.activeTexture(OpenGLContext::DUMMY_TEXTURE_BINDING);
+
+        // Must fit within int8_t.
+        assert_invariant(minLevel <= 0x7f && maxLevel <= 0x7f);
+
+        t->gl.baseLevel = (int8_t)minLevel;
+        glTexParameteri(t->gl.target, GL_TEXTURE_BASE_LEVEL, t->gl.baseLevel);
+
+        t->gl.maxLevel = (int8_t)maxLevel; // NOTE: according to the GL spec, the default value of this 1000
+        glTexParameteri(t->gl.target, GL_TEXTURE_MAX_LEVEL, t->gl.maxLevel);
+    }
+#endif
+}
+
 void OpenGLDriver::update3DImage(Handle<HwTexture> th,
        uint32_t level, uint32_t xoffset, uint32_t yoffset, uint32_t zoffset,
        uint32_t width, uint32_t height, uint32_t depth,
@@ -2549,6 +2509,16 @@ void OpenGLDriver::generateMipmaps(Handle<HwTexture> th) {
    bindTexture(OpenGLContext::DUMMY_TEXTURE_BINDING, t);
    gl.activeTexture(OpenGLContext::DUMMY_TEXTURE_BINDING);

+    t->gl.baseLevel = 0;
+    t->gl.maxLevel = static_cast<int8_t>(t->levels - 1);
+
+#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
+    if (!gl.isES2()) {
+        glTexParameteri(t->gl.target, GL_TEXTURE_BASE_LEVEL, t->gl.baseLevel);
+        glTexParameteri(t->gl.target, GL_TEXTURE_MAX_LEVEL, t->gl.maxLevel);
+    }
+#endif
+
    glGenerateMipmap(t->gl.target);

    CHECK_GL_ERROR(utils::slog.e)
@@ -2658,6 +2628,21 @@ void OpenGLDriver::setTextureData(GLTexture* t, uint32_t level,
        }
    }

+#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
+    if (!gl.isES2()) {
+        // Update the base/max LOD, so we don't access undefined LOD. this allows the app to
+        // specify levels as they become available.
+        if (int8_t(level) < t->gl.baseLevel) {
+            t->gl.baseLevel = int8_t(level);
+            glTexParameteri(t->gl.target, GL_TEXTURE_BASE_LEVEL, t->gl.baseLevel);
+        }
+        if (int8_t(level) > t->gl.maxLevel) {
+            t->gl.maxLevel = int8_t(level);
+            glTexParameteri(t->gl.target, GL_TEXTURE_MAX_LEVEL, t->gl.maxLevel);
+        }
+    }
+#endif
+
    scheduleDestroy(std::move(p));

    CHECK_GL_ERROR(utils::slog.e)
@@ -2744,6 +2729,21 @@ void OpenGLDriver::setCompressedTextureData(GLTexture* t, uint32_t level,
        }
    }

+#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
+    if (!gl.isES2()) {
+        // Update the base/max LOD, so we don't access undefined LOD. this allows the app to
+        // specify levels as they become available.
+        if (int8_t(level) < t->gl.baseLevel) {
+            t->gl.baseLevel = int8_t(level);
+            glTexParameteri(t->gl.target, GL_TEXTURE_BASE_LEVEL, t->gl.baseLevel);
+        }
+        if (int8_t(level) > t->gl.maxLevel) {
+            t->gl.maxLevel = int8_t(level);
+            glTexParameteri(t->gl.target, GL_TEXTURE_MAX_LEVEL, t->gl.maxLevel);
+        }
+    }
+#endif
+
    scheduleDestroy(std::move(p));

    CHECK_GL_ERROR(utils::slog.e)
@@ -2914,9 +2914,6 @@ void OpenGLDriver::beginRenderPass(Handle<HwRenderTarget> rth,
    GLuint const fbo = gl.bindFramebuffer(GL_FRAMEBUFFER, rt->gl.fbo);
    CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_FRAMEBUFFER)

-    // each render-pass starts with a disabled scissor
-    gl.disable(GL_SCISSOR_TEST);
-
    if (gl.ext.EXT_discard_framebuffer
            && !gl.bugs.disable_invalidate_framebuffer) {
        AttachmentArray attachments; // NOLINT
@@ -2929,6 +2926,7 @@ void OpenGLDriver::beginRenderPass(Handle<HwRenderTarget> rth,
        // It's important to clear the framebuffer before drawing, as it resets
        // the fb to a known state (resets fb compression and possibly other things).
        // So we use glClear instead of glInvalidateFramebuffer
+        gl.disable(GL_SCISSOR_TEST);
        clearWithRasterPipe(discardFlags & ~clearFlags, { 0.0f }, 0.0f, 0);
    }

@@ -2944,6 +2942,7 @@ void OpenGLDriver::beginRenderPass(Handle<HwRenderTarget> rth,
    }

    if (any(clearFlags)) {
+        gl.disable(GL_SCISSOR_TEST);
        clearWithRasterPipe(clearFlags,
                params.clearColor, (GLfloat)params.clearDepth, (GLint)params.clearStencil);
    }
@@ -2962,6 +2961,7 @@ void OpenGLDriver::beginRenderPass(Handle<HwRenderTarget> rth,

 #ifndef NDEBUG
    // clear the discarded (but not the cleared ones) buffers in debug builds
+    gl.disable(GL_SCISSOR_TEST);
    clearWithRasterPipe(discardFlags & ~clearFlags,
            { 1, 0, 0, 1 }, 1.0, 0);
 #endif
@@ -3138,6 +3138,64 @@ void OpenGLDriver::setScissor(Viewport const& scissor) noexcept {
 // Setting rendering state
 // ------------------------------------------------------------------------------------------------

+void OpenGLDriver::bindUniformBuffer(uint32_t index, Handle<HwBufferObject> ubh) {
+    DEBUG_MARKER()
+    GLBufferObject* ub = handle_cast<GLBufferObject *>(ubh);
+    assert_invariant(ub->bindingType == BufferObjectBinding::UNIFORM);
+    bindBufferRange(BufferObjectBinding::UNIFORM, index, ubh, 0, ub->byteCount);
+}
+
+void OpenGLDriver::bindBufferRange(BufferObjectBinding bindingType, uint32_t index,
+        Handle<HwBufferObject> ubh, uint32_t offset, uint32_t size) {
+    DEBUG_MARKER()
+    auto& gl = mContext;
+
+    assert_invariant(bindingType == BufferObjectBinding::SHADER_STORAGE ||
+                     bindingType == BufferObjectBinding::UNIFORM);
+
+    GLBufferObject* ub = handle_cast<GLBufferObject *>(ubh);
+
+    assert_invariant(offset + size <= ub->byteCount);
+
+    if (UTILS_UNLIKELY(ub->bindingType == BufferObjectBinding::UNIFORM && gl.isES2())) {
+        gl.setEs2UniformBinding(index,
+                ub->gl.id,
+                static_cast<uint8_t const*>(ub->gl.buffer) + offset,
+                ub->age);
+    } else {
+        GLenum const target = GLUtils::getBufferBindingType(bindingType);
+
+        assert_invariant(bindingType == BufferObjectBinding::SHADER_STORAGE ||
+                         ub->gl.binding == target);
+
+        gl.bindBufferRange(target, GLuint(index), ub->gl.id, offset, size);
+    }
+
+    CHECK_GL_ERROR(utils::slog.e)
+}
+
+void OpenGLDriver::unbindBuffer(BufferObjectBinding bindingType, uint32_t index) {
+    DEBUG_MARKER()
+    auto& gl = mContext;
+
+    if (UTILS_UNLIKELY(bindingType == BufferObjectBinding::UNIFORM && gl.isES2())) {
+        gl.setEs2UniformBinding(index, 0, nullptr, 0);
+        return;
+    }
+
+    GLenum const target = GLUtils::getBufferBindingType(bindingType);
+    gl.bindBufferRange(target, GLuint(index), 0, 0, 0);
+    CHECK_GL_ERROR(utils::slog.e)
+}
+
+void OpenGLDriver::bindSamplers(uint32_t index, Handle<HwSamplerGroup> sbh) {
+    DEBUG_MARKER()
+    assert_invariant(index < Program::SAMPLER_BINDING_COUNT);
+    GLSamplerGroup* sb = handle_cast<GLSamplerGroup *>(sbh);
+    mSamplerBindings[index] = sb;
+    CHECK_GL_ERROR(utils::slog.e)
+}
+
 void OpenGLDriver::insertEventMarker(char const* string) {
 #ifndef __EMSCRIPTEN__
 #ifdef GL_EXT_debug_marker
@@ -3467,8 +3525,8 @@ void OpenGLDriver::beginFrame(
    }
 }

-void OpenGLDriver::setFrameScheduledCallback(Handle<HwSwapChain> sch, CallbackHandler* handler,
-        FrameScheduledCallback&& callback, uint64_t flags) {
+void OpenGLDriver::setFrameScheduledCallback(Handle<HwSwapChain> sch,
+        CallbackHandler* handler, FrameScheduledCallback&& callback) {
    DEBUG_MARKER()
 }

@@ -3503,26 +3561,6 @@ void OpenGLDriver::endFrame(UTILS_UNUSED uint32_t frameId) {
    insertEventMarker("endFrame");
 }

-void OpenGLDriver::updateDescriptorSetBuffer(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_binding_t binding,
-        backend::BufferObjectHandle boh,
-        uint32_t offset, uint32_t size) {
-    GLDescriptorSet* ds = handle_cast<GLDescriptorSet*>(dsh);
-    GLBufferObject* bo = boh ? handle_cast<GLBufferObject*>(boh) : nullptr;
-    ds->update(mContext, binding, bo, offset, size);
-}
-
-void OpenGLDriver::updateDescriptorSetTexture(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_binding_t binding,
-        backend::TextureHandle th,
-        SamplerParams params) {
-    GLDescriptorSet* ds = handle_cast<GLDescriptorSet*>(dsh);
-    GLTexture* t = th ? handle_cast<GLTexture*>(th) : nullptr;
-    ds->update(mContext, binding, t, params);
-}
-
 void OpenGLDriver::flush(int) {
    DEBUG_MARKER()
    auto& gl = mContext;
@@ -3767,6 +3805,15 @@ void OpenGLDriver::blit(
    gl.unbindFramebuffer(GL_DRAW_FRAMEBUFFER);
    gl.unbindFramebuffer(GL_READ_FRAMEBUFFER);
    glDeleteFramebuffers(2, fbo);
+
+    if (any(d->usage & TextureUsage::SAMPLEABLE)) {
+        // In a sense, blitting to a texture level is similar to calling setTextureData on it; in
+        // both cases, we update the base/max LOD to give shaders access to levels as they become
+        // available.  Note that this can only expand the LOD range (never shrink it), and that
+        // users can override this range by calling setMinMaxLevels().
+        updateTextureLodRange(d, int8_t(dstLevel));
+    }
+
 #endif
 }

@@ -3837,6 +3884,29 @@ void OpenGLDriver::blitDEPRECATED(TargetBufferFlags buffers,
 #endif
 }

+void OpenGLDriver::updateTextureLodRange(GLTexture* texture, int8_t targetLevel) noexcept {
+#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
+    auto& gl = mContext;
+    if (!gl.isES2()) {
+        if (texture && any(texture->usage & TextureUsage::SAMPLEABLE)) {
+            if (targetLevel < texture->gl.baseLevel || targetLevel > texture->gl.maxLevel) {
+                bindTexture(OpenGLContext::DUMMY_TEXTURE_BINDING, texture);
+                gl.activeTexture(OpenGLContext::DUMMY_TEXTURE_BINDING);
+                if (targetLevel < texture->gl.baseLevel) {
+                    texture->gl.baseLevel = targetLevel;
+                    glTexParameteri(texture->gl.target, GL_TEXTURE_BASE_LEVEL, targetLevel);
+                }
+                if (targetLevel > texture->gl.maxLevel) {
+                    texture->gl.maxLevel = targetLevel;
+                    glTexParameteri(texture->gl.target, GL_TEXTURE_MAX_LEVEL, targetLevel);
+                }
+            }
+            CHECK_GL_ERROR(utils::slog.e)
+        }
+    }
+#endif
+}
+
 void OpenGLDriver::bindPipeline(PipelineState const& state) {
    DEBUG_MARKER()
    auto& gl = mContext;
@@ -3846,8 +3916,6 @@ void OpenGLDriver::bindPipeline(PipelineState const& state) {
    OpenGLProgram* const p = handle_cast<OpenGLProgram*>(state.program);
    mValidProgram = useProgram(p);
    (*mCurrentPushConstants) = p->getPushConstants();
-    mCurrentSetLayout = state.pipelineLayout.setLayout;
-    // TODO: we should validate that the pipeline layout matches the program's
 }

 void OpenGLDriver::bindRenderPrimitive(Handle<HwRenderPrimitive> rph) {
@@ -3871,83 +3939,18 @@ void OpenGLDriver::bindRenderPrimitive(Handle<HwRenderPrimitive> rph) {
    mBoundRenderPrimitive = rp;
 }

-void OpenGLDriver::bindDescriptorSet(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_set_t set,
-        backend::DescriptorSetOffsetArray&& offsets) {
-    // handle_cast<> here also serves to validate the handle (it actually cannot return nullptr)
-    GLDescriptorSet const* const ds = handle_cast<GLDescriptorSet*>(dsh);
-    if (ds) {
-        assert_invariant(set < MAX_DESCRIPTOR_SET_COUNT);
-        if (mBoundDescriptorSets[set].dsh != dsh) {
-            // if the descriptor itself changed, we mark this descriptor binding
-            // invalid -- it will be re-bound at the next draw.
-            mInvalidDescriptorSetBindings.set(set, true);
-        } else if (!offsets.empty()) {
-            // if we reset offsets, we mark the offsets invalid so these descriptors only can
-            // be re-bound at the next draw.
-            mInvalidDescriptorSetBindingOffsets.set(set, true);
-        }
-
-        // `offsets` data's lifetime will end when this function returns. We have to make a copy.
-        // (the data is allocated inside the CommandStream)
-        mBoundDescriptorSets[set].dsh = dsh;
-        assert_invariant(offsets.data() != nullptr || ds->getDynamicBufferCount() == 0);
-        std::copy_n(offsets.data(), ds->getDynamicBufferCount(),
-                mBoundDescriptorSets[set].offsets.data());
-    }
-}
-
-void OpenGLDriver::updateDescriptors(utils::bitset8 invalidDescriptorSets) noexcept {
-    assert_invariant(mBoundProgram);
-    auto const offsetOnly = mInvalidDescriptorSetBindingOffsets & ~mInvalidDescriptorSetBindings;
-    invalidDescriptorSets.forEachSetBit([this, offsetOnly,
-            &boundDescriptorSets = mBoundDescriptorSets,
-            &context = mContext,
-            &boundProgram = *mBoundProgram](size_t set) {
-        assert_invariant(set < MAX_DESCRIPTOR_SET_COUNT);
-        auto const& entry = boundDescriptorSets[set];
-        if (entry.dsh) {
-            GLDescriptorSet* const ds = handle_cast<GLDescriptorSet*>(entry.dsh);
-#ifndef NDEBUG
-            if (UTILS_UNLIKELY(!offsetOnly[set])) {
-                // validate that this descriptor-set layout matches the layout set in the pipeline
-                // we don't need to do the check if only the offset is changing
-                ds->validate(mHandleAllocator, mCurrentSetLayout[set]);
-            }
-#endif
-            ds->bind(context, mHandleAllocator, boundProgram,
-                    set, entry.offsets.data(), offsetOnly[set]);
-        }
-    });
-    mInvalidDescriptorSetBindings.clear();
-    mInvalidDescriptorSetBindingOffsets.clear();
-}
-
 void OpenGLDriver::draw2(uint32_t indexOffset, uint32_t indexCount, uint32_t instanceCount) {
    DEBUG_MARKER()
-    assert_invariant(!mContext.isES2());
-    assert_invariant(mBoundRenderPrimitive);
-#if FILAMENT_ENABLE_MATDBG
-    if (UTILS_UNLIKELY(!mValidProgram)) {
+    GLRenderPrimitive const* const rp = mBoundRenderPrimitive;
+    if (UTILS_UNLIKELY(!rp || !mValidProgram)) {
        return;
    }
-#endif
-    assert_invariant(mBoundProgram);
-    assert_invariant(mValidProgram);
-
-    // When the program changes, we might have to rebind all or some descriptors
-    auto const invalidDescriptorSets =
-            mInvalidDescriptorSetBindings | mInvalidDescriptorSetBindingOffsets;
-    if (UTILS_UNLIKELY(invalidDescriptorSets.any())) {
-        updateDescriptors(invalidDescriptorSets);
-    }

 #ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
-    GLRenderPrimitive const* const rp = mBoundRenderPrimitive;
+    assert_invariant(!mContext.isES2());
    glDrawElementsInstanced(GLenum(rp->type), (GLsizei)indexCount,
            rp->gl.getIndicesType(),
-            reinterpret_cast<const void*>(indexOffset << rp->gl.indicesShift),
+            reinterpret_cast<const void*>(indexOffset * rp->gl.indicesSize),
            (GLsizei)instanceCount);
 #endif

@@ -3958,30 +3961,19 @@ void OpenGLDriver::draw2(uint32_t indexOffset, uint32_t indexCount, uint32_t ins
 #endif
 }

-// This is the ES2 version of draw2().
 void OpenGLDriver::draw2GLES2(uint32_t indexOffset, uint32_t indexCount, uint32_t instanceCount) {
    DEBUG_MARKER()
-    assert_invariant(mContext.isES2());
-    assert_invariant(mBoundRenderPrimitive);
-#if FILAMENT_ENABLE_MATDBG
-    if (UTILS_UNLIKELY(!mValidProgram)) {
+    GLRenderPrimitive const* const rp = mBoundRenderPrimitive;
+    if (UTILS_UNLIKELY(!rp || !mValidProgram)) {
        return;
    }
-#endif
-    assert_invariant(mBoundProgram);
-    assert_invariant(mValidProgram);

-    // When the program changes, we might have to rebind all or some descriptors
-    auto const invalidDescriptorSets =
-            mInvalidDescriptorSetBindings | mInvalidDescriptorSetBindingOffsets;
-    if (UTILS_UNLIKELY(invalidDescriptorSets.any())) {
-        updateDescriptors(invalidDescriptorSets);
-    }
-
-    GLRenderPrimitive const* const rp = mBoundRenderPrimitive;
+    assert_invariant(mContext.isES2());
    assert_invariant(instanceCount == 1);
+
    glDrawElements(GLenum(rp->type), (GLsizei)indexCount, rp->gl.getIndicesType(),
-            reinterpret_cast<const void*>(indexOffset << rp->gl.indicesShift));
+            reinterpret_cast<const void*>(indexOffset * rp->gl.indicesSize));
+

 #if FILAMENT_ENABLE_MATDBG
    CHECK_GL_ERROR_NON_FATAL(utils::slog.e)
@@ -21,8 +21,6 @@
 #include "OpenGLContext.h"
 #include "OpenGLTimerQuery.h"
 #include "GLBufferObject.h"
-#include "GLDescriptorSet.h"
-#include "GLDescriptorSetLayout.h"
 #include "GLTexture.h"
 #include "ShaderCompilerService.h"

@@ -38,7 +36,6 @@
 #include "private/backend/Driver.h"
 #include "private/backend/HandleAllocator.h"

-#include <utils/bitset.h>
 #include <utils/FixedCapacityVector.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
@@ -55,7 +52,6 @@
 #include <tuple>
 #include <type_traits>
 #include <utility>
-#include <variant>
 #include <vector>

 #include <stddef.h>
@@ -127,6 +123,16 @@ public:
        } gl;
    };

+    struct GLSamplerGroup : public HwSamplerGroup {
+        using HwSamplerGroup::HwSamplerGroup;
+        struct Entry {
+            Handle<HwTexture> th;
+            GLuint sampler = 0u;
+        };
+        utils::FixedCapacityVector<Entry> textureUnitEntries;
+        explicit GLSamplerGroup(size_t size) noexcept : textureUnitEntries(size) { }
+    };
+
    struct GLRenderPrimitive : public HwRenderPrimitive {
        using HwRenderPrimitive::HwRenderPrimitive;
        OpenGLContext::RenderPrimitive gl;
@@ -139,10 +145,6 @@ public:

    using GLTimerQuery = filament::backend::GLTimerQuery;

-    using GLDescriptorSetLayout = filament::backend::GLDescriptorSetLayout;
-
-    using GLDescriptorSet = filament::backend::GLDescriptorSet;
-
    struct GLStream : public HwStream {
        using HwStream::HwStream;
        struct Info {
@@ -315,6 +317,10 @@ private:
    void resolvePass(ResolveAction action, GLRenderTarget const* rt,
            TargetBufferFlags discardFlags) noexcept;

+    const std::array<GLSamplerGroup*, Program::SAMPLER_BINDING_COUNT>& getSamplerBindings() const {
+        return mSamplerBindings;
+    }
+
    using AttachmentArray = std::array<GLenum, MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT + 2>;
    static GLsizei getAttachments(AttachmentArray& attachments, TargetBufferFlags buffers,
            bool isDefaultFramebuffer) noexcept;
@@ -327,16 +333,8 @@ private:
    GLboolean mRenderPassStencilWrite{};

    GLRenderPrimitive const* mBoundRenderPrimitive = nullptr;
-    OpenGLProgram* mBoundProgram = nullptr;
    bool mValidProgram = false;
-    utils::bitset8 mInvalidDescriptorSetBindings;
-    utils::bitset8 mInvalidDescriptorSetBindingOffsets;
-    void updateDescriptors(utils::bitset8 invalidDescriptorSets) noexcept;

-    struct {
-        backend::DescriptorSetHandle dsh;
-        std::array<uint32_t, CONFIG_UNIFORM_BINDING_COUNT> offsets;
-    } mBoundDescriptorSets[MAX_DESCRIPTOR_SET_COUNT];

    void clearWithRasterPipe(TargetBufferFlags clearFlags,
            math::float4 const& linearColor, GLfloat depth, GLint stencil) noexcept;
@@ -348,6 +346,9 @@ private:
    // ES2 only. Uniform buffer emulation binding points
    GLuint mLastAssignedEmulatedUboId = 0;

+    // sampler buffer binding points (nullptr if not used)
+    std::array<GLSamplerGroup*, Program::SAMPLER_BINDING_COUNT> mSamplerBindings = {};   // 4 pointers
+
    // this must be accessed from the driver thread only
    std::vector<GLTexture*> mTexturesWithStreamsAttached;

@@ -358,6 +359,8 @@ private:
    void detachStream(GLTexture* t) noexcept;
    void replaceStream(GLTexture* t, GLStream* stream) noexcept;

+    void updateTextureLodRange(GLTexture* texture, int8_t targetLevel) noexcept;
+
 #ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
    // tasks executed on the main thread after the fence signaled
    void whenGpuCommandsComplete(const std::function<void()>& fn) noexcept;
@@ -381,7 +384,6 @@ private:
    bool mRec709OutputColorspace = false;

    PushConstantBundle* mCurrentPushConstants = nullptr;
-    PipelineLayout::SetLayout mCurrentSetLayout;
 };

 // ------------------------------------------------------------------------------------------------
@@ -17,7 +17,6 @@
 #include "OpenGLProgram.h"

 #include "GLUtils.h"
-#include "GLTexture.h"
 #include "OpenGLDriver.h"
 #include "ShaderCompilerService.h"

@@ -25,7 +24,6 @@
 #include <backend/Program.h>
 #include <backend/Handle.h>

-#include <utils/BitmaskEnum.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
 #include <utils/FixedCapacityVector.h>
@@ -34,10 +32,9 @@

 #include <algorithm>
 #include <array>
-#include <algorithm>
-#include <new>
 #include <string_view>
 #include <utility>
+#include <new>

 #include <stddef.h>
 #include <stdint.h>
@@ -49,8 +46,9 @@ using namespace utils;
 using namespace backend;

 struct OpenGLProgram::LazyInitializationData {
-    Program::DescriptorSetInfo descriptorBindings;
-    Program::BindingUniformsInfo bindingUniformInfo;
+    Program::UniformBlockInfo uniformBlockInfo;
+    Program::SamplerGroupInfo samplerGroupInfo;
+    std::array<Program::UniformInfo, Program::UNIFORM_BINDING_COUNT> bindingUniformInfo;
    utils::FixedCapacityVector<Program::PushConstant> vertexPushConstants;
    utils::FixedCapacityVector<Program::PushConstant> fragmentPushConstants;
 };
@@ -59,14 +57,16 @@ struct OpenGLProgram::LazyInitializationData {
 OpenGLProgram::OpenGLProgram() noexcept = default;

 OpenGLProgram::OpenGLProgram(OpenGLDriver& gld, Program&& program) noexcept
-        : HwProgram(std::move(program.getName())), mRec709Location(-1) {
+        : HwProgram(std::move(program.getName())) {
    auto* const lazyInitializationData = new(std::nothrow) LazyInitializationData();
+    lazyInitializationData->samplerGroupInfo = std::move(program.getSamplerGroupInfo());
    if (UTILS_UNLIKELY(gld.getContext().isES2())) {
        lazyInitializationData->bindingUniformInfo = std::move(program.getBindingUniformInfo());
+    } else {
+        lazyInitializationData->uniformBlockInfo = std::move(program.getUniformBlockBindings());
    }
    lazyInitializationData->vertexPushConstants = std::move(program.getPushConstants(ShaderStage::VERTEX));
    lazyInitializationData->fragmentPushConstants = std::move(program.getPushConstants(ShaderStage::FRAGMENT));
-    lazyInitializationData->descriptorBindings = std::move(program.getDescriptorBindings());

    ShaderCompilerService& compiler = gld.getShaderCompilerService();
    mToken = compiler.createProgram(name, std::move(program));
@@ -124,86 +124,36 @@ void OpenGLProgram::initializeProgramState(OpenGLContext& context, GLuint progra

    SYSTRACE_CALL();

-    // from the pipeline layout we compute a mapping from {set, binding} to {binding}
-    // for both buffers and textures
-
-    for (auto&& entry: lazyInitializationData.descriptorBindings) {
-        std::sort(entry.begin(), entry.end(),
-                [](Program::Descriptor const& lhs, Program::Descriptor const& rhs) {
-                    return lhs.binding < rhs.binding;
-                });
-    }
-
-    GLuint tmu = 0;
-    GLuint binding = 0;
-
-    // needed for samplers
-    context.useProgram(program);
-
-    UTILS_NOUNROLL
-    for (backend::descriptor_set_t set = 0; set < MAX_DESCRIPTOR_SET_COUNT; set++) {
-        for (Program::Descriptor const& entry: lazyInitializationData.descriptorBindings[set]) {
-            switch (entry.type) {
-                case DescriptorType::UNIFORM_BUFFER:
-                case DescriptorType::SHADER_STORAGE_BUFFER: {
-                    if (!entry.name.empty()) {
 #ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
-                        if (UTILS_LIKELY(!context.isES2())) {
-                            GLuint const index = glGetUniformBlockIndex(program,
-                                    entry.name.c_str());
-                            if (index != GL_INVALID_INDEX) {
-                                // this can fail if the program doesn't use this descriptor
-                                glUniformBlockBinding(program, index, binding);
-                                mBindingMap.insert(set, entry.binding,
-                                        { binding, entry.type });
-                                ++binding;
-                            }
-                        } else
-#endif
-                        {
-                            auto pos = std::find_if(lazyInitializationData.bindingUniformInfo.begin(),
-                                    lazyInitializationData.bindingUniformInfo.end(),
-                                    [&name = entry.name](const auto& item) {
-                                return std::get<1>(item) == name;
-                            });
-                            if (pos != lazyInitializationData.bindingUniformInfo.end()) {
-                                binding = std::get<0>(*pos);
-                                mBindingMap.insert(set, entry.binding, { binding, entry.type });
-                            }
-                        }
-                    }
-                    break;
+    if (!context.isES2()) {
+        // Note: This is only needed, because the layout(binding=) syntax is not permitted in glsl
+        // (ES3.0 and GL4.1). The backend needs a way to associate a uniform block to a binding point.
+        UTILS_NOUNROLL
+        for (GLuint binding = 0, n = lazyInitializationData.uniformBlockInfo.size();
+                binding < n; binding++) {
+            auto const& name = lazyInitializationData.uniformBlockInfo[binding];
+            if (!name.empty()) {
+                GLuint const index = glGetUniformBlockIndex(program, name.c_str());
+                if (index != GL_INVALID_INDEX) {
+                    glUniformBlockBinding(program, index, binding);
                }
-                case DescriptorType::SAMPLER: {
-                    if (!entry.name.empty()) {
-                        GLint const loc = glGetUniformLocation(program, entry.name.c_str());
-                        if (loc >= 0) {
-                            // this can fail if the program doesn't use this descriptor
-                            mBindingMap.insert(set, entry.binding, { tmu, entry.type });
-                            glUniform1i(loc, GLint(tmu));
-                            ++tmu;
-                        }
-                    }
-                    break;
-                }
-                case DescriptorType::INPUT_ATTACHMENT:
-                    break;
+                CHECK_GL_ERROR(utils::slog.e)
            }
-            CHECK_GL_ERROR(utils::slog.e)
        }
-    }
-
-    if (context.isES2()) {
+    } else
+#endif
+    {
        // ES2 initialization of (fake) UBOs
        UniformsRecord* const uniformsRecords = new(std::nothrow) UniformsRecord[Program::UNIFORM_BINDING_COUNT];
        UTILS_NOUNROLL
-        for (auto&& [index, name, uniforms] : lazyInitializationData.bindingUniformInfo) {
-            uniformsRecords[index].locations.reserve(uniforms.size());
-            uniformsRecords[index].locations.resize(uniforms.size());
+        for (GLuint binding = 0, n = Program::UNIFORM_BINDING_COUNT; binding < n; binding++) {
+            Program::UniformInfo& uniforms = lazyInitializationData.bindingUniformInfo[binding];
+            uniformsRecords[binding].locations.reserve(uniforms.size());
+            uniformsRecords[binding].locations.resize(uniforms.size());
            for (size_t j = 0, c = uniforms.size(); j < c; j++) {
                GLint const loc = glGetUniformLocation(program, uniforms[j].name.c_str());
-                uniformsRecords[index].locations[j] = loc;
-                if (UTILS_UNLIKELY(index == 0)) {
+                uniformsRecords[binding].locations[j] = loc;
+                if (UTILS_UNLIKELY(binding == 0)) {
                    // This is a bit of a gross hack here, we stash the location of
                    // "frameUniforms.rec709", which obviously the backend shouldn't know about,
                    // which is used for emulating the "rec709" colorspace in the shader.
@@ -215,11 +165,51 @@ void OpenGLProgram::initializeProgramState(OpenGLContext& context, GLuint progra
                    }
                }
            }
-            uniformsRecords[index].uniforms = std::move(uniforms);
+            uniformsRecords[binding].uniforms = std::move(uniforms);
        }
        mUniformsRecords = uniformsRecords;
    }

+    uint8_t usedBindingCount = 0;
+    uint8_t tmu = 0;
+
+    UTILS_NOUNROLL
+    for (size_t i = 0, c = lazyInitializationData.samplerGroupInfo.size(); i < c; i++) {
+        auto const& samplers = lazyInitializationData.samplerGroupInfo[i].samplers;
+        if (samplers.empty()) {
+            // this binding point doesn't have any samplers, skip it.
+            continue;
+        }
+
+        // keep this in the loop, so we skip it in the rare case a program doesn't have
+        // sampler. The context cache will prevent repeated calls to GL.
+        context.useProgram(program);
+
+        bool atLeastOneSamplerUsed = false;
+        UTILS_NOUNROLL
+        for (const Program::Sampler& sampler: samplers) {
+            // find its location and associate a TMU to it
+            GLint const loc = glGetUniformLocation(program, sampler.name.c_str());
+            if (loc >= 0) {
+                // this can fail if the program doesn't use this sampler
+                glUniform1i(loc, tmu);
+                atLeastOneSamplerUsed = true;
+            }
+            tmu++;
+        }
+
+        // if this program doesn't use any sampler from this HwSamplerGroup, just cancel the
+        // whole group.
+        if (atLeastOneSamplerUsed) {
+            // Cache the sampler uniform locations for each interface block
+            mUsedSamplerBindingPoints[usedBindingCount] = i;
+            usedBindingCount++;
+        } else {
+            tmu -= samplers.size();
+        }
+    }
+    mUsedBindingsCount = usedBindingCount;
+
    auto& vertexConstants = lazyInitializationData.vertexPushConstants;
    auto& fragmentConstants = lazyInitializationData.fragmentPushConstants;

@@ -236,8 +226,41 @@ void OpenGLProgram::initializeProgramState(OpenGLContext& context, GLuint progra
    }
 }

-void OpenGLProgram::updateUniforms(
-        uint32_t index, GLuint id, void const* buffer, uint16_t age) const noexcept {
+void OpenGLProgram::updateSamplers(OpenGLDriver* const gld) const noexcept {
+    using GLTexture = OpenGLDriver::GLTexture;
+
+#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
+    bool const es2 = gld->getContext().isES2();
+#endif
+
+    // cache a few member variable locally, outside the loop
+    auto const& UTILS_RESTRICT samplerBindings = gld->getSamplerBindings();
+    auto const& UTILS_RESTRICT usedBindingPoints = mUsedSamplerBindingPoints;
+
+    for (uint8_t i = 0, tmu = 0, n = mUsedBindingsCount; i < n; i++) {
+        size_t const binding = usedBindingPoints[i];
+        assert_invariant(binding < Program::SAMPLER_BINDING_COUNT);
+        auto const * const sb = samplerBindings[binding];
+        assert_invariant(sb);
+        if (!sb) continue; // should never happen, this would be a user error.
+        for (uint8_t j = 0, m = sb->textureUnitEntries.size(); j < m; ++j, ++tmu) { // "<=" on purpose here
+            Handle<HwTexture> th = sb->textureUnitEntries[j].th;
+            if (th) { // program may not use all samplers of sampler group
+                GLTexture const* const t = gld->handle_cast<GLTexture const*>(th);
+                gld->bindTexture(tmu, t);
+#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
+                if (UTILS_LIKELY(!es2)) {
+                    GLuint const s = sb->textureUnitEntries[j].sampler;
+                    gld->bindSampler(tmu, s);
+                }
+#endif
+            }
+        }
+    }
+    CHECK_GL_ERROR(utils::slog.e)
+}
+
+void OpenGLProgram::updateUniforms(uint32_t index, GLuint id, void const* buffer, uint16_t age) noexcept {
    assert_invariant(mUniformsRecords);
    assert_invariant(buffer);

@@ -19,20 +19,17 @@

 #include "DriverBase.h"

-#include "BindingMap.h"
 #include "OpenGLContext.h"
 #include "ShaderCompilerService.h"

 #include <private/backend/Driver.h>
-
-#include <backend/DriverEnums.h>
 #include <backend/Program.h>

-#include <utils/bitset.h>
 #include <utils/compiler.h>
 #include <utils/FixedCapacityVector.h>
 #include <utils/Slice.h>

+#include <array>
 #include <limits>

 #include <stddef.h>
@@ -72,25 +69,32 @@ public:
        }

        context.useProgram(gl.program);
+        if (UTILS_UNLIKELY(mUsedBindingsCount)) {
+            // We rely on GL state tracking to avoid unnecessary glBindTexture / glBindSampler
+            // calls.
+
+            // we need to do this if:
+            // - the content of mSamplerBindings has changed
+            // - the content of any bound sampler buffer has changed
+            // ... since last time we used this program
+
+            // Turns out the former might be relatively cheap to check, the latter requires
+            // a bit less. Compared to what updateSamplers() actually does, which is
+            // pretty little, I'm not sure if we'll get ahead.
+
+            updateSamplers(gld);
+        }
        return true;
    }

-    GLuint getBufferBinding(descriptor_set_t set, descriptor_binding_t binding) const noexcept {
-        return mBindingMap.get(set, binding);
-    }
-
-    GLuint getTextureUnit(descriptor_set_t set, descriptor_binding_t binding) const noexcept {
-        return mBindingMap.get(set, binding);
-    }
-
-    utils::bitset64 getActiveDescriptors(descriptor_set_t set) const noexcept {
-        return mBindingMap.getActiveDescriptors(set);
-    }
-
    // For ES2 only
-    void updateUniforms(uint32_t index, GLuint id, void const* buffer, uint16_t age) const noexcept;
+    void updateUniforms(uint32_t index, GLuint id, void const* buffer, uint16_t age) noexcept;
    void setRec709ColorSpace(bool rec709) const noexcept;

+    struct {
+        GLuint program = 0;
+    } gl;                                               // 4 bytes
+
    PushConstantBundle getPushConstants() {
        auto fragBegin = mPushConstants.begin() + mPushConstantFragmentStageOffset;
        return {
@@ -108,15 +112,22 @@ private:
    void initializeProgramState(OpenGLContext& context, GLuint program,
            LazyInitializationData& lazyInitializationData) noexcept;

-    BindingMap mBindingMap;     // 8 bytes + out-of-line 256 bytes
+    void updateSamplers(OpenGLDriver* gld) const noexcept;
+
+    // number of bindings actually used by this program
+    std::array<uint8_t, Program::SAMPLER_BINDING_COUNT> mUsedSamplerBindingPoints;   // 4 bytes

    ShaderCompilerService::program_token_t mToken{};    // 16 bytes

-    // Note that this can be replaced with a raw pointer and an uint8_t (for size) to reduce the
-    // size of the container to 9 bytes if there is a need in the future.
-    utils::FixedCapacityVector<std::pair<GLint, ConstantType>> mPushConstants;// 16 bytes
+    uint8_t mUsedBindingsCount = 0u;                    // 1 byte
+    UTILS_UNUSED uint8_t padding[2] = {};               // 2 byte
+
+    // Push constant array offset for fragment stage constants.
+    uint8_t mPushConstantFragmentStageOffset = 0u;      // 1 byte

    // only needed for ES2
+    GLint mRec709Location = -1;                         // 4 bytes
+
    using LocationInfo = utils::FixedCapacityVector<GLint>;
    struct UniformsRecord {
        Program::UniformInfo uniforms;
@@ -124,20 +135,15 @@ private:
        mutable GLuint id = 0;
        mutable uint16_t age = std::numeric_limits<uint16_t>::max();
    };
-    UniformsRecord const* mUniformsRecords = nullptr;
-    GLint mRec709Location : 24;     // 4 bytes
+    UniformsRecord const* mUniformsRecords = nullptr;               // 8 bytes

-    // Push constant array offset for fragment stage constants.
-    GLint mPushConstantFragmentStageOffset : 8;      // 1 byte
-
-public:
-    struct {
-        GLuint program = 0;
-    } gl;                                               // 4 bytes
+    // Note that this can be replaced with a raw pointer and an uint8_t (for size) to reduce the
+    // size of the container to 9 bytes if there is a need in the future.
+    utils::FixedCapacityVector<std::pair<GLint, ConstantType>> mPushConstants;// 16 bytes
 };

-// if OpenGLProgram is larger than 96 bytes, it'll fall in a larger Handle bucket.
-static_assert(sizeof(OpenGLProgram) <= 96); // currently 96 bytes
+// if OpenGLProgram is larger tha 64 bytes, it'll fall in a larger Handle bucket.
+static_assert(sizeof(OpenGLProgram) <= 64); // currently 64 bytes

 } // namespace filament::backend

@@ -155,6 +155,10 @@ Driver* PlatformEGL::createDriver(void* sharedContext, const Platform::DriverCon
    ext.egl.KHR_no_config_context = extensions.has("EGL_KHR_no_config_context");
    ext.egl.KHR_surfaceless_context = extensions.has("EGL_KHR_surfaceless_context");
    ext.egl.EXT_protected_content = extensions.has("EGL_EXT_protected_content");
+    if (ext.egl.KHR_create_context) {
+        // KHR_create_context implies KHR_surfaceless_context for ES3.x contexts
+        ext.egl.KHR_surfaceless_context = true;
+    }

    eglCreateSyncKHR = (PFNEGLCREATESYNCKHRPROC) eglGetProcAddress("eglCreateSyncKHR");
    eglDestroySyncKHR = (PFNEGLDESTROYSYNCKHRPROC) eglGetProcAddress("eglDestroySyncKHR");
@@ -553,8 +557,6 @@ void PlatformEGL::destroySwapChain(Platform::SwapChain* swapChain) noexcept {
    if (swapChain) {
        SwapChainEGL const* const sc = static_cast<SwapChainEGL const*>(swapChain);
        if (sc->sur != EGL_NO_SURFACE) {
-            // - if EGL_KHR_surfaceless_context is supported, mEGLDummySurface is EGL_NO_SURFACE.
-            // - this is actually a bit too aggressive, but it is a rare operation.
            egl.makeCurrent(mEGLDummySurface, mEGLDummySurface);
            eglDestroySurface(mEGLDisplay, sc->sur);
            delete sc;
@@ -25,14 +25,12 @@
 #include "ExternalStreamManagerAndroid.h"

 #include <android/api-level.h>
-#include <android/native_window.h>
 #include <android/hardware_buffer.h>

 #include <utils/android/PerformanceHintManager.h>

 #include <utils/compiler.h>
 #include <utils/ostream.h>
-#include <utils/Panic.h>
 #include <utils/Log.h>

 #include <EGL/egl.h>
@@ -44,9 +42,7 @@

 #include <chrono>
 #include <new>
-#include <string_view>

-#include <dlfcn.h>
 #include <unistd.h>

 #include <stddef.h>
@@ -84,6 +80,8 @@ UTILS_PRIVATE PFNEGLGETFRAMETIMESTAMPSANDROIDPROC eglGetFrameTimestampsANDROID =
 }
 using namespace glext;

+using EGLStream = Platform::Stream;
+
 // ---------------------------------------------------------------------------------------------

 PlatformEGLAndroid::InitializeJvmForPerformanceManagerIfNeeded::InitializeJvmForPerformanceManagerIfNeeded() {
@@ -103,73 +101,38 @@ PlatformEGLAndroid::PlatformEGLAndroid() noexcept
          mExternalStreamManager(ExternalStreamManagerAndroid::create()),
          mInitializeJvmForPerformanceManagerIfNeeded(),
          mPerformanceHintManager() {
-    mOSVersion = android_get_device_api_level();
-    if (mOSVersion < 0) {
-        mOSVersion = __ANDROID_API_FUTURE__;
+
+    char scratch[PROP_VALUE_MAX + 1];
+    int length = __system_property_get("ro.build.version.release", scratch);
+    int const androidVersion = length >= 0 ? atoi(scratch) : 1;
+    if (!androidVersion) {
+        mOSVersion = 1000; // if androidVersion is 0, it means "future"
+    } else {
+        length = __system_property_get("ro.build.version.sdk", scratch);
+        mOSVersion = length >= 0 ? atoi(scratch) : 1;
    }

-    mNativeWindowLib = dlopen("libnativewindow.so", RTLD_LOCAL | RTLD_NOW);
-    if (mNativeWindowLib) {
-        ANativeWindow_getBuffersDefaultDataSpace =
-                (int32_t(*)(ANativeWindow*))dlsym(mNativeWindowLib,
-                        "ANativeWindow_getBuffersDefaultDataSpace");
-    }
+    // This disables an ANGLE optimization on ARM, which turns out to be more costly for us
+    // see b/229017581
+    // We need to do this before we create the GL context.
+    // An alternative solution is use a system property:
+    //            __system_property_set(
+    //                    "debug.angle.feature_overrides_disabled",
+    //                    "preferSubmitAtFBOBoundary");
+    // but that would outlive this process, so the environment variable is better.
+    // We also make sure to not update the variable if it already exists.
+    // There is no harm setting this if we're not on ANGLE or ARM.
+    setenv("ANGLE_FEATURE_OVERRIDES_DISABLED", "preferSubmitAtFBOBoundary", false);
 }

-PlatformEGLAndroid::~PlatformEGLAndroid() noexcept {
-    if (mNativeWindowLib) {
-        dlclose(mNativeWindowLib);
-    }
-}
+PlatformEGLAndroid::~PlatformEGLAndroid() noexcept = default;
+

 void PlatformEGLAndroid::terminate() noexcept {
    ExternalStreamManagerAndroid::destroy(&mExternalStreamManager);
    PlatformEGL::terminate();
 }

-static constexpr const std::string_view kNativeWindowInvalidMsg =
-        "ANativeWindow is invalid. It probably has been destroyed. EGL surface = ";
-
-bool PlatformEGLAndroid::makeCurrent(ContextType type,
-        SwapChain* drawSwapChain,
-        SwapChain* readSwapChain) noexcept {
-
-    // fast & safe path
-    if (UTILS_LIKELY(!mAssertNativeWindowIsValid)) {
-        return PlatformEGL::makeCurrent(type, drawSwapChain, readSwapChain);
-    }
-
-    SwapChainEGL const* const dsc = static_cast<SwapChainEGL const*>(drawSwapChain);
-    if (ANativeWindow_getBuffersDefaultDataSpace) {
-        // anw can be nullptr if we're using a pbuffer surface
-        if (UTILS_LIKELY(dsc->nativeWindow)) {
-            // this a proxy of is_valid()
-            auto result = ANativeWindow_getBuffersDefaultDataSpace(dsc->nativeWindow);
-            FILAMENT_CHECK_POSTCONDITION(result >= 0) << kNativeWindowInvalidMsg << dsc->sur;
-        }
-    } else {
-        // If we don't have ANativeWindow_getBuffersDefaultDataSpace, we revert to using the
-        // private query() call.
-        // Shadow version if the real ANativeWindow, so we can access the query() hook. Query
-        // has existed since forever, probably Android 1.0.
-        struct NativeWindow {
-            // is valid query enum value
-            enum { IS_VALID = 17 };
-            uint64_t pad[18];
-            int (* query)(ANativeWindow const*, int, int*);
-        } const* pWindow = reinterpret_cast<NativeWindow const*>(dsc->nativeWindow);
-        int isValid = 0;
-        if (UTILS_LIKELY(pWindow->query)) { // just in case it's nullptr
-            int const err = pWindow->query(dsc->nativeWindow, NativeWindow::IS_VALID, &isValid);
-            if (UTILS_LIKELY(err >= 0)) { // in case the IS_VALID enum is not recognized
-                // query call succeeded
-                FILAMENT_CHECK_POSTCONDITION(isValid) << kNativeWindowInvalidMsg << dsc->sur;
-            }
-        }
-    }
-    return PlatformEGL::makeCurrent(type, drawSwapChain, readSwapChain);
-}
-
 void PlatformEGLAndroid::beginFrame(
        int64_t monotonic_clock_ns,
        int64_t refreshIntervalNs,
@@ -226,8 +189,6 @@ Driver* PlatformEGLAndroid::createDriver(void* sharedContext,
                "eglGetFrameTimestampsANDROID");
    }

-    mAssertNativeWindowIsValid = driverConfig.assertNativeWindowIsValid;
-
    return driver;
 }

@@ -1,149 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include <backend/platforms/PlatformOSMesa.h>
-
-#include <utils/Log.h>
-#include <utils/Panic.h>
-
-#include <dlfcn.h>
-#include <memory>
-
-namespace filament::backend {
-
-using namespace backend;
-
-namespace {
-
-using BackingType = GLfloat;
-#define BACKING_GL_TYPE GL_FLOAT
-
-struct OSMesaSwapchain {
-    OSMesaSwapchain(uint32_t width, uint32_t height)
-        : width(width),
-          height(height),
-          buffer(new uint8_t[width * height * 4 * sizeof(BackingType)]) {}
-
-    uint32_t width = 0;
-    uint32_t height = 0;
-    std::unique_ptr<uint8_t[]> buffer;
-};
-
-struct OSMesaAPI {
-private:
-    using CreateContextFunc = OSMesaContext (*)(GLenum format, OSMesaContext);
-    using DestroyContextFunc = GLboolean (*)(OSMesaContext);
-    using MakeCurrentFunc = GLboolean (*)(OSMesaContext ctx, void* buffer, GLenum type,
-            GLsizei width, GLsizei height);
-    using GetProcAddressFunc = OSMESAproc (*)(const char* funcName);
-
-public:
-    CreateContextFunc OSMesaCreateContext;
-    DestroyContextFunc OSMesaDestroyContext;
-    MakeCurrentFunc OSMesaMakeCurrent;
-    GetProcAddressFunc OSMesaGetProcAddress;
-
-    OSMesaAPI() {
-        constexpr char const* libraryNames[] = {"libOSMesa.so", "libosmesa.so"};
-        for (char const* libName: libraryNames) {
-            mLib = dlopen(libName, RTLD_GLOBAL | RTLD_NOW);
-            if (mLib) {
-                break;
-            }
-        }
-        FILAMENT_CHECK_PRECONDITION(mLib)
-                << "Unable to dlopen libOSMesa to create a software GL context";
-
-        OSMesaGetProcAddress = (GetProcAddressFunc) dlsym(mLib, "OSMesaGetProcAddress");
-
-        OSMesaCreateContext = (CreateContextFunc) OSMesaGetProcAddress("OSMesaCreateContext");
-        OSMesaDestroyContext =
-                (DestroyContextFunc) OSMesaGetProcAddress("OSMesaDestroyContext");
-        OSMesaMakeCurrent = (MakeCurrentFunc) OSMesaGetProcAddress("OSMesaMakeCurrent");
-    }
-
-    ~OSMesaAPI() {
-        dlclose(mLib);
-    }
-private:
-    void* mLib = nullptr;
-};
-
-}// anonymous namespace
-
-Driver* PlatformOSMesa::createDriver(void* const sharedGLContext,
-        const DriverConfig& driverConfig) noexcept {
-    OSMesaAPI* api = new OSMesaAPI();
-    mOsMesaApi = api;
-
-    FILAMENT_CHECK_PRECONDITION(sharedGLContext == nullptr)
-            << "shared GL context is not supported with PlatformOSMesa";
-    mContext = api->OSMesaCreateContext(GL_RGBA, NULL);
-
-    // We need to do a no-op makecurrent here so that the context will be in a correct state before
-    // any GL calls.
-    auto chain = createSwapChain(1, 1, 0);
-    makeCurrent(ContextType::UNPROTECTED, chain, nullptr);
-    destroySwapChain(chain);
-
-    int result = bluegl::bind();
-    FILAMENT_CHECK_POSTCONDITION(!result) << "Unable to load OpenGL entry points.";
-
-    return OpenGLPlatform::createDefaultDriver(this, sharedGLContext, driverConfig);
-}
-
-void PlatformOSMesa::terminate() noexcept {
-    OSMesaAPI* api = (OSMesaAPI*) mOsMesaApi;
-    api->OSMesaDestroyContext(mContext);
-    delete api;
-    mOsMesaApi = nullptr;
-
-    bluegl::unbind();
-}
-
-Platform::SwapChain* PlatformOSMesa::createSwapChain(void* nativeWindow, uint64_t flags) noexcept {
-    FILAMENT_CHECK_POSTCONDITION(false) << "Cannot create non-headless swapchain";
-    return (SwapChain*) nativeWindow;
-}
-
-Platform::SwapChain* PlatformOSMesa::createSwapChain(uint32_t width, uint32_t height,
-        uint64_t flags) noexcept {
-    OSMesaSwapchain* swapchain = new OSMesaSwapchain(width, height);
-    return (SwapChain*) swapchain;
-}
-
-void PlatformOSMesa::destroySwapChain(Platform::SwapChain* swapChain) noexcept {
-    OSMesaSwapchain* impl = (OSMesaSwapchain*) swapChain;
-    delete impl;
-}
-
-bool PlatformOSMesa::makeCurrent(ContextType type, SwapChain* drawSwapChain,
-        SwapChain* readSwapChain) noexcept {
-    OSMesaAPI* api = (OSMesaAPI*) mOsMesaApi;
-    OSMesaSwapchain* impl = (OSMesaSwapchain*) drawSwapChain;
-
-    auto result = api->OSMesaMakeCurrent(mContext, (BackingType*) impl->buffer.get(),
-            BACKING_GL_TYPE, impl->width, impl->height);
-    FILAMENT_CHECK_POSTCONDITION(result == GL_TRUE) << "OSMesaMakeCurrent failed!";
-
-    return true;
-}
-
-void PlatformOSMesa::commit(Platform::SwapChain* swapChain) noexcept {
-    // No-op since we are not scanning out to a display.
-}
-
-} // namespace filament::backend
@@ -410,6 +410,7 @@ io::ostream& operator<<(io::ostream& out, const RasterState& rs) {
 io::ostream& operator<<(io::ostream& out, const TargetBufferInfo& tbi) {
    return out << "TargetBufferInfo{"
    << "handle=" << tbi.handle
+    << ", baseViewIndex=" << tbi.baseViewIndex
    << ", level=" << tbi.level
    << ", layer=" << tbi.layer << "}";
 }
@@ -15,7 +15,6 @@
 */

 #include "VulkanBlitter.h"
-#include "VulkanCommands.h"
 #include "VulkanContext.h"
 #include "VulkanFboCache.h"
 #include "VulkanHandles.h"
@@ -34,10 +33,9 @@ namespace filament::backend {

 namespace {

-inline void blitFast(VulkanCommandBuffer* commands, VkImageAspectFlags aspect, VkFilter filter,
+inline void blitFast(const VkCommandBuffer cmdbuffer, VkImageAspectFlags aspect, VkFilter filter,
        VulkanAttachment src, VulkanAttachment dst,
        const VkOffset3D srcRect[2], const VkOffset3D dstRect[2]) {
-    VkCommandBuffer const cmdbuf = commands->buffer();
    if constexpr (FVK_ENABLED(FVK_DEBUG_BLITTER)) {
        FVK_LOGD << "Fast blit from=" << src.texture->getVkImage() << ",level=" << (int) src.level
                      << " layout=" << src.getLayout()
@@ -51,8 +49,8 @@ inline void blitFast(VulkanCommandBuffer* commands, VkImageAspectFlags aspect, V
    VulkanLayout oldSrcLayout = src.getLayout();
    VulkanLayout oldDstLayout = dst.getLayout();

-    src.texture->transitionLayout(commands, srcRange, VulkanLayout::TRANSFER_SRC);
-    dst.texture->transitionLayout(commands, dstRange, VulkanLayout::TRANSFER_DST);
+    src.texture->transitionLayout(cmdbuffer, srcRange, VulkanLayout::TRANSFER_SRC);
+    dst.texture->transitionLayout(cmdbuffer, dstRange, VulkanLayout::TRANSFER_DST);

    const VkImageBlit blitRegions[1] = {{
            .srcSubresource = { aspect, src.level, src.layer, 1 },
@@ -60,24 +58,23 @@ inline void blitFast(VulkanCommandBuffer* commands, VkImageAspectFlags aspect, V
            .dstSubresource = { aspect, dst.level, dst.layer, 1 },
            .dstOffsets = { dstRect[0], dstRect[1] },
    }};
-    vkCmdBlitImage(cmdbuf,
+    vkCmdBlitImage(cmdbuffer,
            src.getImage(), imgutil::getVkLayout(VulkanLayout::TRANSFER_SRC),
            dst.getImage(), imgutil::getVkLayout(VulkanLayout::TRANSFER_DST),
            1, blitRegions, filter);

    if (oldSrcLayout == VulkanLayout::UNDEFINED) {
-        oldSrcLayout = src.texture->getDefaultLayout();
+        oldSrcLayout = imgutil::getDefaultLayout(src.texture->usage);
    }
    if (oldDstLayout == VulkanLayout::UNDEFINED) {
-        oldDstLayout = dst.texture->getDefaultLayout();
+        oldDstLayout = imgutil::getDefaultLayout(dst.texture->usage);
    }
-    src.texture->transitionLayout(commands, srcRange, oldSrcLayout);
-    dst.texture->transitionLayout(commands, dstRange, oldDstLayout);
+    src.texture->transitionLayout(cmdbuffer, srcRange, oldSrcLayout);
+    dst.texture->transitionLayout(cmdbuffer, dstRange, oldDstLayout);
 }

-inline void resolveFast(VulkanCommandBuffer* commands, VkImageAspectFlags aspect,
+inline void resolveFast(const VkCommandBuffer cmdbuffer, VkImageAspectFlags aspect,
        VulkanAttachment src, VulkanAttachment dst) {
-    VkCommandBuffer const cmdbuffer = commands->buffer();
    if constexpr (FVK_ENABLED(FVK_DEBUG_BLITTER)) {
        FVK_LOGD << "Fast blit from=" << src.texture->getVkImage() << ",level=" << (int) src.level
                      << " layout=" << src.getLayout()
@@ -91,8 +88,8 @@ inline void resolveFast(VulkanCommandBuffer* commands, VkImageAspectFlags aspect
    VulkanLayout oldSrcLayout = src.getLayout();
    VulkanLayout oldDstLayout = dst.getLayout();

-    src.texture->transitionLayout(commands, srcRange, VulkanLayout::TRANSFER_SRC);
-    dst.texture->transitionLayout(commands, dstRange, VulkanLayout::TRANSFER_DST);
+    src.texture->transitionLayout(cmdbuffer, srcRange, VulkanLayout::TRANSFER_SRC);
+    dst.texture->transitionLayout(cmdbuffer, dstRange, VulkanLayout::TRANSFER_DST);

    assert_invariant(
            aspect != VK_IMAGE_ASPECT_DEPTH_BIT && "Resolve with depth is not yet supported.");
@@ -109,13 +106,13 @@ inline void resolveFast(VulkanCommandBuffer* commands, VkImageAspectFlags aspect
            1, resolveRegions);

    if (oldSrcLayout == VulkanLayout::UNDEFINED) {
-        oldSrcLayout = src.texture->getDefaultLayout();
+        oldSrcLayout = imgutil::getDefaultLayout(src.texture->usage);
    }
    if (oldDstLayout == VulkanLayout::UNDEFINED) {
-        oldDstLayout = dst.texture->getDefaultLayout();
+        oldDstLayout = imgutil::getDefaultLayout(dst.texture->usage);
    }
-    src.texture->transitionLayout(commands, srcRange, oldSrcLayout);
-    dst.texture->transitionLayout(commands, dstRange, oldDstLayout);
+    src.texture->transitionLayout(cmdbuffer, srcRange, oldSrcLayout);
+    dst.texture->transitionLayout(cmdbuffer, dstRange, oldDstLayout);
 }

 struct BlitterUniforms {
@@ -152,9 +149,10 @@ void VulkanBlitter::resolve(VulkanAttachment dst, VulkanAttachment src) {
 #endif

    VulkanCommandBuffer& commands = mCommands->get();
+    VkCommandBuffer const cmdbuffer = commands.buffer();
    commands.acquire(src.texture);
    commands.acquire(dst.texture);
-    resolveFast(&commands, aspect, src, dst);
+    resolveFast(cmdbuffer, aspect, src, dst);
 }

 void VulkanBlitter::blit(VkFilter filter,
@@ -177,9 +175,10 @@ void VulkanBlitter::blit(VkFilter filter,
    // src and dst should have the same aspect here
    VkImageAspectFlags const aspect = src.texture->getImageAspect();
    VulkanCommandBuffer& commands = mCommands->get();
+    VkCommandBuffer const cmdbuffer = commands.buffer();
    commands.acquire(src.texture);
    commands.acquire(dst.texture);
-    blitFast(&commands, aspect, filter, src, dst, srcRectPair, dstRectPair);
+    blitFast(cmdbuffer, aspect, filter, src, dst, srcRectPair, dstRectPair);
 }

 void VulkanBlitter::terminate() noexcept {
@@ -297,11 +297,11 @@ bool VulkanCommands::flush() {
 #endif

    auto& cmdfence = currentbuf->fence;
-    UTILS_UNUSED_IN_RELEASE VkResult result = VK_SUCCESS;
-    {
-        auto scope = cmdfence->setValue(VK_NOT_READY);
-        result = vkQueueSubmit(mQueue, 1, &submitInfo, cmdfence->getFence());
-    }
+    std::unique_lock<utils::Mutex> lock(cmdfence->mutex);
+    cmdfence->status.store(VK_NOT_READY);
+    UTILS_UNUSED_IN_RELEASE VkResult result = vkQueueSubmit(mQueue, 1, &submitInfo, cmdfence->fence);
+    cmdfence->condition.notify_all();
+    lock.unlock();

 #if FVK_ENABLED(FVK_DEBUG_COMMAND_BUFFER)
    if (result != VK_SUCCESS) {
@@ -340,7 +340,7 @@ void VulkanCommands::wait() {
        auto wrapper = mStorage[i].get();
        if (wrapper->buffer() != VK_NULL_HANDLE
                && mCurrentCommandBufferIndex != static_cast<int8_t>(i)) {
-            fences[count++] = wrapper->fence->getFence();
+            fences[count++] = wrapper->fence->fence;
        }
    }
    if (count > 0) {
@@ -361,13 +361,12 @@ void VulkanCommands::gc() {
        if (wrapper->buffer() == VK_NULL_HANDLE) {
            continue;
        }
-        auto const vkfence = wrapper->fence->getFence();
-        VkResult const result = vkGetFenceStatus(mDevice, vkfence);
+        VkResult const result = vkGetFenceStatus(mDevice, wrapper->fence->fence);
        if (result != VK_SUCCESS) {
            continue;
        }
-        fences[count++] = vkfence;
-        wrapper->fence->setValue(VK_SUCCESS);
+        fences[count++] = wrapper->fence->fence;
+        wrapper->fence->status.store(VK_SUCCESS);
        wrapper->reset();
        mAvailableBufferCount++;
    }
@@ -384,9 +383,9 @@ void VulkanCommands::updateFences() {
        if (wrapper->buffer() != VK_NULL_HANDLE) {
            VulkanCmdFence* fence = wrapper->fence.get();
            if (fence) {
-                VkResult status = vkGetFenceStatus(mDevice, fence->getFence());
+                VkResult status = vkGetFenceStatus(mDevice, fence->fence);
                // This is either VK_SUCCESS, VK_NOT_READY, or VK_ERROR_DEVICE_LOST.
-                fence->setValue(status);
+                fence->status.store(status, std::memory_order_relaxed);
            }
        }
    }
@@ -61,40 +61,8 @@ private:

 // Wrapper to enable use of shared_ptr for implementing shared ownership of low-level Vulkan fences.
 struct VulkanCmdFence {
-    struct SetValueScope {
-    public:
-        ~SetValueScope() {
-            mHolder->mutex.unlock();
-            mHolder->condition.notify_all();
-        }
-
-    private:
-        SetValueScope(VulkanCmdFence* fenceHolder, VkResult result) :
-            mHolder(fenceHolder) {
-            mHolder->mutex.lock();
-            mHolder->status.store(result);
-        }
-        VulkanCmdFence* mHolder;
-        friend struct VulkanCmdFence;
-    };
-
    VulkanCmdFence(VkFence ifence);
    ~VulkanCmdFence() = default;
-
-    SetValueScope setValue(VkResult value) {
-        return {this, value};
-    }
-
-    VkFence& getFence() {
-        return fence;
-    }
-
-    VkResult getStatus() {
-        std::unique_lock<utils::Mutex> lock(mutex);
-        return status.load(std::memory_order_acquire);
-    }
-
-private:
    VkFence fence;
    utils::Condition condition;
    utils::Mutex mutex;
@@ -43,6 +43,7 @@ struct VulkanCommandBuffer;
 struct VulkanAttachment {
    VulkanTexture* texture = nullptr;
    uint8_t level = 0;
+    uint8_t baseViewIndex = 0;
    uint8_t layerCount = 1;
    uint16_t layer = 0;

@@ -144,10 +145,6 @@ public:
        return mPhysicalDeviceFeatures.shaderClipDistance == VK_TRUE;
    }

-    inline bool isLazilyAllocatedMemorySupported() const noexcept {
-        return mLazilyAllocatedMemorySupported;
-    }
-
 private:
    VkPhysicalDeviceMemoryProperties mMemoryProperties = {};
    VkPhysicalDeviceProperties mPhysicalDeviceProperties = {};
@@ -155,7 +152,6 @@ private:
    bool mDebugMarkersSupported = false;
    bool mDebugUtilsSupported = false;
    bool mMultiviewEnabled = false;
-    bool mLazilyAllocatedMemorySupported = false;

    VkFormatList mDepthStencilFormats;
    VkFormatList mBlittableDepthStencilFormats;
@@ -88,6 +88,28 @@ VmaAllocator createAllocator(VkInstance instance, VkPhysicalDevice physicalDevic
    return allocator;
 }

+VulkanTexture* createEmptyTexture(VkDevice device, VkPhysicalDevice physicalDevice,
+        VulkanContext const& context, VmaAllocator allocator, VulkanCommands* commands,
+        VulkanStagePool& stagePool) {
+    VulkanTexture* emptyTexture = new VulkanTexture(device, physicalDevice, context, allocator,
+            commands, SamplerType::SAMPLER_2D, 1, TextureFormat::RGBA8, 1, 1, 1, 1,
+            TextureUsage::DEFAULT | TextureUsage::COLOR_ATTACHMENT | TextureUsage::SUBPASS_INPUT,
+            stagePool, true /* heap allocated */);
+    uint32_t black = 0;
+    PixelBufferDescriptor pbd(&black, 4, PixelDataFormat::RGBA, PixelDataType::UBYTE);
+    emptyTexture->updateImage(pbd, 1, 1, 1, 0, 0, 0, 0);
+    return emptyTexture;
+}
+
+VulkanBufferObject* createEmptyBufferObject(VmaAllocator allocator, VulkanStagePool& stagePool,
+        VulkanCommands* commands) {
+    VulkanBufferObject* obj =
+            new VulkanBufferObject(allocator, stagePool, 1, BufferObjectBinding::UNIFORM);
+    uint8_t byte = 0;
+    obj->buffer.loadFromCpu(commands->get().buffer(), &byte, 0, 1);
+    return obj;
+}
+
 #if FVK_ENABLED(FVK_DEBUG_VALIDATION)
 VKAPI_ATTR VkBool32 VKAPI_CALL debugReportCallback(VkDebugReportFlagsEXT flags,
        VkDebugReportObjectTypeEXT objectType, uint64_t object, size_t location,
@@ -127,7 +149,6 @@ VKAPI_ATTR VkBool32 VKAPI_CALL debugUtilsCallback(VkDebugUtilsMessageSeverityFla
 }
 #endif // FVK_EANBLED(FVK_DEBUG_DEBUG_UTILS)

-
 }// anonymous namespace

 #if FVK_ENABLED(FVK_DEBUG_DEBUG_UTILS)
@@ -233,6 +254,17 @@ VulkanDriver::VulkanDriver(VulkanPlatform* platform, VulkanContext const& contex
 #endif

    mTimestamps = std::make_unique<VulkanTimestamps>(mPlatform->getDevice());
+
+    mEmptyTexture = createEmptyTexture(mPlatform->getDevice(), mPlatform->getPhysicalDevice(),
+            mContext, mAllocator, &mCommands, mStagePool);
+    mEmptyBufferObject = createEmptyBufferObject(mAllocator, mStagePool, &mCommands);
+
+    mDescriptorSetManager.setPlaceHolders(mSamplerCache.getSampler({}), mEmptyTexture,
+            mEmptyBufferObject);
+
+    mGetPipelineFunction = [this](VulkanDescriptorSetLayoutList const& layouts, VulkanProgram* program) {
+        return mPipelineLayoutCache.getLayout(layouts, program);
+    };
 }

 VulkanDriver::~VulkanDriver() noexcept = default;
@@ -297,6 +329,9 @@ void VulkanDriver::terminate() {
    // to those commands are no longer referenced.
    finish(0);

+    delete mEmptyBufferObject;
+    delete mEmptyTexture;
+
    // Command buffers should come first since it might have commands depending on resources that
    // are about to be destroyed.
    mCommands.terminate();
@@ -352,6 +387,7 @@ void VulkanDriver::collectGarbage() {
    mStagePool.gc();
    mFramebufferCache.gc();
    mPipelineCache.gc();
+    mDescriptorSetManager.gc();

 #if FVK_ENABLED(FVK_DEBUG_RESOURCE_LEAK)
    mResourceAllocator.print();
@@ -367,8 +403,8 @@ void VulkanDriver::beginFrame(int64_t monotonic_clock_ns,
    FVK_SYSTRACE_END();
 }

-void VulkanDriver::setFrameScheduledCallback(Handle<HwSwapChain> sch, CallbackHandler* handler,
-        FrameScheduledCallback&& callback, uint64_t flags) {
+void VulkanDriver::setFrameScheduledCallback(Handle<HwSwapChain> sch,
+        CallbackHandler* handler, FrameScheduledCallback&& callback) {
 }

 void VulkanDriver::setFrameCompletedCallback(Handle<HwSwapChain> sch,
@@ -386,28 +422,6 @@ void VulkanDriver::endFrame(uint32_t frameId) {
    FVK_SYSTRACE_END();
 }

-void VulkanDriver::updateDescriptorSetBuffer(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_binding_t binding,
-        backend::BufferObjectHandle boh,
-        uint32_t offset,
-        uint32_t size) {
-    VulkanDescriptorSet* set = mResourceAllocator.handle_cast<VulkanDescriptorSet*>(dsh);
-    VulkanBufferObject* obj = mResourceAllocator.handle_cast<VulkanBufferObject*>(boh);
-    mDescriptorSetManager.updateBuffer(set, binding, obj, offset, size);
-}
-
-void VulkanDriver::updateDescriptorSetTexture(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_binding_t binding,
-        backend::TextureHandle th,
-        SamplerParams params) {
-    VulkanDescriptorSet* set = mResourceAllocator.handle_cast<VulkanDescriptorSet*>(dsh);
-    VulkanTexture* texture = mResourceAllocator.handle_cast<VulkanTexture*>(th);
-    VkSampler const vksampler = mSamplerCache.getSampler(params);
-    mDescriptorSetManager.updateSampler(set, binding, texture, vksampler);
-}
-
 void VulkanDriver::flush(int) {
    FVK_SYSTRACE_CONTEXT();
    FVK_SYSTRACE_START("flush");
@@ -426,6 +440,12 @@ void VulkanDriver::finish(int dummy) {
    FVK_SYSTRACE_END();
 }

+void VulkanDriver::createSamplerGroupR(Handle<HwSamplerGroup> sbh, uint32_t count,
+        utils::FixedSizeString<32> debugName) {
+    auto sg = mResourceAllocator.construct<VulkanSamplerGroup>(sbh, count);
+    mResourceManager.acquire(sg);
+}
+
 void VulkanDriver::createRenderPrimitiveR(Handle<HwRenderPrimitive> rph,
        Handle<HwVertexBuffer> vbh, Handle<HwIndexBuffer> ibh,
        PrimitiveType pt) {
@@ -508,56 +528,23 @@ void VulkanDriver::createTextureR(Handle<HwTexture> th, SamplerType target, uint
        TextureFormat format, uint8_t samples, uint32_t w, uint32_t h, uint32_t depth,
        TextureUsage usage) {
    auto vktexture = mResourceAllocator.construct<VulkanTexture>(th, mPlatform->getDevice(),
-            mPlatform->getPhysicalDevice(), mContext, mAllocator, &mCommands, &mResourceAllocator,
-            target, levels,
+            mPlatform->getPhysicalDevice(), mContext, mAllocator, &mCommands, target, levels,
            format, samples, w, h, depth, usage, mStagePool);
    mResourceManager.acquire(vktexture);
 }

-//void VulkanDriver::createTextureSwizzledR(Handle<HwTexture> th, SamplerType target, uint8_t levels,
-//        TextureFormat format, uint8_t samples, uint32_t w, uint32_t h, uint32_t depth,
-//        TextureUsage usage,
-//        TextureSwizzle r, TextureSwizzle g, TextureSwizzle b, TextureSwizzle a) {
-//    TextureSwizzle swizzleArray[] = {r, g, b, a};
-//    const VkComponentMapping swizzleMap = getSwizzleMap(swizzleArray);
-//    auto vktexture = mResourceAllocator.construct<VulkanTexture>(th, mPlatform->getDevice(),
-//            mPlatform->getPhysicalDevice(), mContext, mAllocator, &mCommands, &mResourceAllocator,
-//            target, levels, format, samples, w, h, depth, usage, mStagePool,
-//            false /*heap allocated */, swizzleMap);
-//    mResourceManager.acquire(vktexture);
-//}
-
-void VulkanDriver::createTextureViewR(Handle<HwTexture> th, Handle<HwTexture> srch,
-        uint8_t baseLevel, uint8_t levelCount) {
-    VulkanTexture const* src = mResourceAllocator.handle_cast<VulkanTexture const*>(srch);
+void VulkanDriver::createTextureSwizzledR(Handle<HwTexture> th, SamplerType target, uint8_t levels,
+        TextureFormat format, uint8_t samples, uint32_t w, uint32_t h, uint32_t depth,
+        TextureUsage usage,
+        TextureSwizzle r, TextureSwizzle g, TextureSwizzle b, TextureSwizzle a) {
+    TextureSwizzle swizzleArray[] = {r, g, b, a};
+    const VkComponentMapping swizzleMap = getSwizzleMap(swizzleArray);
    auto vktexture = mResourceAllocator.construct<VulkanTexture>(th, mPlatform->getDevice(),
-            mPlatform->getPhysicalDevice(), mContext, mAllocator, &mCommands, &mResourceAllocator,
-            src, baseLevel, levelCount);
+            mPlatform->getPhysicalDevice(), mContext, mAllocator, &mCommands, target, levels,
+            format, samples, w, h, depth, usage, mStagePool, false /*heap allocated */, swizzleMap);
    mResourceManager.acquire(vktexture);
 }

-void VulkanDriver::createTextureViewSwizzleR(Handle<HwTexture> th, Handle<HwTexture> srch,
-        backend::TextureSwizzle r, backend::TextureSwizzle g, backend::TextureSwizzle b,
-        backend::TextureSwizzle a) {
-    TextureSwizzle const swizzleArray[] = {r, g, b, a};
-    VkComponentMapping const swizzle = getSwizzleMap(swizzleArray);
-
-    VulkanTexture const* src = mResourceAllocator.handle_cast<VulkanTexture const*>(srch);
-    auto vktexture = mResourceAllocator.construct<VulkanTexture>(th, mPlatform->getDevice(),
-            mPlatform->getPhysicalDevice(), mContext, mAllocator, &mCommands, &mResourceAllocator,
-            src, swizzle);
-    mResourceManager.acquire(vktexture);
-}
-
-void VulkanDriver::createTextureExternalImageR(Handle<HwTexture> th, backend::TextureFormat format,
-        uint32_t width, uint32_t height, backend::TextureUsage usage, void* image) {
-}
-
-void VulkanDriver::createTextureExternalImagePlaneR(Handle<HwTexture> th,
-        backend::TextureFormat format, uint32_t width, uint32_t height, backend::TextureUsage usage,
-        void* image, uint32_t plane) {
-}
-
 void VulkanDriver::importTextureR(Handle<HwTexture> th, intptr_t id,
        SamplerType target, uint8_t levels,
        TextureFormat format, uint8_t samples, uint32_t w, uint32_t h, uint32_t depth,
@@ -584,6 +571,7 @@ void VulkanDriver::destroyProgram(Handle<HwProgram> ph) {
        return;
    }
    auto vkprogram = mResourceAllocator.handle_cast<VulkanProgram*>(ph);
+    mDescriptorSetManager.clearProgram(vkprogram);
    mResourceManager.release(vkprogram);
 }

@@ -607,6 +595,7 @@ void VulkanDriver::createRenderTargetR(Handle<HwRenderTarget> rth,
            colorTargets[i] = {
                .texture = mResourceAllocator.handle_cast<VulkanTexture*>(color[i].handle),
                .level = color[i].level,
+                .baseViewIndex = color[i].baseViewIndex,
                .layerCount = layerCount,
                .layer = color[i].layer,
            };
@@ -622,6 +611,7 @@ void VulkanDriver::createRenderTargetR(Handle<HwRenderTarget> rth,
        depthStencil[0] = {
            .texture = mResourceAllocator.handle_cast<VulkanTexture*>(depth.handle),
            .level = depth.level,
+            .baseViewIndex = depth.baseViewIndex,
            .layerCount = layerCount,
            .layer = depth.layer,
        };
@@ -635,6 +625,7 @@ void VulkanDriver::createRenderTargetR(Handle<HwRenderTarget> rth,
        depthStencil[1] = {
            .texture = mResourceAllocator.handle_cast<VulkanTexture*>(stencil.handle),
            .level = stencil.level,
+            .baseViewIndex = stencil.baseViewIndex,
            .layerCount = layerCount,
            .layer = stencil.layer,
        };
@@ -650,10 +641,9 @@ void VulkanDriver::createRenderTargetR(Handle<HwRenderTarget> rth,
    assert_invariant(tmin == tmax);
    assert_invariant(tmin.x >= width && tmin.y >= height);

-    auto renderTarget = mResourceAllocator.construct<VulkanRenderTarget>(rth,
-            mPlatform->getDevice(), mPlatform->getPhysicalDevice(), mContext, mAllocator,
-            &mCommands, &mResourceAllocator, width, height, samples, colorTargets, depthStencil,
-            mStagePool, layerCount);
+    auto renderTarget = mResourceAllocator.construct<VulkanRenderTarget>(rth, mPlatform->getDevice(),
+            mPlatform->getPhysicalDevice(), mContext, mAllocator, &mCommands, width, height,
+            samples, colorTargets, depthStencil, mStagePool, layerCount);
    mResourceManager.acquire(renderTarget);
 }

@@ -681,7 +671,7 @@ void VulkanDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow,
        flags = flags | ~(backend::SWAP_CHAIN_CONFIG_SRGB_COLORSPACE);
    }
    auto swapChain = mResourceAllocator.construct<VulkanSwapChain>(sch, mPlatform, mContext,
-            mAllocator, &mCommands, &mResourceAllocator, mStagePool, nativeWindow, flags);
+            mAllocator, &mCommands, mStagePool, nativeWindow, flags);
    mResourceManager.acquire(swapChain);
 }

@@ -694,8 +684,7 @@ void VulkanDriver::createSwapChainHeadlessR(Handle<HwSwapChain> sch, uint32_t wi
    }
    assert_invariant(width > 0 && height > 0 && "Vulkan requires non-zero swap chain dimensions.");
    auto swapChain = mResourceAllocator.construct<VulkanSwapChain>(sch, mPlatform, mContext,
-            mAllocator, &mCommands, &mResourceAllocator, mStagePool,
-            nullptr, flags, VkExtent2D{width, height});
+            mAllocator, &mCommands, mStagePool, nullptr, flags, VkExtent2D{width, height});
    mResourceManager.acquire(swapChain);
 }

@@ -703,25 +692,6 @@ void VulkanDriver::createTimerQueryR(Handle<HwTimerQuery> tqh, int) {
    // nothing to do, timer query was constructed in createTimerQueryS
 }

-void VulkanDriver::createDescriptorSetLayoutR(Handle<HwDescriptorSetLayout> dslh,
-        backend::DescriptorSetLayout&& info) {
-    VulkanDescriptorSetLayout* layout = mResourceAllocator.construct<VulkanDescriptorSetLayout>(
-            dslh, info);
-
-    // This will create a VkDescriptorSetLayout (which is cached) for this object.
-    mDescriptorSetManager.initVkLayout(layout);
-    mResourceManager.acquire(layout);
-}
-
-void VulkanDriver::createDescriptorSetR(Handle<HwDescriptorSet> dsh,
-        Handle<HwDescriptorSetLayout> dslh) {
-    auto layout = mResourceAllocator.handle_cast<VulkanDescriptorSetLayout*>(dslh);
-    mDescriptorSetManager.createSet(dsh, layout);
-
-    auto set = mResourceAllocator.handle_cast<VulkanDescriptorSet*>(dsh);
-    mResourceManager.acquire(set);
-}
-
 Handle<HwVertexBufferInfo> VulkanDriver::createVertexBufferInfoS() noexcept {
    return mResourceAllocator.allocHandle<VulkanVertexBufferInfo>();
 }
@@ -742,19 +712,7 @@ Handle<HwTexture> VulkanDriver::createTextureS() noexcept {
    return mResourceAllocator.allocHandle<VulkanTexture>();
 }

-Handle<HwTexture> VulkanDriver::createTextureViewS() noexcept {
-    return mResourceAllocator.allocHandle<VulkanTexture>();
-}
-
-Handle<HwTexture> VulkanDriver::createTextureViewSwizzleS() noexcept {
-    return mResourceAllocator.allocHandle<VulkanTexture>();
-}
-
-Handle<HwTexture> VulkanDriver::createTextureExternalImageS() noexcept {
-    return mResourceAllocator.allocHandle<VulkanTexture>();
-}
-
-Handle<HwTexture> VulkanDriver::createTextureExternalImagePlaneS() noexcept {
+Handle<HwTexture> VulkanDriver::createTextureSwizzledS() noexcept {
    return mResourceAllocator.allocHandle<VulkanTexture>();
 }

@@ -762,6 +720,10 @@ Handle<HwTexture> VulkanDriver::importTextureS() noexcept {
    return mResourceAllocator.allocHandle<VulkanTexture>();
 }

+Handle<HwSamplerGroup> VulkanDriver::createSamplerGroupS() noexcept {
+    return mResourceAllocator.allocHandle<VulkanSamplerGroup>();
+}
+
 Handle<HwRenderPrimitive> VulkanDriver::createRenderPrimitiveS() noexcept {
    return mResourceAllocator.allocHandle<VulkanRenderPrimitive>();
 }
@@ -800,12 +762,21 @@ Handle<HwTimerQuery> VulkanDriver::createTimerQueryS() noexcept {
    return tqh;
 }

-Handle<HwDescriptorSetLayout> VulkanDriver::createDescriptorSetLayoutS() noexcept {
-    return mResourceAllocator.allocHandle<VulkanDescriptorSetLayout>();
-}
-
-Handle<HwDescriptorSet> VulkanDriver::createDescriptorSetS() noexcept {
-    return mResourceAllocator.allocHandle<VulkanDescriptorSet>();
+void VulkanDriver::destroySamplerGroup(Handle<HwSamplerGroup> sbh) {
+    if (!sbh) {
+        return;
+    }
+    // Unlike most of the other "Hw" handles, the sampler buffer is an abstract concept and does
+    // not map to any Vulkan objects. To handle destruction, the only thing we need to do is
+    // ensure that the next draw call doesn't try to access a zombie sampler buffer. Therefore,
+    // simply replace all weak references with null.
+    auto* hwsb = mResourceAllocator.handle_cast<VulkanSamplerGroup*>(sbh);
+    for (auto& binding : mSamplerBindings) {
+        if (binding == hwsb) {
+            binding = nullptr;
+        }
+    }
+    mResourceManager.release(hwsb);
 }

 void VulkanDriver::destroySwapChain(Handle<HwSwapChain> sch) {
@@ -830,17 +801,6 @@ void VulkanDriver::destroyTimerQuery(Handle<HwTimerQuery> tqh) {
    mThreadSafeResourceManager.release(vtq);
 }

-void VulkanDriver::destroyDescriptorSetLayout(Handle<HwDescriptorSetLayout> dslh) {
-    VulkanDescriptorSetLayout* layout = mResourceAllocator.handle_cast<VulkanDescriptorSetLayout*>(dslh);
-    mResourceManager.release(layout);
-}
-
-void VulkanDriver::destroyDescriptorSet(Handle<HwDescriptorSet> dsh) {
-    mDescriptorSetManager.destroySet(dsh);
-    VulkanDescriptorSet* set = mResourceAllocator.handle_cast<VulkanDescriptorSet*>(dsh);
-    mResourceManager.release(set);
-}
-
 Handle<HwStream> VulkanDriver::createStreamNative(void* nativeStream) {
    return {};
 }
@@ -878,7 +838,8 @@ FenceStatus VulkanDriver::getFenceStatus(Handle<HwFence> fh) {

    // Internally we use the VK_INCOMPLETE status to mean "not yet submitted".
    // When this fence gets submitted, its status changes to VK_NOT_READY.
-    if (cmdfence->getStatus() == VK_SUCCESS) {
+    std::unique_lock<utils::Mutex> lock(cmdfence->mutex);
+    if (cmdfence->status.load() == VK_SUCCESS) {
        return FenceStatus::CONDITION_SATISFIED;
    }

@@ -929,9 +890,7 @@ bool VulkanDriver::isRenderTargetFormatSupported(TextureFormat format) {
 }

 bool VulkanDriver::isFrameBufferFetchSupported() {
-    // TODO: we must fix this before landing descriptor set change.  Otherwise, the scuba tests will fail.
-    //return true;
-    return false;
+    return true;
 }

 bool VulkanDriver::isFrameBufferFetchMultiSampleSupported() {
@@ -1119,6 +1078,10 @@ void VulkanDriver::resetBufferObject(Handle<HwBufferObject> boh) {
    // This is only useful if updateBufferObjectUnsynchronized() is implemented unsynchronizedly.
 }

+void VulkanDriver::setMinMaxLevels(Handle<HwTexture> th, uint32_t minLevel, uint32_t maxLevel) {
+    mResourceAllocator.handle_cast<VulkanTexture*>(th)->setPrimaryRange(minLevel, maxLevel);
+}
+
 void VulkanDriver::update3DImage(Handle<HwTexture> th, uint32_t level, uint32_t xoffset,
        uint32_t yoffset, uint32_t zoffset, uint32_t width, uint32_t height, uint32_t depth,
        PixelBufferDescriptor&& data) {
@@ -1204,6 +1167,23 @@ void VulkanDriver::generateMipmaps(Handle<HwTexture> th) {
        srcw = dstw;
        srch = dsth;
    } while ((srcw > 1 || srch > 1) && level < t->levels);
+    t->setPrimaryRange(0, t->levels - 1);
+}
+
+void VulkanDriver::updateSamplerGroup(Handle<HwSamplerGroup> sbh,
+        BufferDescriptor&& data) {
+    auto* sb = mResourceAllocator.handle_cast<VulkanSamplerGroup*>(sbh);
+
+    // FIXME: we shouldn't be using SamplerGroup here, instead the backend should create
+    //        a descriptor or any internal data-structure that represents the textures/samplers.
+    //        It's preferable to do as much work as possible here.
+    //        Here, we emulate the older backend API by re-creating a SamplerGroup from the
+    //        passed data.
+    SamplerGroup samplerGroup(data.size / sizeof(SamplerDescriptor));
+    memcpy(samplerGroup.data(), data.buffer, data.size);
+    *sb->sb = std::move(samplerGroup);
+
+    scheduleDestroy(std::move(data));
 }

 void VulkanDriver::compilePrograms(CompilerPriorityQueue priority,
@@ -1218,7 +1198,7 @@ void VulkanDriver::beginRenderPass(Handle<HwRenderTarget> rth, const RenderPassP
    FVK_SYSTRACE_START("beginRenderPass");

    VulkanRenderTarget* const rt = mResourceAllocator.handle_cast<VulkanRenderTarget*>(rth);
-    VkExtent2D const extent = rt->getExtent();
+    const VkExtent2D extent = rt->getExtent();
    assert_invariant(rt == mDefaultRenderTarget || extent.width > 0 && extent.height > 0);

    // Filament has the expectation that the contents of the swap chain are not preserved on the
@@ -1249,10 +1229,34 @@ void VulkanDriver::beginRenderPass(Handle<HwRenderTarget> rth, const RenderPassP
    VulkanCommandBuffer& commands = mCommands.get();
    VkCommandBuffer const cmdbuffer = commands.buffer();

-    // Scissor is reset with each render pass
-    // This also takes care of VUID-vkCmdDrawIndexed-None-07832.
-    VkRect2D const scissor{ .offset = { 0, 0 }, .extent = extent };
-    vkCmdSetScissor(cmdbuffer, 0, 1, &scissor);
+    UTILS_NOUNROLL
+    for (uint8_t samplerGroupIdx = 0; samplerGroupIdx < Program::SAMPLER_BINDING_COUNT;
+            samplerGroupIdx++) {
+        VulkanSamplerGroup* vksb = mSamplerBindings[samplerGroupIdx];
+        if (!vksb) {
+            continue;
+        }
+        SamplerGroup* sb = vksb->sb.get();
+        for (size_t i = 0; i < sb->getSize(); i++) {
+            SamplerDescriptor const* boundSampler = sb->data() + i;
+            if (UTILS_LIKELY(boundSampler->t)) {
+                VulkanTexture* texture
+                        = mResourceAllocator.handle_cast<VulkanTexture*>(boundSampler->t);
+                if (!any(texture->usage & TextureUsage::DEPTH_ATTACHMENT)) {
+                    continue;
+                }
+                if (texture->getPrimaryImageLayout() == VulkanLayout::DEPTH_SAMPLER) {
+                    continue;
+                }
+                commands.acquire(texture);
+
+                // Transition the primary view, which is the sampler's view into the right layout.
+                texture->transitionLayout(cmdbuffer, texture->getPrimaryViewRange(),
+                        VulkanLayout::DEPTH_SAMPLER);
+                break;
+            }
+        }
+    }

    VulkanLayout currentDepthLayout = depth.getLayout();

@@ -1266,39 +1270,40 @@ void VulkanDriver::beginRenderPass(Handle<HwRenderTarget> rth, const RenderPassP
        // If the depth attachment texture was previously sampled, then we need to manually
        // transition it to an attachment. This is necessary to also set up a barrier between the
        // previous read and the potentially coming write.
-        depth.texture->transitionLayout(&commands, depth.getSubresourceRange(),
-                VulkanLayout::DEPTH_ATTACHMENT);
-        currentDepthLayout = VulkanLayout::DEPTH_ATTACHMENT;
+        if (currentDepthLayout == VulkanLayout::DEPTH_SAMPLER) {
+            depth.texture->transitionLayout(cmdbuffer, depth.getSubresourceRange(),
+                    VulkanLayout::DEPTH_ATTACHMENT);
+            currentDepthLayout = VulkanLayout::DEPTH_ATTACHMENT;
+        }
    }

    uint8_t const renderTargetLayerCount = rt->getLayerCount();

    // Create the VkRenderPass or fetch it from cache.
    VulkanFboCache::RenderPassKey rpkey = {
+        .initialColorLayoutMask = 0,
+        .initialDepthLayout = currentDepthLayout,
        .depthFormat = depth.getFormat(),
        .clear = clearVal,
        .discardStart = discardStart,
        .discardEnd = discardEndVal,
-        .initialDepthLayout = currentDepthLayout,
        .samples = rt->getSamples(),
-        .needsResolveMask = 0,
-        .usesLazilyAllocatedMemory = 0,
        .subpassMask = uint8_t(params.subpassMask),
        .viewCount = renderTargetLayerCount,
    };
    for (int i = 0; i < MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT; i++) {
-        VulkanAttachment const& info = rt->getColor(i);
+        const VulkanAttachment& info = rt->getColor(i);
        if (info.texture) {
            assert_invariant(info.layerCount == renderTargetLayerCount);
+            rpkey.initialColorLayoutMask |= 1 << i;
            rpkey.colorFormat[i] = info.getFormat();
-            if (rpkey.samples > 1) {
-                const VulkanTexture* sidecar = info.texture->getSidecar();
-                if (sidecar && sidecar->isTransientAttachment()) {
-                    rpkey.usesLazilyAllocatedMemory |= (1 << i);
-                }
-                if (info.texture->samples == 1) {
-                    rpkey.needsResolveMask |= (1 << i);
-                }
+            if (rpkey.samples > 1 && info.texture->samples == 1) {
+                rpkey.needsResolveMask |= (1 << i);
+            }
+            if (info.texture->getPrimaryImageLayout() != VulkanLayout::COLOR_ATTACHMENT) {
+                ((VulkanTexture*) info.texture)
+                        ->transitionLayout(cmdbuffer, info.getSubresourceRange(),
+                                VulkanLayout::COLOR_ATTACHMENT);
            }
        } else {
            rpkey.colorFormat[i] = VK_FORMAT_UNDEFINED;
@@ -1318,43 +1323,28 @@ void VulkanDriver::beginRenderPass(Handle<HwRenderTarget> rth, const RenderPassP
    };
    auto& renderPassAttachments = mRenderPassFboInfo.attachments;
    for (int i = 0; i < MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT; i++) {
-        VulkanAttachment& attachment = rt->getColor(i);
-        if (!attachment.texture) {
+        if (!rt->getColor(i).texture) {
            fbkey.color[i] = VK_NULL_HANDLE;
            fbkey.resolve[i] = VK_NULL_HANDLE;
-            continue;
-        }
-
-        if (fbkey.samples == 1) {
-            auto const& range = attachment.getSubresourceRange();
-            auto tex = attachment.texture;
-            if (tex->getLayout(range.baseMipLevel, range.baseArrayLayer) !=
-                            VulkanLayout::COLOR_ATTACHMENT &&
-                    !tex->transitionLayout(&commands, range, VulkanLayout::COLOR_ATTACHMENT)) {
-                // If the layout transition did not emit a barrier, we do it manually here.
-                tex->samplerToAttachmentBarrier(&commands, range);
-            }
-            renderPassAttachments.insert(attachment);
-
-            fbkey.color[i] = attachment.getImageView();
+        } else if (fbkey.samples == 1) {
+            auto& colorAttachment = rt->getColor(i);
+            renderPassAttachments.insert(colorAttachment);
+            fbkey.color[i] = colorAttachment.getImageView();
            fbkey.resolve[i] = VK_NULL_HANDLE;
            assert_invariant(fbkey.color[i]);
        } else {
            auto& msaaColorAttachment = rt->getMsaaColor(i);
-            auto const& msaaRange = attachment.getSubresourceRange();
-            msaaColorAttachment.texture->transitionLayout(&commands,
-                    msaaRange, VulkanLayout::COLOR_ATTACHMENT);
            renderPassAttachments.insert(msaaColorAttachment);

+            auto& colorAttachment = rt->getColor(i);
            fbkey.color[i] = msaaColorAttachment.getImageView();

-            VulkanTexture* texture = attachment.texture;
+            VulkanTexture* texture = colorAttachment.texture;
            if (texture->samples == 1) {
-                auto const& range = attachment.getSubresourceRange();
-                attachment.texture->transitionLayout(&commands,
-                        range, VulkanLayout::COLOR_ATTACHMENT);
-                renderPassAttachments.insert(attachment);
-                fbkey.resolve[i] = attachment.getImageView();
+                mRenderPassFboInfo.hasColorResolve = true;
+
+                renderPassAttachments.insert(colorAttachment);
+                fbkey.resolve[i] = colorAttachment.getImageView();
                assert_invariant(fbkey.resolve[i]);
            }
            assert_invariant(fbkey.color[i]);
@@ -1472,27 +1462,57 @@ void VulkanDriver::endRenderPass(int) {
    assert_invariant(rt);

    // Since we might soon be sampling from the render target that we just wrote to, we need a
-    // pipeline barrier between framebuffer writes and shader reads.
+    // pipeline barrier between framebuffer writes and shader reads. This is a memory barrier rather
+    // than an image barrier. If we were to use image barriers here, we would potentially need to
+    // issue several of them when considering MRT. This would be very complex to set up and would
+    // require more state tracking, so we've chosen to use a memory barrier for simplicity and
+    // correctness.
    if (!rt->isSwapChain()) {
-        for (auto& attachment: mRenderPassFboInfo.attachments) {
-            auto const& range = attachment.getSubresourceRange();
+        for (auto const& attachment: mRenderPassFboInfo.attachments) {
            bool const isDepth = attachment.isDepth();
-            auto texture = attachment.texture;
-            if (isDepth) {
-                texture->setLayout(range, VulkanFboCache::FINAL_DEPTH_ATTACHMENT_LAYOUT);
-                if (!texture->transitionLayout(&commands, range, VulkanLayout::DEPTH_SAMPLER)) {
-                    texture->attachmentToSamplerBarrier(&commands, range);
-                }
-            } else {
-                texture->setLayout(range, VulkanFboCache::FINAL_COLOR_ATTACHMENT_LAYOUT);
-                if (!texture->transitionLayout(&commands, range, VulkanLayout::READ_WRITE)) {
-                    texture->attachmentToSamplerBarrier(&commands, range);
-                }
+            VkPipelineStageFlags srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+
+            // This is a workaround around a validation issue (might not be an actual driver issue).
+            if (mRenderPassFboInfo.hasColorResolve && !isDepth) {
+                srcStageMask = VK_PIPELINE_STAGE_ALL_GRAPHICS_BIT;
            }
+
+            VkPipelineStageFlags dstStageMask =
+                    VK_PIPELINE_STAGE_VERTEX_SHADER_BIT | VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT;
+            VkAccessFlags srcAccess = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+            VkAccessFlags dstAccess = VK_ACCESS_SHADER_READ_BIT;
+            VulkanLayout layout = VulkanFboCache::FINAL_COLOR_ATTACHMENT_LAYOUT;
+            if (isDepth) {
+                srcAccess = VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT;
+                dstAccess = VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT;
+                srcStageMask = VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT;
+                dstStageMask = VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT;
+                layout =  VulkanFboCache::FINAL_DEPTH_ATTACHMENT_LAYOUT;
+            }
+
+            auto const vkLayout = imgutil::getVkLayout(layout);
+            auto const& range = attachment.getSubresourceRange();
+            VkImageMemoryBarrier barrier = {
+                .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
+                .pNext = nullptr,
+                .srcAccessMask = srcAccess,
+                .dstAccessMask = dstAccess,
+                .oldLayout = vkLayout,
+                .newLayout = vkLayout,
+                .srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
+                .dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
+                .image = attachment.getImage(),
+                .subresourceRange = range,
+            };
+
+            attachment.texture->setLayout(range, layout);
+            vkCmdPipelineBarrier(cmdbuffer, srcStageMask, dstStageMask, 0, 0, nullptr, 0, nullptr,
+                    1, &barrier);
        }
    }

-    mRenderPassFboInfo = {};
+    mRenderPassFboInfo.clear();
+    mDescriptorSetManager.clearState();
    mCurrentRenderPass.renderTarget = nullptr;
    mCurrentRenderPass.renderPass = VK_NULL_HANDLE;
    FVK_SYSTRACE_END();
@@ -1551,6 +1571,33 @@ void VulkanDriver::commit(Handle<HwSwapChain> sch) {
    FVK_SYSTRACE_END();
 }

+void VulkanDriver::bindUniformBuffer(uint32_t index, Handle<HwBufferObject> boh) {
+    auto* bo = mResourceAllocator.handle_cast<VulkanBufferObject*>(boh);
+    VkDeviceSize const offset = 0;
+    VkDeviceSize const size = VK_WHOLE_SIZE;
+    mDescriptorSetManager.updateBuffer({}, (uint32_t) index, bo, offset, size);
+}
+
+void VulkanDriver::bindBufferRange(BufferObjectBinding bindingType, uint32_t index,
+        Handle<HwBufferObject> boh, uint32_t offset, uint32_t size) {
+
+    assert_invariant(bindingType == BufferObjectBinding::UNIFORM);
+
+    // TODO: implement BufferObjectBinding::SHADER_STORAGE case
+
+    auto* bo = mResourceAllocator.handle_cast<VulkanBufferObject*>(boh);
+    mDescriptorSetManager.updateBuffer({}, (uint32_t) index, bo, offset, size);
+}
+
+void VulkanDriver::unbindBuffer(BufferObjectBinding bindingType, uint32_t index) {
+    mDescriptorSetManager.clearBuffer((uint32_t) index);
+}
+
+void VulkanDriver::bindSamplers(uint32_t index, Handle<HwSamplerGroup> sbh) {
+    auto* hwsb = mResourceAllocator.handle_cast<VulkanSamplerGroup*>(sbh);
+    mSamplerBindings[index] = hwsb;
+}
+
 void VulkanDriver::setPushConstant(backend::ShaderStage stage, uint8_t index,
        backend::PushConstantVariant value) {
    assert_invariant(mBoundPipeline.program && "Expect a program when writing to push constants");
@@ -1751,8 +1798,8 @@ void VulkanDriver::bindPipeline(PipelineState const& pipelineState) {
            *mResourceAllocator.handle_cast<VulkanVertexBufferInfo*>(pipelineState.vertexBufferInfo);

    Handle<HwProgram> programHandle = pipelineState.program;
-    RasterState const& rasterState = pipelineState.rasterState;
-    PolygonOffset const& depthOffset = pipelineState.polygonOffset;
+    RasterState rasterState = pipelineState.rasterState;
+    PolygonOffset depthOffset = pipelineState.polygonOffset;

    auto* program = mResourceAllocator.handle_cast<VulkanProgram*>(programHandle);
    commands->acquire(program);
@@ -1796,31 +1843,69 @@ void VulkanDriver::bindPipeline(PipelineState const& pipelineState) {
    mPipelineCache.bindPrimitiveTopology(topology);
    mPipelineCache.bindVertexArray(attribDesc, bufferDesc, vbi.getAttributeCount());

-    auto& setLayouts = pipelineState.pipelineLayout.setLayout;
-    VulkanDescriptorSetLayout::DescriptorSetLayoutArray layoutList;
-    uint8_t layoutCount = 0;
-    std::transform(setLayouts.begin(), setLayouts.end(), layoutList.begin(),
-            [&](Handle<HwDescriptorSetLayout> handle) -> VkDescriptorSetLayout {
-                if (!handle) {
-                    return VK_NULL_HANDLE;
-                }
-                auto layout = mResourceAllocator.handle_cast<VulkanDescriptorSetLayout*>(handle);
-                layoutCount++;
-                return layout->getVkLayout();
-            });
-    auto pipelineLayout = mPipelineLayoutCache.getLayout(layoutList, program);
+    // Query the program for the mapping from (SamplerGroupBinding,Offset) to (SamplerBinding),
+    // where "SamplerBinding" is the integer in the GLSL, and SamplerGroupBinding is the abstract
+    // Filament concept used to form groups of samplers.

-    constexpr uint8_t descriptorSetMaskTable[4] = {0x1, 0x3, 0x7, 0xF};
+    auto const& bindingToSamplerIndex = program->getBindingToSamplerIndex();
+#if FVK_ENABLED_DEBUG_SAMPLER_NAME
+    auto const& bindingToName = program->getBindingToName();
+#endif

+    for (auto binding: program->getBindings()) {
+        uint16_t const indexPair = bindingToSamplerIndex[binding];
+        if (indexPair == 0xffff) {
+            continue;
+        }
+
+        uint16_t const samplerGroupInd = (indexPair >> 8) & 0xff;
+        uint16_t const samplerInd = (indexPair & 0xff);
+
+        VulkanSamplerGroup* vksb = mSamplerBindings[samplerGroupInd];
+        if (!vksb) {
+            continue;
+        }
+        SamplerDescriptor const* boundSampler = ((SamplerDescriptor*) vksb->sb->data()) + samplerInd;
+
+        if (UTILS_UNLIKELY(!boundSampler->t)) {
+            continue;
+        }
+        VulkanTexture* texture = mResourceAllocator.handle_cast<VulkanTexture*>(boundSampler->t);
+
+        // TODO: can this uninitialized check be checked in a higher layer?
+        // This fallback path is very flaky because the dummy texture might not have
+        // matching characteristics. (e.g. if the missing texture is a 3D texture)
+        if (UTILS_UNLIKELY(texture->getPrimaryImageLayout() == VulkanLayout::UNDEFINED)) {
+#if FVK_ENABLED(FVK_DEBUG_TEXTURE) && FVK_ENABLED_DEBUG_SAMPLER_NAME
+            FVK_LOGW << "Uninitialized texture bound to '" << bindingToName[binding] << "'";
+            FVK_LOGW << " in material '" << program->name.c_str() << "'";
+            FVK_LOGW << " at binding point " << +binding << utils::io::endl;
+#endif
+            texture = mEmptyTexture;
+        }
+
+        VkSampler const vksampler = mSamplerCache.getSampler(boundSampler->s);
+#if FVK_ENABLED_DEBUG_SAMPLER_NAME
+        VulkanDriver::DebugUtils::setName(VK_OBJECT_TYPE_SAMPLER,
+                reinterpret_cast<uint64_t>(vksampler), bindingToName[binding].c_str());
+#endif
+        mDescriptorSetManager.updateSampler({}, binding, texture, vksampler);
+    }
+
+    auto const pipelineLayout = mDescriptorSetManager.bind(commands, program, mGetPipelineFunction);
    mBoundPipeline = {
        .program = program,
        .pipelineLayout = pipelineLayout,
-        .descriptorSetMask = DescriptorSetMask(descriptorSetMaskTable[layoutCount]),
    };

    mPipelineCache.bindLayout(pipelineLayout);
    mPipelineCache.bindPipeline(commands);

+    // Since we don't statically define scissor as part of the pipeline, we need to call scissor at
+    // least once. Context: VUID-vkCmdDrawIndexed-None-07832.
+    auto const& extent = rt->getExtent();
+    scissor({0, 0, extent.width, extent.height});
+
    FVK_SYSTRACE_END();
 }

@@ -1853,14 +1938,6 @@ void VulkanDriver::bindRenderPrimitive(Handle<HwRenderPrimitive> rph) {
    FVK_SYSTRACE_END();
 }

-void VulkanDriver::bindDescriptorSet(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_set_t setIndex,
-        backend::DescriptorSetOffsetArray&& offsets) {
-    VulkanDescriptorSet* set = mResourceAllocator.handle_cast<VulkanDescriptorSet*>(dsh);
-    mDescriptorSetManager.bind(setIndex, set, std::move(offsets));
-}
-
 void VulkanDriver::draw2(uint32_t indexOffset, uint32_t indexCount, uint32_t instanceCount) {
    FVK_SYSTRACE_CONTEXT();
    FVK_SYSTRACE_START("draw2");
@@ -1868,8 +1945,8 @@ void VulkanDriver::draw2(uint32_t indexOffset, uint32_t indexCount, uint32_t ins
    VulkanCommandBuffer& commands = mCommands.get();
    VkCommandBuffer cmdbuffer = commands.buffer();

-    mDescriptorSetManager.commit(&commands, mBoundPipeline.pipelineLayout,
-            mBoundPipeline.descriptorSetMask);
+    // Bind "dynamic" UBOs if they need to change.
+    mDescriptorSetManager.dynamicBind(&commands, {});

    // Finally, make the actual draw call. TODO: support subranges
    const uint32_t firstIndex = indexOffset;
@@ -1899,9 +1976,6 @@ void VulkanDriver::scissor(Viewport scissorBox) {
    VulkanCommandBuffer& commands = mCommands.get();
    VkCommandBuffer cmdbuffer = commands.buffer();

-    // TODO: it's a common case that scissor() is called with (0, 0, maxint, maxint)
-    //       we should maybe have a fast path for this and avoid vkCmdSetScissor() if possible
-
    // Set scissoring.
    // clamp left-bottom to 0,0 and avoid overflows
    constexpr int32_t maxvali  = std::numeric_limits<int32_t>::max();
@@ -1920,7 +1994,7 @@ void VulkanDriver::scissor(Viewport scissorBox) {
            .extent = { uint32_t(r - l), uint32_t(t - b) }
    };

-    VulkanRenderTarget const* rt = mCurrentRenderPass.renderTarget;
+    const VulkanRenderTarget* rt = mCurrentRenderPass.renderTarget;
    rt->transformClientRectToPlatform(&scissor);
    vkCmdSetScissor(cmdbuffer, 0, 1, &scissor);
 }
@@ -47,6 +47,21 @@ struct VulkanSamplerGroup;
 constexpr uint8_t MAX_RENDERTARGET_ATTACHMENT_TEXTURES =
        MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT * 2 + 1;

+// We need to store information about a render pass to enable better barriers at the end of a
+// renderpass.
+struct RenderPassFboBundle {
+    using AttachmentArray =
+            CappedArray<VulkanAttachment, MAX_RENDERTARGET_ATTACHMENT_TEXTURES>;
+
+    AttachmentArray attachments;
+    bool hasColorResolve = false;
+
+    void clear() {
+        attachments.clear();
+        hasColorResolve = false;
+    }
+};
+
 class VulkanDriver final : public DriverBase {
 public:
    static Driver* create(VulkanPlatform* platform, VulkanContext const& context,
@@ -115,6 +130,10 @@ private:
    VulkanPlatform* mPlatform = nullptr;
    std::unique_ptr<VulkanTimestamps> mTimestamps;

+    // Placeholder resources
+    VulkanTexture* mEmptyTexture;
+    VulkanBufferObject* mEmptyBufferObject;
+
    VulkanSwapChain* mCurrentSwapChain = nullptr;
    VulkanRenderTarget* mDefaultRenderTarget = nullptr;
    VulkanRenderPass mCurrentRenderPass = {};
@@ -140,19 +159,15 @@ private:
    VulkanReadPixels mReadPixels;
    VulkanDescriptorSetManager mDescriptorSetManager;

+    VulkanDescriptorSetManager::GetPipelineLayoutFunction mGetPipelineFunction;
+
    // This is necessary for us to write to push constants after binding a pipeline.
-    struct {
+    struct BoundPipeline {
        VulkanProgram* program;
        VkPipelineLayout pipelineLayout;
-        DescriptorSetMask descriptorSetMask;
-    } mBoundPipeline = {};
-
-    // We need to store information about a render pass to enable better barriers at the end of a
-    // renderpass.
-    struct {
-        using AttachmentArray = CappedArray<VulkanAttachment, MAX_RENDERTARGET_ATTACHMENT_TEXTURES>;
-        AttachmentArray attachments;
-    } mRenderPassFboInfo = {};
+    };
+    BoundPipeline mBoundPipeline = {};
+    RenderPassFboBundle mRenderPassFboInfo;

    bool const mIsSRGBSwapChainSupported;
    backend::StereoscopicType const mStereoscopicType;
@@ -31,6 +31,7 @@ namespace filament::backend {

 bool VulkanFboCache::RenderPassEq::operator()(const RenderPassKey& k1,
        const RenderPassKey& k2) const {
+    if (k1.initialColorLayoutMask != k2.initialColorLayoutMask) return false;
    if (k1.initialDepthLayout != k2.initialDepthLayout) return false;
    for (int i = 0; i < MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT; i++) {
        if (k1.colorFormat[i] != k2.colorFormat[i]) return false;
@@ -41,7 +42,6 @@ bool VulkanFboCache::RenderPassEq::operator()(const RenderPassKey& k1,
    if (k1.discardEnd != k2.discardEnd) return false;
    if (k1.samples != k2.samples) return false;
    if (k1.needsResolveMask != k2.needsResolveMask) return false;
-    if (k1.usesLazilyAllocatedMemory != k2.usesLazilyAllocatedMemory) return false;
    if (k1.subpassMask != k2.subpassMask) return false;
    if (k1.viewCount != k2.viewCount) return false;
    return true;
@@ -255,10 +255,12 @@ VkRenderPass VulkanFboCache::getRenderPass(RenderPassKey config) noexcept {
            .format = config.colorFormat[i],
            .samples = (VkSampleCountFlagBits) config.samples,
            .loadOp = clear ? kClear : (discard ? kDontCare : kKeep),
-            .storeOp = (config.usesLazilyAllocatedMemory & (1 << i)) ? kDisableStore : kEnableStore,
+            .storeOp = kEnableStore,
            .stencilLoadOp = kDontCare,
            .stencilStoreOp = kDisableStore,
-            .initialLayout = imgutil::getVkLayout(VulkanLayout::COLOR_ATTACHMENT),
+            .initialLayout = ((!discard && config.initialColorLayoutMask & (1 << i)) || clear)
+                                     ? imgutil::getVkLayout(VulkanLayout::COLOR_ATTACHMENT)
+                                     : imgutil::getVkLayout(VulkanLayout::UNDEFINED),
            .finalLayout = imgutil::getVkLayout(FINAL_COLOR_ATTACHMENT_LAYOUT),
        };
    }
@@ -42,25 +42,36 @@ public:
    // RenderPassKey is a small POD representing the immutable state that is used to construct
    // a VkRenderPass. It is hashed and used as a lookup key.
    struct alignas(8) RenderPassKey {
+        // For each target, we need to know three image layouts: the layout BEFORE the pass, the
+        // layout DURING the pass, and the layout AFTER the pass. Here are the rules:
+        // - For depth, we explicitly specify all three layouts.
+        // - Color targets have their initial image layout specified with a bitmask.
+        // - For each color target, the pre-existing layout is either UNDEFINED (0) or GENERAL (1).
+        // - The render pass and final images layout for color buffers is always
+        //   VulkanLayout::COLOR_ATTACHMENT.
+        uint8_t initialColorLayoutMask;
+
+        // Note that if VulkanLayout grows beyond 16, we'd need to up this.
+        VulkanLayout initialDepthLayout : 8;
+        uint8_t padding0;
+        uint8_t padding1;
+
        VkFormat colorFormat[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT]; // 32 bytes
        VkFormat depthFormat; // 4 bytes
        TargetBufferFlags clear; // 4 bytes
        TargetBufferFlags discardStart; // 4 bytes
        TargetBufferFlags discardEnd; // 4 bytes
-
-        VulkanLayout initialDepthLayout; // 1 byte
        uint8_t samples; // 1 byte
        uint8_t needsResolveMask; // 1 byte
-        uint8_t usesLazilyAllocatedMemory; // 1 byte
        uint8_t subpassMask; // 1 byte
        uint8_t viewCount; // 1 byte
-		uint8_t padding[2];
    };
    struct RenderPassVal {
        VkRenderPass handle;
        uint32_t timestamp;
    };
    static_assert(0 == MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT % 8);
+    static_assert(sizeof(RenderPassKey::initialColorLayoutMask) == MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT / 8);
    static_assert(sizeof(TargetBufferFlags) == 4, "TargetBufferFlags has unexpected size.");
    static_assert(sizeof(VkFormat) == 4, "VkFormat has unexpected size.");
    static_assert(sizeof(RenderPassKey) == 56, "RenderPassKey has unexpected size.");
@@ -17,14 +17,11 @@
 #include "VulkanHandles.h"

 #include "VulkanConstants.h"
-
-// TODO: remove this by moving DebugUtils out of VulkanDriver
 #include "VulkanDriver.h"
-
 #include "VulkanMemory.h"
-#include "VulkanResourceAllocator.h"
 #include "VulkanUtility.h"
 #include "spirv/VulkanSpirvUtils.h"
+#include "utils/Log.h"

 #include <backend/platforms/VulkanPlatform.h>

@@ -56,14 +53,62 @@ void clampToFramebuffer(VkRect2D* rect, uint32_t fbWidth, uint32_t fbHeight) {
 }

 template<typename Bitmask>
-inline void fromStageFlags(backend::ShaderStageFlags stage, descriptor_binding_t binding,
-        Bitmask& mask) {
-    if ((bool) (stage & ShaderStageFlags::VERTEX)) {
-        mask.set(binding + getVertexStageShift<Bitmask>());
+static constexpr Bitmask fromStageFlags(ShaderStageFlags2 flags, uint8_t binding) {
+    Bitmask ret = 0;
+    if (flags & ShaderStageFlags2::VERTEX) {
+        ret |= (getVertexStage<Bitmask>() << binding);
    }
-    if ((bool) (stage & ShaderStageFlags::FRAGMENT)) {
-        mask.set(binding + getFragmentStageShift<Bitmask>());
+    if (flags & ShaderStageFlags2::FRAGMENT) {
+        ret |= (getFragmentStage<Bitmask>() << binding);
    }
+    return ret;
+}
+
+constexpr decltype(VulkanProgram::MAX_SHADER_MODULES) MAX_SHADER_MODULES =
+        VulkanProgram::MAX_SHADER_MODULES;
+
+using LayoutDescriptionList = VulkanProgram::LayoutDescriptionList;
+
+template<typename Bitmask>
+void addDescriptors(Bitmask mask,
+        utils::FixedCapacityVector<DescriptorSetLayoutBinding>& outputList) {
+    constexpr uint8_t MODULE_OFFSET = (sizeof(Bitmask) * 8) / MAX_SHADER_MODULES;
+    for (uint8_t i = 0; i < MODULE_OFFSET; ++i) {
+        bool const hasVertex = (mask & (1ULL << i)) != 0;
+        bool const hasFragment = (mask & (1ULL << (MODULE_OFFSET + i))) != 0;
+        if (!hasVertex && !hasFragment) {
+            continue;
+        }
+
+        DescriptorSetLayoutBinding binding{
+            .binding = i,
+            .flags = DescriptorFlags::NONE,
+            .count = 0,// This is always 0 for now as we pass the size of the UBOs in the Driver API
+                       // instead.
+        };
+        if (hasVertex) {
+            binding.stageFlags = ShaderStageFlags2::VERTEX;
+        }
+        if (hasFragment) {
+            binding.stageFlags = static_cast<ShaderStageFlags2>(
+                    binding.stageFlags | ShaderStageFlags2::FRAGMENT);
+        }
+        if constexpr (std::is_same_v<Bitmask, UniformBufferBitmask>) {
+            binding.type = DescriptorType::UNIFORM_BUFFER;
+        } else if constexpr (std::is_same_v<Bitmask, SamplerBitmask>) {
+            binding.type = DescriptorType::SAMPLER;
+        } else if constexpr (std::is_same_v<Bitmask, InputAttachmentBitmask>) {
+            binding.type = DescriptorType::INPUT_ATTACHMENT;
+        }
+        outputList.push_back(binding);
+    }
+}
+
+inline VkDescriptorSetLayout createDescriptorSetLayout(VkDevice device,
+        VkDescriptorSetLayoutCreateInfo const& info) {
+    VkDescriptorSetLayout layout;
+    vkCreateDescriptorSetLayout(device, &info, VKALLOC, &layout);
+    return layout;
 }

 inline VkShaderStageFlags getVkStage(backend::ShaderStage stage) {
@@ -77,48 +122,20 @@ inline VkShaderStageFlags getVkStage(backend::ShaderStage stage) {
    }
 }

-using BitmaskGroup = VulkanDescriptorSetLayout::Bitmask;
-BitmaskGroup fromBackendLayout(DescriptorSetLayout const& layout) {
-    BitmaskGroup mask;
-    for (auto const& binding: layout.bindings) {
-        switch (binding.type) {
-            case DescriptorType::UNIFORM_BUFFER: {
-                if ((binding.flags & DescriptorFlags::DYNAMIC_OFFSET) != DescriptorFlags::NONE) {
-                    fromStageFlags(binding.stageFlags, binding.binding, mask.dynamicUbo);
-                } else {
-                    fromStageFlags(binding.stageFlags, binding.binding, mask.ubo);
-                }
-                break;
-            }
-            case DescriptorType::SAMPLER: {
-                fromStageFlags(binding.stageFlags, binding.binding, mask.sampler);
-                break;
-            }
-            case DescriptorType::INPUT_ATTACHMENT: {
-                fromStageFlags(binding.stageFlags, binding.binding, mask.inputAttachment);
-                break;
-            }
-            case DescriptorType::SHADER_STORAGE_BUFFER:
-                PANIC_POSTCONDITION("Shader storage is not supported");
-                break;
-        }
-    }
-    return mask;
-}
-
 } // anonymous namespace

-VulkanDescriptorSetLayout::VulkanDescriptorSetLayout(DescriptorSetLayout const& layout)
+
+VulkanDescriptorSetLayout::VulkanDescriptorSetLayout(VkDevice device,
+        VkDescriptorSetLayoutCreateInfo const& info, Bitmask const& bitmask)
    : VulkanResource(VulkanResourceType::DESCRIPTOR_SET_LAYOUT),
-      bitmask(fromBackendLayout(layout)),
+      mDevice(device),
+      vklayout(createDescriptorSetLayout(device, info)),
+      bitmask(bitmask),
+      bindings(getBindings(bitmask)),
      count(Count::fromLayoutBitmask(bitmask)) {}

-void VulkanDescriptorSet::acquire(VulkanTexture* texture) {
-    mResources.acquire(texture);
-}
-
-void VulkanDescriptorSet::acquire(VulkanBufferObject* bufferObject) {
-    mResources.acquire(bufferObject);
+VulkanDescriptorSetLayout::~VulkanDescriptorSetLayout() {
+    vkDestroyDescriptorSetLayout(mDevice, vklayout, VKALLOC);
 }

 PushConstantDescription::PushConstantDescription(backend::Program const& program) noexcept {
@@ -172,11 +189,24 @@ VulkanProgram::VulkanProgram(VkDevice device, Program const& builder) noexcept
      mInfo(new(std::nothrow) PipelineInfo(builder)),
      mDevice(device) {

+    constexpr uint8_t UBO_MODULE_OFFSET = (sizeof(UniformBufferBitmask) * 8) / MAX_SHADER_MODULES;
+    constexpr uint8_t SAMPLER_MODULE_OFFSET = (sizeof(SamplerBitmask) * 8) / MAX_SHADER_MODULES;
+    constexpr uint8_t INPUT_ATTACHMENT_MODULE_OFFSET =
+            (sizeof(InputAttachmentBitmask) * 8) / MAX_SHADER_MODULES;
+
    Program::ShaderSource const& blobs = builder.getShadersSource();
    auto& modules = mInfo->shaders;
+
    auto const& specializationConstants = builder.getSpecializationConstants();
+
    std::vector<uint32_t> shader;

+    // TODO: this will be moved out of the shader as the descriptor set layout will be provided by
+    // Filament instead of parsed from the shaders. See [GDSR] in VulkanDescriptorSetManager.h
+    UniformBufferBitmask uboMask = 0;
+    SamplerBitmask samplerMask = 0;
+    InputAttachmentBitmask inputAttachmentMask = 0;
+
    static_assert(static_cast<ShaderStage>(0) == ShaderStage::VERTEX &&
            static_cast<ShaderStage>(1) == ShaderStage::FRAGMENT &&
            MAX_SHADER_MODULES == 2);
@@ -193,6 +223,12 @@ VulkanProgram::VulkanProgram(VkDevice device, Program const& builder) noexcept
            dataSize = shader.size() * 4;
        }

+        auto const [ubo, sampler, inputAttachment] = getProgramBindings(blob);
+        uboMask |= (static_cast<UniformBufferBitmask>(ubo) << (UBO_MODULE_OFFSET * i));
+        samplerMask |= (static_cast<SamplerBitmask>(sampler) << (SAMPLER_MODULE_OFFSET * i));
+        inputAttachmentMask |= (static_cast<InputAttachmentBitmask>(inputAttachment)
+                                << (INPUT_ATTACHMENT_MODULE_OFFSET * i));
+
        VkShaderModule& module = modules[i];
        VkShaderModuleCreateInfo moduleInfo = {
            .sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO,
@@ -220,6 +256,40 @@ VulkanProgram::VulkanProgram(VkDevice device, Program const& builder) noexcept
 #endif
    }

+    LayoutDescriptionList& layouts = mInfo->layouts;
+    layouts[0].bindings = utils::FixedCapacityVector<DescriptorSetLayoutBinding>::with_capacity(
+            countBits(collapseStages(uboMask)));
+    layouts[1].bindings = utils::FixedCapacityVector<DescriptorSetLayoutBinding>::with_capacity(
+            countBits(collapseStages(samplerMask)));
+    layouts[2].bindings = utils::FixedCapacityVector<DescriptorSetLayoutBinding>::with_capacity(
+            countBits(collapseStages(inputAttachmentMask)));
+
+    addDescriptors(uboMask, layouts[0].bindings);
+    addDescriptors(samplerMask, layouts[1].bindings);
+    addDescriptors(inputAttachmentMask, layouts[2].bindings);
+
+#if FVK_ENABLED_DEBUG_SAMPLER_NAME
+    auto& bindingToName = mInfo->bindingToName;
+#endif
+
+    auto& groupInfo = builder.getSamplerGroupInfo();
+    auto& bindingToSamplerIndex = mInfo->bindingToSamplerIndex;
+    auto& bindings = mInfo->bindings;
+    for (uint8_t groupInd = 0; groupInd < Program::SAMPLER_BINDING_COUNT; groupInd++) {
+        auto const& group = groupInfo[groupInd];
+        auto const& samplers = group.samplers;
+        for (size_t i = 0; i < samplers.size(); ++i) {
+            uint32_t const binding = samplers[i].binding;
+            bindingToSamplerIndex[binding] = (groupInd << 8) | (0xff & i);
+            assert_invariant(bindings.find(binding) == bindings.end());
+            bindings.insert(binding);
+
+#if FVK_ENABLED_DEBUG_SAMPLER_NAME
+            bindingToName[binding] = samplers[i].name.c_str();
+#endif
+        }
+    }
+
 #if FVK_ENABLED(FVK_DEBUG_SHADER_MODULE)
    FVK_LOGD << "Created VulkanProgram " << builder << ", shaders = (" << modules[0]
             << ", " << modules[1] << ")" << utils::io::endl;
@@ -250,7 +320,6 @@ void VulkanRenderTarget::bindToSwapChain(VulkanSwapChain& swapChain) {

 VulkanRenderTarget::VulkanRenderTarget(VkDevice device, VkPhysicalDevice physicalDevice,
        VulkanContext const& context, VmaAllocator allocator, VulkanCommands* commands,
-        VulkanResourceAllocator* handleAllocator,
        uint32_t width, uint32_t height, uint8_t samples,
        VulkanAttachment color[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT],
        VulkanAttachment depthStencil[2], VulkanStagePool& stagePool, uint8_t layerCount)
@@ -282,16 +351,10 @@ VulkanRenderTarget::VulkanRenderTarget(VkDevice device, VkPhysicalDevice physica
        if (texture && texture->samples == 1) {
            auto msTexture = texture->getSidecar();
            if (UTILS_UNLIKELY(!msTexture)) {
-                // Clear all usage flags that are not related to attachments, so that we can
-                // use the transient usage flag.
-                const TextureUsage usage = texture->usage & TextureUsage::ALL_ATTACHMENTS;
-                assert_invariant(static_cast<uint16_t>(usage) != 0U);
-
                // TODO: This should be allocated with the ResourceAllocator.
                msTexture = new VulkanTexture(device, physicalDevice, context, allocator, commands,
-                        handleAllocator,
                        texture->target, ((VulkanTexture const*) texture)->levels, texture->format,
-                        samples, texture->width, texture->height, texture->depth, usage,
+                        samples, texture->width, texture->height, texture->depth, texture->usage,
                        stagePool, true /* heap allocated */);
                texture->setSidecar(msTexture);
            }
@@ -319,8 +382,7 @@ VulkanRenderTarget::VulkanRenderTarget(VkDevice device, VkPhysicalDevice physica
    VulkanTexture* msTexture = depthTexture->getSidecar();
    if (UTILS_UNLIKELY(!msTexture)) {
        msTexture = new VulkanTexture(device, physicalDevice, context, allocator,
-                commands, handleAllocator,
-                depthTexture->target, msLevel, depthTexture->format, samples,
+                commands, depthTexture->target, msLevel, depthTexture->format, samples,
                depthTexture->width, depthTexture->height, depthTexture->depth, depthTexture->usage,
                stagePool, true /* heap allocated */);
        depthTexture->setSidecar(msTexture);
@@ -472,7 +534,15 @@ bool VulkanTimerQuery::isCompleted() noexcept {
    // timestamp has at least been written into a processed command buffer.

    // This fence indicates that the corresponding buffer has been completed.
-    return mFence && mFence->getStatus() == VK_SUCCESS;
+    if (!mFence) {
+        return false;
+    }
+    VkResult status = mFence->status.load(std::memory_order_relaxed);
+    if (status != VK_SUCCESS) {
+        return false;
+    }
+
+    return true;
 }

 VulkanTimerQuery::~VulkanTimerQuery() = default;
@@ -488,4 +558,35 @@ VulkanRenderPrimitive::VulkanRenderPrimitive(VulkanResourceAllocator* resourceAl
    mResources.acquire(indexBuffer);
 }

+using Bitmask = VulkanDescriptorSetLayout::Bitmask;
+
+Bitmask Bitmask::fromBackendLayout(descset::DescriptorSetLayout const& layout) {
+    Bitmask mask;
+    for (auto const& binding: layout.bindings) {
+        switch (binding.type) {
+            case descset::DescriptorType::UNIFORM_BUFFER: {
+                if (binding.flags == descset::DescriptorFlags::DYNAMIC_OFFSET) {
+                    mask.dynamicUbo |= fromStageFlags<UniformBufferBitmask>(binding.stageFlags,
+                            binding.binding);
+                } else {
+                    mask.ubo |= fromStageFlags<UniformBufferBitmask>(binding.stageFlags,
+                            binding.binding);
+                }
+                break;
+            }
+            case descset::DescriptorType::SAMPLER: {
+                mask.sampler |= fromStageFlags<SamplerBitmask>(binding.stageFlags, binding.binding);
+                break;
+            }
+            case descset::DescriptorType::INPUT_ATTACHMENT: {
+                mask.inputAttachment |=
+                        fromStageFlags<InputAttachmentBitmask>(binding.stageFlags, binding.binding);
+                break;
+            }
+        }
+    }
+    return mask;
+}
+
+
 } // namespace filament::backend
@@ -29,52 +29,39 @@
 #include <private/backend/SamplerGroup.h>
 #include <backend/Program.h>

-#include <utils/bitset.h>
 #include <utils/FixedCapacityVector.h>
 #include <utils/Mutex.h>
 #include <utils/StructureOfArrays.h>

 namespace filament::backend {

-namespace {
-// Counts the total number of descriptors for both vertex and fragment stages.
-template<typename Bitmask>
-inline uint8_t collapsedCount(Bitmask const& mask) {
-    static_assert(sizeof(mask) <= 64);
-    constexpr uint64_t VERTEX_MASK = (1ULL << getFragmentStageShift<Bitmask>()) - 1ULL;
-    constexpr uint64_t FRAGMENT_MASK = (VERTEX_MASK << getFragmentStageShift<Bitmask>());
-    uint64_t val = mask.getValue();
-    val = ((val & VERTEX_MASK) >> getVertexStageShift<Bitmask>()) |
-        ((val & FRAGMENT_MASK) >> getFragmentStageShift<Bitmask>());
-    return (uint8_t) Bitmask(val).count();
-}
-
-} // anonymous namespace
+using namespace descset;

 class VulkanTimestamps;
-struct VulkanBufferObject;

-struct VulkanDescriptorSetLayout : public VulkanResource, HwDescriptorSetLayout {
-    static constexpr uint8_t UNIQUE_DESCRIPTOR_SET_COUNT = 4;
-    static constexpr uint8_t MAX_BINDINGS = 25;
-
-    using DescriptorSetLayoutArray = std::array<VkDescriptorSetLayout,
-            VulkanDescriptorSetLayout::UNIQUE_DESCRIPTOR_SET_COUNT>;
+struct VulkanDescriptorSetLayout : public VulkanResource {
+    static constexpr uint8_t UNIQUE_DESCRIPTOR_SET_COUNT = 3;

    // The bitmask representation of a set layout.
    struct Bitmask {
-        // TODO: better utiltize the space below and use bitset instead.
-        UniformBufferBitmask ubo;         // 8 bytes
-        UniformBufferBitmask dynamicUbo;  // 8 bytes
-        SamplerBitmask sampler;           // 8 bytes
-        InputAttachmentBitmask inputAttachment; // 8 bytes
+        UniformBufferBitmask ubo = 0;         // 4 bytes
+        UniformBufferBitmask dynamicUbo = 0;  // 4 bytes
+        SamplerBitmask sampler = 0;           // 8 bytes
+        InputAttachmentBitmask inputAttachment = 0; // 1 bytes
+
+        // Because we're using this struct as hash key, must make it's 8-bytes aligned, with no
+        // unaccounted bytes.
+        uint8_t padding0 = 0; // 1 bytes
+        uint16_t padding1 = 0;// 2 bytes
+        uint32_t padding2 = 0;// 4 bytes

        bool operator==(Bitmask const& right) const {
            return ubo == right.ubo && dynamicUbo == right.dynamicUbo && sampler == right.sampler &&
                   inputAttachment == right.inputAttachment;
        }
+
+        static Bitmask fromBackendLayout(descset::DescriptorSetLayout const& layout);
    };
-    static_assert(sizeof(Bitmask) == 32);

    // This is a convenience struct to quickly check layout compatibility in terms of descriptor set
    // pools.
@@ -84,10 +71,6 @@ struct VulkanDescriptorSetLayout : public VulkanResource, HwDescriptorSetLayout
        uint32_t sampler = 0;
        uint32_t inputAttachment = 0;

-        inline uint32_t total() const {
-            return ubo + dynamicUbo + sampler + inputAttachment;
-        }
-
        bool operator==(Count const& right) const noexcept {
            return ubo == right.ubo && dynamicUbo == right.dynamicUbo && sampler == right.sampler &&
                   inputAttachment == right.inputAttachment;
@@ -95,10 +78,10 @@ struct VulkanDescriptorSetLayout : public VulkanResource, HwDescriptorSetLayout

        static inline Count fromLayoutBitmask(Bitmask const& mask) {
            return {
-                .ubo = collapsedCount(mask.ubo),
-                .dynamicUbo = collapsedCount(mask.dynamicUbo),
-                .sampler = collapsedCount(mask.sampler),
-                .inputAttachment = collapsedCount(mask.inputAttachment),
+                    .ubo = countBits(collapseStages(mask.ubo)),
+                    .dynamicUbo = countBits(collapseStages(mask.dynamicUbo)),
+                    .sampler = countBits(collapseStages(mask.sampler)),
+                    .inputAttachment = countBits(collapseStages(mask.inputAttachment)),
            };
        }

@@ -114,50 +97,89 @@ struct VulkanDescriptorSetLayout : public VulkanResource, HwDescriptorSetLayout
        }
    };

-    VulkanDescriptorSetLayout(DescriptorSetLayout const& layout);
+    static_assert(sizeof(Bitmask) % 8 == 0);

-    ~VulkanDescriptorSetLayout() = default;
+    explicit VulkanDescriptorSetLayout(VkDevice device, VkDescriptorSetLayoutCreateInfo const& info,
+            Bitmask const& bitmask);

-    VkDescriptorSetLayout getVkLayout() const { return mVkLayout; }
-    void setVkLayout(VkDescriptorSetLayout vklayout) { mVkLayout = vklayout; }
+    ~VulkanDescriptorSetLayout();

+    VkDevice const mDevice;
+    VkDescriptorSetLayout const vklayout;
    Bitmask const bitmask;
+
+    // This is a convenience struct so that we don't have to iterate through all the bits of the
+    // bitmask (which correspondings to binding indices).
+    struct _Bindings {
+        utils::FixedCapacityVector<uint8_t> const ubo;
+        utils::FixedCapacityVector<uint8_t> const dynamicUbo;
+        utils::FixedCapacityVector<uint8_t> const sampler;
+        utils::FixedCapacityVector<uint8_t> const inputAttachment;
+    } bindings;
+
    Count const count;

 private:
-    VkDescriptorSetLayout mVkLayout = VK_NULL_HANDLE;
+
+    template <typename MaskType>
+    utils::FixedCapacityVector<uint8_t> bits(MaskType mask) {
+        utils::FixedCapacityVector<uint8_t> ret =
+                utils::FixedCapacityVector<uint8_t>::with_capacity(countBits(mask));
+        for (uint8_t i = 0; i < sizeof(mask) * 4; ++i) {
+            if (mask & (1 << i)) {
+                ret.push_back(i);
+            }
+        }
+        return ret;
+    }
+
+    _Bindings getBindings(Bitmask const& bitmask) {
+        auto const uboCollapsed = collapseStages(bitmask.ubo);
+        auto const dynamicUboCollapsed = collapseStages(bitmask.dynamicUbo);
+        auto const samplerCollapsed = collapseStages(bitmask.sampler);
+        auto const inputAttachmentCollapsed = collapseStages(bitmask.inputAttachment);
+        return {
+            bits(uboCollapsed),
+            bits(dynamicUboCollapsed),
+            bits(samplerCollapsed),
+            bits(inputAttachmentCollapsed),
+        };
+    }
 };

-struct VulkanDescriptorSet : public VulkanResource, HwDescriptorSet {
+using VulkanDescriptorSetLayoutList = std::array<Handle<VulkanDescriptorSetLayout>,
+        VulkanDescriptorSetLayout::UNIQUE_DESCRIPTOR_SET_COUNT>;
+
+struct VulkanDescriptorSet : public VulkanResource {
 public:
    // Because we need to recycle descriptor sets not used, we allow for a callback that the "Pool"
    // can use to repackage the vk handle.
-    using OnRecycle = std::function<void(VulkanDescriptorSet*)>;
+    using OnRecycle = std::function<void()>;

-    VulkanDescriptorSet(VulkanResourceAllocator* allocator, VkDescriptorSet rawSet,
-            OnRecycle&& onRecycleFn)
+    VulkanDescriptorSet(VulkanResourceAllocator* allocator,
+            VkDescriptorSet rawSet, OnRecycle&& onRecycleFn)
        : VulkanResource(VulkanResourceType::DESCRIPTOR_SET),
+          resources(allocator),
          vkSet(rawSet),
-          mResources(allocator),
          mOnRecycleFn(std::move(onRecycleFn)) {}

    ~VulkanDescriptorSet() {
        if (mOnRecycleFn) {
-            mOnRecycleFn(this);
+            mOnRecycleFn();
        }
    }

-    void acquire(VulkanTexture* texture);
-
-    void acquire(VulkanBufferObject* texture);
-
+    // TODO: maybe change to fixed size for performance.
+    VulkanAcquireOnlyResourceManager resources;
    VkDescriptorSet const vkSet;

 private:
-    VulkanAcquireOnlyResourceManager mResources;
    OnRecycle mOnRecycleFn;
 };

+using VulkanDescriptorSetList = std::array<Handle<VulkanDescriptorSet>,
+        VulkanDescriptorSetLayout::UNIQUE_DESCRIPTOR_SET_COUNT>;
+
 using PushConstantNameArray = utils::FixedCapacityVector<char const*>;
 using PushConstantNameByStage = std::array<PushConstantNameArray, Program::SHADER_TYPE_COUNT>;

@@ -194,10 +216,24 @@ struct VulkanProgram : public HwProgram, VulkanResource {

    inline VkShaderModule getFragmentShader() const { return mInfo->shaders[1]; }

+    inline utils::FixedCapacityVector<uint16_t> const& getBindingToSamplerIndex() const {
+        return mInfo->bindingToSamplerIndex;
+    }
+
    // Get a list of the sampler binding indices so that we don't have to loop through all possible
    // samplers.
    inline BindingList const& getBindings() const { return mInfo->bindings; }

+    // TODO: this is currently not used. This will replace getLayoutDescriptionList below.
+    // inline descset::DescriptorSetLayout const& getLayoutDescription() const {
+    //    return mInfo->layout;
+    // }
+    // In the usual case, we would have just one layout per program. But in the current setup, we
+    // have a set/layout for each descriptor type. This will be changed in the future.
+    using LayoutDescriptionList = std::array<descset::DescriptorSetLayout,
+            VulkanDescriptorSetLayout::UNIQUE_DESCRIPTOR_SET_COUNT>;
+    inline LayoutDescriptionList const& getLayoutDescriptionList() const { return mInfo->layouts; }
+
    inline uint32_t getPushConstantRangeCount() const {
        return mInfo->pushConstantDescription.getVkRangeCount();
    }
@@ -224,7 +260,8 @@ struct VulkanProgram : public HwProgram, VulkanResource {
 private:
    struct PipelineInfo {
        explicit PipelineInfo(backend::Program const& program) noexcept
-            : pushConstantDescription(program)
+            : bindingToSamplerIndex(MAX_SAMPLER_COUNT, 0xffff),
+              pushConstantDescription(program)
 #if FVK_ENABLED_DEBUG_SAMPLER_NAME
            , bindingToName(MAX_SAMPLER_COUNT, "")
 #endif
@@ -232,8 +269,14 @@ private:

        BindingList bindings;

+        // We store the samplerGroupIndex as the top 8-bit and the index within each group as the lower 8-bit.
+        utils::FixedCapacityVector<uint16_t> bindingToSamplerIndex;
        VkShaderModule shaders[MAX_SHADER_MODULES] = { VK_NULL_HANDLE };

+        // TODO: Use this instead of `layouts` after Filament-side Descriptor Set API is in place.
+        // descset::DescriptorSetLayout layout;
+        LayoutDescriptionList layouts;
+
        PushConstantDescription pushConstantDescription;

 #if FVK_ENABLED_DEBUG_SAMPLER_NAME
@@ -259,9 +302,7 @@ struct VulkanRenderTarget : private HwRenderTarget, VulkanResource {
    // Creates an offscreen render target.
    VulkanRenderTarget(VkDevice device, VkPhysicalDevice physicalDevice,
            VulkanContext const& context, VmaAllocator allocator,
-            VulkanCommands* commands,
-            VulkanResourceAllocator* handleAllocator,
-            uint32_t width, uint32_t height,
+            VulkanCommands* commands, uint32_t width, uint32_t height,
            uint8_t samples, VulkanAttachment color[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT],
            VulkanAttachment depthStencil[2], VulkanStagePool& stagePool, uint8_t layerCount);

@@ -443,7 +484,6 @@ private:
    utils::Mutex mFenceMutex;
 };

-
 inline constexpr VkBufferUsageFlagBits getBufferObjectUsage(
        BufferObjectBinding bindingType) noexcept {
    switch(bindingType) {
@@ -131,18 +131,14 @@ getVkTransition(const VulkanLayoutTransition& transition) {

 }// anonymous namespace

-bool transitionLayout(VkCommandBuffer cmdbuffer,
+void transitionLayout(VkCommandBuffer cmdbuffer,
        VulkanLayoutTransition transition) {
    if (transition.oldLayout == transition.newLayout) {
-        return false;
+        return;
    }
    auto [srcAccessMask, dstAccessMask, srcStage, dstStage, oldLayout, newLayout]
            = getVkTransition(transition);

-    if (oldLayout == newLayout) {
-        return false;
-    }
-
    assert_invariant(transition.image != VK_NULL_HANDLE && "No image for transition");
    VkImageMemoryBarrier barrier = {
            .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
@@ -156,7 +152,6 @@ bool transitionLayout(VkCommandBuffer cmdbuffer,
            .subresourceRange = transition.subresources,
    };
    vkCmdPipelineBarrier(cmdbuffer, srcStage, dstStage, 0, 0, nullptr, 0, nullptr, 1, &barrier);
-    return true;
 }

 }// namespace filament::backend
@@ -76,6 +76,36 @@ inline VkImageViewType getViewType(SamplerType target) {
    }
 }

+inline VulkanLayout getDefaultLayout(TextureUsage usage) {
+    if (any(usage & TextureUsage::DEPTH_ATTACHMENT)) {
+        if (any(usage & TextureUsage::SAMPLEABLE)) {
+            return VulkanLayout::DEPTH_SAMPLER;
+        } else {
+            return VulkanLayout::DEPTH_ATTACHMENT;
+        }
+    }
+
+    if (any(usage & TextureUsage::COLOR_ATTACHMENT)) {
+        return VulkanLayout::COLOR_ATTACHMENT;
+    }
+    // Finally, the layout for an immutable texture is optimal read-only.
+    return VulkanLayout::READ_ONLY;
+}
+
+inline VulkanLayout getDefaultLayout(VkImageUsageFlags vkusage) {
+    TextureUsage usage{};
+    if (vkusage & VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT) {
+        usage = usage | TextureUsage::DEPTH_ATTACHMENT;
+    }
+    if (vkusage & VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT) {
+        usage = usage | TextureUsage::COLOR_ATTACHMENT;
+    }
+    if (vkusage & VK_IMAGE_USAGE_SAMPLED_BIT) {
+        usage = usage | TextureUsage::SAMPLEABLE;
+    }
+    return getDefaultLayout(usage);
+}
+
 constexpr inline VkImageLayout getVkLayout(VulkanLayout layout) {
    switch (layout) {
        case VulkanLayout::UNDEFINED:
@@ -105,9 +135,7 @@ constexpr inline VkImageLayout getVkLayout(VulkanLayout layout) {
    }
 }

-// Returns true if a transition has been added to the command buffer, false otherwis (where there is
-// no transition necessary).
-bool transitionLayout(VkCommandBuffer cmdbuffer, VulkanLayoutTransition transition);
+void transitionLayout(VkCommandBuffer cmdbuffer, VulkanLayoutTransition transition);

 } // namespace imgutil

@@ -98,7 +98,7 @@ VulkanPipelineCache::PipelineCacheEntry* VulkanPipelineCache::createPipeline() n
    VkPipelineColorBlendStateCreateInfo colorBlendState;
    colorBlendState = VkPipelineColorBlendStateCreateInfo{};
    colorBlendState.sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO;
-    colorBlendState.attachmentCount = mPipelineRequirements.rasterState.colorTargetCount;    
+    colorBlendState.attachmentCount = 1;
    colorBlendState.pAttachments = colorBlendAttachments;

    // If we reach this point, we need to create and stash a brand new pipeline object.
@@ -210,8 +210,8 @@ VulkanPipelineCache::PipelineCacheEntry* VulkanPipelineCache::createPipeline() n
    pipelineCreateInfo.pDynamicState = &dynamicState;

    // Filament assumes consistent blend state across all color attachments.
-    for (uint8_t i = 0; i < colorBlendState.attachmentCount; ++i) {
-        auto& target = colorBlendAttachments[i];
+    colorBlendState.attachmentCount = mPipelineRequirements.rasterState.colorTargetCount;
+    for (auto& target : colorBlendAttachments) {
        target.blendEnable = mPipelineRequirements.rasterState.blendEnable;
        target.srcColorBlendFactor = mPipelineRequirements.rasterState.srcColorBlendFactor;
        target.dstColorBlendFactor = mPipelineRequirements.rasterState.dstColorBlendFactor;
@@ -268,7 +268,7 @@ void VulkanReadPixels::run(VulkanRenderTarget* srcTarget, uint32_t const x, uint
            imgutil::getVkLayout(VulkanLayout::TRANSFER_DST), 1, &imageCopyRegion);

    // Restore the source image layout.
-    srcTexture->transitionLayout(cmdbuffer, srcRange, srcTexture->getDefaultLayout());
+    srcTexture->transitionLayout(cmdbuffer, srcRange, VulkanLayout::COLOR_ATTACHMENT);

    vkEndCommandBuffer(cmdbuffer);

@@ -26,14 +26,12 @@ using namespace utils;
 namespace filament::backend {

 VulkanSwapChain::VulkanSwapChain(VulkanPlatform* platform, VulkanContext const& context,
-        VmaAllocator allocator, VulkanCommands* commands, VulkanResourceAllocator* handleAllocator,
-        VulkanStagePool& stagePool,
+        VmaAllocator allocator, VulkanCommands* commands, VulkanStagePool& stagePool,
        void* nativeWindow, uint64_t flags, VkExtent2D extent)
    : VulkanResource(VulkanResourceType::SWAP_CHAIN),
      mPlatform(platform),
      mCommands(commands),
      mAllocator(allocator),
-      mHandleAllocator(handleAllocator),
      mStagePool(stagePool),
      mHeadless(extent.width != 0 && extent.height != 0 && !nativeWindow),
      mFlushAndWaitOnResize(platform->getCustomization().flushAndWaitOnWindowResize),
@@ -64,12 +62,12 @@ void VulkanSwapChain::update() {
    VkDevice const device = mPlatform->getDevice();

    for (auto const color: bundle.colors) {
-        mColors.push_back(std::make_unique<VulkanTexture>(device, mAllocator, mCommands, mHandleAllocator,
-                color, bundle.colorFormat, 1, bundle.extent.width, bundle.extent.height,
+        mColors.push_back(std::make_unique<VulkanTexture>(device, mAllocator, mCommands, color,
+                bundle.colorFormat, 1, bundle.extent.width, bundle.extent.height,
                TextureUsage::COLOR_ATTACHMENT, mStagePool, true /* heap allocated */));
    }
-    mDepth = std::make_unique<VulkanTexture>(device, mAllocator, mCommands, mHandleAllocator,
-            bundle.depth, bundle.depthFormat, 1, bundle.extent.width, bundle.extent.height,
+    mDepth = std::make_unique<VulkanTexture>(device, mAllocator, mCommands, bundle.depth,
+            bundle.depthFormat, 1, bundle.extent.width, bundle.extent.height,
            TextureUsage::DEPTH_ATTACHMENT, mStagePool, true /* heap allocated */);

    mExtent = bundle.extent;
@@ -77,7 +75,7 @@ void VulkanSwapChain::update() {

 void VulkanSwapChain::present() {
    if (!mHeadless && mTransitionSwapChainImageLayoutForPresent) {
-        VulkanCommandBuffer& commands = mCommands->get();
+        VkCommandBuffer const cmdbuf = mCommands->get().buffer();
        VkImageSubresourceRange const subresources{
                .aspectMask = VK_IMAGE_ASPECT_COLOR_BIT,
                .baseMipLevel = 0,
@@ -85,7 +83,7 @@ void VulkanSwapChain::present() {
                .baseArrayLayer = 0,
                .layerCount = 1,
        };
-        mColors[mCurrentSwapIndex]->transitionLayout(&commands, subresources, VulkanLayout::PRESENT);
+        mColors[mCurrentSwapIndex]->transitionLayout(cmdbuf, subresources, VulkanLayout::PRESENT);
    }

    mCommands->flush();
@@ -36,13 +36,11 @@ namespace filament::backend {

 struct VulkanHeadlessSwapChain;
 struct VulkanSurfaceSwapChain;
-class VulkanResourceAllocator;

 // A wrapper around the platform implementation of swapchain.
 struct VulkanSwapChain : public HwSwapChain, VulkanResource {
    VulkanSwapChain(VulkanPlatform* platform, VulkanContext const& context, VmaAllocator allocator,
-            VulkanCommands* commands, VulkanResourceAllocator* handleAllocator,
-            VulkanStagePool& stagePool,
+            VulkanCommands* commands, VulkanStagePool& stagePool,
            void* nativeWindow, uint64_t flags, VkExtent2D extent = {0, 0});

    ~VulkanSwapChain();
@@ -82,7 +80,6 @@ private:
    VulkanPlatform* mPlatform;
    VulkanCommands* mCommands;
    VmaAllocator mAllocator;
-    VulkanResourceAllocator* const mHandleAllocator;
    VulkanStagePool& mStagePool;
    bool const mHeadless;
    bool const mFlushAndWaitOnResize;
@@ -15,7 +15,6 @@
 */

 #include "VulkanMemory.h"
-#include "VulkanResourceAllocator.h"
 #include "VulkanTexture.h"
 #include "VulkanUtility.h"

@@ -29,185 +28,50 @@ using namespace bluevk;

 namespace filament::backend {

-namespace {
-
-inline uint8_t getLayerCount(SamplerType const target, uint32_t const depth) {
-    switch (target) {
-        case SamplerType::SAMPLER_2D:
-        case SamplerType::SAMPLER_3D:
-        case SamplerType::SAMPLER_EXTERNAL:
-            return 1;
-        case SamplerType::SAMPLER_CUBEMAP:
-            return 6;
-        case SamplerType::SAMPLER_CUBEMAP_ARRAY:
-            return depth * 6;
-        case SamplerType::SAMPLER_2D_ARRAY:
-            return depth;
-    }
-}
-
-VkComponentMapping composeSwizzle(VkComponentMapping const& prev, VkComponentMapping const& next) {
-    static constexpr VkComponentSwizzle IDENTITY[] = {
-        VK_COMPONENT_SWIZZLE_R,
-        VK_COMPONENT_SWIZZLE_G,
-        VK_COMPONENT_SWIZZLE_B,
-        VK_COMPONENT_SWIZZLE_A,
-    };
-
-    auto const compose = [](VkComponentSwizzle out, VkComponentMapping const& prev,
-                                 uint8_t channelIndex) {
-        // We need to first change all identities to its equivalent channel.
-        if (out == VK_COMPONENT_SWIZZLE_IDENTITY) {
-            out = IDENTITY[channelIndex];
-        }
-        switch (out) {
-            case VK_COMPONENT_SWIZZLE_R:
-                out = prev.r;
-                break;
-            case VK_COMPONENT_SWIZZLE_G:
-                out = prev.g;
-                break;
-            case VK_COMPONENT_SWIZZLE_B:
-                out = prev.b;
-                break;
-            case VK_COMPONENT_SWIZZLE_A:
-                out = prev.a;
-                break;
-            case VK_COMPONENT_SWIZZLE_IDENTITY:
-            case VK_COMPONENT_SWIZZLE_ZERO:
-            case VK_COMPONENT_SWIZZLE_ONE:
-                return out;
-            // Below is not exposed in Vulkan's API, but needs to be there for compilation.
-            case VK_COMPONENT_SWIZZLE_MAX_ENUM:
-                break;
-        }
-        // If the result correctly corresponds to the identity, just return identity.
-        if (IDENTITY[channelIndex] == out) {
-            return VK_COMPONENT_SWIZZLE_IDENTITY;
-        }
-        return out;
-    };
-
-    auto const identityToChannel = [](VkComponentSwizzle val, uint8_t channelIndex) {
-        if (val != VK_COMPONENT_SWIZZLE_IDENTITY) {
-            return val;
-        }
-        return IDENTITY[channelIndex];
-    };
-
-    // We make sure all all identities are mapped into respective channels so that actual channel
-    // mapping will be passed onto the output.
-    VkComponentMapping const prevExplicit = {
-            identityToChannel(prev.r, 0),
-            identityToChannel(prev.g, 1),
-            identityToChannel(prev.b, 2),
-            identityToChannel(prev.a, 3),
-    };
-
-    // Note that the channel index corresponds to the VkComponentMapping struct layout.
-    return {
-        compose(next.r, prevExplicit, 0),
-        compose(next.g, prevExplicit, 1),
-        compose(next.b, prevExplicit, 2),
-        compose(next.a, prevExplicit, 3),
-    };
-}
-
-inline VulkanLayout getDefaultLayoutImpl(TextureUsage usage) {
-    if (any(usage & TextureUsage::DEPTH_ATTACHMENT)) {
-        if (any(usage & TextureUsage::SAMPLEABLE)) {
-            return VulkanLayout::DEPTH_SAMPLER;
-        } else {
-            return VulkanLayout::DEPTH_ATTACHMENT;
-        }
-    }
-
-    if (any(usage & TextureUsage::COLOR_ATTACHMENT)) {
-        return VulkanLayout::COLOR_ATTACHMENT;
-    }
-    // Finally, the layout for an immutable texture is optimal read-only.
-    return VulkanLayout::READ_ONLY;
-}
-
-inline VulkanLayout getDefaultLayoutImpl(VkImageUsageFlags vkusage) {
-    TextureUsage usage{};
-    if (vkusage & VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT) {
-        usage = usage | TextureUsage::DEPTH_ATTACHMENT;
-    }
-    if (vkusage & VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT) {
-        usage = usage | TextureUsage::COLOR_ATTACHMENT;
-    }
-    if (vkusage & VK_IMAGE_USAGE_SAMPLED_BIT) {
-        usage = usage | TextureUsage::SAMPLEABLE;
-    }
-    return getDefaultLayoutImpl(usage);
-}
-
-} // anonymous namespace
-
-VulkanTextureState::VulkanTextureState(VkDevice device, VmaAllocator allocator,
-        VulkanCommands* commands, VulkanStagePool& stagePool, VkFormat format,
-        VkImageViewType viewType, uint8_t levels, uint8_t layerCount, VulkanLayout defaultLayout)
-    : VulkanResource(VulkanResourceType::HEAP_ALLOCATED),
+VulkanTexture::VulkanTexture(VkDevice device, VmaAllocator allocator, VulkanCommands* commands,
+        VkImage image, VkFormat format, uint8_t samples, uint32_t width, uint32_t height,
+        TextureUsage tusage, VulkanStagePool& stagePool, bool heapAllocated)
+    : HwTexture(SamplerType::SAMPLER_2D, 1, samples, width, height, 1, TextureFormat::UNUSED,
+            tusage),
+      VulkanResource(
+              heapAllocated ? VulkanResourceType::HEAP_ALLOCATED : VulkanResourceType::TEXTURE),
      mVkFormat(format),
-      mViewType(viewType),
-      mFullViewRange{filament::backend::getImageAspect(format), 0, levels, 0, layerCount},
-      mDefaultLayout(defaultLayout),
+      mViewType(imgutil::getViewType(target)),
+      mSwizzle({}),
+      mTextureImage(image),
+      mFullViewRange{
+              .aspectMask = getImageAspect(),
+              .baseMipLevel = 0,
+              .levelCount = 1,
+              .baseArrayLayer = 0,
+              .layerCount = 1,
+      },
+      mPrimaryViewRange(mFullViewRange),
      mStagePool(stagePool),
      mDevice(device),
      mAllocator(allocator),
-      mCommands(commands),
-      mIsTransientAttachment(false) {}
+      mCommands(commands) {}

-VulkanTextureState* VulkanTexture::getSharedState() {
-    VulkanTextureState* state = mAllocator->handle_cast<VulkanTextureState*>(mState);
-    return state;
-}
-
-VulkanTextureState const* VulkanTexture::getSharedState() const {
-    VulkanTextureState const* state = mAllocator->handle_cast<VulkanTextureState const*>(mState);
-    return state;
-}
-
-// Constructor for internally passed VkImage
-VulkanTexture::VulkanTexture(
-        VkDevice device, VmaAllocator allocator, VulkanCommands* commands,
-        VulkanResourceAllocator* handleAllocator,
-        VkImage image, VkFormat format, uint8_t samples, uint32_t width, uint32_t height,
-        TextureUsage tusage, VulkanStagePool& stagePool, bool heapAllocated)
-        : HwTexture(SamplerType::SAMPLER_2D, 1, samples, width, height, 1, TextureFormat::UNUSED,
-                tusage),
-          VulkanResource(
-                  heapAllocated ? VulkanResourceType::HEAP_ALLOCATED : VulkanResourceType::TEXTURE),
-          mAllocator(handleAllocator),
-          mState(handleAllocator->initHandle<VulkanTextureState>(
-                  device, allocator, commands, stagePool,
-                  format, imgutil::getViewType(SamplerType::SAMPLER_2D), 1, 1,
-                  getDefaultLayoutImpl(tusage))) {
-    auto* const state = getSharedState();
-    state->mTextureImage = image;
-    mPrimaryViewRange = state->mFullViewRange;
-}
-
-// Constructor for user facing texture
 VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
        VulkanContext const& context, VmaAllocator allocator, VulkanCommands* commands,
-        VulkanResourceAllocator* handleAllocator, SamplerType target, uint8_t levels,
-        TextureFormat tformat, uint8_t samples, uint32_t w, uint32_t h, uint32_t depth,
-        TextureUsage tusage, VulkanStagePool& stagePool, bool heapAllocated)
+        SamplerType target, uint8_t levels, TextureFormat tformat, uint8_t samples, uint32_t w,
+        uint32_t h, uint32_t depth, TextureUsage tusage, VulkanStagePool& stagePool,
+        bool heapAllocated, VkComponentMapping swizzle)
    : HwTexture(target, levels, samples, w, h, depth, tformat, tusage),
      VulkanResource(
              heapAllocated ? VulkanResourceType::HEAP_ALLOCATED : VulkanResourceType::TEXTURE),
-      mAllocator(handleAllocator),
-      mState(handleAllocator->initHandle<VulkanTextureState>(device, allocator, commands, stagePool,
-              backend::getVkFormat(tformat), imgutil::getViewType(target), levels,
-              getLayerCount(target, depth), VulkanLayout::UNDEFINED)) {
-    auto* const state = getSharedState();
+      mVkFormat(backend::getVkFormat(tformat)),
+      mViewType(imgutil::getViewType(target)),
+      mSwizzle(swizzle),
+      mStagePool(stagePool),
+      mDevice(device),
+      mAllocator(allocator),
+      mCommands(commands) {

    // Create an appropriately-sized device-only VkImage, but do not fill it yet.
    VkImageCreateInfo imageInfo{.sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
            .imageType = target == SamplerType::SAMPLER_3D ? VK_IMAGE_TYPE_3D : VK_IMAGE_TYPE_2D,
-            .format = state->mVkFormat,
+            .format = mVkFormat,
            .extent = {w, h, depth},
            .mipLevels = levels,
            .arrayLayers = 1,
@@ -240,27 +104,14 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
        imageInfo.usage |= VK_IMAGE_USAGE_TRANSFER_DST_BIT;
    }

-    // Determine if we can use the transient usage flag combined with lazily allocated memory.
-    const bool useTransientAttachment =
-        // Lazily allocated memory is available.
-        context.isLazilyAllocatedMemorySupported() &&
-        // Usage consists of attachment flags only.
-        none(tusage & ~TextureUsage::ALL_ATTACHMENTS) &&
-        // Usage contains at least one attachment flag.
-        any(tusage & TextureUsage::ALL_ATTACHMENTS);
-    state->mIsTransientAttachment = useTransientAttachment;
-
-    const VkImageUsageFlags transientFlag =
-       useTransientAttachment ? VK_IMAGE_USAGE_TRANSIENT_ATTACHMENT_BIT : 0U;
-
    if (any(usage & TextureUsage::SAMPLEABLE)) {

 #if FVK_ENABLED(FVK_DEBUG_TEXTURE)
        // Validate that the format is actually sampleable.
        VkFormatProperties props;
-        vkGetPhysicalDeviceFormatProperties(physicalDevice, state->mVkFormat, &props);
+        vkGetPhysicalDeviceFormatProperties(physicalDevice, mVkFormat, &props);
        if (!(props.optimalTilingFeatures & VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT)) {
-            FVK_LOGW << "Texture usage is SAMPLEABLE but format " << state->mVkFormat << " is not "
+            FVK_LOGW << "Texture usage is SAMPLEABLE but format " << mVkFormat << " is not "
                    "sampleable with optimal tiling." << utils::io::endl;
        }
 #endif
@@ -268,19 +119,19 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
        imageInfo.usage |= VK_IMAGE_USAGE_SAMPLED_BIT;
    }
    if (any(usage & TextureUsage::COLOR_ATTACHMENT)) {
-        imageInfo.usage |= VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | transientFlag;
+        imageInfo.usage |= VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
        if (any(usage & TextureUsage::SUBPASS_INPUT)) {
            imageInfo.usage |= VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT;
        }
    }
    if (any(usage & TextureUsage::STENCIL_ATTACHMENT)) {
-        imageInfo.usage |= VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT | transientFlag;
+        imageInfo.usage |= VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT;
    }
    if (any(usage & TextureUsage::UPLOADABLE)) {
        imageInfo.usage |= VK_IMAGE_USAGE_TRANSFER_DST_BIT;
    }
    if (any(usage & TextureUsage::DEPTH_ATTACHMENT)) {
-        imageInfo.usage |= VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT | transientFlag;
+        imageInfo.usage |= VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT;

        // Depth resolves uses a custom shader and therefore needs to be sampleable.
        if (samples > 1) {
@@ -293,7 +144,7 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
    // any kind of attachment (color or depth).
    const auto& limits = context.getPhysicalDeviceLimits();
    if (imageInfo.usage & VK_IMAGE_USAGE_SAMPLED_BIT) {
-        samples = reduceSampleCount(samples, isVkDepthFormat(state->mVkFormat)
+        samples = reduceSampleCount(samples, isVkDepthFormat(mVkFormat)
                                                     ? limits.sampledImageDepthSampleCounts
                                                     : limits.sampledImageColorSampleCounts);
    }
@@ -307,12 +158,12 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
    this->samples = samples;
    imageInfo.samples = (VkSampleCountFlagBits) samples;

-    VkResult error = vkCreateImage(state->mDevice, &imageInfo, VKALLOC, &state->mTextureImage);
+    VkResult error = vkCreateImage(mDevice, &imageInfo, VKALLOC, &mTextureImage);
    if (error || FVK_ENABLED(FVK_DEBUG_TEXTURE)) {
        FVK_LOGD << "vkCreateImage: "
-            << "image = " << state->mTextureImage << ", "
+            << "image = " << mTextureImage << ", "
            << "result = " << error << ", "
-            << "handle = " << utils::io::hex << state->mTextureImage << utils::io::dec << ", "
+            << "handle = " << utils::io::hex << mTextureImage << utils::io::dec << ", "
            << "extent = " << w << "x" << h << "x"<< depth << ", "
            << "mipLevels = " << int(levels) << ", "
            << "TextureUsage = " << static_cast<int>(usage) << ", "
@@ -321,19 +172,16 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
            << "type = " << imageInfo.imageType << ", "
            << "flags = " << imageInfo.flags << ", "
            << "target = " << static_cast<int>(target) <<", "
-            << "format = " << state->mVkFormat << utils::io::endl;
+            << "format = " << mVkFormat << utils::io::endl;
    }
    FILAMENT_CHECK_POSTCONDITION(!error) << "Unable to create image.";

    // Allocate memory for the VkImage and bind it.
    VkMemoryRequirements memReqs = {};
-    vkGetImageMemoryRequirements(state->mDevice, state->mTextureImage, &memReqs);
+    vkGetImageMemoryRequirements(mDevice, mTextureImage, &memReqs);

-    const VkFlags requiredMemoryFlags =
-        VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT |
-        (useTransientAttachment ? VK_MEMORY_PROPERTY_LAZILY_ALLOCATED_BIT : 0U);
    uint32_t memoryTypeIndex
-            = context.selectMemoryType(memReqs.memoryTypeBits, requiredMemoryFlags);
+            = context.selectMemoryType(memReqs.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);

    FILAMENT_CHECK_POSTCONDITION(memoryTypeIndex < VK_MAX_MEMORY_TYPES)
            << "VulkanTexture: unable to find a memory type that meets requirements.";
@@ -343,70 +191,58 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
        .allocationSize = memReqs.size,
        .memoryTypeIndex = memoryTypeIndex,
    };
-    error = vkAllocateMemory(state->mDevice, &allocInfo, nullptr, &state->mTextureImageMemory);
+    error = vkAllocateMemory(mDevice, &allocInfo, nullptr, &mTextureImageMemory);
    FILAMENT_CHECK_POSTCONDITION(!error) << "Unable to allocate image memory.";
-    error = vkBindImageMemory(state->mDevice, state->mTextureImage, state->mTextureImageMemory, 0);
+    error = vkBindImageMemory(mDevice, mTextureImage, mTextureImageMemory, 0);
    FILAMENT_CHECK_POSTCONDITION(!error) << "Unable to bind image.";

+    uint32_t layerCount = 0;
+    if (target == SamplerType::SAMPLER_CUBEMAP) {
+        layerCount = 6;
+    } else if (target == SamplerType::SAMPLER_CUBEMAP_ARRAY) {
+        layerCount = depth * 6;
+    } else if (target == SamplerType::SAMPLER_2D_ARRAY) {
+        layerCount = depth;
+    } else if (target == SamplerType::SAMPLER_3D) {
+        layerCount = 1;
+    } else {
+        layerCount = 1;
+    }
+
+    mFullViewRange = {
+        .aspectMask = getImageAspect(),
+        .baseMipLevel = 0,
+        .levelCount = levels,
+        .baseArrayLayer = 0,
+        .layerCount = layerCount,
+    };
+
    // Spec out the "primary" VkImageView that shaders use to sample from the image.
-    mPrimaryViewRange = state->mFullViewRange;
+    mPrimaryViewRange = mFullViewRange;

    // Go ahead and create the primary image view.
-    getImageView(mPrimaryViewRange, state->mViewType, mSwizzle);
+    getImageView(mPrimaryViewRange, mViewType, mSwizzle);

-    VulkanCommandBuffer& commandsBuf = state->mCommands->get();
-    commandsBuf.acquire(this);
-
-    auto const defaultLayout = state->mDefaultLayout = getDefaultLayoutImpl(imageInfo.usage);
-    transitionLayout(&commandsBuf, mPrimaryViewRange, defaultLayout);
-}
-
-// Constructor for creating a texture view
-VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
-        VulkanContext const& context, VmaAllocator allocator, VulkanCommands* commands,
-        VulkanResourceAllocator* handleAllocator, VulkanTexture const* src, uint8_t baseLevel,
-        uint8_t levelCount)
-    : HwTexture(src->target, src->levels, src->samples, src->width, src->height, src->depth,
-              src->format, src->usage),
-      VulkanResource(VulkanResourceType::TEXTURE),
-      mAllocator(handleAllocator) {
-    mState = src->mState;
-    auto* state = getSharedState();
-
-    state->refs++;
-    mPrimaryViewRange = src->mPrimaryViewRange;
-    mPrimaryViewRange.baseMipLevel = src->mPrimaryViewRange.baseMipLevel + baseLevel;
-    mPrimaryViewRange.levelCount = levelCount;
-}
-
-// Constructor for creating a texture view with swizzle
-VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
-        VulkanContext const& context, VmaAllocator allocator, VulkanCommands* commands,
-        VulkanResourceAllocator* handleAllocator, VulkanTexture const* src,
-        VkComponentMapping swizzle)
-    : HwTexture(src->target, src->levels, src->samples, src->width, src->height, src->depth,
-              src->format, src->usage),
-      VulkanResource(VulkanResourceType::TEXTURE),
-      mAllocator(handleAllocator) {
-    mState = src->mState;
-    auto* state = getSharedState();
-    state->refs++;
-    mPrimaryViewRange = src->mPrimaryViewRange;
-    mSwizzle = composeSwizzle(src->mSwizzle, swizzle);
+    // Transition the layout of each image slice that might be used as a render target.
+    // We do not transition images that are merely SAMPLEABLE, this is deferred until upload time
+    // because we do not know how many layers and levels will actually be used.
+    if (imageInfo.usage
+        & (VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT
+           | VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT)) {
+        VulkanCommandBuffer& commands = mCommands->get();
+        VkCommandBuffer const cmdbuf = commands.buffer();
+        commands.acquire(this);
+        transitionLayout(cmdbuf, mFullViewRange, imgutil::getDefaultLayout(imageInfo.usage));
+    }
 }

 VulkanTexture::~VulkanTexture() {
-    auto* const state = getSharedState();
-    state->refs--;
-    if (state->refs == 0) {
-        if (state->mTextureImageMemory != VK_NULL_HANDLE) {
-            vkDestroyImage(state->mDevice, state->mTextureImage, VKALLOC);
-            vkFreeMemory(state->mDevice, state->mTextureImageMemory, VKALLOC);
-        }
-        for (auto entry: state->mCachedImageViews) {
-            vkDestroyImageView(state->mDevice, entry.second, VKALLOC);
-        }
-        mAllocator->destruct<VulkanTextureState>(mState);
+    if (mTextureImageMemory != VK_NULL_HANDLE) {
+        vkDestroyImage(mDevice, mTextureImage, VKALLOC);
+        vkFreeMemory(mDevice, mTextureImageMemory, VKALLOC);
+    }
+    for (auto entry : mCachedImageViews) {
+        vkDestroyImageView(mDevice, entry.second, VKALLOC);
    }
 }

@@ -415,7 +251,7 @@ void VulkanTexture::updateImage(const PixelBufferDescriptor& data, uint32_t widt
    assert_invariant(width <= this->width && height <= this->height);
    assert_invariant(depth <= this->depth * ((target == SamplerType::SAMPLER_CUBEMAP ||
                        target == SamplerType::SAMPLER_CUBEMAP_ARRAY) ? 6 : 1));
-    auto* const state = getSharedState();
+
    const PixelBufferDescriptor* hostData = &data;
    PixelBufferDescriptor reshapedData;

@@ -428,7 +264,7 @@ void VulkanTexture::updateImage(const PixelBufferDescriptor& data, uint32_t widt

    // If format conversion is both required and supported, use vkCmdBlitImage.
    const VkFormat hostFormat = backend::getVkFormat(hostData->format, hostData->type);
-    const VkFormat deviceFormat = getVkFormatLinear(state->mVkFormat);
+    const VkFormat deviceFormat = getVkFormatLinear(mVkFormat);
    if (hostFormat != deviceFormat && hostFormat != VK_FORMAT_UNDEFINED) {
        assert_invariant(xoffset == 0 && yoffset == 0 && zoffset == 0 &&
                "Offsets not yet supported when format conversion is required.");
@@ -440,14 +276,14 @@ void VulkanTexture::updateImage(const PixelBufferDescriptor& data, uint32_t widt

    // Otherwise, use vkCmdCopyBufferToImage.
    void* mapped = nullptr;
-    VulkanStage const* stage = state->mStagePool.acquireStage(hostData->size);
+    VulkanStage const* stage = mStagePool.acquireStage(hostData->size);
    assert_invariant(stage->memory);
-    vmaMapMemory(state->mAllocator, stage->memory, &mapped);
+    vmaMapMemory(mAllocator, stage->memory, &mapped);
    memcpy(mapped, hostData->buffer, hostData->size);
-    vmaUnmapMemory(state->mAllocator, stage->memory);
-    vmaFlushAllocation(state->mAllocator, stage->memory, 0, hostData->size);
+    vmaUnmapMemory(mAllocator, stage->memory);
+    vmaFlushAllocation(mAllocator, stage->memory, 0, hostData->size);

-    VulkanCommandBuffer& commands = state->mCommands->get();
+    VulkanCommandBuffer& commands = mCommands->get();
    VkCommandBuffer const cmdbuf = commands.buffer();
    commands.acquire(this);

@@ -490,28 +326,27 @@ void VulkanTexture::updateImage(const PixelBufferDescriptor& data, uint32_t widt
    VkImageLayout const newVkLayout = imgutil::getVkLayout(newLayout);

    if (nextLayout == VulkanLayout::UNDEFINED) {
-        nextLayout = getDefaultLayout();
+        nextLayout = imgutil::getDefaultLayout(this->usage);
    }

-    transitionLayout(&commands, transitionRange, newLayout);
+    transitionLayout(cmdbuf, transitionRange, newLayout);

-    vkCmdCopyBufferToImage(cmdbuf, stage->buffer, state->mTextureImage, newVkLayout, 1, &copyRegion);
+    vkCmdCopyBufferToImage(cmdbuf, stage->buffer, mTextureImage, newVkLayout, 1, &copyRegion);

-    transitionLayout(&commands, transitionRange, nextLayout);
+    transitionLayout(cmdbuf, transitionRange, nextLayout);
 }

 void VulkanTexture::updateImageWithBlit(const PixelBufferDescriptor& hostData, uint32_t width,
        uint32_t height, uint32_t depth, uint32_t miplevel) {
-    auto* const state = getSharedState();
    void* mapped = nullptr;
    VulkanStageImage const* stage
-            = state->mStagePool.acquireImage(hostData.format, hostData.type, width, height);
-    vmaMapMemory(state->mAllocator, stage->memory, &mapped);
+            = mStagePool.acquireImage(hostData.format, hostData.type, width, height);
+    vmaMapMemory(mAllocator, stage->memory, &mapped);
    memcpy(mapped, hostData.buffer, hostData.size);
-    vmaUnmapMemory(state->mAllocator, stage->memory);
-    vmaFlushAllocation(state->mAllocator, stage->memory, 0, hostData.size);
+    vmaUnmapMemory(mAllocator, stage->memory);
+    vmaFlushAllocation(mAllocator, stage->memory, 0, hostData.size);

-    VulkanCommandBuffer& commands = state->mCommands->get();
+    VulkanCommandBuffer& commands = mCommands->get();
    VkCommandBuffer const cmdbuf = commands.buffer();
    commands.acquire(this);

@@ -533,17 +368,19 @@ void VulkanTexture::updateImageWithBlit(const PixelBufferDescriptor& hostData, u

    VulkanLayout const newLayout = VulkanLayout::TRANSFER_DST;
    VulkanLayout const oldLayout = getLayout(layer, miplevel);
-    transitionLayout(&commands, range, newLayout);
+    transitionLayout(cmdbuf, range, newLayout);

    vkCmdBlitImage(cmdbuf, stage->image, imgutil::getVkLayout(VulkanLayout::TRANSFER_SRC),
-            state->mTextureImage, imgutil::getVkLayout(newLayout), 1, blitRegions, VK_FILTER_NEAREST);
+            mTextureImage, imgutil::getVkLayout(newLayout), 1, blitRegions, VK_FILTER_NEAREST);

-    transitionLayout(&commands, range, oldLayout);
+    transitionLayout(cmdbuf, range, oldLayout);
 }

-VulkanLayout VulkanTexture::getDefaultLayout() const {
-    auto* const state = getSharedState();
-    return state->mDefaultLayout;
+void VulkanTexture::setPrimaryRange(uint32_t minMiplevel, uint32_t maxMiplevel) {
+    maxMiplevel = filament::math::min(int(maxMiplevel), int(this->levels - 1));
+    mPrimaryViewRange.baseMipLevel = minMiplevel;
+    mPrimaryViewRange.levelCount = maxMiplevel - minMiplevel + 1;
+    getImageView(mPrimaryViewRange, mViewType, mSwizzle);
 }

 VkImageView VulkanTexture::getAttachmentView(VkImageSubresourceRange range) {
@@ -562,42 +399,35 @@ VkImageView VulkanTexture::getViewForType(VkImageSubresourceRange const& range,

 VkImageView VulkanTexture::getImageView(VkImageSubresourceRange range, VkImageViewType viewType,
        VkComponentMapping swizzle) {
-    auto* const state = getSharedState();
-    VulkanTextureState::ImageViewKey const key{ range, viewType, swizzle };
-    auto iter = state->mCachedImageViews.find(key);
-    if (iter != state->mCachedImageViews.end()) {
+    ImageViewKey const key {range, viewType, swizzle};
+    auto iter = mCachedImageViews.find(key);
+    if (iter != mCachedImageViews.end()) {
        return iter->second;
    }
    VkImageViewCreateInfo viewInfo = {
        .sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO,
        .pNext = nullptr,
        .flags = 0,
-        .image = state->mTextureImage,
+        .image = mTextureImage,
        .viewType = viewType,
-        .format = state->mVkFormat,
+        .format = mVkFormat,
        .components = swizzle,
        .subresourceRange = range,
    };
    VkImageView imageView;
-    vkCreateImageView(state->mDevice, &viewInfo, VKALLOC, &imageView);
-    state->mCachedImageViews.emplace(key, imageView);
+    vkCreateImageView(mDevice, &viewInfo, VKALLOC, &imageView);
+    mCachedImageViews.emplace(key, imageView);
    return imageView;
 }

 VkImageAspectFlags VulkanTexture::getImageAspect() const {
    // Helper function in VulkanUtility
-    auto* const state = getSharedState();
-    return filament::backend::getImageAspect(state->mVkFormat);
+    return filament::backend::getImageAspect(mVkFormat);
 }

-bool VulkanTexture::transitionLayout(VulkanCommandBuffer* commands,
-        VkImageSubresourceRange const& range, VulkanLayout newLayout) {
-    return transitionLayout(commands->buffer(), range, newLayout);
-}
-
-bool VulkanTexture::transitionLayout(VkCommandBuffer cmdbuf, VkImageSubresourceRange const& range,
+void VulkanTexture::transitionLayout(VkCommandBuffer cmdbuf, const VkImageSubresourceRange& range,
        VulkanLayout newLayout) {
-    auto* const state = getSharedState();
+
    VulkanLayout const oldLayout = getLayout(range.baseArrayLayer, range.baseMipLevel);

    uint32_t const firstLayer = range.baseArrayLayer;
@@ -608,7 +438,7 @@ bool VulkanTexture::transitionLayout(VkCommandBuffer cmdbuf, VkImageSubresourceR
    // If we are transitioning more than one layer/level (slice), we need to know whether they are
    // all of the same layer.  If not, we need to transition slice-by-slice. Otherwise it would
    // trigger the validation layer saying that the `oldLayout` provided is incorrect.
-    // TODO: transition by multiple slices with more sophisticated range finding.
+    // TODO: transition by multiple slices with more sophiscated range finding.
    bool transitionSliceBySlice = false;
    for (uint32_t i = firstLayer; i < lastLayer; ++i) {
        for (uint32_t j = firstLevel; j < lastLevel; ++j) {
@@ -619,107 +449,50 @@ bool VulkanTexture::transitionLayout(VkCommandBuffer cmdbuf, VkImageSubresourceR
        }
    }

-    bool hasTransitions = false;
+#if FVK_ENABLED(FVK_DEBUG_LAYOUT_TRANSITION)
+    FVK_LOGD << "transition texture=" << mTextureImage
+                  << " (" << range.baseArrayLayer
+                  << "," << range.baseMipLevel << ")"
+                  << " count=(" << range.layerCount
+                  << "," << range.levelCount << ")"
+                  << " from=" << oldLayout << " to=" << newLayout
+                  << " format=" << mVkFormat
+                  << " depth=" << isVkDepthFormat(mVkFormat)
+                  << " slice-by-slice=" << transitionSliceBySlice
+                  << utils::io::endl;
+#endif
+
    if (transitionSliceBySlice) {
        for (uint32_t i = firstLayer; i < lastLayer; ++i) {
            for (uint32_t j = firstLevel; j < lastLevel; ++j) {
                VulkanLayout const layout = getLayout(i, j);
-                if (layout == newLayout) {
-                    continue;
-                }
-                hasTransitions = hasTransitions || imgutil::transitionLayout(cmdbuf, {
-                    .image = state->mTextureImage,
-                    .oldLayout = layout,
-                    .newLayout = newLayout,
-                    .subresources = {
-                        .aspectMask = range.aspectMask,
-                        .baseMipLevel = j,
-                        .levelCount = 1,
-                        .baseArrayLayer = i,
-                        .layerCount = 1,
-                    },
-                });
+                imgutil::transitionLayout(cmdbuf, {
+                        .image = mTextureImage,
+                        .oldLayout = layout,
+                        .newLayout = newLayout,
+                        .subresources = {
+                            .aspectMask = range.aspectMask,
+                            .baseMipLevel = j,
+                            .levelCount = 1,
+                            .baseArrayLayer = i,
+                            .layerCount = 1,
+                        },
+                    });
            }
        }
-    } else if (newLayout != oldLayout) {
-        hasTransitions = imgutil::transitionLayout(cmdbuf, {
-            .image = state->mTextureImage,
+    } else {
+        imgutil::transitionLayout(cmdbuf, {
+            .image = mTextureImage,
            .oldLayout = oldLayout,
            .newLayout = newLayout,
            .subresources = range,
        });
    }

-    // Even if we didn't carry out the transition, we should assume that the new layout is defined
-    // through this call.
    setLayout(range, newLayout);
-
-    if (hasTransitions) {
-#if FVK_ENABLED(FVK_DEBUG_LAYOUT_TRANSITION)
-        FVK_LOGD << "transition texture=" << state->mTextureImage << " (" << range.baseArrayLayer
-                 << "," << range.baseMipLevel << ")" << " count=(" << range.layerCount << ","
-                 << range.levelCount << ")" << " from=" << oldLayout << " to=" << newLayout
-                 << " format=" << state->mVkFormat << " depth=" << isVkDepthFormat(state->mVkFormat)
-                 << " slice-by-slice=" << transitionSliceBySlice << utils::io::endl;
-#endif
-    } else {
-#if FVK_ENABLED(FVK_DEBUG_LAYOUT_TRANSITION)
-        FVK_LOGD << "transition texture=" << state->mTextureImage << " (" << range.baseArrayLayer
-                 << "," << range.baseMipLevel << ")" << " count=(" << range.layerCount << ","
-                 << range.levelCount << ")" << " to=" << newLayout
-                 << " is skipped because of no change in layout" << utils::io::endl;
-#endif
-    }
-    return hasTransitions;
 }

-void VulkanTexture::samplerToAttachmentBarrier(VulkanCommandBuffer* commands,
-        VkImageSubresourceRange const& range) {
-    VkCommandBuffer const cmdbuf = commands->buffer();
-    auto* const state = getSharedState();
-    VkImageLayout const layout =
-            imgutil::getVkLayout(getLayout(range.baseArrayLayer, range.baseMipLevel));
-    VkImageMemoryBarrier barrier = {
-            .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
-            .srcAccessMask = VK_ACCESS_SHADER_READ_BIT,
-            .dstAccessMask =
-                    VK_ACCESS_COLOR_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT,
-            .oldLayout = layout,
-            .newLayout = layout,
-            .srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
-            .dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
-            .image = state->mTextureImage,
-            .subresourceRange = range,
-    };
-    vkCmdPipelineBarrier(cmdbuf, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT,
-            VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT |
-                    VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
-            0, 0, nullptr, 0, nullptr, 1, &barrier);
-}
-
-void VulkanTexture::attachmentToSamplerBarrier(VulkanCommandBuffer* commands,
-        VkImageSubresourceRange const& range) {
-    VkCommandBuffer const cmdbuf = commands->buffer();
-    auto* const state = getSharedState();
-    VkImageLayout const layout
-            = imgutil::getVkLayout(getLayout(range.baseArrayLayer, range.baseMipLevel));
-    VkImageMemoryBarrier barrier = {
-            .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
-            .srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT,
-            .dstAccessMask = VK_ACCESS_SHADER_READ_BIT,
-            .oldLayout = layout,
-            .newLayout = layout,
-            .srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
-            .dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
-            .image = state->mTextureImage,
-            .subresourceRange = range,
-    };
-    vkCmdPipelineBarrier(cmdbuf, VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
-            VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, 0, 0, nullptr, 0, nullptr, 1, &barrier);
-}
-
-void VulkanTexture::setLayout(VkImageSubresourceRange const& range, VulkanLayout newLayout) {
-    auto* const state = getSharedState();
+void VulkanTexture::setLayout(const VkImageSubresourceRange& range, VulkanLayout newLayout) {
    uint32_t const firstLayer = range.baseArrayLayer;
    uint32_t const lastLayer = firstLayer + range.layerCount;
    uint32_t const firstLevel = range.baseMipLevel;
@@ -732,34 +505,32 @@ void VulkanTexture::setLayout(VkImageSubresourceRange const& range, VulkanLayout
        for (uint32_t layer = firstLayer; layer < lastLayer; ++layer) {
            uint32_t const first = (layer << 16) | firstLevel;
            uint32_t const last = (layer << 16) | lastLevel;
-            state->mSubresourceLayouts.clear(first, last);
+            mSubresourceLayouts.clear(first, last);
        }
    } else {
        for (uint32_t layer = firstLayer; layer < lastLayer; ++layer) {
            uint32_t const first = (layer << 16) | firstLevel;
            uint32_t const last = (layer << 16) | lastLevel;
-            state->mSubresourceLayouts.add(first, last, newLayout);
+            mSubresourceLayouts.add(first, last, newLayout);
        }
    }
 }

 VulkanLayout VulkanTexture::getLayout(uint32_t layer, uint32_t level) const {
    assert_invariant(level <= 0xffff && layer <= 0xffff);
-    auto* const state = getSharedState();
    const uint32_t key = (layer << 16) | level;
-    if (!state->mSubresourceLayouts.has(key)) {
+    if (!mSubresourceLayouts.has(key)) {
        return VulkanLayout::UNDEFINED;
    }
-    return state->mSubresourceLayouts.get(key);
+    return mSubresourceLayouts.get(key);
 }

 #if FVK_ENABLED(FVK_DEBUG_TEXTURE)
 void VulkanTexture::print() const {
-    auto* const state = getSharedState();
    uint32_t const firstLayer = 0;
-    uint32_t const lastLayer = firstLayer + state->mFullViewRange.layerCount;
+    uint32_t const lastLayer = firstLayer + mFullViewRange.layerCount;
    uint32_t const firstLevel = 0;
-    uint32_t const lastLevel = firstLevel + state->mFullViewRange.levelCount;
+    uint32_t const lastLevel = firstLevel + mFullViewRange.levelCount;

    for (uint32_t layer = firstLayer; layer < lastLayer; ++layer) {
        for (uint32_t level = firstLevel; level < lastLevel; ++level) {
@@ -768,16 +539,16 @@ void VulkanTexture::print() const {
                layer < (mPrimaryViewRange.baseArrayLayer + mPrimaryViewRange.layerCount) &&
                level >= mPrimaryViewRange.baseMipLevel &&
                level < (mPrimaryViewRange.baseMipLevel + mPrimaryViewRange.levelCount);
-            FVK_LOGD << "[" << state->mTextureImage << "]: (" << layer << "," << level
+            FVK_LOGD << "[" << mTextureImage << "]: (" << layer << "," << level
                          << ")=" << getLayout(layer, level)
                          << " primary=" << primary
                          << utils::io::endl;
        }
    }

-    for (auto view: state->mCachedImageViews) {
+    for (auto view: mCachedImageViews) {
        auto& range = view.first.range;
-        FVK_LOGD << "[" << state->mTextureImage << ", imageView=" << view.second << "]=>"
+        FVK_LOGD << "[" << mTextureImage << ", imageView=" << view.second << "]=>"
                      << " (" << range.baseArrayLayer << "," << range.baseMipLevel << ")"
                      << " count=(" << range.layerCount << "," << range.levelCount << ")"
                      << " aspect=" << range.aspectMask << " viewType=" << view.first.type
@@ -30,12 +30,88 @@

 namespace filament::backend {

-class VulkanResourceAllocator;
+struct VulkanTexture : public HwTexture, VulkanResource {
+    // Standard constructor for user-facing textures.
+    VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice, VulkanContext const& context,
+            VmaAllocator allocator, VulkanCommands* commands, SamplerType target, uint8_t levels,
+            TextureFormat tformat, uint8_t samples, uint32_t w, uint32_t h, uint32_t depth,
+            TextureUsage tusage, VulkanStagePool& stagePool, bool heapAllocated = false,
+            VkComponentMapping swizzle = {});

-struct VulkanTextureState : public VulkanResource {
-    VulkanTextureState(VkDevice device, VmaAllocator allocator, VulkanCommands* commands,
-            VulkanStagePool& stagePool, VkFormat format, VkImageViewType viewType, uint8_t levels,
-            uint8_t layerCount, VulkanLayout defaultLayout);
+    // Specialized constructor for internally created textures (e.g. from a swap chain)
+    // The texture will never destroy the given VkImage, but it does manages its subresources.
+    VulkanTexture(VkDevice device, VmaAllocator allocator, VulkanCommands* commands, VkImage image,
+            VkFormat format, uint8_t samples, uint32_t width, uint32_t height, TextureUsage tusage,
+            VulkanStagePool& stagePool, bool heapAllocated = false);
+
+    ~VulkanTexture();
+
+    // Uploads data into a subregion of a 2D or 3D texture.
+    void updateImage(const PixelBufferDescriptor& data, uint32_t width, uint32_t height,
+            uint32_t depth, uint32_t xoffset, uint32_t yoffset, uint32_t zoffset, uint32_t miplevel);
+
+    // Returns the primary image view, which is used for shader sampling.
+    VkImageView getPrimaryImageView() {
+        return getImageView(mPrimaryViewRange, mViewType, mSwizzle);
+    }
+
+    VkImageViewType getViewType() const { return mViewType; }
+
+    // Sets the min/max range of miplevels in the primary image view.
+    void setPrimaryRange(uint32_t minMiplevel, uint32_t maxMiplevel);
+
+    VkImageSubresourceRange getPrimaryViewRange() const { return mPrimaryViewRange; }
+
+    VkImageSubresourceRange getFullViewRange() const { return mFullViewRange; }
+
+    VulkanLayout getPrimaryImageLayout() const {
+        return getLayout(mPrimaryViewRange.baseArrayLayer, mPrimaryViewRange.baseMipLevel);
+    }
+
+    // Gets or creates a cached VkImageView for a single subresource that can be used as a render
+    // target attachment.  Unlike the primary image view, this always has type VK_IMAGE_VIEW_TYPE_2D
+    // and the identity swizzle.
+    VkImageView getAttachmentView(VkImageSubresourceRange range);
+
+    // Gets or creates a cached VkImageView for a single subresource that can be used as a render
+    // target attachment when rendering with multiview.
+    VkImageView getMultiviewAttachmentView(VkImageSubresourceRange range);
+
+    // This is a workaround for the first few frames where we're waiting for the texture to actually
+    // be uploaded.  In that case, we bind the sampler to an empty texture, but the corresponding
+    // imageView needs to be of the right type. Hence, we provide an option to indicate the
+    // view type. Swizzle option does not matter in this case.
+    VkImageView getViewForType(VkImageSubresourceRange const& range, VkImageViewType type);
+
+    VkFormat getVkFormat() const { return mVkFormat; }
+    VkImage getVkImage() const { return mTextureImage; }
+
+    VulkanLayout getLayout(uint32_t layer, uint32_t level) const;
+
+    void setSidecar(VulkanTexture* sidecar) {
+        mSidecarMSAA.reset(sidecar);
+    }
+
+    VulkanTexture* getSidecar() const {
+        return mSidecarMSAA.get();
+    }
+
+    void transitionLayout(VkCommandBuffer commands, const VkImageSubresourceRange& range,
+            VulkanLayout newLayout);
+
+    // Returns the preferred data plane of interest for all image views.
+    // For now this always returns either DEPTH or COLOR.
+    VkImageAspectFlags getImageAspect() const;
+
+    // For implicit transition like the end of a render pass, we need to be able to set the layout
+    // manually (outside of calls to transitionLayout).
+    void setLayout(const VkImageSubresourceRange& range, VulkanLayout newLayout);
+
+#if FVK_ENABLED(FVK_DEBUG_TEXTURE)
+    void print() const;
+#endif
+
+private:

    struct ImageViewKey {
        VkImageSubresourceRange range;  // 4 * 5 bytes
@@ -58,155 +134,6 @@ struct VulkanTextureState : public VulkanResource {

    using ImageViewHash = utils::hash::MurmurHashFn<ImageViewKey>;

-    uint32_t refs = 1;
-
-    // The texture with the sidecar owns the sidecar.
-    std::unique_ptr<VulkanTexture> mSidecarMSAA;
-    VkDeviceMemory mTextureImageMemory = VK_NULL_HANDLE;
-
-    VkFormat const mVkFormat;
-    VkImageViewType const mViewType;
-    VkImageSubresourceRange const mFullViewRange;
-    VkImage mTextureImage = VK_NULL_HANDLE;
-    VulkanLayout mDefaultLayout;
-
-    // Track the image layout of each subresource using a sparse range map.
-    utils::RangeMap<uint32_t, VulkanLayout> mSubresourceLayouts;
-
-    std::unordered_map<ImageViewKey, VkImageView, ImageViewHash> mCachedImageViews;
-    VulkanStagePool& mStagePool;
-    VkDevice mDevice;
-    VmaAllocator mAllocator;
-    VulkanCommands* mCommands;
-    bool mIsTransientAttachment;
-};
-
-
-struct VulkanTexture : public HwTexture, VulkanResource {
-    // Standard constructor for user-facing textures.
-    VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice, VulkanContext const& context,
-            VmaAllocator allocator, VulkanCommands* commands,
-            VulkanResourceAllocator* handleAllocator,
-            SamplerType target, uint8_t levels,
-            TextureFormat tformat, uint8_t samples, uint32_t w, uint32_t h, uint32_t depth,
-            TextureUsage tusage, VulkanStagePool& stagePool, bool heapAllocated = false);
-
-    // Specialized constructor for internally created textures (e.g. from a swap chain)
-    // The texture will never destroy the given VkImage, but it does manages its subresources.
-    VulkanTexture(VkDevice device, VmaAllocator allocator, VulkanCommands* commands,
-            VulkanResourceAllocator* handleAllocator,
-            VkImage image,
-            VkFormat format, uint8_t samples, uint32_t width, uint32_t height, TextureUsage tusage,
-            VulkanStagePool& stagePool, bool heapAllocated = false);
-
-    // Constructor for creating a texture view for wrt specific mip range
-    VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice, VulkanContext const& context,
-            VmaAllocator allocator, VulkanCommands* commands,
-            VulkanResourceAllocator* handleAllocator,
-            VulkanTexture const* src, uint8_t baseLevel, uint8_t levelCount);
-
-    // Constructor for creating a texture view for swizzle.
-    VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice, VulkanContext const& context,
-            VmaAllocator allocator, VulkanCommands* commands,
-            VulkanResourceAllocator* handleAllocator,
-            VulkanTexture const* src, VkComponentMapping swizzle);
-
-    ~VulkanTexture();
-
-    // Uploads data into a subregion of a 2D or 3D texture.
-    void updateImage(const PixelBufferDescriptor& data, uint32_t width, uint32_t height,
-            uint32_t depth, uint32_t xoffset, uint32_t yoffset, uint32_t zoffset, uint32_t miplevel);
-
-    // Returns the primary image view, which is used for shader sampling.
-    VkImageView getPrimaryImageView() {
-        VulkanTextureState* state = getSharedState();
-        return getImageView(mPrimaryViewRange, state->mViewType, mSwizzle);
-    }
-
-    VkImageViewType getViewType() const {
-        VulkanTextureState const* state = getSharedState();
-        return state->mViewType;
-    }
-
-    VkImageSubresourceRange getPrimaryViewRange() const { return mPrimaryViewRange; }
-
-    VulkanLayout getPrimaryImageLayout() const {
-        return getLayout(mPrimaryViewRange.baseArrayLayer, mPrimaryViewRange.baseMipLevel);
-    }
-
-    // Returns the layout for the intended use of this texture (and not the expected layout at the
-    // time of the call.
-    VulkanLayout getDefaultLayout() const;
-
-    // Gets or creates a cached VkImageView for a single subresource that can be used as a render
-    // target attachment.  Unlike the primary image view, this always has type VK_IMAGE_VIEW_TYPE_2D
-    // and the identity swizzle.
-    VkImageView getAttachmentView(VkImageSubresourceRange range);
-
-    // Gets or creates a cached VkImageView for a single subresource that can be used as a render
-    // target attachment when rendering with multiview.
-    VkImageView getMultiviewAttachmentView(VkImageSubresourceRange range);
-
-    // This is a workaround for the first few frames where we're waiting for the texture to actually
-    // be uploaded.  In that case, we bind the sampler to an empty texture, but the corresponding
-    // imageView needs to be of the right type. Hence, we provide an option to indicate the
-    // view type. Swizzle option does not matter in this case.
-    VkImageView getViewForType(VkImageSubresourceRange const& range, VkImageViewType type);
-
-    VkFormat getVkFormat() const {
-        VulkanTextureState const* state = getSharedState();
-        return state->mVkFormat;
-    }
-    VkImage getVkImage() const {
-        VulkanTextureState const* state = getSharedState();
-        return state->mTextureImage;
-    }
-
-    VulkanLayout getLayout(uint32_t layer, uint32_t level) const;
-
-    void setSidecar(VulkanTexture* sidecar) {
-        VulkanTextureState* state = getSharedState();
-        state->mSidecarMSAA.reset(sidecar);
-    }
-
-    VulkanTexture* getSidecar() const {
-        VulkanTextureState const* state = getSharedState();
-        return state->mSidecarMSAA.get();
-    }
-
-    bool isTransientAttachment() const {
-        VulkanTextureState const* state = getSharedState();
-        return state->mIsTransientAttachment;
-    }
-
-    bool transitionLayout(VulkanCommandBuffer* commands, VkImageSubresourceRange const& range,
-            VulkanLayout newLayout);
-
-    bool transitionLayout(VkCommandBuffer cmdbuf, VkImageSubresourceRange const& range,
-            VulkanLayout newLayout);
-
-    void attachmentToSamplerBarrier(VulkanCommandBuffer* commands,
-            VkImageSubresourceRange const& range);
-
-    void samplerToAttachmentBarrier(VulkanCommandBuffer* commands,
-            VkImageSubresourceRange const& range);
-
-    // Returns the preferred data plane of interest for all image views.
-    // For now this always returns either DEPTH or COLOR.
-    VkImageAspectFlags getImageAspect() const;
-
-    // For implicit transition like the end of a render pass, we need to be able to set the layout
-    // manually (outside of calls to transitionLayout).
-    void setLayout(VkImageSubresourceRange const& range, VulkanLayout newLayout);
-
-#if FVK_ENABLED(FVK_DEBUG_TEXTURE)
-    void print() const;
-#endif
-
-private:
-    VulkanTextureState* getSharedState();
-    VulkanTextureState const* getSharedState() const;
-
    // Gets or creates a cached VkImageView for a range of miplevels, array layers, viewType, and
    // swizzle (or not).
    VkImageView getImageView(VkImageSubresourceRange range, VkImageViewType viewType,
@@ -215,15 +142,28 @@ private:
    void updateImageWithBlit(const PixelBufferDescriptor& hostData, uint32_t width, uint32_t height,
            uint32_t depth, uint32_t miplevel);

-    VulkanResourceAllocator* const mAllocator;
+    // The texture with the sidecar owns the sidecar.
+    std::unique_ptr<VulkanTexture> mSidecarMSAA;
+    const VkFormat mVkFormat;
+    const VkImageViewType mViewType;
+    const VkComponentMapping mSwizzle;
+    VkImage mTextureImage = VK_NULL_HANDLE;
+    VkDeviceMemory mTextureImageMemory = VK_NULL_HANDLE;

-    Handle<VulkanTextureState> mState;
+    // Track the image layout of each subresource using a sparse range map.
+    utils::RangeMap<uint32_t, VulkanLayout> mSubresourceLayouts;
+
+    VkImageSubresourceRange mFullViewRange;

    // Track the range of subresources that define the "primary" image view, which is the special
    // image view that gets bound to an actual texture sampler.
    VkImageSubresourceRange mPrimaryViewRange;

-    VkComponentMapping mSwizzle {};
+    std::unordered_map<ImageViewKey, VkImageView, ImageViewHash> mCachedImageViews;
+    VulkanStagePool& mStagePool;
+    VkDevice mDevice;
+    VmaAllocator mAllocator;
+    VulkanCommands* mCommands;
 };

 } // namespace filament::backend
@@ -577,7 +577,7 @@ uint32_t getComponentCount(VkFormat format) {
    return {};
 }

-VkComponentMapping getSwizzleMap(TextureSwizzle const swizzle[4]) {
+VkComponentMapping getSwizzleMap(TextureSwizzle swizzle[4]) {
    VkComponentMapping map;
    VkComponentSwizzle* dst = &map.r;
    for (int i = 0; i < 4; ++i, ++dst) {
@@ -19,7 +19,6 @@

 #include <backend/DriverEnums.h>

-#include <utils/bitset.h>
 #include <utils/FixedCapacityVector.h>

 #include <bluevk/BlueVK.h>
@@ -39,7 +38,7 @@ VkCullModeFlags getCullMode(CullingMode mode);
 VkFrontFace getFrontFace(bool inverseFrontFaces);
 PixelDataType getComponentType(VkFormat format);
 uint32_t getComponentCount(VkFormat format);
-VkComponentMapping getSwizzleMap(TextureSwizzle const swizzle[4]);
+VkComponentMapping getSwizzleMap(TextureSwizzle swizzle[4]);
 VkShaderStageFlags getShaderStageFlags(ShaderStageFlags stageFlags);

 bool equivalent(const VkRect2D& a, const VkRect2D& b);
@@ -406,13 +405,12 @@ constexpr VkFormat ALL_VK_FORMATS[] = {
        VK_FORMAT_R16G16_S10_5_NV,
 };

-// An Array that will be statically fixed in capacity, but the "size" (as in user added elements) is
-// variable. Note that this class is movable.
+// An Array that will be fixed capacity, but the "size" (as in user added elements) is variable.
+// Note that this class is movable.
 template<typename T, uint16_t CAPACITY>
 class CappedArray {
 private:
    using FixedSizeArray = std::array<T, CAPACITY>;
-
 public:
    using const_iterator = typename FixedSizeArray::const_iterator;
    using iterator = typename FixedSizeArray::iterator;
@@ -450,20 +448,6 @@ public:
        return mArray.cend();
    }

-    inline iterator begin() {
-        if (mInd == 0) {
-            return mArray.end();
-        }
-        return mArray.begin();
-    }
-
-    inline iterator end() {
-        if (mInd > 0 && mInd < CAPACITY) {
-            return mArray.begin() + mInd;
-        }
-        return mArray.end();
-    }
-
    inline T back() {
        assert_invariant(mInd > 0);
        return *(mArray.begin() + mInd);
@@ -528,28 +512,125 @@ private:
    uint32_t mInd = 0;
 };

-using UniformBufferBitmask = utils::bitset64;
-using SamplerBitmask = utils::bitset64;
+// TODO: ok to remove once Filament-side API is complete
+namespace descset {
+
+// Used to describe the descriptor binding in shader stages. We assume that the binding index does
+// not exceed 31. We also assume that we have two shader stages - vertex and fragment.  The below
+// types and struct are used across VulkanDescriptorSet and VulkanProgram.
+using UniformBufferBitmask = uint32_t;
+using SamplerBitmask = uint64_t;

 // We only have at most one input attachment, so this bitmask exists only to make the code more
 // general.
-using InputAttachmentBitmask = utils::bitset64;
+using InputAttachmentBitmask = uint8_t;
+
+constexpr UniformBufferBitmask UBO_VERTEX_STAGE = 0x1;
+constexpr UniformBufferBitmask UBO_FRAGMENT_STAGE = (0x1ULL << (sizeof(UniformBufferBitmask) * 4));
+constexpr SamplerBitmask SAMPLER_VERTEX_STAGE = 0x1;
+constexpr SamplerBitmask SAMPLER_FRAGMENT_STAGE = (0x1ULL << (sizeof(SamplerBitmask) * 4));
+constexpr InputAttachmentBitmask INPUT_ATTACHMENT_VERTEX_STAGE = 0x1;
+constexpr InputAttachmentBitmask INPUT_ATTACHMENT_FRAGMENT_STAGE =
+        (0x1ULL << (sizeof(InputAttachmentBitmask) * 4));

 template<typename Bitmask>
-static constexpr uint8_t getVertexStageShift() noexcept {
-    // We assume the bottom half of bits are for vertex stages.
-    return 0;
+static constexpr Bitmask getVertexStage() noexcept {
+    if constexpr (std::is_same_v<Bitmask, UniformBufferBitmask>) {
+        return UBO_VERTEX_STAGE;
+    }
+    if constexpr (std::is_same_v<Bitmask, SamplerBitmask>) {
+        return SAMPLER_VERTEX_STAGE;
+    }
+    if constexpr (std::is_same_v<Bitmask, InputAttachmentBitmask>) {
+        return INPUT_ATTACHMENT_VERTEX_STAGE;
+    }
 }

 template<typename Bitmask>
-static constexpr uint8_t getFragmentStageShift() noexcept {
-    // We assume the top half of bits are for fragment stages.
-    return sizeof(Bitmask) * 4;
+static constexpr Bitmask getFragmentStage() noexcept {
+    if constexpr (std::is_same_v<Bitmask, UniformBufferBitmask>) {
+        return UBO_FRAGMENT_STAGE;
+    }
+    if constexpr (std::is_same_v<Bitmask, SamplerBitmask>) {
+        return SAMPLER_FRAGMENT_STAGE;
+    }
+    if constexpr (std::is_same_v<Bitmask, InputAttachmentBitmask>) {
+        return INPUT_ATTACHMENT_FRAGMENT_STAGE;
+    }
 }

-// We have at most 4 descriptor sets. This is to indicate which ones are active.
-using DescriptorSetMask = utils::bitset8;
+typedef enum ShaderStageFlags2 : uint8_t {
+    NONE        =    0,
+    VERTEX      =    0x1,
+    FRAGMENT    =    0x2,
+} ShaderStageFlags2;

+enum class DescriptorType : uint8_t {
+    UNIFORM_BUFFER,
+    SAMPLER,
+    INPUT_ATTACHMENT,
+};
+
+enum class DescriptorFlags : uint8_t {
+    NONE = 0x00,
+    DYNAMIC_OFFSET = 0x01
+};
+
+struct DescriptorSetLayoutBinding {
+    DescriptorType type;
+    ShaderStageFlags2 stageFlags;
+    uint8_t binding;
+    DescriptorFlags flags;
+    uint16_t count;
+};
+
+struct DescriptorSetLayout {
+    utils::FixedCapacityVector<DescriptorSetLayoutBinding> bindings;
+};
+
+} // namespace descset
+
+namespace {
+// Use constexpr to statically generate a bit count table for 8-bit numbers.
+struct _BitCountHelper {
+    constexpr _BitCountHelper() : data{} {
+        for (uint16_t i = 0; i < 256; ++i) {
+            data[i] = 0;
+            for (auto j = i; j > 0; j /= 2) {
+                if (j & 1) {
+                    data[i]++;
+                }
+            }
+        }
+    }
+
+    template<typename MaskType>
+    constexpr uint8_t count(MaskType num) {
+        uint8_t count = 0;
+        for (uint8_t i = 0; i < sizeof(MaskType) * 8; i+=8) {
+            count += data[(num >> i) & 0xFF];
+        }
+        return count;
+    }
+
+private:
+    uint8_t data[256];
+};
+} // namespace anonymous
+
+template<typename MaskType>
+inline uint8_t countBits(MaskType num) {
+    static _BitCountHelper BitCounter = {};
+    return BitCounter.count(num);
+}
+
+// This is useful for counting the total number of descriptors for both vertex and fragment stages.
+template<typename MaskType>
+inline MaskType collapseStages(MaskType mask) {
+    constexpr uint8_t NBITS_DIV_2 = sizeof(MaskType) * 4;
+    // First zero out the top-half and then or the bottom-half against the original top-half.
+    return ((mask << NBITS_DIV_2) >> NBITS_DIV_2) | (mask >> NBITS_DIV_2);
+}

 } // namespace filament::backend

@@ -30,10 +30,12 @@
 #include <bluevk/BlueVK.h>
 #include <tsl/robin_map.h>

-#include <memory>
+#include <functional>

 namespace filament::backend {

+using namespace descset;
+
 // [GDSR]: Great-Descriptor-Set-Refactor: As of 03/20/24, the Filament frontend is planning to
 // introduce descriptor set. This PR will arrive before that change is complete. As such, some of
 // the methods introduced here will be obsolete, and certain logic will be generalized.
@@ -43,76 +45,67 @@ class VulkanDescriptorSetManager {
 public:
    static constexpr uint8_t UNIQUE_DESCRIPTOR_SET_COUNT =
            VulkanDescriptorSetLayout::UNIQUE_DESCRIPTOR_SET_COUNT;
-
-    using DescriptorSetLayoutArray = VulkanDescriptorSetLayout::DescriptorSetLayoutArray;
+    using GetPipelineLayoutFunction = std::function<VkPipelineLayout(
+            VulkanDescriptorSetLayoutList const&, VulkanProgram* program)>;

    VulkanDescriptorSetManager(VkDevice device, VulkanResourceAllocator* resourceAllocator);
-    ~VulkanDescriptorSetManager();

    void terminate() noexcept;

-    void updateBuffer(VulkanDescriptorSet* set, uint8_t binding,
+    void gc();
+
+    // TODO: Obsolete after [GDSR].
+    // This will write/update/bind all of the descriptor set. After [GDSR], the binding for
+    // descriptor sets will not depend on the layout described in the program.
+    VkPipelineLayout bind(VulkanCommandBuffer* commands, VulkanProgram* program,
+            GetPipelineLayoutFunction& getPipelineLayoutFn);
+
+    // TODO: Obsolete after [GDSR].
+    // This is to "dynamically" bind UBOs that might have offsets changed between pipeline binding
+    // and the draw call. We do this because UBOs for primitives that are part of the same
+    // renderable can be stored within one buffer. This can be a no-op if there were no range
+    // changes between the pipeline bind and the draw call. We will re-use applicable states
+    // provided within the bind() call, including the UBO descriptor set layout. TODO: make it a
+    // proper dynamic binding when Filament-side descriptor changes are completed.
+    void dynamicBind(VulkanCommandBuffer* commands, Handle<VulkanDescriptorSetLayout> uboLayout);
+
+    // TODO: Obsolete after [GDSR].
+    // Since we use program pointer as cache key, we need to clear the cache when it's freed.
+    void clearProgram(VulkanProgram* program) noexcept;
+
+    Handle<VulkanDescriptorSetLayout> createLayout(descset::DescriptorSetLayout const& layout);
+
+    void destroyLayout(Handle<VulkanDescriptorSetLayout> layout);
+
+    void updateBuffer(Handle<VulkanDescriptorSet> set, uint8_t binding,
            VulkanBufferObject* bufferObject, VkDeviceSize offset, VkDeviceSize size) noexcept;

-    void updateSampler(VulkanDescriptorSet* set, uint8_t binding,
+    void updateSampler(Handle<VulkanDescriptorSet> set, uint8_t binding,
            VulkanTexture* texture, VkSampler sampler) noexcept;

-    void updateInputAttachment(VulkanDescriptorSet* set, VulkanAttachment attachment) noexcept;
+    void updateInputAttachment(Handle<VulkanDescriptorSet> set, VulkanAttachment attachment) noexcept;

-    void bind(uint8_t setIndex, VulkanDescriptorSet* set, backend::DescriptorSetOffsetArray&& offsets);
-
-    void commit(VulkanCommandBuffer* commands, VkPipelineLayout pipelineLayout,
-            DescriptorSetMask const& setMask);
+    void clearBuffer(uint32_t bindingIndex);

    void setPlaceHolders(VkSampler sampler, VulkanTexture* texture,
            VulkanBufferObject* bufferObject) noexcept;

-    void createSet(Handle<HwDescriptorSet> handle, VulkanDescriptorSetLayout* layout);
+    void clearState() noexcept;

-    void destroySet(Handle<HwDescriptorSet> handle);
+    // TODO: To be completed after [GDSR]
+    Handle<VulkanDescriptorSet> createSet(Handle<VulkanDescriptorSetLayout> layout) {
+        return Handle<VulkanDescriptorSet>();
+    }

-    void initVkLayout(VulkanDescriptorSetLayout* layout);
+    // TODO: To be completed after [GDSR]
+    void destroySet(Handle<VulkanDescriptorSet> set) {}

 private:
-    class DescriptorSetHistory;
-    class DescriptorSetLayoutManager;
-    class DescriptorInfinitePool;
-
-    void eraseSetFromHistory(VulkanDescriptorSet* set);
-
-    using DescriptorSetHistoryArray =
-            std::array<DescriptorSetHistory*, UNIQUE_DESCRIPTOR_SET_COUNT>;
-
-    struct BoundInfo {
-        VkPipelineLayout pipelineLayout = VK_NULL_HANDLE;
-        DescriptorSetMask setMask;
-        DescriptorSetHistoryArray boundSets;
-
-        bool operator==(BoundInfo const& info) const {
-            if (pipelineLayout != info.pipelineLayout || setMask != info.setMask) {
-                return false;
-            }
-            bool equal = true;
-            setMask.forEachSetBit([&](size_t i) {
-                if (boundSets[i] != info.boundSets[i]) {
-                    equal = false;
-                }
-            });
-            return equal;
-        }
-    };
-
-    VkDevice mDevice;
-    VulkanResourceAllocator* mResourceAllocator;
-    std::unique_ptr<DescriptorSetLayoutManager> mLayoutManager;
-    std::unique_ptr<DescriptorInfinitePool> mDescriptorPool;
-    std::pair<VulkanAttachment, VkDescriptorImageInfo> mInputAttachment;
-    std::unordered_map<VulkanDescriptorSet*, std::unique_ptr<DescriptorSetHistory>> mHistory;
-    DescriptorSetHistoryArray mStashedSets = {};
-
-    BoundInfo mLastBoundInfo;
+    class Impl;
+    Impl* mImpl;
 };

 }// namespace filament::backend

 #endif// TNT_FILAMENT_BACKEND_CACHING_VULKANDESCRIPTORSETMANAGER_H
+
@@ -21,20 +21,19 @@
 namespace filament::backend {

 VkPipelineLayout VulkanPipelineLayoutCache::getLayout(
-        DescriptorSetLayoutArray const& descriptorSetLayouts, VulkanProgram* program) {
+        VulkanDescriptorSetLayoutList const& descriptorSetLayouts, VulkanProgram* program) {
    PipelineLayoutKey key = {};
    uint8_t descSetLayoutCount = 0;
-    key.descSetLayouts = descriptorSetLayouts;
    for (auto layoutHandle: descriptorSetLayouts) {
-        if (layoutHandle == VK_NULL_HANDLE) {
-            break;
+        if (layoutHandle) {
+            auto layout = mAllocator->handle_cast<VulkanDescriptorSetLayout*>(layoutHandle);
+            key.descSetLayouts[descSetLayoutCount++] = layout->vklayout;
        }
-        descSetLayoutCount++;
    }

    // build the push constant layout key
-    uint32_t const pushConstantRangeCount = program->getPushConstantRangeCount();
-    auto const& pushConstantRanges = program->getPushConstantRanges();
+    uint32_t pushConstantRangeCount = program->getPushConstantRangeCount();
+    auto const& pushConstantRanges = program->getPushConstantRanges();    
    if (pushConstantRangeCount > 0) {
        assert_invariant(pushConstantRangeCount <= Program::SHADER_TYPE_COUNT);
        for (uint8_t i = 0; i < pushConstantRangeCount; ++i) {
@@ -53,8 +52,8 @@ VkPipelineLayout VulkanPipelineLayoutCache::getLayout(
        }
    }

-    if (auto iter = mPipelineLayouts.find(key); iter != mPipelineLayouts.end()) {
-        PipelineLayoutCacheEntry& entry = iter->second;
+    if (PipelineLayoutMap::iterator iter = mPipelineLayouts.find(key); iter != mPipelineLayouts.end()) {
+        PipelineLayoutCacheEntry& entry = iter.value();
        entry.lastUsed = mTimestamp++;
        return entry.handle;
    }
@@ -22,40 +22,41 @@

 #include <utils/Hash.h>

-#include <unordered_map>
+#include <tsl/robin_map.h>

 namespace filament::backend {

 class VulkanPipelineLayoutCache {
 public:
-    using DescriptorSetLayoutArray = VulkanDescriptorSetLayout::DescriptorSetLayoutArray;
-    
    VulkanPipelineLayoutCache(VkDevice device, VulkanResourceAllocator* allocator)
        : mDevice(device),
+          mAllocator(allocator),
          mTimestamp(0) {}

    void terminate() noexcept;

    struct PushConstantKey {
-        uint8_t stage = 0;// We have one set of push constant per shader stage (fragment, vertex, etc).
-        uint8_t size = 0;
+        uint8_t stage;// We have one set of push constant per shader stage (fragment, vertex, etc).
+        uint8_t size;
        // Note that there is also an offset parameter for push constants, but
        // we always assume our update range will have the offset 0.
    };

    struct PipelineLayoutKey {
-        DescriptorSetLayoutArray descSetLayouts = {};                                     // 8 * 4
-        PushConstantKey pushConstant[Program::SHADER_TYPE_COUNT] = {};                    // 2 * 3
+        using DescriptorSetLayoutArray = std::array<VkDescriptorSetLayout,
+                VulkanDescriptorSetLayout::UNIQUE_DESCRIPTOR_SET_COUNT>;
+        DescriptorSetLayoutArray descSetLayouts = {};                   // 8 * 3
+        PushConstantKey pushConstant[Program::SHADER_TYPE_COUNT] = {};  // 2 * 3
        uint16_t padding = 0;
    };
-    static_assert(sizeof(PipelineLayoutKey) == 40);
+    static_assert(sizeof(PipelineLayoutKey) == 32);

    VulkanPipelineLayoutCache(VulkanPipelineLayoutCache const&) = delete;
    VulkanPipelineLayoutCache& operator=(VulkanPipelineLayoutCache const&) = delete;

    // A pipeline layout depends on the descriptor set layout and the push constant ranges, which
    // are described in the program.
-    VkPipelineLayout getLayout(DescriptorSetLayoutArray const& descriptorSetLayouts,
+    VkPipelineLayout getLayout(VulkanDescriptorSetLayoutList const& descriptorSetLayouts,
            VulkanProgram* program);

 private:
@@ -72,14 +73,15 @@ private:
        }
    };

-    using PipelineLayoutMap = std::unordered_map<PipelineLayoutKey, PipelineLayoutCacheEntry,
+    using PipelineLayoutMap = tsl::robin_map<PipelineLayoutKey, PipelineLayoutCacheEntry,
            PipelineLayoutKeyHashFn, PipelineLayoutKeyEqual>;

    VkDevice mDevice;
+    VulkanResourceAllocator* mAllocator;
    Timestamp mTimestamp;
    PipelineLayoutMap mPipelineLayouts;
 };

-} // filament::backend
+}

 #endif // TNT_FILAMENT_BACKEND_VULKANPIPELINECACHE_H
@@ -740,20 +740,6 @@ Driver* VulkanPlatform::createDriver(void* sharedContext,
    context.mDebugMarkersSupported = setContains(deviceExts, VK_EXT_DEBUG_MARKER_EXTENSION_NAME);
    context.mMultiviewEnabled = setContains(deviceExts, VK_KHR_MULTIVIEW_EXTENSION_NAME);

-    // Check the availability of lazily allocated memory
-    {
-        context.mLazilyAllocatedMemorySupported = false;
-        const uint32_t typeCount = context.mMemoryProperties.memoryTypeCount;
-        for(uint32_t i = 0; i < typeCount; ++i) {
-            const VkMemoryType type = context.mMemoryProperties.memoryTypes[i];
-            if (type.propertyFlags & VK_MEMORY_PROPERTY_LAZILY_ALLOCATED_BIT) {
-                context.mLazilyAllocatedMemorySupported = true;
-                assert_invariant(type.propertyFlags & VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
-                break;
-            }
-        }
-    }
-
 #ifdef NDEBUG
    // If we are in release build, we should not have turned on debug extensions
    FILAMENT_CHECK_POSTCONDITION(!context.mDebugUtilsSupported && !context.mDebugMarkersSupported)
@@ -31,22 +31,22 @@ namespace {
 std::tuple<VkImage, VkDeviceMemory> createImageAndMemory(VulkanContext const& context,
        VkDevice device, VkExtent2D extent, VkFormat format) {
    bool const isDepth = isVkDepthFormat(format);
-    // Filament expects blit() to work with any texture, so we almost always set these usage flags
-    // (see copyFrame() and readPixels()).
-    VkImageUsageFlags const blittable =
-            VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_TRANSFER_SRC_BIT;
-
-    VkImageCreateInfo imageInfo {
-        .sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
-        .imageType = VK_IMAGE_TYPE_2D,
-        .format = format,
-        .extent = {extent.width, extent.height, 1},
-        .mipLevels = 1,
-        .arrayLayers = 1,
-        .samples = VK_SAMPLE_COUNT_1_BIT,
-        .tiling = VK_IMAGE_TILING_OPTIMAL,
-        .usage = blittable | (isDepth ? VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT
-                                      : VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT),
+    // Filament expects blit() to work with any texture, so we almost always set these usage flags.
+    // TODO: investigate performance implications of setting these flags.
+    VkImageUsageFlags const blittable
+            = VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_TRANSFER_SRC_BIT;
+    VkImageCreateInfo imageInfo{
+            .sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
+            .imageType = VK_IMAGE_TYPE_2D,
+            .format = format,
+            .extent = {extent.width, extent.height, 1},
+            .mipLevels = 1,
+            .arrayLayers = 1,
+            .samples = VK_SAMPLE_COUNT_1_BIT,
+            .tiling = VK_IMAGE_TILING_OPTIMAL,
+            .usage = blittable
+                     | (isDepth ? VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT
+                                : VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT),
    };
    VkImage image;
    VkResult result = vkCreateImage(device, &imageInfo, VKALLOC, &image);
@@ -220,7 +220,7 @@ VkResult VulkanPlatformSurfaceSwapChain::create() {
            .imageArrayLayers = 1,
            .imageUsage
            = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT
-              | VK_IMAGE_USAGE_TRANSFER_DST_BIT // Allows use as a blit destination (for copyFrame)
+              | VK_IMAGE_USAGE_TRANSFER_DST_BIT // Allows use as a blit destination.
              | VK_IMAGE_USAGE_TRANSFER_SRC_BIT,// Allows use as a blit source (for readPixels)

            // TODO: Setting the preTransform to IDENTITY means we are letting the Android
@@ -239,7 +239,7 @@ VkResult VulkanPlatformSurfaceSwapChain::create() {
    };
    VkResult result = vkCreateSwapchainKHR(mDevice, &createInfo, VKALLOC, &mSwapchain);
    FILAMENT_CHECK_POSTCONDITION(result == VK_SUCCESS)
-            << "vkCreateSwapchainKHR error: " << static_cast<int32_t>(result);
+            << "vkGetPhysicalDeviceSurfaceFormatsKHR error: " << static_cast<int32_t>(result);

    mSwapChainBundle.colors = enumerate(vkGetSwapchainImagesKHR, mDevice, mSwapchain);
    mSwapChainBundle.colorFormat = surfaceFormat.format;
@@ -112,10 +112,9 @@ void BackendTest::fullViewport(Viewport& viewport) {
 }

 void BackendTest::renderTriangle(
-        PipelineLayout const& pipelineLayout,
-        Handle<filament::backend::HwRenderTarget> renderTarget,
-        Handle<filament::backend::HwSwapChain> swapChain,
-        Handle<filament::backend::HwProgram> program) {
+        filament::backend::Handle<filament::backend::HwRenderTarget> renderTarget,
+        filament::backend::Handle<filament::backend::HwSwapChain> swapChain,
+        filament::backend::Handle<filament::backend::HwProgram> program) {
    RenderPassParams params = {};
    fullViewport(params);
    params.flags.clear = TargetBufferFlags::COLOR;
@@ -124,15 +123,11 @@ void BackendTest::renderTriangle(
    params.flags.discardEnd = TargetBufferFlags::NONE;
    params.viewport.height = 512;
    params.viewport.width = 512;
-    renderTriangle(pipelineLayout, renderTarget, swapChain, program, params);
+    renderTriangle(renderTarget, swapChain, program, params);
 }

-void BackendTest::renderTriangle(
-        PipelineLayout const& pipelineLayout,
-        Handle<HwRenderTarget> renderTarget,
-        Handle<HwSwapChain> swapChain,
-        Handle<HwProgram> program,
-        const RenderPassParams& params) {
+void BackendTest::renderTriangle(Handle<HwRenderTarget> renderTarget,
+        Handle<HwSwapChain> swapChain, Handle<HwProgram> program, const RenderPassParams& params) {
    auto& api = getDriverApi();

    TrianglePrimitive triangle(api);
@@ -143,7 +138,6 @@ void BackendTest::renderTriangle(

    PipelineState state;
    state.program = program;
-    state.pipelineLayout = pipelineLayout;
    state.rasterState.colorWrite = true;
    state.rasterState.depthWrite = false;
    state.rasterState.depthFunc = RasterState::DepthFunc::A;
@@ -51,15 +51,10 @@ protected:
    static void fullViewport(filament::backend::RenderPassParams& params);
    static void fullViewport(filament::backend::Viewport& viewport);

-    void renderTriangle(
-            filament::backend::PipelineLayout const& pipelineLayout,
-            filament::backend::Handle<filament::backend::HwRenderTarget> renderTarget,
+    void renderTriangle(filament::backend::Handle<filament::backend::HwRenderTarget> renderTarget,
            filament::backend::Handle<filament::backend::HwSwapChain> swapChain,
            filament::backend::Handle<filament::backend::HwProgram> program);
-
-    void renderTriangle(
-            filament::backend::PipelineLayout const& pipelineLayout,
-            filament::backend::Handle<filament::backend::HwRenderTarget> renderTarget,
+    void renderTriangle(filament::backend::Handle<filament::backend::HwRenderTarget> renderTarget,
            filament::backend::Handle<filament::backend::HwSwapChain> swapChain,
            filament::backend::Handle<filament::backend::HwProgram> program,
            const filament::backend::RenderPassParams& params);
@@ -1,159 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include <gtest/gtest.h>
-
-#include "../src/metal/MetalContext.h"
-
-namespace test {
-
-TEST(MetalDynamicOffsets, none) {
-    filament::backend::MetalDynamicOffsets dynamicOffsets;
-    const auto [count, offsets] = dynamicOffsets.getOffsets();
-    EXPECT_EQ(count, 0u);
-}
-
-TEST(MetalDynamicOffsets, basic) {
-    filament::backend::MetalDynamicOffsets dynamicOffsets;
-    {
-        const auto [count, offsets] = dynamicOffsets.getOffsets();
-        EXPECT_EQ(count, 0u);
-    }
-
-    {
-        uint32_t o[2] = { 1, 2 };
-        dynamicOffsets.setOffsets(0, o, 2);
-        const auto [count, offsets] = dynamicOffsets.getOffsets();
-        EXPECT_EQ(count, 2);
-        EXPECT_EQ(offsets[0], 1);
-        EXPECT_EQ(offsets[1], 2);
-    }
-
-    {
-        uint32_t o[3] = { 3, 4, 5 };
-        dynamicOffsets.setOffsets(1, o, 3);
-        const auto [count, offsets] = dynamicOffsets.getOffsets();
-        EXPECT_EQ(count, 5);
-        EXPECT_EQ(offsets[0], 1);
-        EXPECT_EQ(offsets[1], 2);
-        EXPECT_EQ(offsets[2], 3);
-        EXPECT_EQ(offsets[3], 4);
-        EXPECT_EQ(offsets[4], 5);
-    }
-
-    // skip descriptor set index 2
-
-    {
-        uint32_t o[1] = { 6 };
-        dynamicOffsets.setOffsets(3, o, 1);
-        const auto [count, offsets] = dynamicOffsets.getOffsets();
-        EXPECT_EQ(count, 6);
-        EXPECT_EQ(offsets[0], 1);
-        EXPECT_EQ(offsets[1], 2);
-        EXPECT_EQ(offsets[2], 3);
-        EXPECT_EQ(offsets[3], 4);
-        EXPECT_EQ(offsets[4], 5);
-        EXPECT_EQ(offsets[5], 6);
-    }
-}
-
-TEST(MetalDynamicOffsets, outOfOrder) {
-    filament::backend::MetalDynamicOffsets dynamicOffsets;
-    uint32_t o1[2] = { 2, 3 };
-    dynamicOffsets.setOffsets(1, o1, 2);
-    uint32_t o2[2] = { 0, 1 };
-    dynamicOffsets.setOffsets(0, o2, 2);
-    uint32_t o3[2] = { 4, 5 };
-    dynamicOffsets.setOffsets(2, o3, 2);
-
-    const auto [count, offsets] = dynamicOffsets.getOffsets();
-    EXPECT_EQ(count, 6);
-    EXPECT_EQ(offsets[0], 0);
-    EXPECT_EQ(offsets[1], 1);
-    EXPECT_EQ(offsets[2], 2);
-    EXPECT_EQ(offsets[3], 3);
-    EXPECT_EQ(offsets[4], 4);
-    EXPECT_EQ(offsets[5], 5);
-};
-
-TEST(MetalDynamicOffsets, removal) {
-    filament::backend::MetalDynamicOffsets dynamicOffsets;
-    uint32_t o1[2] = { 2, 3 };
-    dynamicOffsets.setOffsets(1, o1, 2);
-    uint32_t o2[2] = { 0, 1 };
-    dynamicOffsets.setOffsets(0, o2, 2);
-    uint32_t o3[2] = { 4, 5 };
-    dynamicOffsets.setOffsets(2, o3, 2);
-    dynamicOffsets.setOffsets(1, nullptr, 0);
-
-    const auto [count, offsets] = dynamicOffsets.getOffsets();
-    EXPECT_EQ(count, 4);
-    EXPECT_EQ(offsets[0], 0);
-    EXPECT_EQ(offsets[1], 1);
-    EXPECT_EQ(offsets[2], 4);
-    EXPECT_EQ(offsets[3], 5);
-};
-
-TEST(MetalDynamicOffsets, resize) {
-    filament::backend::MetalDynamicOffsets dynamicOffsets;
-    uint32_t o1[2] = { 2, 3 };
-    dynamicOffsets.setOffsets(1, o1, 2);
-    uint32_t o2[2] = { 0, 1 };
-    dynamicOffsets.setOffsets(0, o2, 2);
-    uint32_t o3[2] = { 6, 7 };
-    dynamicOffsets.setOffsets(2, o3, 2);
-    uint32_t o4[4] = { 2, 3, 4, 5 };
-    dynamicOffsets.setOffsets(1, o4, 4);
-
-    const auto [count, offsets] = dynamicOffsets.getOffsets();
-    EXPECT_EQ(count, 8);
-    EXPECT_EQ(offsets[0], 0);
-    EXPECT_EQ(offsets[1], 1);
-    EXPECT_EQ(offsets[2], 2);
-    EXPECT_EQ(offsets[3], 3);
-    EXPECT_EQ(offsets[4], 4);
-    EXPECT_EQ(offsets[5], 5);
-    EXPECT_EQ(offsets[6], 6);
-    EXPECT_EQ(offsets[7], 7);
-};
-
-TEST(MetalDynamicOffsets, dirty) {
-    filament::backend::MetalDynamicOffsets dynamicOffsets;
-    EXPECT_FALSE(dynamicOffsets.isDirty());
-
-    uint32_t o1[2] = { 2, 3 };
-    dynamicOffsets.setOffsets(1, o1, 2);
-    EXPECT_TRUE(dynamicOffsets.isDirty());
-
-    dynamicOffsets.setDirty(false);
-    EXPECT_FALSE(dynamicOffsets.isDirty());
-
-    // Setting the same offsets should not mark the offsets as dirty
-    dynamicOffsets.setOffsets(1, o1, 2);
-    EXPECT_FALSE(dynamicOffsets.isDirty());
-
-    // Resizing the offsets should mark the offsets as dirty
-    uint32_t o2[3] = { 4, 5, 6 };
-    dynamicOffsets.setOffsets(1, o2, 3);
-    EXPECT_TRUE(dynamicOffsets.isDirty());
-};
-
-};
-
-int main(int argc, char **argv) {
-    testing::InitGoogleTest(&argc, argv);
-    return RUN_ALL_TESTS();
-}
@@ -73,13 +73,12 @@ void ShaderGenerator::shutdown() {
    FinalizeProcess();
 }

-ShaderGenerator::ShaderGenerator(std::string vertex, std::string fragment, Backend backend,
-        bool isMobile, filamat::DescriptorSets&& descriptorSets) noexcept
-    : mBackend(backend),
-      mVertexBlob(transpileShader(
-              ShaderStage::VERTEX, std::move(vertex), backend, isMobile, descriptorSets)),
-      mFragmentBlob(transpileShader(
-              ShaderStage::FRAGMENT, std::move(fragment), backend, isMobile, descriptorSets)) {
+ShaderGenerator::ShaderGenerator(std::string vertex, std::string fragment,
+        Backend backend, bool isMobile, const filament::SamplerInterfaceBlock* sib) noexcept
+        : mBackend(backend),
+          mVertexBlob(transpileShader(ShaderStage::VERTEX, std::move(vertex), backend, isMobile, sib)),
+          mFragmentBlob(transpileShader(ShaderStage::FRAGMENT, std::move(fragment), backend,
+                  isMobile, sib)) {
    switch (backend) {
        case Backend::OPENGL:
            mShaderLanguage = filament::backend::ShaderLanguage::ESSL3;
@@ -96,8 +95,9 @@ ShaderGenerator::ShaderGenerator(std::string vertex, std::string fragment, Backe
    }
 }

-ShaderGenerator::Blob ShaderGenerator::transpileShader(ShaderStage stage, std::string shader,
-        Backend backend, bool isMobile, const filamat::DescriptorSets& descriptorSets) noexcept {
+ShaderGenerator::Blob ShaderGenerator::transpileShader(
+        ShaderStage stage, std::string shader, Backend backend, bool isMobile,
+        const filament::SamplerInterfaceBlock* sib) noexcept {
    TProgram program;
    const EShLanguage language = stage == ShaderStage::VERTEX ? EShLangVertex : EShLangFragment;
    TShader tShader(language);
@@ -161,8 +161,9 @@ ShaderGenerator::Blob ShaderGenerator::transpileShader(ShaderStage stage, std::s
        return { result.c_str(), result.c_str() + result.length() + 1 };
    } else if (backend == Backend::METAL) {
        const auto sm = isMobile ? ShaderModel::MOBILE : ShaderModel::DESKTOP;
-        filamat::GLSLPostProcessor::spirvToMsl(
-                &spirv, &result, stage, sm, false, descriptorSets, nullptr);
+        filamat::SibVector sibs = filamat::SibVector::with_capacity(1);
+        if (sib) { sibs.emplace_back(0, sib); }
+        filamat::GLSLPostProcessor::spirvToMsl(&spirv, &result, sm, false, sibs, nullptr);
        return { result.c_str(), result.c_str() + result.length() + 1 };
    } else if (backend == Backend::VULKAN) {
        return { (uint8_t*)spirv.data(), (uint8_t*)(spirv.data() + spirv.size()) };
@@ -22,7 +22,6 @@
 #include "private/filament/SamplerInterfaceBlock.h"
 #include "private/backend/DriverApi.h"
 #include "backend/Program.h"
-#include "../src/GLSLPostProcessor.h"

 #include <string>

@@ -41,7 +40,7 @@ public:
     * @param fragment The fragment shader, written in GLSL 450 core.
     */
    ShaderGenerator(std::string vertex, std::string fragment, Backend backend, bool isMobile,
-            filamat::DescriptorSets&& descriptorSets = {}) noexcept;
+            const filament::SamplerInterfaceBlock* sib = nullptr) noexcept;

    ShaderGenerator(const ShaderGenerator& rhs) = delete;
    ShaderGenerator& operator=(const ShaderGenerator& rhs) = delete;
@@ -53,7 +52,7 @@ private:

    using Blob = std::vector<char>;
    static Blob transpileShader(ShaderStage stage, std::string shader, Backend backend,
-            bool isMobile, const filamat::DescriptorSets& descriptorSets) noexcept;
+            bool isMobile, const filament::SamplerInterfaceBlock* sib = nullptr) noexcept;

    Backend mBackend;

@@ -53,7 +53,8 @@ test::NativeView getNativeView() {
    nativeView.width = static_cast<size_t>(drawableSize.width);
    nativeView.height = static_cast<size_t>(drawableSize.height);

-    exit(test::runTests());
+    test::runTests();
+    // exit(runTests());
 }

 - (NSView*)createView {
@@ -38,7 +38,7 @@ using namespace utils;

 static const char* const triangleVs = R"(#version 450 core
 layout(location = 0) in vec4 mesh_position;
-layout(binding = 0, set = 1) uniform Params { highp vec4 color; highp vec4 scale; } params;
+uniform Params { highp vec4 color; highp vec4 scale; } params;
 void main() {
    gl_Position = vec4((mesh_position.xy + 0.5) * params.scale.xy, params.scale.z, 1.0);
 #if defined(TARGET_VULKAN_ENVIRONMENT)
@@ -50,7 +50,7 @@ void main() {
 static const char* const triangleFs = R"(#version 450 core
 precision mediump int; precision highp float;
 layout(location = 0) out vec4 fragColor;
-layout(binding = 0, set = 1) uniform Params { highp vec4 color; highp vec4 scale; } params;
+uniform Params { highp vec4 color; highp vec4 scale; } params;
 void main() {
    fragColor = params.color;
 })";
@@ -348,26 +348,12 @@ TEST_F(BackendTest, ColorResolve) {
    // Create a program.
    ProgramHandle program;
    {
-        filamat::DescriptorSets descriptors;
-        descriptors[1] = { { "Params",
-                { DescriptorType::UNIFORM_BUFFER, ShaderStageFlags::ALL_SHADER_STAGE_FLAGS, 0 },
-                {} } };
-        ShaderGenerator shaderGen(
-                triangleVs, triangleFs, sBackend, sIsMobilePlatform, std::move(descriptors));
+        ShaderGenerator shaderGen(triangleVs, triangleFs, sBackend, sIsMobilePlatform);
        Program prog = shaderGen.getProgram(api);
-        prog.descriptorBindings(1, {{ "Params", DescriptorType::UNIFORM_BUFFER, 0 }});
+        prog.uniformBlockBindings({{"params", 1}});
        program = api.createProgram(std::move(prog));
    }

-    DescriptorSetLayoutHandle descriptorSetLayout = api.createDescriptorSetLayout({
-            {{
-                     DescriptorType::UNIFORM_BUFFER,
-                     ShaderStageFlags::ALL_SHADER_STAGE_FLAGS, 0,
-                     DescriptorFlags::NONE, 0
-             }}});
-
-    DescriptorSetHandle descriptorSet = api.createDescriptorSet(descriptorSetLayout);
-
    // Create a VertexBuffer, IndexBuffer, and RenderPrimitive.
    TrianglePrimitive const triangle(api);

@@ -402,7 +388,6 @@ TEST_F(BackendTest, ColorResolve) {

    PipelineState state = {};
    state.program = program;
-    state.pipelineLayout.setLayout[1] = { descriptorSetLayout };
    state.rasterState.colorWrite = true;
    state.rasterState.depthWrite = false;
    state.rasterState.depthFunc = RasterState::DepthFunc::A;
@@ -416,12 +401,10 @@ TEST_F(BackendTest, ColorResolve) {
        .scale = float4(1, 1, 0.5, 0),
    });

-    api.updateDescriptorSetBuffer(descriptorSet, 0, ubuffer, 0, sizeof(MaterialParams));
-    api.bindDescriptorSet(descriptorSet, 1, {});
-
    // FIXME: on Metal this triangle is not drawn. Can't understand why.
    api.beginFrame(0, 0, 0);
        api.beginRenderPass(srcRenderTarget, params);
+            api.bindUniformBuffer(0, ubuffer);
            api.draw(state, triangle.getRenderPrimitive(), 0, 3, 1);
        api.endRenderPass();
    api.endFrame(0);
@@ -445,8 +428,6 @@ TEST_F(BackendTest, ColorResolve) {
    EXPECT_TRUE(sparams.pixelHashResult == expected);

    // Cleanup.
-    api.destroyDescriptorSet(descriptorSet);
-    api.destroyDescriptorSetLayout(descriptorSetLayout);
    api.destroyBufferObject(ubuffer);
    api.destroyProgram(program);
    api.destroyTexture(srcColorTexture);
--- a/Show More
+++ b/Show More