Testing rendering to quad

2024-08-27 13:47:43 -07:00
323 changed files with 8750 additions and 15254 deletions
--- a/.github/actions/android-continuous/action.yml
+++ b/.github/actions/android-continuous/action.yml
@@ -1,17 +0,0 @@
-name: 'Android Continuous'
-inputs:
-  build-abi:
-    description: 'The target platform ABI'
-    required: true
-    default: 'armeabi-v7a'
-runs:
-  using: "composite"
-  steps:
-    - uses: actions/setup-java@v3
-      with:
-        distribution: 'temurin'
-        java-version: '17'
-    - name: Run build script
-      run: |
-        cd build/android && printf "y" | ./build.sh continuous ${{ inputs.build-abi }}
-      shell: bash
--- a/.github/actions/ubuntu-apt-add-src/action.yml
+++ b/.github/actions/ubuntu-apt-add-src/action.yml
@@ -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
--- a/.github/workflows/android-continuous.yml
+++ b/.github/workflows/android-continuous.yml
@@ -10,13 +10,30 @@ on:
 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
+    runs-on: macos-14

    steps:
      - uses: actions/checkout@v4.1.6
-      - name: Run Android Continuous
-        uses: ./.github/actions/android-continuous
+      - uses: actions/setup-java@v3
        with:
-          build-abi: armeabi-v7a,arm64-v8a,x86_64
+          distribution: 'temurin'
+          java-version: '17'
+      - name: Run build script
+        run: |
+          cd build/android && printf "y" | ./build.sh continuous
+      - uses: actions/upload-artifact@v1.0.0
+        with:
+          name: filament-android
+          path: out/filament-android-release.aar
+      - uses: actions/upload-artifact@v1.0.0
+        with:
+          name: filamat-android-full
+          path: out/filamat-android-release.aar
+      - uses: actions/upload-artifact@v1.0.0
+        with:
+          name: gltfio-android-release
+          path: out/gltfio-android-release.aar
+      - uses: actions/upload-artifact@v1.0.0
+        with:
+          name: filament-utils-android-release
+          path: out/filament-utils-android-release.aar
--- a/.github/workflows/ios-continuous.yml
+++ b/.github/workflows/ios-continuous.yml
@@ -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
--- a/.github/workflows/linux-continuous.yml
+++ b/.github/workflows/linux-continuous.yml
@@ -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
--- a/.github/workflows/mac-continuous.yml
+++ b/.github/workflows/mac-continuous.yml
@@ -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
--- a/.github/workflows/presubmit.yml
+++ b/.github/workflows/presubmit.yml
@@ -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
@@ -49,14 +49,12 @@ jobs:
          distribution: 'temurin'
          java-version: '17'
      - name: Run build script
-        # Only build 1 64 bit target during presubmit to cut down build times during presubmit
-        # Continuous builds will build everything
        run: |
-          cd build/android && printf "y" | ./build.sh presubmit arm64-v8a
+          cd build/android && printf "y" | ./build.sh presubmit

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

    steps:
      - uses: actions/checkout@v4.1.6
@@ -69,25 +67,10 @@ 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
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -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:
@@ -120,7 +120,7 @@ jobs:
        env:
          TAG: ${{ steps.git_ref.outputs.tag }}
        run: |
-          cd build/android && printf "y" | ./build.sh release armeabi-v7a,arm64-v8a,x86,x86_64
+          cd build/android && printf "y" | ./build.sh release
          cd ../..
          mv out/filament-android-release.aar out/filament-${TAG}-android.aar
          mv out/filamat-android-release.aar out/filamat-${TAG}-android.aar
@@ -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
--- a/.github/workflows/web-continuous.yml
+++ b/.github/workflows/web-continuous.yml
@@ -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
--- a/.github/workflows/windows-continuous.yml
+++ b/.github/workflows/windows-continuous.yml
@@ -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
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -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)
--- a/NEW_RELEASE_NOTES.md
+++ b/NEW_RELEASE_NOTES.md
@@ -7,4 +7,3 @@ for next branch cut* header.
 appropriate header in [RELEASE_NOTES.md](./RELEASE_NOTES.md).

 ## Release notes for next branch cut
- vk: fix stage pool gc logic
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@ repositories {
 }

 dependencies {
-    implementation 'com.google.android.filament:filament-android:1.56.0'
+    implementation 'com.google.android.filament:filament-android:1.54.0'
 }
 ```

@@ -51,9 +51,19 @@ 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', '~> 1.56.0'
+pod 'Filament', '~> 1.54.0'
 ```

+### Snapshots
+
+If you prefer to live on the edge, you can download a continuous build by following the following
+steps:
+
+1. Find the [commit](https://github.com/google/filament/commits/main) you're interested in.
+2. Click the green check mark under the commit message.
+3. Click on the _Details_ link for the platform you're interested in.
+4. On the top left click _Summary_, then in the _Artifacts_ section choose the desired artifact.
+
 ## Documentation

 - [Filament](https://google.github.io/filament/Filament.html), an in-depth explanation of
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -7,32 +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).

-## v1.56.1
-
-## v1.56.0
-
- backend: descriptor layouts distinguish samplers and external samplers (b/376089915) [⚠️ **New Material Version**]
-
-## 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
-
-
-## v1.54.2
-
- Add a `name` API to Filament objects for debugging handle use-after-free assertions
-
 ## v1.54.1


@@ -660,7 +634,7 @@ Instead, if you are authoring a PR for the main branch, add your release note to

 - engine: Binary size improvements.
 - engine: Add basic support for instanced renderables [**NEW API**].
- engine: Fix, first imaged passed to `Stream::SetAcquiredImage` is ignored and leaked.
+- engine: Fix, first imaged passsed to `Stream::SetAcquiredImage` is ignored and leaked.
 - Vulkan: Robustness improvements.
 - Java: Fix, lookAt z axis negated.
 - gltfio: Be graceful when model has > 4 weights per vert.
--- a/android/build.gradle
+++ b/android/build.gradle
@@ -83,12 +83,12 @@ buildscript {
        'minSdk': 21,
        'targetSdk': 34,
        'compileSdk': 34,
-        'kotlin': '2.0.21',
-        'kotlin_coroutines': '1.9.0',
-        'buildTools': '35.0.0',
+        'kotlin': '2.0.0',
+        'kotlin_coroutines': '1.9.0-RC',
+        'buildTools': '34.0.0',
        'ndk': '27.0.11718014',
        'androidx_core': '1.13.1',
-        'androidx_annotations': '1.9.0'
+        'androidx_annotations': '1.8.0'
    ]

    ext.deps = [
@@ -104,7 +104,7 @@ buildscript {
    ]

    dependencies {
-        classpath 'com.android.tools.build:gradle:8.6.1'
+        classpath 'com.android.tools.build:gradle:8.4.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:${versions.kotlin}"
    }

--- a/android/filament-android/src/main/cpp/Engine.cpp
+++ b/android/filament-android/src/main/cpp/Engine.cpp
@@ -499,37 +499,6 @@ Java_com_google_android_filament_Engine_nGetActiveFeatureLevel(JNIEnv *, jclass,
    return (jint)engine->getActiveFeatureLevel();
 }

-extern "C"
-JNIEXPORT jboolean JNICALL
-Java_com_google_android_filament_Engine_nHasFeatureFlag(JNIEnv *env, jclass clazz,
-        jlong nativeEngine, jstring name_) {
-    Engine* engine = (Engine*) nativeEngine;
-    const char *name = env->GetStringUTFChars(name_, 0);
-    std::optional<bool> result = engine->getFeatureFlag(name);
-    env->ReleaseStringUTFChars(name_, name);
-    return result.has_value();
-}
-extern "C"
-JNIEXPORT jboolean JNICALL
-Java_com_google_android_filament_Engine_nSetFeatureFlag(JNIEnv *env, jclass clazz,
-        jlong nativeEngine, jstring name_, jboolean value) {
-    Engine* engine = (Engine*) nativeEngine;
-    const char *name = env->GetStringUTFChars(name_, 0);
-    jboolean result = engine->setFeatureFlag(name, (bool)value);
-    env->ReleaseStringUTFChars(name_, name);
-    return result;
-}
-extern "C"
-JNIEXPORT jboolean JNICALL
-Java_com_google_android_filament_Engine_nGetFeatureFlag(JNIEnv *env, jclass clazz,
-        jlong nativeEngine, jstring name_) {
-    Engine* engine = (Engine*) nativeEngine;
-    const char *name = env->GetStringUTFChars(name_, 0);
-    std::optional<bool> result = engine->getFeatureFlag(name);
-    env->ReleaseStringUTFChars(name_, name);
-    return result.value_or(false); // we should never fail here
-}
-
 extern "C" JNIEXPORT jlong JNICALL Java_com_google_android_filament_Engine_nCreateBuilder(JNIEnv*,
        jclass) {
    Engine::Builder* builder = new Engine::Builder{};
@@ -551,12 +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,
@@ -565,6 +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,
@@ -573,7 +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);
 }
@@ -596,16 +566,6 @@ extern "C" JNIEXPORT void JNICALL Java_com_google_android_filament_Engine_nSetBu
    builder->paused((bool) paused);
 }

-extern "C"
-JNIEXPORT void JNICALL
-Java_com_google_android_filament_Engine_nSetBuilderFeature(JNIEnv *env, jclass clazz,
-        jlong nativeBuilder, jstring name_, jboolean value) {
-    Engine::Builder* builder = (Engine::Builder*) nativeBuilder;
-    const char *name = env->GetStringUTFChars(name_, 0);
-    builder->feature(name, (bool)value);
-    env->ReleaseStringUTFChars(name_, name);
-}
-
 extern "C" JNIEXPORT jlong JNICALL
 Java_com_google_android_filament_Engine_nBuilderBuild(JNIEnv*, jclass, jlong nativeBuilder) {
    Engine::Builder* builder = (Engine::Builder*) nativeBuilder;
--- a/android/filament-android/src/main/cpp/View.cpp
+++ b/android/filament-android/src/main/cpp/View.cpp
@@ -222,20 +222,6 @@ Java_com_google_android_filament_View_nIsFrontFaceWindingInverted(JNIEnv*,
    return static_cast<jboolean>(view->isFrontFaceWindingInverted());
 }

-extern "C" JNIEXPORT void JNICALL
-Java_com_google_android_filament_View_nSetTransparentPickingEnabled(JNIEnv*,
-        jclass, jlong nativeView, jboolean enabled) {
-    View* view = (View*) nativeView;
-    view->setTransparentPickingEnabled(enabled);
-}
-
-extern "C" JNIEXPORT jboolean JNICALL
-Java_com_google_android_filament_View_nIsTransparentPickingEnabled(JNIEnv*,
-        jclass, jlong nativeView) {
-    View* view = (View*) nativeView;
-    return static_cast<jboolean>(view->isTransparentPickingEnabled());
-}
-
 extern "C" JNIEXPORT void JNICALL
 Java_com_google_android_filament_View_nSetAmbientOcclusion(JNIEnv*, jclass, jlong nativeView, jint ordinal) {
    View* view = (View*) nativeView;
--- a/android/filament-android/src/main/java/com/google/android/filament/Engine.java
+++ b/android/filament-android/src/main/java/com/google/android/filament/Engine.java
@@ -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;
        }

@@ -258,17 +259,6 @@ public class Engine {
            return this;
        }

-        /**
-         * Set a feature flag value. This is the only way to set constant feature flags.
-         * @param name feature name
-         * @param value true to enable, false to disable
-         * @return A reference to this Builder for chaining calls.
-         */
-        public Builder feature(@NonNull String name, boolean value) {
-            nSetBuilderFeature(mNativeBuilder, name, value);
-            return this;
-        }
-
        /**
         * Creates an instance of Engine
         *
@@ -404,7 +394,6 @@ public class Engine {
        /**
         * Set to `true` to forcibly disable parallel shader compilation in the backend.
         * Currently only honored by the GL backend.
-         * @Deprecated use "backend.disable_parallel_shader_compile" feature flag instead
         */
        public boolean disableParallelShaderCompile = false;

@@ -430,12 +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.
@@ -443,13 +432,12 @@ public class Engine {
         */
        public long resourceAllocatorCacheMaxAge = 1;

-        /**
+        /*
         * Disable backend handles use-after-free checks.
-         * @Deprecated use "backend.disable_handle_use_after_free_check" feature flag instead
         */
        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
@@ -471,20 +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
-         * @Deprecated use "backend.opengl.assert_native_window_is_valid" feature flag instead
-         */
-        public boolean assertNativeWindowIsValid = false;
    }

    private Engine(long nativeEngine, Config config) {
@@ -707,11 +687,11 @@ public class Engine {

    /**
     * Returns the maximum number of stereoscopic eyes supported by Filament. The actual number of
-     * eyes rendered is set at Engine creation time with the {@link Config#stereoscopicEyeCount}
-     * setting.
+     * eyes rendered is set at Engine creation time with the {@link
+     * Engine#Config#stereoscopicEyeCount} setting.
     *
     * @return the max number of stereoscopic eyes supported
-     * @see Config#stereoscopicEyeCount
+     * @see Engine#Config#stereoscopicEyeCount
     */
    public long getMaxStereoscopicEyes() {
        return nGetMaxStereoscopicEyes(getNativeObject());
@@ -908,8 +888,7 @@ public class Engine {

    /**
     * Returns whether the object is valid.
-     * @param ma Material
-     * @param mi MaterialInstance to check for validity
+     * @param object Object to check for validity
     * @return returns true if the specified object is valid.
     */
    public boolean isValidMaterialInstance(@NonNull Material ma, MaterialInstance mi) {
@@ -1331,39 +1310,6 @@ public class Engine {
     */
    public static native long getSteadyClockTimeNano();

-
-    /**
-     * Checks if a feature flag exists
-     * @param name name of the feature flag to check
-     * @return true if it exists false otherwise
-     */
-    public boolean hasFeatureFlag(@NonNull String name) {
-        return nHasFeatureFlag(mNativeObject, name);
-    }
-
-    /**
-     * Set the value of a non-constant feature flag.
-     * @param name name of the feature flag to set
-     * @param value value to set
-     * @return true if the value was set, false if the feature flag is constant or doesn't exist.
-     */
-    public boolean setFeatureFlag(@NonNull String name, boolean value) {
-        return nSetFeatureFlag(mNativeObject, name, value);
-    }
-
-    /**
-     * Retrieves the value of any feature flag.
-     * @param name name of the feature flag
-     * @return the value of the flag if it exists
-     * @exception IllegalArgumentException is thrown if the feature flag doesn't exist
-     */
-    public boolean getFeatureFlag(@NonNull String name) {
-        if (!hasFeatureFlag(name)) {
-            throw new IllegalArgumentException("The feature flag \"" + name + "\" doesn't exist");
-        }
-        return nGetFeatureFlag(mNativeObject, name);
-    }
-
    @UsedByReflection("TextureHelper.java")
    public long getNativeObject() {
        if (mNativeObject == 0) {
@@ -1453,9 +1399,6 @@ public class Engine {
    private static native int nGetSupportedFeatureLevel(long nativeEngine);
    private static native int nSetActiveFeatureLevel(long nativeEngine, int ordinal);
    private static native int nGetActiveFeatureLevel(long nativeEngine);
-    private static native boolean nHasFeatureFlag(long nativeEngine, String name);
-    private static native boolean nSetFeatureFlag(long nativeEngine, String name, boolean value);
-    private static native boolean nGetFeatureFlag(long nativeEngine, String name);

    private static native long nCreateBuilder();
    private static native void nDestroyBuilder(long nativeBuilder);
@@ -1463,14 +1406,14 @@ 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);
-    private static native void nSetBuilderFeature(long nativeBuilder, String name, boolean value);
    private static native long nBuilderBuild(long nativeBuilder);
 }
--- a/android/filament-android/src/main/java/com/google/android/filament/View.java
+++ b/android/filament-android/src/main/java/com/google/android/filament/View.java
@@ -745,33 +745,6 @@ public class View {
        nSetFrontFaceWindingInverted(getNativeObject(), inverted);
    }

-    /**
-     * Returns true if transparent picking is enabled.
-     *
-     * @see #setTransparentPickingEnabled
-     */
-    public boolean isTransparentPickingEnabled() {
-        return nIsTransparentPickingEnabled(getNativeObject());
-    }
-
-    /**
-     * Enables or disables transparent picking. Disabled by default.
-     *
-     * When transparent picking is enabled, View::pick() will pick from both
-     * transparent and opaque renderables. When disabled, View::pick() will only
-     * pick from opaque renderables.
-     *
-     * <p>
-     * Transparent picking will create an extra pass for rendering depth
-     * from both transparent and opaque renderables. 
-     * </p>
-     *
-     * @param enabled true enables transparent picking, false disables it.
-     */
-    public void setTransparentPickingEnabled(boolean enabled) {
-        nSetTransparentPickingEnabled(getNativeObject(), enabled);
-    }
-
    /**
     * Sets options relative to dynamic lighting for this view.
     *
@@ -1308,8 +1281,6 @@ public class View {
    private static native boolean nIsPostProcessingEnabled(long nativeView);
    private static native void nSetFrontFaceWindingInverted(long nativeView, boolean inverted);
    private static native boolean nIsFrontFaceWindingInverted(long nativeView);
-    private static native void nSetTransparentPickingEnabled(long nativeView, boolean enabled);
-    private static native boolean nIsTransparentPickingEnabled(long nativeView);
    private static native void nSetAmbientOcclusion(long nativeView, int ordinal);
    private static native int nGetAmbientOcclusion(long nativeView);
    private static native void nSetAmbientOcclusionOptions(long nativeView, float radius, float bias, float power, float resolution, float intensity, float bilateralThreshold, int quality, int lowPassFilter, int upsampling, boolean enabled, boolean bentNormals, float minHorizonAngleRad);
--- a/android/gradle.properties
+++ b/android/gradle.properties
@@ -1,5 +1,5 @@
 GROUP=com.google.android.filament
-VERSION_NAME=1.56.0
+VERSION_NAME=1.54.0

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

--- a/android/gradle/wrapper/gradle-wrapper.properties
+++ b/android/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
 #Wed Nov 17 10:40:18 PST 2021
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.8-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.6-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
--- a/android/samples/sample-gltf-viewer/build.gradle
+++ b/android/samples/sample-gltf-viewer/build.gradle
@@ -6,10 +6,6 @@ plugins {

 project.ext.isSample = true

-kotlin {
-    jvmToolchain(versions.jdk)
-}
-
 filamentTools {
    cmgenArgs = "-q --format=ktx --size=256 --extract-blur=0.1 --deploy=src/main/assets/envs/default_env"
    iblInputFile = project.layout.projectDirectory.file("../../../third_party/environments/lightroom_14b.hdr")
@@ -17,7 +13,7 @@ filamentTools {
 }

 // don't forget to update MainACtivity.kt when/if changing this.
-tasks.register('copyMesh', Copy) {
+task copyMesh(type: Copy) {
    from "../../../third_party/models/BusterDrone"
    into "src/main/assets/models"
 }
--- a/android/samples/sample-hello-triangle/src/main/java/com/google/android/filament/hellotriangle/MainActivity.kt
+++ b/android/samples/sample-hello-triangle/src/main/java/com/google/android/filament/hellotriangle/MainActivity.kt
@@ -112,13 +112,7 @@ class MainActivity : Activity() {
    }

    private fun setupFilament() {
-        val config = Engine.Config()
-        //config.forceGLES2Context = true
-
-        engine = Engine.Builder()
-            .config(config)
-            .featureLevel(Engine.FeatureLevel.FEATURE_LEVEL_0)
-            .build()
+        engine = Engine.Builder().featureLevel(Engine.FeatureLevel.FEATURE_LEVEL_0).build()
        renderer = engine.createRenderer()
        scene = engine.createScene()
        view = engine.createView()
@@ -129,9 +123,7 @@ class MainActivity : Activity() {
        scene.skybox = Skybox.Builder().color(0.035f, 0.035f, 0.035f, 1.0f).build(engine)

        // post-processing is not supported at feature level 0
-        if (engine.activeFeatureLevel == Engine.FeatureLevel.FEATURE_LEVEL_0) {
-            view.isPostProcessingEnabled = false
-        }
+        view.isPostProcessingEnabled = false

        // Tell the view which camera we want to use
        view.camera = camera
--- a/build.sh
+++ b/build.sh
@@ -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: -${OPTARG}" >&2
            echo ""
--- a/build/android/build.sh
+++ b/build/android/build.sh
@@ -60,7 +60,13 @@ if [[ ! -d "${ANDROID_HOME}/ndk/$FILAMENT_NDK_VERSION" ]]; then
    yes | ${ANDROID_HOME}/cmdline-tools/latest/bin/sdkmanager --licenses
    ${ANDROID_HOME}/cmdline-tools/latest/bin/sdkmanager "ndk;$FILAMENT_NDK_VERSION"
 fi
+
+# Only build 1 64 bit target during presubmit to cut down build times during presubmit
+# Continuous builds will build everything
 ANDROID_ABIS=
+if [[ "$TARGET" == "presubmit" ]]; then
+  ANDROID_ABIS="-q arm64-v8a"
+fi

 # Build the Android sample-gltf-viewer APK during release.
 BUILD_SAMPLES=
@@ -68,19 +74,5 @@ if [[ "$TARGET" == "release" ]]; then
    BUILD_SAMPLES="-k sample-gltf-viewer"
 fi

-function build_android() {
-    local ABI=$1
-
-    # Do the following in two steps so that we do not run out of space
-    if [[ -n "${BUILD_DEBUG}" ]]; then
-        FILAMENT_NDK_VERSION=${FILAMENT_NDK_VERSION} ./build.sh -p android -q ${ABI} -c ${BUILD_SAMPLES} ${GENERATE_ARCHIVES} ${BUILD_DEBUG}
-        rm -rf out/cmake-android-debug-*
-    fi
-    if [[ -n "${BUILD_RELEASE}" ]]; then
-        FILAMENT_NDK_VERSION=${FILAMENT_NDK_VERSION} ./build.sh -p android -q ${ABI} -c ${BUILD_SAMPLES} ${GENERATE_ARCHIVES} ${BUILD_RELEASE}
-        rm -rf out/cmake-android-release-*
-    fi
-}
-
 pushd `dirname $0`/../.. > /dev/null
-build_android $2
+FILAMENT_NDK_VERSION=${FILAMENT_NDK_VERSION} ./build.sh -p android $ANDROID_ABIS -c $BUILD_SAMPLES $GENERATE_ARCHIVES $BUILD_DEBUG $BUILD_RELEASE
--- a/build/web/ci-common.sh
+++ b/build/web/ci-common.sh
@@ -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
--- a/build/windows/build-github.bat
+++ b/build/windows/build-github.bat
@@ -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%
--- a/docs/Materials.md.html
+++ b/docs/Materials.md.html
@@ -1308,12 +1308,7 @@ Description
      declare a variable called `eyeDirection` you can access it in the fragment shader using
      `variable_eyeDirection`. In the vertex shader, the interpolant name is simply a member of
      the `MaterialVertexInputs` structure (`material.eyeDirection` in your example). Each
-      interpolant is of type `float4` (`vec4`) in the shaders. By default the precision of the
-      interpolant is `highp` in *both* the vertex and fragment shaders.
-      An alternate syntax can be used to specify both the name and precision of the interpolant.
-      In this case the specified precision is used as-is in both fragment and vertex stages, in
-      particular if `default` is specified the default precision is used is the fragment shader
-      (`mediump`) and in the vertex shader (`highp`).
+      interpolant is of type `float4` (`vec4`) in the shaders.

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ JSON
 material {
@@ -1325,11 +1320,7 @@ material {
        }
    ],
    variables : [
-         eyeDirection,
-         {
-            name : eyeColor,
-            precision : medium
-         }
+         eyeDirection
    ],
    vertexDomain : device,
    depthWrite : false,
--- a/docs/remote/filament.js
+++ b/docs/remote/filament.js
--- a/docs/remote/filament.wasm
+++ b/docs/remote/filament.wasm
--- a/filament/CMakeLists.txt
+++ b/filament/CMakeLists.txt
@@ -61,12 +61,10 @@ set(SRCS
        src/Engine.cpp
        src/Exposure.cpp
        src/Fence.cpp
-        src/FilamentBuilder.cpp
        src/FrameInfo.cpp
        src/FrameSkipper.cpp
        src/Froxelizer.cpp
        src/Frustum.cpp
-        src/HwDescriptorSetLayoutFactory.cpp
        src/HwRenderPrimitiveFactory.cpp
        src/HwVertexBufferInfoFactory.cpp
        src/IndexBuffer.cpp
@@ -77,6 +75,8 @@ 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 +125,6 @@ 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 +148,23 @@ 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 +192,6 @@ 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 +209,7 @@ 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
@@ -308,11 +297,6 @@ if (FILAMENT_ENABLE_MULTIVIEW)
    add_definitions(-DFILAMENT_ENABLE_MULTIVIEW)
 endif()

-# Whether to force the profiling mode.
-if (FILAMENT_FORCE_PROFILING_MODE)
-    add_definitions(-DFILAMENT_FORCE_PROFILING_MODE)
-endif()
-
 # ==================================================================================================
 # Definitions
 # ==================================================================================================
@@ -612,13 +596,6 @@ else()
            -Wover-aligned
            -Werror
    )
-    if (CMAKE_CXX_STANDARD EQUAL 20)
-        # The lambdas for passes in PostProcessManager.cpp capture this
-        # implicitly in a way that's deprecated in c++20, but can't easily be
-        # fixed in a way that's backwards compatible with c++17:
-        # https://www.nextptr.com/tutorial/ta1430524603/capture-this-in-lambda-expression-timeline-of-change
-        list(APPEND FILAMENT_WARNINGS -Wno-deprecated-this-capture)
-    endif()
 endif()

 target_compile_options(${TARGET} PRIVATE
--- a/filament/backend/CMakeLists.txt
+++ b/filament/backend/CMakeLists.txt
@@ -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)
@@ -179,18 +172,11 @@ if (FILAMENT_SUPPORTS_VULKAN)
            src/vulkan/caching/VulkanDescriptorSetManager.h
            src/vulkan/caching/VulkanPipelineLayoutCache.cpp
            src/vulkan/caching/VulkanPipelineLayoutCache.h
-            src/vulkan/memory/ResourceManager.cpp
-            src/vulkan/memory/ResourceManager.h
-            src/vulkan/memory/ResourcePointer.h
-            src/vulkan/memory/Resource.cpp
-            src/vulkan/memory/Resource.h
            src/vulkan/platform/VulkanPlatform.cpp
            src/vulkan/platform/VulkanPlatformSwapChainImpl.cpp
            src/vulkan/platform/VulkanPlatformSwapChainImpl.h
            src/vulkan/spirv/VulkanSpirvUtils.cpp
            src/vulkan/spirv/VulkanSpirvUtils.h
-            src/vulkan/VulkanAsyncHandles.cpp
-            src/vulkan/VulkanAsyncHandles.h
            src/vulkan/VulkanBlitter.cpp
            src/vulkan/VulkanBlitter.h
            src/vulkan/VulkanBuffer.cpp
@@ -221,6 +207,9 @@ if (FILAMENT_SUPPORTS_VULKAN)
            src/vulkan/VulkanSwapChain.h
            src/vulkan/VulkanReadPixels.cpp
            src/vulkan/VulkanReadPixels.h
+            src/vulkan/VulkanResourceAllocator.h
+            src/vulkan/VulkanResources.cpp
+            src/vulkan/VulkanResources.h
            src/vulkan/VulkanTexture.cpp
            src/vulkan/VulkanTexture.h
            src/vulkan/VulkanUtility.cpp
@@ -372,11 +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()
@@ -388,9 +372,6 @@ else()
            -Wover-aligned
            -Werror
    )
-    if (CMAKE_CXX_STANDARD EQUAL 20)
-        list(APPEND FILAMENT_WARNINGS -Wno-deprecated-this-capture)
-    endif()
 endif()

 if (APPLE)
@@ -400,7 +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}>
 )
@@ -410,7 +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}>
 )

@@ -445,7 +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
@@ -517,40 +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()
--- a/filament/backend/include/backend/DescriptorSetOffsetArray.h
+++ b/filament/backend/include/backend/DescriptorSetOffsetArray.h
@@ -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
--- a/filament/backend/include/backend/DriverEnums.h
+++ b/filament/backend/include/backend/DriverEnums.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
@@ -196,71 +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,
-    SAMPLER_EXTERNAL
-};
-
-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
 */
@@ -319,20 +249,9 @@ struct Viewport {
    int32_t right() const noexcept { return left + int32_t(width); }
    //! get the top coordinate in window space of the viewport
    int32_t top() const noexcept { return bottom + int32_t(height); }
-
-    friend bool operator==(Viewport const& lhs, Viewport const& rhs) noexcept {
-        // clang can do this branchless with xor/or
-        return lhs.left == rhs.left && lhs.bottom == rhs.bottom &&
-               lhs.width == rhs.width && lhs.height == rhs.height;
-    }
-
-    friend bool operator!=(Viewport const& lhs, Viewport const& rhs) noexcept {
-        // clang is being dumb and uses branches
-        return bool(((lhs.left ^ rhs.left) | (lhs.bottom ^ rhs.bottom)) |
-                    ((lhs.width ^ rhs.width) | (lhs.height ^ rhs.height)));
-    }
 };

+
 /**
 * Specifies the mapping of the near and far clipping plane to window coordinates.
 */
@@ -351,6 +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);

 /**
@@ -440,18 +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
@@ -777,27 +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,
@@ -989,9 +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;
@@ -1000,9 +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;
@@ -1010,12 +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);
    }
@@ -1183,6 +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.
@@ -1347,8 +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>
--- a/filament/backend/include/backend/Handle.h
+++ b/filament/backend/include/backend/Handle.h
@@ -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

--- a/filament/backend/include/backend/PipelineState.h
+++ b/filament/backend/include/backend/PipelineState.h
@@ -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
--- a/filament/backend/include/backend/Platform.h
+++ b/filament/backend/include/backend/Platform.h
@@ -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;
--- a/filament/backend/include/backend/Program.h
+++ b/filament/backend/include/backend/Program.h
@@ -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.
--- a/filament/backend/include/backend/TargetBufferInfo.h
+++ b/filament/backend/include/backend/TargetBufferInfo.h
@@ -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 }} {
    }
 };

--- a/filament/backend/include/backend/platforms/PlatformEGLAndroid.h
+++ b/filament/backend/include/backend/platforms/PlatformEGLAndroid.h
@@ -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
--- a/filament/backend/include/backend/platforms/PlatformOSMesa.h
+++ b/filament/backend/include/backend/platforms/PlatformOSMesa.h
@@ -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
--- a/filament/backend/include/backend/platforms/VulkanPlatform.h
+++ b/filament/backend/include/backend/platforms/VulkanPlatform.h
@@ -88,7 +88,6 @@ public:
        VkFormat colorFormat = VK_FORMAT_UNDEFINED;
        VkFormat depthFormat = VK_FORMAT_UNDEFINED;
        VkExtent2D extent = {0, 0};
-        bool isProtected = false;
    };

    struct ImageSyncData {
@@ -200,13 +199,6 @@ public:
     */
    virtual bool hasResized(SwapChainPtr handle);

-    /**
-     * Check if the surface is protected.
-     * @param handle             The handle returned by createSwapChain()
-     * @return                   Whether the swapchain is protected
-     */
-    virtual bool isProtected(SwapChainPtr handle);
-
    /**
     * Carry out a recreation of the swapchain.
     * @param handle             The handle returned by createSwapChain()
@@ -275,23 +267,6 @@ public:
     */
    VkQueue getGraphicsQueue() const noexcept;

-    /**
-    * @return The family index of the protected graphics queue selected for the
-    *          Vulkan backend.
-    */
-    uint32_t getProtectedGraphicsQueueFamilyIndex() const noexcept;
-
-    /**
-     * @return The index of the protected graphics queue (if there are multiple
-     *          graphics queues) selected for the Vulkan backend.
-     */
-    uint32_t getProtectedGraphicsQueueIndex() const noexcept;
-
-    /**
-     * @return The protected queue that was selected for the Vulkan backend.
-     */
-    VkQueue getProtectedGraphicsQueue() const noexcept;
-
 private:
    static ExtensionSet getSwapchainInstanceExtensions();

--- a/filament/backend/include/private/backend/Driver.h
+++ b/filament/backend/include/private/backend/Driver.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>
--- a/filament/backend/include/private/backend/DriverAPI.inc
+++ b/filament/backend/include/private/backend/DriverAPI.inc
@@ -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,
@@ -163,10 +162,6 @@ DECL_DRIVER_API_0(finish)
 // reset state tracking, if the driver does any state tracking (e.g. GL)
 DECL_DRIVER_API_0(resetState)

-DECL_DRIVER_API_N(setDebugTag,
-        backend::HandleBase::HandleId, handleId,
-        utils::CString, tag)
-
 /*
 * Creating driver objects
 * -----------------------
@@ -201,33 +196,20 @@ 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 +221,9 @@ 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 +257,25 @@ 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 +342,15 @@ 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 +365,10 @@ 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,
@@ -451,16 +415,37 @@ 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,
        backend::PushConstantVariant, value)

 DECL_DRIVER_API_N(insertEventMarker,
-        const char*, string)
+        const char*, string,
+        uint32_t, len = 0)

 DECL_DRIVER_API_N(pushGroupMarker,
-        const char*, string)
+        const char*, string,
+        uint32_t, len = 0)

 DECL_DRIVER_API_0(popGroupMarker)

--- a/filament/backend/include/private/backend/DriverApi.h
+++ b/filament/backend/include/private/backend/DriverApi.h
@@ -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
--- a/filament/backend/include/private/backend/HandleAllocator.h
+++ b/filament/backend/include/private/backend/HandleAllocator.h
@@ -20,12 +20,11 @@
 #include <backend/Handle.h>

 #include <utils/Allocator.h>
-#include <utils/CString.h>
 #include <utils/Log.h>
-#include <utils/Panic.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
 #include <utils/ostream.h>
+#include <utils/Panic.h>

 #include <tsl/robin_map.h>

@@ -38,7 +37,7 @@
 #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

@@ -169,31 +168,13 @@ 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);
                uint8_t const expectedAge = pNode[-1].age;
-                // getHandleTag() is only called if the check fails.
-                FILAMENT_CHECK_POSTCONDITION(expectedAge == age)
-                        << "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();
-                }
+                FILAMENT_CHECK_POSTCONDITION(expectedAge == age) <<
+                        "use-after-free of Handle with id=" << handle.getId();
            }
        }

@@ -202,18 +183,14 @@ 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>
@@ -224,29 +201,6 @@ public:
        return handle_cast<Dp>(const_cast<Handle<B>&>(handle));
    }

-    void associateTagToHandle(HandleBase::HandleId id, utils::CString&& tag) noexcept {
-        // TODO: for now, only pool handles check for use-after-free, so we only keep tags for
-        // those
-        if (isPoolHandle(id)) {
-            // Truncate the age to get the debug tag
-            uint32_t const key = id & ~(HANDLE_DEBUG_TAG_MASK ^ HANDLE_AGE_MASK);
-            // This line is the costly part. In the future, we could potentially use a custom
-            // allocator.
-            mDebugTags[key] = std::move(tag);
-        }
-    }
-
-    utils::CString getHandleTag(HandleBase::HandleId id) const noexcept {
-        if (!isPoolHandle(id)) {
-            return "(no tag)";
-        }
-        uint32_t const key = id & ~(HANDLE_DEBUG_TAG_MASK ^ HANDLE_AGE_MASK);
-        if (auto pos = mDebugTags.find(key); pos != mDebugTags.end()) {
-            return pos->second;
-        }
-        return "(no tag)";
-    }
-
 private:

    template<typename D>
@@ -364,24 +318,12 @@ private:
        }
    }

-    // number if bits allotted to the handle's age (currently 4 max)
-    static constexpr uint32_t HANDLE_AGE_BIT_COUNT = 4;
-    // number if bits allotted to the handle's debug tag (HANDLE_AGE_BIT_COUNT max)
-    static constexpr uint32_t HANDLE_DEBUG_TAG_BIT_COUNT = 2;
-    // bit shift for both the age and debug tag
-    static constexpr uint32_t HANDLE_AGE_SHIFT = 27;
-    // mask for the heap (vs pool) flag
-    static constexpr uint32_t HANDLE_HEAP_FLAG = 0x80000000u;
-    // mask for the age
-    static constexpr uint32_t HANDLE_AGE_MASK =
-            ((1 << HANDLE_AGE_BIT_COUNT) - 1) << HANDLE_AGE_SHIFT;
-    // mask for the debug tag
-    static constexpr uint32_t HANDLE_DEBUG_TAG_MASK =
-            ((1 << HANDLE_DEBUG_TAG_BIT_COUNT) - 1) << HANDLE_AGE_SHIFT;
-    // mask for the index
-    static constexpr uint32_t HANDLE_INDEX_MASK = 0x07FFFFFFu;
-
-    static_assert(HANDLE_DEBUG_TAG_BIT_COUNT <= HANDLE_AGE_BIT_COUNT);
+    // we handle a 4 bits age per address
+    static constexpr uint32_t HANDLE_HEAP_FLAG      = 0x80000000u;      // pool vs heap handle
+    static constexpr uint32_t HANDLE_AGE_MASK       = 0x78000000u;      // handle's age
+    static constexpr uint32_t HANDLE_INDEX_MASK     = 0x07FFFFFFu;      // handle index
+    static constexpr uint32_t HANDLE_TAG_MASK       = HANDLE_AGE_MASK;
+    static constexpr uint32_t HANDLE_AGE_SHIFT      = 27;

    static bool isPoolHandle(HandleBase::HandleId id) noexcept {
        return (id & HANDLE_HEAP_FLAG) == 0u;
@@ -396,7 +338,7 @@ private:
        // a non-pool handle.
        if (UTILS_LIKELY(isPoolHandle(id))) {
            char* const base = (char*)mHandleArena.getArea().begin();
-            uint32_t const tag = id & HANDLE_AGE_MASK;
+            uint32_t const tag = id & HANDLE_TAG_MASK;
            size_t const offset = (id & HANDLE_INDEX_MASK) * Allocator::getAlignment();
            return { static_cast<void*>(base + offset), tag };
        }
@@ -411,7 +353,7 @@ private:
        size_t const offset = (char*)p - base;
        assert_invariant((offset % Allocator::getAlignment()) == 0);
        auto id = HandleBase::HandleId(offset / Allocator::getAlignment());
-        id |= tag & HANDLE_AGE_MASK;
+        id |= tag & HANDLE_TAG_MASK;
        assert_invariant((id & HANDLE_HEAP_FLAG) == 0);
        return id;
    }
@@ -421,7 +363,6 @@ private:
    // Below is only used when running out of space in the HandleArena
    mutable utils::Mutex mLock;
    tsl::robin_map<HandleBase::HandleId, void*> mOverflowMap;
-    tsl::robin_map<HandleBase::HandleId, utils::CString> mDebugTags;
    HandleBase::HandleId mId = 0;
    bool mUseAfterFreeCheckDisabled = false;
 };
--- a/filament/backend/src/CircularBuffer.cpp
+++ b/filament/backend/src/CircularBuffer.cpp
@@ -24,7 +24,7 @@
 #include <utils/debug.h>
 #include <utils/ostream.h>

-#if !defined(WIN32) && !defined(__EMSCRIPTEN__)
+#if !defined(WIN32) && !defined(__EMSCRIPTEN__) && !defined(IOS)
 #    include <sys/mman.h>
 #    include <unistd.h>
 #    define HAS_MMAP 1
--- a/filament/backend/src/CommandStream.cpp
+++ b/filament/backend/src/CommandStream.cpp
@@ -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);
--- a/filament/backend/src/DriverBase.h
+++ b/filament/backend/src/DriverBase.h
@@ -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;
 };
--- a/filament/backend/src/HandleAllocator.cpp
+++ b/filament/backend/src/HandleAllocator.cpp
@@ -80,9 +80,6 @@ HandleAllocator<P0, P1, P2>::HandleAllocator(const char* name, size_t size,
        bool disableUseAfterFreeCheck) noexcept
    : mHandleArena(name, size, disableUseAfterFreeCheck),
      mUseAfterFreeCheckDisabled(disableUseAfterFreeCheck) {
-    // Reserve initial space for debug tags. This prevents excessive calls to malloc when the first
-    // few tags are set.
-    mDebugTags.reserve(512);
 }

 template <size_t P0, size_t P1, size_t P2>
--- a/filament/backend/src/PlatformFactory.cpp
+++ b/filament/backend/src/PlatformFactory.cpp
@@ -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
--- a/filament/backend/src/Program.cpp
+++ b/filament/backend/src/Program.cpp
@@ -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;
 }
--- a/filament/backend/src/SystraceProfile.h
+++ b/filament/backend/src/SystraceProfile.h
@@ -1,28 +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_SYSTRACEPROFILE_H
-#define TNT_FILAMENT_BACKEND_SYSTRACEPROFILE_H
-
-#include <utils/Systrace.h>
-
-#define PROFILE_SCOPE(marker)       SYSTRACE_NAME(marker)
-
-#define PROFILE_NAME_BEGINFRAME    "backend::beginFrame"
-#define PROFILE_NAME_ENDFRAME      "backend::endFrame"
-
-#endif // TNT_FILAMENT_BACKEND_SYSTRACEPROFILE_H
-
--- a/filament/backend/src/metal/MetalBuffer.h
+++ b/filament/backend/src/metal/MetalBuffer.h
@@ -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;
        }
    }

@@ -163,8 +160,6 @@ public:
         size_t size, bool forceGpuBuffer = false);
    ~MetalBuffer();

-    [[nodiscard]] bool wasAllocationSuccessful() const noexcept { return mBuffer || mCpuBuffer; }
-
    MetalBuffer(const MetalBuffer& rhs) = delete;
    MetalBuffer& operator=(const MetalBuffer& rhs) = delete;

@@ -174,10 +169,8 @@ 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 +180,7 @@ public:
     * is no device allocation.
     *
     */
-    id<MTLBuffer> getGpuBufferForDraw() noexcept;
+    id<MTLBuffer> getGpuBufferForDraw(id<MTLCommandBuffer> cmdBuffer) noexcept;

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

@@ -216,10 +209,8 @@ 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;
--- a/filament/backend/src/metal/MetalBuffer.mm
+++ b/filament/backend/src/metal/MetalBuffer.mm
@@ -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.
    {
@@ -56,8 +53,8 @@ MetalBuffer::MetalBuffer(MetalContext& context, BufferObjectBinding bindingType,
        mBuffer = { [context.device newBufferWithLength:size options:MTLResourceStorageModePrivate],
            TrackedMetalBuffer::Type::GENERIC };
    }
-    // mBuffer might fail to be allocated. Clients can check for this by calling
-    // wasAllocationSuccessful().
+    FILAMENT_CHECK_POSTCONDITION(mBuffer)
+            << "Could not allocate Metal buffer of size " << size << ".";
 }

 MetalBuffer::~MetalBuffer() {
@@ -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);
--- a/filament/backend/src/metal/MetalContext.h
+++ b/filament/backend/src/metal/MetalContext.h
@@ -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;

@@ -158,10 +108,11 @@ 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;
-    ScissorRectStateTracker scissorRectState;
    Handle<HwRenderPrimitive> currentRenderPrimitive;

    // State caches.
@@ -174,17 +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;

@@ -197,7 +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;

--- a/filament/backend/src/metal/MetalContext.mm
+++ b/filament/backend/src/metal/MetalContext.mm
@@ -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);
--- a/filament/backend/src/metal/MetalDriver.h
+++ b/filament/backend/src/metal/MetalDriver.h
@@ -32,7 +32,6 @@
 #include <functional>
 #include <mutex>
 #include <vector>
-#include <deque>

 namespace filament {
 namespace backend {
@@ -58,11 +57,11 @@ class MetalDriver final : public DriverBase {

 public:
    static Driver* create(MetalPlatform* platform, const Platform::DriverConfig& driverConfig);
+    void runAtNextTick(const std::function<void()>& fn) noexcept;

 private:

    friend class MetalSwapChain;
-    friend struct MetalDescriptorSet;

    MetalPlatform& mPlatform;
    MetalContext* mContext;
@@ -74,23 +73,10 @@ private:

    /*
     * Tasks run regularly on the driver thread.
-     * Not thread-safe; tasks are run from the driver thead and must be enqueued from the driver
-     * thread.
     */
-    void runAtNextTick(const std::function<void()>& fn) noexcept;
    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;
+    std::mutex mTickOpsLock;

    /*
     * Driver interface
@@ -151,6 +137,7 @@ 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);

--- a/filament/backend/src/metal/MetalDriver.mm
+++ b/filament/backend/src/metal/MetalDriver.mm
--- a/filament/backend/src/metal/MetalEnums.h
+++ b/filament/backend/src/metal/MetalEnums.h
@@ -71,8 +71,7 @@ constexpr inline MTLIndexType getIndexType(size_t elementSize) noexcept {
    } else if (elementSize == 4) {
        return MTLIndexTypeUInt32;
    }
-    assert_invariant(false);
-    return MTLIndexTypeUInt16;
+    FILAMENT_CHECK_POSTCONDITION(false) << "Index element size not supported.";
 }

 constexpr inline MTLVertexFormat getMetalFormat(ElementType type, bool normalized) noexcept {
--- a/filament/backend/src/metal/MetalExternalImage.h
+++ b/filament/backend/src/metal/MetalExternalImage.h
@@ -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
--- a/filament/backend/src/metal/MetalExternalImage.mm
+++ b/filament/backend/src/metal/MetalExternalImage.mm
@@ -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
--- a/filament/backend/src/metal/MetalHandles.h
+++ b/filament/backend/src/metal/MetalHandles.h
@@ -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;
 };
@@ -202,11 +200,12 @@ public:
    MetalProgram(MetalContext& context, Program&& program) noexcept;

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

 private:
    void initialize();

+    Program::SamplerGroupInfo samplerGroupInfo;
    MetalContext& mContext;
    MetalShaderCompiler::MetalFunctionBundle mFunctionBundle;
    MetalShaderCompiler::program_token_t mToken;
@@ -228,42 +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
@@ -272,6 +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;
@@ -282,12 +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 {
@@ -438,67 +541,12 @@ struct MetalTimerQuery : public HwTimerQuery {

    struct Status {
        std::atomic<bool> available {false};
-        std::atomic<uint64_t> elapsed {0};   // only valid if available is true
+        uint64_t elapsed {0};   // only valid if available is true
    };

    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

--- a/filament/backend/src/metal/MetalHandles.mm
+++ b/filament/backend/src/metal/MetalHandles.mm
@@ -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(
@@ -254,6 +257,10 @@ void MetalSwapChain::present() {
    }
 }

+#ifndef FILAMENT_RELEASE_PRESENT_DRAWABLE_MAIN_THREAD
+#define FILAMENT_RELEASE_PRESENT_DRAWABLE_MAIN_THREAD 1
+#endif
+
 class PresentDrawableData {
 public:
    PresentDrawableData() = delete;
@@ -261,10 +268,10 @@ 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 +279,20 @@ 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);
-            });
-        }
+#if FILAMENT_RELEASE_PRESENT_DRAWABLE_MAIN_THREAD == 1
+        // 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); });
+#else
+        that->mDriver->runAtNextTick([that]() { cleanupAndDestroy(that); });
+#endif
    }

 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 +307,6 @@ 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 +323,8 @@ 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 +339,14 @@ 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 +381,12 @@ 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 +482,11 @@ 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);
 }
@@ -495,10 +496,6 @@ const MetalShaderCompiler::MetalFunctionBundle& MetalProgram::getFunctions() {
    return mFunctionBundle;
 }

-const MetalShaderCompiler::MetalFunctionBundle& MetalProgram::getFunctionsIfPresent() const {
-    return mFunctionBundle;
-}
-
 void MetalProgram::initialize() {
    if (!mToken) {
        return;
@@ -509,9 +506,10 @@ 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)
@@ -597,28 +595,16 @@ 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.
@@ -632,30 +618,44 @@ 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) {
@@ -774,12 +774,15 @@ 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,
@@ -903,6 +906,98 @@ 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) :
@@ -1248,195 +1343,5 @@ 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:
-            case DescriptorType::SAMPLER_EXTERNAL: {
-                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:
-            case DescriptorType::SAMPLER_EXTERNAL: {
-                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
--- a/filament/backend/src/metal/MetalShaderCompiler.h
+++ b/filament/backend/src/metal/MetalShaderCompiler.h
@@ -83,10 +83,6 @@ public:
            return std::get<Compute>(mPrograms);
        }

-        bool isRaster() const { return std::holds_alternative<Raster>(mPrograms); }
-
-        bool isCompute() const { return std::holds_alternative<Compute>(mPrograms); }
-
        static MetalFunctionBundle none() {
            return MetalFunctionBundle(None{});
        }
--- a/filament/backend/src/metal/MetalState.h
+++ b/filament/backend/src/metal/MetalState.h
@@ -28,35 +28,37 @@

 #include <memory>
 #include <tsl/robin_map.h>
-
 #include <utils/Hash.h>
-#include <utils/Invocable.h>

 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.
@@ -69,11 +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);
@@ -162,8 +163,6 @@ template<typename StateType,
         typename HashFn = utils::hash::MurmurHashFn<StateType>>
 class StateCache {

-    using MapType = tsl::robin_map<StateType, MetalType, HashFn>;
-
 public:

    StateCache() = default;
@@ -173,18 +172,6 @@ public:

    void setDevice(id<MTLDevice> device) noexcept { mDevice = device; }

-    void removeIf(utils::Invocable<bool(const StateType&)> fn) noexcept {
-        typename MapType::const_iterator it = mStateCache.begin();
-        while (it != mStateCache.end()) {
-            const auto& [key, _] = *it;
-            if (UTILS_UNLIKELY(fn(key))) {
-                it = mStateCache.erase(it);
-            } else {
-                ++it;
-            }
-        }
-    }
-
    MetalType getOrCreateState(const StateType& state) noexcept {
        assert_invariant(mDevice);

@@ -212,7 +199,7 @@ private:
    StateCreator creator;
    id<MTLDevice> mDevice = nil;

-    MapType mStateCache;
+    tsl::robin_map<StateType, MetalType, HashFn> mStateCache;

 };

@@ -220,8 +207,9 @@ private:
 // Different kinds of state, like pipeline state, uniform buffer state, etc., are passed to the
 // current Metal command encoder and persist throughout the lifetime of the encoder (a frame).
 // StateTracker is used to prevent calling redundant state change methods.
-template <typename StateType, typename StateEqual = std::equal_to<StateType>>
+template<typename StateType>
 class StateTracker {
+
 public:

    // Call to force the state to dirty at the beginning of each frame, as all state must be
@@ -229,7 +217,7 @@ public:
    void invalidate() noexcept { mStateDirty = true; }

    void updateState(const StateType& newState) noexcept {
-        if (!StateEqual()(mCurrentState, newState)) {
+        if (mCurrentState != newState) {
            mCurrentState = newState;
            mStateDirty = true;
        }
@@ -250,6 +238,7 @@ private:

    bool mStateDirty = true;
    StateType mCurrentState = {};
+
 };

 // Pipeline state
@@ -357,16 +346,6 @@ using DepthStencilStateTracker = StateTracker<DepthStencilState>;
 using DepthStencilStateCache = StateCache<DepthStencilState, id<MTLDepthStencilState>,
        DepthStateCreator>;

-struct MtlScissorRectEqual {
-    bool operator()(const MTLScissorRect& lhs, const MTLScissorRect& rhs) const {
-        return lhs.height == rhs.height &&
-            lhs.width == rhs.width &&
-            lhs.x == rhs.x &&
-            lhs.y == rhs.y;
-    }
-};
-using ScissorRectStateTracker = StateTracker<MTLScissorRect, MtlScissorRectEqual>;
-
 // Uniform buffers

 class MetalBufferObject;
@@ -408,17 +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 {
@@ -440,30 +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

--- a/filament/backend/src/metal/MetalState.mm
+++ b/filament/backend/src/metal/MetalState.mm
@@ -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
--- a/filament/backend/src/noop/NoopDriver.cpp
+++ b/filament/backend/src/noop/NoopDriver.cpp
@@ -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) {
@@ -298,14 +303,27 @@ 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) {
 }

-void NoopDriver::insertEventMarker(char const* string) {
+void NoopDriver::insertEventMarker(char const* string, uint32_t len) {
 }

-void NoopDriver::pushGroupMarker(char const* string) {
+void NoopDriver::pushGroupMarker(char const* string,  uint32_t len) {
 }

 void NoopDriver::popGroupMarker(int) {
@@ -374,28 +392,4 @@ 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) {
-}
-
 } // namespace filament
--- a/filament/backend/src/opengl/BindingMap.h
+++ b/filament/backend/src/opengl/BindingMap.h
@@ -1,91 +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 ||
-                                   entry.type == DescriptorType::SAMPLER_EXTERNAL };
-        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
--- a/filament/backend/src/opengl/GLDescriptorSet.cpp
+++ b/filament/backend/src/opengl/GLDescriptorSet.cpp
@@ -1,364 +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:
-            case DescriptorType::SAMPLER_EXTERNAL:
-                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
--- a/filament/backend/src/opengl/GLDescriptorSet.h
+++ b/filament/backend/src/opengl/GLDescriptorSet.h
@@ -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
--- a/filament/backend/src/opengl/GLDescriptorSetLayout.h
+++ b/filament/backend/src/opengl/GLDescriptorSetLayout.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
--- a/filament/backend/src/opengl/GLTexture.h
+++ b/filament/backend/src/opengl/GLTexture.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;
 };

--- a/filament/backend/src/opengl/OpenGLContext.cpp
+++ b/filament/backend/src/opengl/OpenGLContext.cpp
@@ -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;
        }
@@ -614,7 +606,7 @@ FeatureLevel OpenGLContext::resolveFeatureLevel(GLint major, GLint minor,
                featureLevel = FeatureLevel::FEATURE_LEVEL_2;
                if (gets.max_texture_image_units >= MAX_FRAGMENT_SAMPLER_COUNT &&
                    gets.max_combined_texture_image_units >=
-                            (MAX_FRAGMENT_SAMPLER_COUNT + MAX_VERTEX_SAMPLER_COUNT)) {
+                    (MAX_FRAGMENT_SAMPLER_COUNT + MAX_VERTEX_SAMPLER_COUNT)) {
                    featureLevel = FeatureLevel::FEATURE_LEVEL_3;
                }
            }
@@ -623,13 +615,15 @@ FeatureLevel OpenGLContext::resolveFeatureLevel(GLint major, GLint minor,
 #   ifndef IOS // IOS is guaranteed to have ES3.x
    else if (UTILS_UNLIKELY(major == 2)) {
        // Runtime OpenGL version is ES 2.x
-        // note: mandatory extensions (all supported by Mali-400 and Adreno 304)
-        //      OES_depth_texture
-        //      OES_depth24
-        //      OES_packed_depth_stencil
-        //      OES_rgb8_rgba8
-        //      OES_standard_derivatives
-        //      OES_texture_npot
+#       if defined(BACKEND_OPENGL_LEVEL_GLES30)
+        // mandatory extensions (all supported by Mali-400 and Adreno 304)
+        assert_invariant(exts.OES_depth_texture);
+        assert_invariant(exts.OES_depth24);
+        assert_invariant(exts.OES_packed_depth_stencil);
+        assert_invariant(exts.OES_rgb8_rgba8);
+        assert_invariant(exts.OES_standard_derivatives);
+        assert_invariant(exts.OES_texture_npot);
+#       endif
        featureLevel = FeatureLevel::FEATURE_LEVEL_0;
    }
 #   endif // IOS
@@ -935,19 +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;
        }
    }

@@ -956,13 +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;
+                }
            }
        }
    }
--- a/filament/backend/src/opengl/OpenGLContext.h
+++ b/filament/backend/src/opengl/OpenGLContext.h
@@ -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",
                    ""},
--- a/filament/backend/src/opengl/OpenGLDriver.cpp
+++ b/filament/backend/src/opengl/OpenGLDriver.cpp
--- a/filament/backend/src/opengl/OpenGLDriver.h
+++ b/filament/backend/src/opengl/OpenGLDriver.h
@@ -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;
 };

 // ------------------------------------------------------------------------------------------------
--- a/filament/backend/src/opengl/OpenGLProgram.cpp
+++ b/filament/backend/src/opengl/OpenGLProgram.cpp
@@ -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));
@@ -124,87 +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:
-                case DescriptorType::SAMPLER_EXTERNAL: {
-                    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.
@@ -216,11 +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;

@@ -237,8 +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);

@@ -255,9 +277,7 @@ void OpenGLProgram::updateUniforms(
    for (size_t i = 0, c = records.uniforms.size(); i < c; i++) {
        Program::Uniform const& u = records.uniforms[i];
        GLint const loc = records.locations[i];
-        // mRec709Location is special, it is handled by setRec709ColorSpace() and the corresponding
-        // entry in `buffer` is typically not initialized, so we skip it.
-        if (loc < 0 || loc == mRec709Location) {
+        if (loc < 0) {
            continue;
        }
        // u.offset is in 'uint32_t' units
--- a/filament/backend/src/opengl/OpenGLProgram.h
+++ b/filament/backend/src/opengl/OpenGLProgram.h
@@ -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

--- a/filament/backend/src/opengl/platforms/PlatformEGL.cpp
+++ b/filament/backend/src/opengl/platforms/PlatformEGL.cpp
@@ -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;
--- a/filament/backend/src/opengl/platforms/PlatformEGLAndroid.cpp
+++ b/filament/backend/src/opengl/platforms/PlatformEGLAndroid.cpp
@@ -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;
 }

--- a/filament/backend/src/opengl/platforms/PlatformOSMesa.cpp
+++ b/filament/backend/src/opengl/platforms/PlatformOSMesa.cpp
@@ -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
--- a/filament/backend/src/opengl/platforms/PlatformWGL.cpp
+++ b/filament/backend/src/opengl/platforms/PlatformWGL.cpp
@@ -19,8 +19,8 @@
 #include <Wingdi.h>

 #ifdef _MSC_VER
-    // this variable is checked in BlueGL.h (included from "gl_headers.h" right after this),
-    // and prevents duplicate definition of OpenGL apis when building this file.
+    // this variable is checked in BlueGL.h (included from "gl_headers.h" right after this), 
+    // and prevents duplicate definition of OpenGL apis when building this file. 
    // However, GL_GLEXT_PROTOTYPES need to be defined in BlueGL.h when included from other files.
    #define FILAMENT_PLATFORM_WGL
 #endif
@@ -37,8 +37,9 @@

 namespace {

-void reportWindowsError(DWORD dwError) {
+void reportLastWindowsError() {
    LPSTR lpMessageBuffer = nullptr;
+    DWORD dwError = GetLastError();

    if (dwError == 0) {
        return;
@@ -79,7 +80,6 @@ Driver* PlatformWGL::createDriver(void* const sharedGLContext,
        const Platform::DriverConfig& driverConfig) noexcept {
    int result = 0;
    int pixelFormat = 0;
-    DWORD dwError = 0;

    mPfd = {
        sizeof(PIXELFORMATDESCRIPTOR),
@@ -105,7 +105,6 @@ Driver* PlatformWGL::createDriver(void* const sharedGLContext,
    mHWnd = CreateWindowA("STATIC", "dummy", 0, 0, 0, 1, 1, NULL, NULL, NULL, NULL);
    HDC whdc = mWhdc = GetDC(mHWnd);
    if (whdc == NULL) {
-        dwError = GetLastError();
        utils::slog.e << "CreateWindowA() failed" << utils::io::endl;
        goto error;
    }
@@ -116,7 +115,6 @@ Driver* PlatformWGL::createDriver(void* const sharedGLContext,
    // We need a tmp context to retrieve and call wglCreateContextAttribsARB.
    tempContext = wglCreateContext(whdc);
    if (!wglMakeCurrent(whdc, tempContext)) {
-        dwError = GetLastError();
        utils::slog.e << "wglMakeCurrent() failed, whdc=" << whdc << ", tempContext=" <<
                tempContext << utils::io::endl;
        goto error;
@@ -138,7 +136,6 @@ Driver* PlatformWGL::createDriver(void* const sharedGLContext,
        if (mContext) {
            break;
        }
-        dwError = GetLastError();
    }

    if (!mContext) {
@@ -151,7 +148,6 @@ Driver* PlatformWGL::createDriver(void* const sharedGLContext,
    tempContext = NULL;

    if (!wglMakeCurrent(whdc, mContext)) {
-        dwError = GetLastError();
        utils::slog.e << "wglMakeCurrent() failed, whdc=" << whdc << ", mContext=" <<
                mContext << utils::io::endl;
        goto error;
@@ -166,7 +162,7 @@ error:
    if (tempContext) {
        wglDeleteContext(tempContext);
    }
-    reportWindowsError(dwError);
+    reportLastWindowsError();
    terminate();
    return NULL;
 }
@@ -209,11 +205,9 @@ Platform::SwapChain* PlatformWGL::createSwapChain(void* nativeWindow, uint64_t f
    // on Windows, the nativeWindow maps to a HWND
    swapChain->hWnd = (HWND) nativeWindow;
    swapChain->hDc = GetDC(swapChain->hWnd);
-    if (!swapChain->hDc) {
-        DWORD dwError = GetLastError();
-        ASSERT_POSTCONDITION_NON_FATAL(swapChain->hDc,
-           "Unable to create the SwapChain (nativeWindow = %p)", nativeWindow);
-        reportWindowsError(dwError);
+    if (!ASSERT_POSTCONDITION_NON_FATAL(swapChain->hDc,
+            "Unable to create the SwapChain (nativeWindow = %p)", nativeWindow)) {
+        reportLastWindowsError();
    }

 	// We have to match pixel formats across the HDC and HGLRC (mContext)
@@ -270,10 +264,8 @@ bool PlatformWGL::makeCurrent(ContextType type, SwapChain* drawSwapChain,
    HDC hdc = wglSwapChain->hDc;
    if (hdc != NULL) {
        BOOL success = wglMakeCurrent(hdc, mContext);
-        if (!success) {
-            DWORD dwError = GetLastError();
-            ASSERT_POSTCONDITION_NON_FATAL(success, "wglMakeCurrent() failed. hdc = %p", hdc);
-            reportWindowsError(dwError);
+        if (!ASSERT_POSTCONDITION_NON_FATAL(success, "wglMakeCurrent() failed. hdc = %p", hdc)) {
+            reportLastWindowsError();
            wglMakeCurrent(0, NULL);
        }
    }
--- a/filament/backend/src/ostream.cpp
+++ b/filament/backend/src/ostream.cpp
@@ -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 << "}";
 }
--- a/filament/backend/src/vulkan/VulkanAsyncHandles.cpp
+++ b/filament/backend/src/vulkan/VulkanAsyncHandles.cpp
@@ -1,43 +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 "VulkanAsyncHandles.h"
-
-namespace filament::backend {
-
-VulkanTimerQuery::VulkanTimerQuery(std::tuple<uint32_t, uint32_t> indices)
-    : mStartingQueryIndex(std::get<0>(indices)),
-      mStoppingQueryIndex(std::get<1>(indices)) {}
-
-void VulkanTimerQuery::setFence(std::shared_ptr<VulkanCmdFence> fence) noexcept {
-    std::unique_lock<utils::Mutex> lock(mFenceMutex);
-    mFence = fence;
-}
-
-bool VulkanTimerQuery::isCompleted() noexcept {
-    std::unique_lock<utils::Mutex> lock(mFenceMutex);
-    // QueryValue is a synchronous call and might occur before beginTimerQuery has written anything
-    // into the command buffer, which is an error according to the validation layer that ships in
-    // the Android NDK.  Even when AVAILABILITY_BIT is set, validation seems to require that the
-    // 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;
-}
-
-VulkanTimerQuery::~VulkanTimerQuery() = default;
-
-} // namespace filament::backend
--- a/filament/backend/src/vulkan/VulkanAsyncHandles.h
+++ b/filament/backend/src/vulkan/VulkanAsyncHandles.h
@@ -1,81 +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_VULKANASYNCHANDLES_H
-#define TNT_FILAMENT_BACKEND_VULKANASYNCHANDLES_H
-
-#include <bluevk/BlueVK.h>
-
-#include "DriverBase.h"
-
-#include "vulkan/memory/Resource.h"
-
-#include <utils/Mutex.h>
-#include <utils/Condition.h>
-
-namespace filament::backend {
-
-// Wrapper to enable use of shared_ptr for implementing shared ownership of low-level Vulkan fences.
-struct VulkanCmdFence {
-    VulkanCmdFence(VkResult initialStatus) {
-        // Internally we use the VK_INCOMPLETE status to mean "not yet submitted". When this fence
-        // gets submitted, its status changes to VK_NOT_READY. Finally, when the GPU actually
-        // finishes executing the command buffer, the status changes to VK_SUCCESS.
-        status.store(initialStatus);
-    }
-
-    ~VulkanCmdFence() = default;
-
-    void setStatus(VkResult value) { status.store(value); }
-
-    VkResult getStatus() { return status.load(std::memory_order_acquire); }
-
-private:
-    std::atomic<VkResult> status;
-};
-
-struct VulkanFence : public HwFence, fvkmemory::ThreadSafeResource {
-    VulkanFence() {}
-    std::shared_ptr<VulkanCmdFence> fence;
-};
-
-struct VulkanTimerQuery : public HwTimerQuery, fvkmemory::ThreadSafeResource {
-    explicit VulkanTimerQuery(std::tuple<uint32_t, uint32_t> indices);
-    ~VulkanTimerQuery();
-
-    void setFence(std::shared_ptr<VulkanCmdFence> fence) noexcept;
-
-    bool isCompleted() noexcept;
-
-    uint32_t getStartingQueryIndex() const {
-        return mStartingQueryIndex;
-    }
-
-    uint32_t getStoppingQueryIndex() const {
-        return mStoppingQueryIndex;
-    }
-
-private:
-    uint32_t mStartingQueryIndex;
-    uint32_t mStoppingQueryIndex;
-
-    std::shared_ptr<VulkanCmdFence> mFence;
-    utils::Mutex mFenceMutex;
-};
-
-} // namespace filament::backend
-
-#endif // TNT_FILAMENT_BACKEND_VULKANHASYNCANDLES_H
--- a/filament/backend/src/vulkan/VulkanBlitter.cpp
+++ b/filament/backend/src/vulkan/VulkanBlitter.cpp
@@ -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 {
@@ -126,7 +123,8 @@ struct BlitterUniforms {
 }// anonymous namespace

 VulkanBlitter::VulkanBlitter(VkPhysicalDevice physicalDevice, VulkanCommands* commands) noexcept
-        : mPhysicalDevice(physicalDevice), mCommands(commands) {}
+    : mPhysicalDevice(physicalDevice),
+      mCommands(commands) {}

 void VulkanBlitter::resolve(VulkanAttachment dst, VulkanAttachment src) {

@@ -150,11 +148,11 @@ void VulkanBlitter::resolve(VulkanAttachment dst, VulkanAttachment src) {
    }
 #endif

-    VulkanCommandBuffer& commands = dst.texture->getIsProtected() ?
-            mCommands->getProtected() : mCommands->get();
+    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,
@@ -176,11 +174,11 @@ void VulkanBlitter::blit(VkFilter filter,
 #endif
    // src and dst should have the same aspect here
    VkImageAspectFlags const aspect = src.texture->getImageAspect();
-    VulkanCommandBuffer& commands = dst.texture->getIsProtected() ?
-            mCommands->getProtected() : mCommands->get();
+    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 {
--- a/filament/backend/src/vulkan/VulkanCommands.cpp
+++ b/filament/backend/src/vulkan/VulkanCommands.cpp
@@ -33,194 +33,275 @@ using namespace utils;

 namespace filament::backend {

-namespace {
-
 #if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
 using Timestamp = VulkanGroupMarkers::Timestamp;
 #endif

-VkCommandBuffer createCommandBuffer(VkDevice device, VkCommandPool pool) {
-    VkCommandBuffer cmdbuffer;
-    // Create the low-level command buffer.
-    VkCommandBufferAllocateInfo const allocateInfo{
-        .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO,
-        .commandPool = pool,
-        .level = VK_COMMAND_BUFFER_LEVEL_PRIMARY,
-        .commandBufferCount = 1,
-    };
-    // The buffer allocated here will be implicitly reset when vkBeginCommandBuffer is called.
-    // We don't need to deallocate since destroying the pool will free all of the buffers.
-    vkAllocateCommandBuffers(device, &allocateInfo, &cmdbuffer);
-    return cmdbuffer;
+VulkanCmdFence::VulkanCmdFence(VkFence ifence)
+    : fence(ifence) {
+    // Internally we use the VK_INCOMPLETE status to mean "not yet submitted". When this fence gets
+    // submitted, its status changes to VK_NOT_READY. Finally, when the GPU actually finishes
+    // executing the command buffer, the status changes to VK_SUCCESS.
+    status.store(VK_INCOMPLETE);
 }

-} // anonymous namespace
+VulkanCommandBuffer::VulkanCommandBuffer(VulkanResourceAllocator* allocator, VkDevice device,
+        VkCommandPool pool)
+    : mResourceManager(allocator),
+      mPipeline(VK_NULL_HANDLE) {
+    // Create the low-level command buffer.
+    const VkCommandBufferAllocateInfo allocateInfo{
+            .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO,
+            .commandPool = pool,
+            .level = VK_COMMAND_BUFFER_LEVEL_PRIMARY,
+            .commandBufferCount = 1,
+    };
+
+    // The buffer allocated here will be implicitly reset when vkBeginCommandBuffer is called.
+    // We don't need to deallocate since destroying the pool will free all of the buffers.
+    vkAllocateCommandBuffers(device, &allocateInfo, &mBuffer);
+}
+
+CommandBufferObserver::~CommandBufferObserver() {}
+
+static VkCommandPool createPool(VkDevice device, uint32_t queueFamilyIndex) {
+    VkCommandPoolCreateInfo createInfo = {
+            .sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO,
+            .flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT
+                     | VK_COMMAND_POOL_CREATE_TRANSIENT_BIT,
+            .queueFamilyIndex = queueFamilyIndex,
+    };
+    VkCommandPool pool;
+    vkCreateCommandPool(device, &createInfo, VKALLOC, &pool);
+    return pool;
+}

 #if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
 void VulkanGroupMarkers::push(std::string const& marker, Timestamp start) noexcept {
-    mMarkers.push_back({marker,
-        start.time_since_epoch().count() > 0.0
-        ? start
-        : std::chrono::high_resolution_clock::now()});
+    mMarkers.push_back(marker);
+
+#if FVK_ENABLED(FVK_DEBUG_PRINT_GROUP_MARKERS)
+    mTimestamps.push_back(start.time_since_epoch().count() > 0.0
+                                  ? start
+                                  : std::chrono::high_resolution_clock::now());
+#endif
 }

 std::pair<std::string, Timestamp> VulkanGroupMarkers::pop() noexcept {
-    auto ret = mMarkers.back();
+    auto const marker = mMarkers.back();
    mMarkers.pop_back();
-    return ret;
+
+#if FVK_ENABLED(FVK_DEBUG_PRINT_GROUP_MARKERS)
+    auto const timestamp = mTimestamps.back();
+    mTimestamps.pop_back();
+    return std::make_pair(marker, timestamp);
+#else
+    return std::make_pair(marker, Timestamp{});
+#endif
 }

 std::pair<std::string, Timestamp> VulkanGroupMarkers::pop_bottom() noexcept {
-    auto ret = mMarkers.front();
+    auto const marker = mMarkers.front();
    mMarkers.pop_front();
-    return ret;
+
+#if FVK_ENABLED(FVK_DEBUG_PRINT_GROUP_MARKERS)
+    auto const timestamp = mTimestamps.front();
+    mTimestamps.pop_front();
+    return std::make_pair(marker, timestamp);
+#else
+    return std::make_pair(marker, Timestamp{});
+#endif
 }

-std::pair<std::string, Timestamp> const& VulkanGroupMarkers::top() const {
+std::pair<std::string, Timestamp> VulkanGroupMarkers::top() const {
    assert_invariant(!empty());
-    return mMarkers.back();
+    auto const marker = mMarkers.back();
+#if FVK_ENABLED(FVK_DEBUG_PRINT_GROUP_MARKERS)
+    auto const topTimestamp = mTimestamps.front();
+    return std::make_pair(marker, topTimestamp);
+#else
+    return std::make_pair(marker, Timestamp{});
+#endif
 }

 bool VulkanGroupMarkers::empty() const noexcept {
    return mMarkers.empty();
 }
+
 #endif // FVK_DEBUG_GROUP_MARKERS

-VulkanCommandBuffer::VulkanCommandBuffer(VulkanContext* context, VkDevice device, VkQueue queue,
-        VkCommandPool pool, bool isProtected)
-    : mContext(context),
-      mMarkerCount(0),
-      isProtected(isProtected),
-      mDevice(device),
+VulkanCommands::VulkanCommands(VkDevice device, VkQueue queue, uint32_t queueFamilyIndex,
+        VulkanContext* context, VulkanResourceAllocator* allocator)
+    : mDevice(device),
      mQueue(queue),
-      mBuffer(createCommandBuffer(device, pool)),
-      mFenceStatus(std::make_shared<VulkanCmdFence>(VK_INCOMPLETE)) {
+      mPool(createPool(mDevice, queueFamilyIndex)),
+      mContext(context),
+      mStorage(CAPACITY) {
    VkSemaphoreCreateInfo sci{.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO};
-    vkCreateSemaphore(mDevice, &sci, VKALLOC, &mSubmission);
+    for (auto& semaphore: mSubmissionSignals) {
+        vkCreateSemaphore(mDevice, &sci, nullptr, &semaphore);
+    }

    VkFenceCreateInfo fenceCreateInfo{.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO};
-    vkCreateFence(device, &fenceCreateInfo, VKALLOC, &mFence);
-}
-
-VulkanCommandBuffer::~VulkanCommandBuffer() {
-    vkDestroySemaphore(mDevice, mSubmission, VKALLOC);
-    vkDestroyFence(mDevice, mFence, VKALLOC);
-}
-
-void VulkanCommandBuffer::reset() noexcept {
-    mMarkerCount = 0;
-    mResources.clear();
-    mWaitSemaphores.clear();
-
-    // Internally we use the VK_INCOMPLETE status to mean "not yet submitted". When this fence
-    // gets, gets submitted, its status changes to VK_NOT_READY. Finally, when the GPU actually
-    // finishes executing the command buffer, the status changes to VK_SUCCESS.
-    mFenceStatus = std::make_shared<VulkanCmdFence>(VK_INCOMPLETE);
-    vkResetFences(mDevice, 1, &mFence);
-}
-
-void VulkanCommandBuffer::pushMarker(char const* marker) noexcept {
-    if (mContext->isDebugUtilsSupported()) {
-        VkDebugUtilsLabelEXT labelInfo = {
-                .sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_LABEL_EXT,
-                .pLabelName = marker,
-                .color = {0, 1, 0, 1},
-        };
-        vkCmdBeginDebugUtilsLabelEXT(mBuffer, &labelInfo);
-    } else if (mContext->isDebugMarkersSupported()) {
-        VkDebugMarkerMarkerInfoEXT markerInfo = {
-                .sType = VK_STRUCTURE_TYPE_DEBUG_MARKER_MARKER_INFO_EXT,
-                .pMarkerName = marker,
-                .color = {0.0f, 1.0f, 0.0f, 1.0f},
-        };
-        vkCmdDebugMarkerBeginEXT(mBuffer, &markerInfo);
+    for (auto& fence: mFences) {
+        vkCreateFence(device, &fenceCreateInfo, VKALLOC, &fence);
    }
-    mMarkerCount++;
-}

-void VulkanCommandBuffer::popMarker() noexcept{
-    assert_invariant(mMarkerCount > 0);
-    if (mContext->isDebugUtilsSupported()) {
-        vkCmdEndDebugUtilsLabelEXT(mBuffer);
-    } else if (mContext->isDebugMarkersSupported()) {
-        vkCmdDebugMarkerEndEXT(mBuffer);
+    for (size_t i = 0; i < CAPACITY; ++i) {
+        mStorage[i] = std::make_unique<VulkanCommandBuffer>(allocator, mDevice, mPool);
    }
-    mMarkerCount--;
+
+#if !FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
+    (void) mContext;
+#endif
 }

-void VulkanCommandBuffer::insertEvent(char const* marker) noexcept {
-    if (mContext->isDebugUtilsSupported()) {
-        VkDebugUtilsLabelEXT labelInfo = {
-                .sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_LABEL_EXT,
-                .pLabelName = marker,
-                .color = {1, 1, 0, 1},
-        };
-        vkCmdInsertDebugUtilsLabelEXT(mBuffer, &labelInfo);
-    } else if (mContext->isDebugMarkersSupported()) {
-        VkDebugMarkerMarkerInfoEXT markerInfo = {
-                .sType = VK_STRUCTURE_TYPE_DEBUG_MARKER_MARKER_INFO_EXT,
-                .pMarkerName = marker,
-                .color = {0.0f, 1.0f, 0.0f, 1.0f},
-        };
-        vkCmdDebugMarkerInsertEXT(mBuffer, &markerInfo);
+void VulkanCommands::terminate() {
+    wait();
+    gc();
+    vkDestroyCommandPool(mDevice, mPool, VKALLOC);
+    for (VkSemaphore sema: mSubmissionSignals) {
+        vkDestroySemaphore(mDevice, sema, VKALLOC);
+    }
+    for (VkFence fence: mFences) {
+        vkDestroyFence(mDevice, fence, VKALLOC);
    }
 }

-void VulkanCommandBuffer::begin() noexcept {
-    // Begin writing into the command buffer.
-    VkCommandBufferBeginInfo const binfo{
-        .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO,
-        .flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT,
-    };
-    vkBeginCommandBuffer(mBuffer, &binfo);
-}
-
-VkSemaphore VulkanCommandBuffer::submit() {
-    while (mMarkerCount > 0) {
-        popMarker();
-    }
-
-    vkEndCommandBuffer(mBuffer);
-
-    VkPipelineStageFlags const waitDestStageMasks[2] = {
-        VK_PIPELINE_STAGE_ALL_COMMANDS_BIT,
-        VK_PIPELINE_STAGE_ALL_COMMANDS_BIT,
-    };
-
-    VkSubmitInfo submitInfo{
-        .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
-        .waitSemaphoreCount = mWaitSemaphores.size(),
-        .pWaitSemaphores = mWaitSemaphores.data(),
-        .pWaitDstStageMask = waitDestStageMasks,
-        .commandBufferCount = 1u,
-        .pCommandBuffers = &mBuffer,
-        .signalSemaphoreCount = 1u,
-        .pSignalSemaphores = &mSubmission,
-    };
-    // add submit protection if needed
-    VkProtectedSubmitInfo protectedSubmitInfo{
-        .sType = VK_STRUCTURE_TYPE_PROTECTED_SUBMIT_INFO,
-        .protectedSubmit = VK_TRUE,
-    };
-
-    if (isProtected) {
-        submitInfo.pNext = &protectedSubmitInfo;
+VulkanCommandBuffer& VulkanCommands::get() {
+    if (mCurrentCommandBufferIndex >= 0) {
+        return *mStorage[mCurrentCommandBufferIndex].get();
    }

+    // If we ran out of available command buffers, stall until one finishes. This is very rare.
+    // It occurs only when Filament invokes commit() or endFrame() a large number of times without
+    // presenting the swap chain or waiting on a fence.
+    while (mAvailableBufferCount == 0) {
 #if FVK_ENABLED(FVK_DEBUG_COMMAND_BUFFER)
-    FVK_LOGI << "Submitting cmdbuffer=" << mBuffer
-             << " wait=(";
-    for (size_t s = 0, count = mWaitSemaphores.size(); s < count; ++s) {
-        FVK_LOGI << mWaitSemaphores[s] << " ";
+        FVK_LOGI << "VulkanCommands has stalled. "
+               << "If this occurs frequently, consider increasing VK_MAX_COMMAND_BUFFERS."
+               << io::endl;
+#endif
+        wait();
+        gc();
+    }
+
+    VulkanCommandBuffer* currentbuf = nullptr;
+    // Find an available slot.
+    for (size_t i = 0; i < CAPACITY; ++i) {
+        auto wrapper = mStorage[i].get();
+        if (wrapper->buffer() == VK_NULL_HANDLE) {
+            mCurrentCommandBufferIndex = static_cast<int8_t>(i);
+            currentbuf = wrapper;
+            break;
+        }
+    }
+
+    assert_invariant(currentbuf);
+    mAvailableBufferCount--;
+
+    // Note that the fence wrapper uses shared_ptr because a DriverAPI fence can also have ownership
+    // over it.  The destruction of the low-level fence occurs either in VulkanCommands::gc(), or in
+    // VulkanDriver::destroyFence(), both of which are safe spots.
+    currentbuf->fence = std::make_shared<VulkanCmdFence>(mFences[mCurrentCommandBufferIndex]);
+
+    // Begin writing into the command buffer.
+    const VkCommandBufferBeginInfo binfo{
+            .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO,
+            .flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT,
+    };
+    vkBeginCommandBuffer(currentbuf->buffer(), &binfo);
+
+    // Notify the observer that a new command buffer has been activated.
+    if (mObserver) {
+        mObserver->onCommandBuffer(*currentbuf);
+    }
+
+#if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
+    // We push the current markers onto a temporary stack. This must be placed after currentbuf is
+    // set to the new command buffer since pushGroupMarker also calls get().
+    while (mCarriedOverMarkers && !mCarriedOverMarkers->empty()) {
+        auto [marker, time] = mCarriedOverMarkers->pop();
+        pushGroupMarker(marker.c_str(), time);
+    }
+#endif
+    return *currentbuf;
+}
+
+bool VulkanCommands::flush() {
+    // It's perfectly fine to call flush when no commands have been written.
+    if (mCurrentCommandBufferIndex < 0) {
+        return false;
+    }
+
+    // Before actually submitting, we need to pop any leftover group markers.
+    // Note that this needs to occur before vkEndCommandBuffer.
+#if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
+    while (mGroupMarkers && !mGroupMarkers->empty()) {
+        if (!mCarriedOverMarkers) {
+            mCarriedOverMarkers = std::make_unique<VulkanGroupMarkers>();
+        }
+        auto const [marker, time] = mGroupMarkers->top();
+        mCarriedOverMarkers->push(marker, time);
+        // We still need to call through to vkCmdEndDebugUtilsLabelEXT.
+        popGroupMarker();
    }
-    FVK_LOGI << ") "
-             << " signal=" << mSubmission
-             << " fence=" << mFence << utils::io::endl;
 #endif

-    mFenceStatus->setStatus(VK_NOT_READY);
-    UTILS_UNUSED_IN_RELEASE VkResult result =
-        vkQueueSubmit(mQueue, 1, &submitInfo, mFence);
+    int8_t const index = mCurrentCommandBufferIndex;
+    VulkanCommandBuffer const* currentbuf = mStorage[index].get();
+    VkSemaphore const renderingFinished = mSubmissionSignals[index];
+
+    vkEndCommandBuffer(currentbuf->buffer());
+
+    // If the injected semaphore is an "image available" semaphore that has not yet been signaled,
+    // it is sometimes fine to start executing commands anyway, as along as we stall the GPU at the
+    // VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT stage. However we need to assume the worst
+    // here and use VK_PIPELINE_STAGE_ALL_COMMANDS_BIT. This is a more aggressive stall, but it is
+    // the only safe option because the previously submitted command buffer might have set up some
+    // state that the new command buffer depends on.
+    VkPipelineStageFlags waitDestStageMasks[2] = {
+            VK_PIPELINE_STAGE_ALL_COMMANDS_BIT,
+            VK_PIPELINE_STAGE_ALL_COMMANDS_BIT,
+    };
+
+    VkSemaphore signals[2] = {
+            VK_NULL_HANDLE,
+            VK_NULL_HANDLE,
+    };
+    uint32_t waitSemaphoreCount = 0;
+    if (mSubmissionSignal) {
+        signals[waitSemaphoreCount++] = mSubmissionSignal;
+    }
+    if (mInjectedSignal) {
+        signals[waitSemaphoreCount++] = mInjectedSignal;
+    }
+    VkCommandBuffer const cmdbuffer = currentbuf->buffer();
+    VkSubmitInfo submitInfo{
+            .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
+            .waitSemaphoreCount = waitSemaphoreCount,
+            .pWaitSemaphores = waitSemaphoreCount > 0 ? signals : nullptr,
+            .pWaitDstStageMask = waitDestStageMasks,
+            .commandBufferCount = 1,
+            .pCommandBuffers = &cmdbuffer,
+            .signalSemaphoreCount = 1u,
+            .pSignalSemaphores = &renderingFinished,
+    };
+
+#if FVK_ENABLED(FVK_DEBUG_COMMAND_BUFFER)
+    FVK_LOGI << "Submitting cmdbuffer=" << cmdbuffer
+           << " wait=(" << signals[0] << ", " << signals[1] << ") "
+           << " signal=" << renderingFinished
+           << " fence=" << currentbuf->fence->fence
+           << utils::io::endl;
+#endif
+
+    auto& cmdfence = currentbuf->fence;
+    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) {
@@ -228,298 +309,175 @@ VkSemaphore VulkanCommandBuffer::submit() {
    }
 #endif
    assert_invariant(result == VK_SUCCESS);
-    mWaitSemaphores.clear();
-    return mSubmission;
-}
-
-CommandBufferPool::CommandBufferPool(VulkanContext* context, VkDevice device, VkQueue queue,
-        uint8_t queueFamilyIndex, bool isProtected)
-    : mDevice(device),
-      mRecording(INVALID) {
-    VkCommandPoolCreateInfo createInfo = {
-        .sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO,
-        .flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT |
-                 VK_COMMAND_POOL_CREATE_TRANSIENT_BIT |
-                (isProtected ? VK_COMMAND_POOL_CREATE_PROTECTED_BIT : 0u),
-        .queueFamilyIndex = queueFamilyIndex,
-    };
-    vkCreateCommandPool(device, &createInfo, VKALLOC, &mPool);
-
-    for (size_t i = 0; i < CAPACITY; ++i) {
-        mBuffers.emplace_back(
-                std::make_unique<VulkanCommandBuffer>(context, device, queue, mPool, isProtected));
-    }
-}
-
-CommandBufferPool::~CommandBufferPool() {
-    wait();
-    gc();
-    vkDestroyCommandPool(mDevice, mPool, VKALLOC);
-}
-
-VulkanCommandBuffer& CommandBufferPool::getRecording() {
-    if (isRecording()) {
-        return *mBuffers[mRecording];
-    }
-
-    auto const findNext = [this]() {
-        for (int8_t i = 0; i < CAPACITY; ++i) {
-            if (!mSubmitted[i]) {
-                return i;
-            }
-        }
-        return INVALID;
-    };
-
-    while ((mRecording = findNext()) == INVALID) {
-        wait();
-        gc();
-    }
-
-    auto& recording = *mBuffers[mRecording];
-    recording.begin();
-
-#if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
-    if (mGroupMarkers) {
-        std::unique_ptr<VulkanGroupMarkers> markers = std::make_unique<VulkanGroupMarkers>();
-        while (!mGroupMarkers->empty()) {
-            auto [marker, timestamp] = mGroupMarkers->pop_bottom();
-            recording.pushMarker(marker.c_str());
-            markers->push(marker, timestamp);
-        }
-        std::swap(mGroupMarkers, markers);
-    }
-#endif
-
-    return recording;
-}
-
-void CommandBufferPool::gc() {
-    ActiveBuffers reclaimed;
-    mSubmitted.forEachSetBit([this,&reclaimed] (size_t index) {
-        auto& buffer = mBuffers[index];
-        if (buffer->getStatus() == VK_SUCCESS) {
-            reclaimed.set(index, true);
-            buffer->reset();
-        }
-    });
-    mSubmitted &= ~reclaimed;
-}
-
-void CommandBufferPool::update() {
-    mSubmitted.forEachSetBit([this] (size_t index) {
-        auto& buffer = mBuffers[index];
-        VkResult status = vkGetFenceStatus(mDevice, buffer->getVkFence());
-        if (status == VK_SUCCESS) {
-            buffer->setComplete();
-        }
-    });
-}
-
-VkSemaphore CommandBufferPool::flush() {
-    // We're not recording right now.
-    if (!isRecording()) {
-        return VK_NULL_HANDLE;
-    }
-    auto submitSemaphore = mBuffers[mRecording]->submit();
-    mSubmitted.set(mRecording, true);
-    mRecording = INVALID;
-    return submitSemaphore;
-}
-
-void CommandBufferPool::wait() {
-    uint8_t count = 0;
-    VkFence fences[CAPACITY];
-    mSubmitted.forEachSetBit([this, &count, &fences] (size_t index) {
-        fences[count++] = mBuffers[index]->getVkFence();
-    });
-    vkWaitForFences(mDevice, count, fences, VK_TRUE, UINT64_MAX);
-    update();
-}
-
-void CommandBufferPool::waitFor(VkSemaphore previousAction) {
-    if (!isRecording()) {
-        return;
-    }
-    auto& recording = mBuffers[mRecording];
-    recording->insertWait(previousAction);
-}
-
-#if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
-std::string CommandBufferPool::topMarker() const {
-    if (!mGroupMarkers || mGroupMarkers->empty()) {
-        return "";
-    }
-    return std::get<0>(mGroupMarkers->top());
-}
-
-void CommandBufferPool::pushMarker(char const* marker, VulkanGroupMarkers::Timestamp timestamp) {
-    if (!mGroupMarkers) {
-        mGroupMarkers = std::make_unique<VulkanGroupMarkers>();
-    }
-    mGroupMarkers->push(marker, timestamp);
-    getRecording().pushMarker(marker);
-}
-
-std::pair<std::string, VulkanGroupMarkers::Timestamp> CommandBufferPool::popMarker() {
-    assert_invariant(mGroupMarkers && !mGroupMarkers->empty());
-    auto ret = mGroupMarkers->pop();
-
-    // Note that if we're popping a marker while not recording, we would just pop the conceptual
-    // stack of marker (i.e. mGroupMarkers) and not carry out the pop on the command buffer.
-    if (isRecording()) {
-        getRecording().popMarker();
-    }
-    return ret;
-}
-
-void CommandBufferPool::insertEvent(char const* marker) {
-    getRecording().insertEvent(marker);
-}
-#endif // FVK_DEBUG_GROUP_MARKERS
-
-VulkanCommands::VulkanCommands(VkDevice device, VkQueue queue, uint32_t queueFamilyIndex,
-        VkQueue protectedQueue, uint32_t protectedQueueFamilyIndex, VulkanContext* context)
-    : mDevice(device),
-      mProtectedQueue(protectedQueue),
-      mProtectedQueueFamilyIndex(protectedQueueFamilyIndex),
-      mContext(context),
-      mPool(std::make_unique<CommandBufferPool>(context, device, queue, queueFamilyIndex, false)) {}
-
-void VulkanCommands::terminate() {
-    mPool.reset();
-    mProtectedPool.reset();
-}
-
-VulkanCommandBuffer& VulkanCommands::get() {
-    auto& ret = mPool->getRecording();
-    return ret;
-}
-
-VulkanCommandBuffer& VulkanCommands::getProtected() {
-    assert_invariant(mProtectedQueue != VK_NULL_HANDLE);
-
-    if (!mProtectedPool) {
-        mProtectedPool = std::make_unique<CommandBufferPool>(mContext, mDevice, mProtectedQueue,
-                mProtectedQueueFamilyIndex, true);
-    }
-    auto& ret = mProtectedPool->getRecording();
-    return ret;
-}
-
-bool VulkanCommands::flush() {
-    // It's possible to call flush and wait at "terminate", in which case, we'll just return.
-    if (!mPool && !mProtectedPool) {
-        return false;
-    }
-
-    VkSemaphore dependency = mInjectedDependency;
-    VkSemaphore lastSubmit = mLastSubmit;
-    bool hasFlushed = false;
-
-    // Note that we've ordered it so that the non-protected commands are followed by the protected
-    // commands.  This assumes that the protected commands will be that one doing the rendering into
-    // the protected memory (i.e. protected render target).
-    for (auto pool: {mPool.get(), mProtectedPool.get()}) {
-        if (!pool || !pool->isRecording()) {
-            continue;
-        }
-        if (dependency != VK_NULL_HANDLE) {
-            pool->waitFor(dependency);
-        }
-        if (lastSubmit != VK_NULL_HANDLE) {
-            pool->waitFor(lastSubmit);
-            lastSubmit = VK_NULL_HANDLE;
-        }
-        dependency = pool->flush();
-        hasFlushed = true;
-    }
-
-    if (hasFlushed) {
-        mInjectedDependency = VK_NULL_HANDLE;
-        mLastSubmit = dependency;
-    }

+    mSubmissionSignal = renderingFinished;
+    mInjectedSignal = VK_NULL_HANDLE;
+    mCurrentCommandBufferIndex = -1;
    return true;
 }

+VkSemaphore VulkanCommands::acquireFinishedSignal() {
+    VkSemaphore semaphore = mSubmissionSignal;
+    mSubmissionSignal = VK_NULL_HANDLE;
+#if FVK_ENABLED(FVK_DEBUG_COMMAND_BUFFER)
+    FVK_LOGI << "Acquiring " << semaphore << " (e.g. for vkQueuePresentKHR)" << io::endl;
+#endif
+    return semaphore;
+}
+
+void VulkanCommands::injectDependency(VkSemaphore next) {
+    assert_invariant(mInjectedSignal == VK_NULL_HANDLE);
+    mInjectedSignal = next;
+#if FVK_ENABLED(FVK_DEBUG_COMMAND_BUFFER)
+    FVK_LOGI << "Injecting " << next << " (e.g. due to vkAcquireNextImageKHR)" << io::endl;
+#endif
+}
+
 void VulkanCommands::wait() {
-    // It's possible to call flush and wait at "terminate", in which case, we'll just return.
-    if (!mPool && !mProtectedPool) {
-        return;
+    VkFence fences[CAPACITY];
+    size_t count = 0;
+    for (size_t i = 0; i < CAPACITY; i++) {
+        auto wrapper = mStorage[i].get();
+        if (wrapper->buffer() != VK_NULL_HANDLE
+                && mCurrentCommandBufferIndex != static_cast<int8_t>(i)) {
+            fences[count++] = wrapper->fence->fence;
+        }
    }
-
-    FVK_SYSTRACE_CONTEXT();
-    FVK_SYSTRACE_START("commands::wait");
-
-    mPool->wait();
-    if (mProtectedPool) {
-        mProtectedPool->wait();
+    if (count > 0) {
+        vkWaitForFences(mDevice, count, fences, VK_TRUE, UINT64_MAX);
+        updateFences();
    }
-    FVK_SYSTRACE_END();
 }

 void VulkanCommands::gc() {
    FVK_SYSTRACE_CONTEXT();
    FVK_SYSTRACE_START("commands::gc");

-    mPool->gc();
-    if (mProtectedPool) {
-        mProtectedPool->gc();
+    VkFence fences[CAPACITY];
+    size_t count = 0;
+
+    for (size_t i = 0; i < CAPACITY; i++) {
+        auto wrapper = mStorage[i].get();
+        if (wrapper->buffer() == VK_NULL_HANDLE) {
+            continue;
+        }
+        VkResult const result = vkGetFenceStatus(mDevice, wrapper->fence->fence);
+        if (result != VK_SUCCESS) {
+            continue;
+        }
+        fences[count++] = wrapper->fence->fence;
+        wrapper->fence->status.store(VK_SUCCESS);
+        wrapper->reset();
+        mAvailableBufferCount++;
+    }
+
+    if (count > 0) {
+        vkResetFences(mDevice, count, fences);
    }
    FVK_SYSTRACE_END();
 }

 void VulkanCommands::updateFences() {
-    mPool->update();
-    if (mProtectedPool) {
-        mProtectedPool->update();
+    for (size_t i = 0; i < CAPACITY; i++) {
+        auto wrapper = mStorage[i].get();
+        if (wrapper->buffer() != VK_NULL_HANDLE) {
+            VulkanCmdFence* fence = wrapper->fence.get();
+            if (fence) {
+                VkResult status = vkGetFenceStatus(mDevice, fence->fence);
+                // This is either VK_SUCCESS, VK_NOT_READY, or VK_ERROR_DEVICE_LOST.
+                fence->status.store(status, std::memory_order_relaxed);
+            }
+        }
    }
 }

 #if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)

 void VulkanCommands::pushGroupMarker(char const* str, VulkanGroupMarkers::Timestamp timestamp) {
-    mPool->pushMarker(str, timestamp);
-    if (mProtectedPool) {
-        mProtectedPool->pushMarker(str, timestamp);
-    }
 #if FVK_ENABLED(FVK_DEBUG_PRINT_GROUP_MARKERS)
-    FVK_LOGD << "----> " << str << utils::io::endl;
+    // If the timestamp is not 0, then we are carrying over a marker across buffer submits.
+    // If it is 0, then this is a normal marker push and we should just print debug line as usual.
+    if (timestamp.time_since_epoch().count() == 0.0) {
+        FVK_LOGD << "----> " << str << utils::io::endl;
+    }
 #endif
+
+    // TODO: Add group marker color to the Driver API
+    VkCommandBuffer const cmdbuffer = get().buffer();
+
+    if (!mGroupMarkers) {
+        mGroupMarkers = std::make_unique<VulkanGroupMarkers>();
+    }
+    mGroupMarkers->push(str, timestamp);
+
+    if (mContext->isDebugUtilsSupported()) {
+        VkDebugUtilsLabelEXT labelInfo = {
+                .sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_LABEL_EXT,
+                .pLabelName = str,
+                .color = {0, 1, 0, 1},
+        };
+        vkCmdBeginDebugUtilsLabelEXT(cmdbuffer, &labelInfo);
+    } else if (mContext->isDebugMarkersSupported()) {
+        VkDebugMarkerMarkerInfoEXT markerInfo = {
+                .sType = VK_STRUCTURE_TYPE_DEBUG_MARKER_MARKER_INFO_EXT,
+                .pMarkerName = str,
+                .color = {0.0f, 1.0f, 0.0f, 1.0f},
+        };
+        vkCmdDebugMarkerBeginEXT(cmdbuffer, &markerInfo);
+    }
 }

 void VulkanCommands::popGroupMarker() {
+    assert_invariant(mGroupMarkers);

+    if (!mGroupMarkers->empty()) {
+        VkCommandBuffer const cmdbuffer = get().buffer();
 #if FVK_ENABLED(FVK_DEBUG_PRINT_GROUP_MARKERS)
-    auto ret = mPool->popMarker();
-    auto const& marker = ret.first;
-    auto const& startTime = ret.second;
-    auto const endTime = std::chrono::high_resolution_clock::now();
-    std::chrono::duration<double> diff = endTime - startTime;
-    FVK_LOGD << "<---- " << marker << " elapsed: " << (diff.count() * 1000) << " ms"
-             << utils::io::endl;
+        auto const [marker, startTime] = mGroupMarkers->pop();
+        auto const endTime = std::chrono::high_resolution_clock::now();
+        std::chrono::duration<double> diff = endTime - startTime;
+        FVK_LOGD << "<---- " << marker << " elapsed: " << (diff.count() * 1000) << " ms"
+                      << utils::io::endl;
 #else
-    mPool->popMarker();
-#endif // FVK_DEBUG_PRINT_GROUP_MARKERS
-
-    if (mProtectedPool) {
-        mProtectedPool->popMarker();
+        mGroupMarkers->pop();
+#endif
+        if (mContext->isDebugUtilsSupported()) {
+            vkCmdEndDebugUtilsLabelEXT(cmdbuffer);
+        } else if (mContext->isDebugMarkersSupported()) {
+            vkCmdDebugMarkerEndEXT(cmdbuffer);
+        }
+    } else if (mCarriedOverMarkers && !mCarriedOverMarkers->empty()) {
+        // It could be that pop is called between flush() and get() (new command buffer), in which
+        // case the marker is in "carried over" state, we'd just remove that. Since the
+        // mCarriedOverMarkers is in the opposite order, we pop the bottom instead of the top.
+        mCarriedOverMarkers->pop_bottom();
    }
 }

-void VulkanCommands::insertEventMarker(char const* str, uint32_t len) {
-    mPool->insertEvent(str);
-    if (mProtectedPool) {
-        mProtectedPool->insertEvent(str);
+void VulkanCommands::insertEventMarker(char const* string, uint32_t len) {
+    VkCommandBuffer const cmdbuffer = get().buffer();
+    if (mContext->isDebugUtilsSupported()) {
+        VkDebugUtilsLabelEXT labelInfo = {
+                .sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_LABEL_EXT,
+                .pLabelName = string,
+                .color = {1, 1, 0, 1},
+        };
+        vkCmdInsertDebugUtilsLabelEXT(cmdbuffer, &labelInfo);
+    } else if (mContext->isDebugMarkersSupported()) {
+        VkDebugMarkerMarkerInfoEXT markerInfo = {
+                .sType = VK_STRUCTURE_TYPE_DEBUG_MARKER_MARKER_INFO_EXT,
+                .pMarkerName = string,
+                .color = {0.0f, 1.0f, 0.0f, 1.0f},
+        };
+        vkCmdDebugMarkerInsertEXT(cmdbuffer, &markerInfo);
    }
 }

 std::string VulkanCommands::getTopGroupMarker() const {
-    if (mProtectedPool) {
-        return mProtectedPool->topMarker();
+    if (!mGroupMarkers || mGroupMarkers->empty()) {
+        return "";
    }
-    return mPool->topMarker();
+    return std::get<0>(mGroupMarkers->top());
 }
 #endif // FVK_DEBUG_GROUP_MARKERS

--- a/filament/backend/src/vulkan/VulkanCommands.h
+++ b/filament/backend/src/vulkan/VulkanCommands.h
@@ -21,10 +21,8 @@

 #include "DriverBase.h"

-#include "VulkanAsyncHandles.h"
 #include "VulkanConstants.h"
-#include "VulkanUtility.h"
-#include "vulkan/memory/ResourcePointer.h"
+#include "VulkanResources.h"

 #include <utils/Condition.h>
 #include <utils/FixedCapacityVector.h>
@@ -39,8 +37,6 @@

 namespace filament::backend {

-using namespace fvkmemory;
-
 struct VulkanContext;

 #if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
@@ -51,122 +47,79 @@ public:
    void push(std::string const& marker, Timestamp start = {}) noexcept;
    std::pair<std::string, Timestamp> pop() noexcept;
    std::pair<std::string, Timestamp> pop_bottom() noexcept;
-    std::pair<std::string, Timestamp> const& top() const;
+    std::pair<std::string, Timestamp> top() const;
    bool empty() const noexcept;

 private:
-    std::list<std::pair<std::string, Timestamp>> mMarkers;
+    std::list<std::string> mMarkers;
+#if FVK_ENABLED(FVK_DEBUG_PRINT_GROUP_MARKERS)
+    std::list<Timestamp> mTimestamps;
+#endif
 };

 #endif // FVK_DEBUG_GROUP_MARKERS

+// Wrapper to enable use of shared_ptr for implementing shared ownership of low-level Vulkan fences.
+struct VulkanCmdFence {
+    VulkanCmdFence(VkFence ifence);
+    ~VulkanCmdFence() = default;
+    VkFence fence;
+    utils::Condition condition;
+    utils::Mutex mutex;
+    std::atomic<VkResult> status;
+};
+
 // The submission fence has shared ownership semantics because it is potentially wrapped by a
 // DriverApi fence object and should not be destroyed until both the DriverApi object is freed and
 // we're done waiting on the most recent submission of the given command buffer.
 struct VulkanCommandBuffer {
-    VulkanCommandBuffer(VulkanContext* mContext,
-            VkDevice device, VkQueue queue, VkCommandPool pool, bool isProtected);
+    VulkanCommandBuffer(VulkanResourceAllocator* allocator, VkDevice device, VkCommandPool pool);

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

-    ~VulkanCommandBuffer();
-
-    inline void acquire(fvkmemory::resource_ptr<fvkmemory::Resource> resource) {
-        mResources.push_back(resource);
+    inline void acquire(VulkanResource* resource) {
+        mResourceManager.acquire(resource);
    }

-    void reset() noexcept;
-
-    inline void insertWait(VkSemaphore sem) {
-        mWaitSemaphores.insert(sem);
+    inline void acquire(VulkanAcquireOnlyResourceManager* srcResources) {
+        mResourceManager.acquireAll(srcResources);
    }

-    void pushMarker(char const* marker) noexcept;
-    void popMarker() noexcept;
-    void insertEvent(char const* marker) noexcept;
-
-    void begin() noexcept;
-    VkSemaphore submit();
-
-    inline void setComplete() {
-        mFenceStatus->setStatus(VK_SUCCESS);
+    inline void reset() {
+        fence.reset();
+        mResourceManager.clear();
+        mPipeline = VK_NULL_HANDLE;
    }

-    VkResult getStatus() {
-        return mFenceStatus->getStatus();
+    inline void setPipeline(VkPipeline pipeline) {
+        mPipeline = pipeline;
    }

-    std::shared_ptr<VulkanCmdFence> getFenceStatus() const {
-        return mFenceStatus;
+    inline VkPipeline pipeline() const {
+        return mPipeline;
    }

-    VkFence getVkFence() const {
-        return mFence;
+    inline VkCommandBuffer buffer() const {
+        if (fence) {
+            return mBuffer;
+        }
+        return VK_NULL_HANDLE;
    }

-    VkCommandBuffer buffer() const {
-        return mBuffer;
-    }
+    std::shared_ptr<VulkanCmdFence> fence;

 private:
-    VulkanContext* mContext;
-    uint8_t mMarkerCount;
-    bool const isProtected;
-    VkDevice mDevice;
-    VkQueue mQueue;
-    CappedArray<VkSemaphore, 2> mWaitSemaphores;
+    VulkanAcquireOnlyResourceManager mResourceManager;
    VkCommandBuffer mBuffer;
-    VkSemaphore mSubmission;
-    VkFence mFence;
-    std::shared_ptr<VulkanCmdFence> mFenceStatus;
-    std::vector<fvkmemory::resource_ptr<Resource>> mResources;
+    VkPipeline mPipeline;
 };

-struct CommandBufferPool {
-    using ActiveBuffers = utils::bitset64;
-    static constexpr int8_t INVALID = -1;
-
-    CommandBufferPool(VulkanContext* context, VkDevice device, VkQueue queue,
-            uint8_t queueFamilyIndex, bool isProtected);
-    ~CommandBufferPool();
-
-    VulkanCommandBuffer& getRecording();
-
-    void gc();
-    void update();
-    VkSemaphore flush();
-    void wait();
-    void waitFor(VkSemaphore previousAction);
-
-#if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
-    std::string topMarker() const;
-    void pushMarker(char const* marker, VulkanGroupMarkers::Timestamp timestamp);
-    std::pair<std::string, VulkanGroupMarkers::Timestamp> popMarker();
-    void insertEvent(char const* marker);
-#endif
-
-    inline bool isRecording() const { return mRecording != INVALID; }
-
-private:
-    static constexpr int CAPACITY = FVK_MAX_COMMAND_BUFFERS;
-    // int8 only goes up to 127, therefore capacity must be less than that.
-    static_assert(CAPACITY < 128);
-
-    // The number of bits in ActiveBuffers describe the usage of the buffers in the pool, so must be
-    // larger than the size of the pool.
-    static_assert(sizeof(ActiveBuffers) * 8 >= CAPACITY);
-
-    using BufferList = utils::FixedCapacityVector<std::unique_ptr<VulkanCommandBuffer>>;
-    VkDevice mDevice;
-    VkCommandPool mPool;
-    ActiveBuffers mSubmitted;
-    std::vector<std::unique_ptr<VulkanCommandBuffer>> mBuffers;
-    int8_t mRecording;
-
-#if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
-    std::unique_ptr<VulkanGroupMarkers> mGroupMarkers;
-#endif
+// Allows classes to be notified after a new command buffer has been activated.
+class CommandBufferObserver {
+public:
+    virtual void onCommandBuffer(const VulkanCommandBuffer& cmdbuffer) = 0;
+    virtual ~CommandBufferObserver();
 };

 // Manages a set of command buffers and semaphores, exposing an API that is significantly simpler
@@ -180,6 +133,9 @@ private:
 //    - This creates a guarantee of in-order execution.
 //    - Semaphores are recycled to prevent create / destroy churn.
 //
+// - Notifies listeners when recording begins in a new VkCommandBuffer.
+//    - Used by PipelineCache so that it knows when to clear out its shadow state.
+//
 // - Allows 1 user to inject a "dependency" semaphore that stalls the next flush.
 //    - This is used for asynchronous acquisition of a swap chain image, since the GPU
 //      might require a valid swap chain image when it starts executing the command buffer.
@@ -195,17 +151,13 @@ private:
 class VulkanCommands {
 public:
    VulkanCommands(VkDevice device, VkQueue queue, uint32_t queueFamilyIndex,
-            VkQueue protectedQueue, uint32_t protectedQueueFamilyIndex, VulkanContext* context);
+            VulkanContext* context, VulkanResourceAllocator* allocator);

    void terminate();

    // Creates a "current" command buffer if none exists, otherwise returns the current one.
    VulkanCommandBuffer& get();

-    // Creates a "current" protected capable command buffer if none exists, otherwise
-    // returns the current one.
-    VulkanCommandBuffer& getProtected();
-
    // Submits the current command buffer if it exists, then sets "current" to null.
    // If there are no outstanding commands then nothing happens and this returns false.
    bool flush();
@@ -213,17 +165,11 @@ public:
    // Returns the "rendering finished" semaphore for the most recent flush and removes
    // it from the existing dependency chain. This is especially useful for setting up
    // vkQueuePresentKHR.
-    VkSemaphore acquireFinishedSignal() {
-        VkSemaphore ret= mLastSubmit;
-        mLastSubmit = VK_NULL_HANDLE;
-        return ret;
-    }
+    VkSemaphore acquireFinishedSignal();

    // Takes a semaphore that signals when the next flush can occur. Only one injected
    // semaphore is allowed per flush. Useful after calling vkAcquireNextImageKHR.
-    void injectDependency(VkSemaphore next) {
-        mInjectedDependency = next;
-    }
+    void injectDependency(VkSemaphore next);

    // Destroys all command buffers that are no longer in use.
    void gc();
@@ -234,25 +180,42 @@ public:
    // Updates the atomic "status" variable in every extant fence.
    void updateFences();

+    // Sets an observer who is notified every time a new command buffer has been made "current".
+    // The observer's event handler can only be called during get().
+    void setObserver(CommandBufferObserver* observer) { mObserver = observer; }
+
 #if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
    void pushGroupMarker(char const* str, VulkanGroupMarkers::Timestamp timestamp = {});
+
    void popGroupMarker();
+
    void insertEventMarker(char const* string, uint32_t len);
+
    std::string getTopGroupMarker() const;
 #endif

 private:
+    static constexpr int CAPACITY = FVK_MAX_COMMAND_BUFFERS;
    VkDevice const mDevice;
-    VkQueue const mProtectedQueue;
-    // For defered initialization if/when we need protected content
-    uint32_t const mProtectedQueueFamilyIndex;
-    VulkanContext* mContext;
+    VkQueue const mQueue;
+    VkCommandPool const mPool;
+    VulkanContext const* mContext;

-    std::unique_ptr<CommandBufferPool> mPool;
-    std::unique_ptr<CommandBufferPool> mProtectedPool;
+    // int8 only goes up to 127, therefore capacity must be less than that.
+    static_assert(CAPACITY < 128);
+    int8_t mCurrentCommandBufferIndex = -1;
+    VkSemaphore mSubmissionSignal = {};
+    VkSemaphore mInjectedSignal = {};
+    utils::FixedCapacityVector<std::unique_ptr<VulkanCommandBuffer>> mStorage;
+    VkFence mFences[CAPACITY] = {};
+    VkSemaphore mSubmissionSignals[CAPACITY] = {};
+    uint8_t mAvailableBufferCount = CAPACITY;
+    CommandBufferObserver* mObserver = nullptr;

-    VkSemaphore mInjectedDependency = VK_NULL_HANDLE;
-    VkSemaphore mLastSubmit = VK_NULL_HANDLE;
+#if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
+    std::unique_ptr<VulkanGroupMarkers> mGroupMarkers;
+    std::unique_ptr<VulkanGroupMarkers> mCarriedOverMarkers;
+#endif
 };

 } // namespace filament::backend
--- a/filament/backend/src/vulkan/VulkanConstants.h
+++ b/filament/backend/src/vulkan/VulkanConstants.h
@@ -1,7 +1,7 @@
 /*
 * Copyright (C) 2021 The Android Open Source Project
 *
- * Licensed under the Apache License, Version 2.0 (the "License");
+* 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
 *
@@ -63,7 +63,7 @@
 #define FVK_DEBUG_SHADER_MODULE           0x00000800
 #define FVK_DEBUG_READ_PIXELS             0x00001000
 #define FVK_DEBUG_PIPELINE_CACHE          0x00002000
-#define FVK_DEBUG_STAGING_ALLOCATION      0x00004000
+#define FVK_DEBUG_ALLOCATION              0x00004000

 // Enable the debug utils extension if it is available.
 #define FVK_DEBUG_DEBUG_UTILS             0x00008000
@@ -77,12 +77,8 @@
 // order of calls).
 #define FVK_DEBUG_FORCE_LOG_TO_I          0x00020000

-// Enable a minimal set of traces to assess the performance of the backend.
-// All other debug features must be disabled.
-#define FVK_DEBUG_PROFILING               0x00040000
-
 // Useful default combinations
-#define FVK_DEBUG_EVERYTHING              (0xFFFFFFFF & ~FVK_DEBUG_PROFILING)
+#define FVK_DEBUG_EVERYTHING              0xFFFFFFFF
 #define FVK_DEBUG_PERFORMANCE     \
    FVK_DEBUG_SYSTRACE

@@ -98,12 +94,6 @@
 #define FVK_DEBUG_FLAGS 0
 #endif

-// Override the debug flags if we are forcing profiling mode
-#if defined(FILAMENT_FORCE_PROFILING_MODE)
-#undef FVK_DEBUG_FLAGS
-#define FVK_DEBUG_FLAGS (FVK_DEBUG_PROFILING)
-#endif
-
 #define FVK_ENABLED(flags) (((FVK_DEBUG_FLAGS) & (flags)) == (flags))

 // Group marker only works only if validation or debug utils is enabled since it uses
@@ -122,10 +112,6 @@ static_assert(FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS));
 static_assert(FVK_ENABLED(FVK_DEBUG_VALIDATION));
 #endif

-#if FVK_ENABLED(FVK_DEBUG_PROFILING) && FVK_DEBUG_FLAGS != FVK_DEBUG_PROFILING
-#error PROFILING is exclusive; all other debug features must be disabled.
-#endif
-
 // end dependcy checks

 // Shorthand for combination of enabled debug flags
@@ -137,34 +123,17 @@ static_assert(FVK_ENABLED(FVK_DEBUG_VALIDATION));

 // end shorthands

-#if FVK_DEBUG_FLAGS == FVK_DEBUG_PROFILING
+#if FVK_ENABLED(FVK_DEBUG_SYSTRACE)

-    #ifndef NDEBUG
-        #error PROFILING is meaningless in DEBUG mode.
-    #endif
-
-    #define FVK_SYSTRACE_CONTEXT()
-    #define FVK_SYSTRACE_START(marker)
-    #define FVK_SYSTRACE_END()
-    #define FVK_SYSTRACE_SCOPE()
-    #define FVK_PROFILE_MARKER(marker)  PROFILE_SCOPE(marker)
-
-#elif FVK_ENABLED(FVK_DEBUG_SYSTRACE)
-
-    #include <utils/Systrace.h>
-    
-    #define FVK_SYSTRACE_CONTEXT()      SYSTRACE_CONTEXT()
-    #define FVK_SYSTRACE_START(marker)  SYSTRACE_NAME_BEGIN(marker)
-    #define FVK_SYSTRACE_END()          SYSTRACE_NAME_END()
-    #define FVK_SYSTRACE_SCOPE()        SYSTRACE_NAME(__func__)
-    #define FVK_PROFILE_MARKER(marker)  FVK_SYSTRACE_SCOPE()
+#include <utils/Systrace.h>

+#define FVK_SYSTRACE_CONTEXT()      SYSTRACE_CONTEXT()
+#define FVK_SYSTRACE_START(marker)  SYSTRACE_NAME_BEGIN(marker)
+#define FVK_SYSTRACE_END()          SYSTRACE_NAME_END()
 #else
-    #define FVK_SYSTRACE_CONTEXT()
-    #define FVK_SYSTRACE_START(marker)
-    #define FVK_SYSTRACE_END()
-    #define FVK_SYSTRACE_SCOPE()
-    #define FVK_PROFILE_MARKER(marker)
+#define FVK_SYSTRACE_CONTEXT()
+#define FVK_SYSTRACE_START(marker)
+#define FVK_SYSTRACE_END()
 #endif

 #ifndef FVK_HANDLE_ARENA_SIZE_IN_MB
@@ -196,16 +165,14 @@ constexpr static const int FVK_REQUIRED_VERSION_MINOR = 1;
 // buffers that have been submitted but have not yet finished rendering. Note that Filament can
 // issue multiple commit calls in a single frame, and that we use a triple buffered swap chain on
 // some platforms.
-//
-// Heuristic: Triple Buffering (3) multiplied by maximum number of renderpasses (15).
-constexpr static const int FVK_MAX_COMMAND_BUFFERS = 3 * 15;
+constexpr static const int FVK_MAX_COMMAND_BUFFERS = 10;

 // Number of command buffer submissions that should occur before an unused pipeline is removed
 // from the cache.
 //
 // If this number is low, VkPipeline construction will occur frequently, which can
 // be extremely slow. If this number is high, the memory footprint will be large.
-constexpr static const int FVK_MAX_PIPELINE_AGE = FVK_MAX_COMMAND_BUFFERS;
+constexpr static const int FVK_MAX_PIPELINE_AGE = 10;

 // VulkanPipelineCache does not track which command buffers contain references to which pipelines,
 // instead it simply waits for at least FVK_MAX_COMMAND_BUFFERS submissions to occur before
--- a/filament/backend/src/vulkan/VulkanContext.cpp
+++ b/filament/backend/src/vulkan/VulkanContext.cpp
@@ -25,11 +25,15 @@
 #include <backend/PixelBufferDescriptor.h>

 #include <utils/Panic.h>
+#include <utils/FixedCapacityVector.h>

 #include <algorithm> // for std::max

 using namespace bluevk;

+using utils::FixedCapacityVector;
+
+
 namespace {

 } // end anonymous namespace
@@ -82,7 +86,7 @@ VulkanTimestamps::VulkanTimestamps(VkDevice device) : mDevice(device) {
    VkQueryPoolCreateInfo tqpCreateInfo = {
        .sType = VK_STRUCTURE_TYPE_QUERY_POOL_CREATE_INFO,
        .queryType = VK_QUERY_TYPE_TIMESTAMP,
-    };
+    };  
    std::unique_lock<utils::Mutex> lock(mMutex);
    tqpCreateInfo.queryCount = mUsed.size() * 2;
    VkResult result = vkCreateQueryPool(mDevice, &tqpCreateInfo, VKALLOC, &mPool);
@@ -97,7 +101,7 @@ std::tuple<uint32_t, uint32_t> VulkanTimestamps::getNextQuery() {
    for (size_t timerIndex = 0; timerIndex < maxTimers; ++timerIndex) {
        if (!mUsed.test(timerIndex)) {
            mUsed.set(timerIndex);
-            return std::make_tuple(timerIndex * 2, timerIndex * 2 + 1);
+	    return std::make_tuple(timerIndex * 2, timerIndex * 2 + 1);
        }
    }
    FVK_LOGE << "More than " << maxTimers << " timers are not supported." << utils::io::endl;
@@ -109,7 +113,7 @@ void VulkanTimestamps::clearQuery(uint32_t queryIndex) {
 }

 void VulkanTimestamps::beginQuery(VulkanCommandBuffer const* commands,
-        fvkmemory::resource_ptr<VulkanTimerQuery> query) {
+        VulkanTimerQuery* query) {
    uint32_t const index = query->getStartingQueryIndex();

    auto const cmdbuffer = commands->buffer();
@@ -117,24 +121,23 @@ void VulkanTimestamps::beginQuery(VulkanCommandBuffer const* commands,
    vkCmdWriteTimestamp(cmdbuffer, VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, mPool, index);

    // We stash this because getResult might come before the query is actually processed.
-    query->setFence(commands->getFenceStatus());
+    query->setFence(commands->fence);
 }

 void VulkanTimestamps::endQuery(VulkanCommandBuffer const* commands,
-        fvkmemory::resource_ptr<VulkanTimerQuery> query) {
+        VulkanTimerQuery const* query) {
    uint32_t const index = query->getStoppingQueryIndex();
    vkCmdWriteTimestamp(commands->buffer(), VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, mPool, index);
 }

-VulkanTimestamps::QueryResult VulkanTimestamps::getResult(
-        fvkmemory::resource_ptr<VulkanTimerQuery> query) {
+VulkanTimestamps::QueryResult VulkanTimestamps::getResult(VulkanTimerQuery const* query) {
    uint32_t const index = query->getStartingQueryIndex();
    QueryResult result;
    size_t const dataSize = result.size() * sizeof(uint64_t);
    VkDeviceSize const stride = sizeof(uint64_t) * 2;
    VkResult vkresult =
-            vkGetQueryPoolResults(mDevice, mPool, index, 2, dataSize, (void*) result.data(), stride,
-                    VK_QUERY_RESULT_64_BIT | VK_QUERY_RESULT_WITH_AVAILABILITY_BIT);
+            vkGetQueryPoolResults(mDevice, mPool, index, 2, dataSize, (void*) result.data(),
+                    stride, VK_QUERY_RESULT_64_BIT | VK_QUERY_RESULT_WITH_AVAILABILITY_BIT);
    FILAMENT_CHECK_POSTCONDITION(vkresult == VK_SUCCESS || vkresult == VK_NOT_READY)
            << "vkGetQueryPoolResults error: " << static_cast<int32_t>(vkresult);
    if (vkresult == VK_NOT_READY) {
--- a/filament/backend/src/vulkan/VulkanContext.h
+++ b/filament/backend/src/vulkan/VulkanContext.h
@@ -21,8 +21,6 @@
 #include "VulkanImageUtility.h"
 #include "VulkanUtility.h"

-#include "vulkan/memory/ResourcePointer.h"
-
 #include <utils/bitset.h>
 #include <utils/FixedCapacityVector.h>
 #include <utils/Mutex.h>
@@ -43,10 +41,11 @@ struct VulkanTimerQuery;
 struct VulkanCommandBuffer;

 struct VulkanAttachment {
-    fvkmemory::resource_ptr<VulkanTexture> texture;
+    VulkanTexture* texture = nullptr;
    uint8_t level = 0;
+    uint8_t baseViewIndex = 0;
    uint8_t layerCount = 1;
-    uint8_t layer = 0;
+    uint16_t layer = 0;

    bool isDepth() const;
    VkImage getImage() const;
@@ -72,11 +71,9 @@ public:
    std::tuple<uint32_t, uint32_t> getNextQuery();
    void clearQuery(uint32_t queryIndex);

-    void beginQuery(VulkanCommandBuffer const* commands,
-            fvkmemory::resource_ptr<VulkanTimerQuery> query);
-    void endQuery(VulkanCommandBuffer const* commands,
-            fvkmemory::resource_ptr<VulkanTimerQuery> query);
-    QueryResult getResult(fvkmemory::resource_ptr<VulkanTimerQuery> query);
+    void beginQuery(VulkanCommandBuffer const* commands, VulkanTimerQuery* query);
+    void endQuery(VulkanCommandBuffer const* commands, VulkanTimerQuery const* query);
+    QueryResult getResult(VulkanTimerQuery const* query);

 private:
    VkDevice mDevice;
@@ -86,9 +83,7 @@ private:
 };

 struct VulkanRenderPass {
-    // Between the begin and end command render pass we cache the command buffer
-    VulkanCommandBuffer* commandBuffer;
-    fvkmemory::resource_ptr<VulkanRenderTarget> renderTarget;
+    VulkanRenderTarget* renderTarget;
    VkRenderPass renderPass;
    RenderPassParams params;
    int currentSubpass;
@@ -99,9 +94,6 @@ struct VulkanRenderPass {
 struct VulkanContext {
 public:
    inline uint32_t selectMemoryType(uint32_t flags, VkFlags reqs) const {
-        if ((reqs & VK_MEMORY_PROPERTY_PROTECTED_BIT) != 0) {
-            assert_invariant(isProtectedMemorySupported() == true);
-        }
        for (uint32_t i = 0; i < VK_MAX_MEMORY_TYPES; i++) {
            if (flags & 1) {
                if ((mMemoryProperties.memoryTypes[i].propertyFlags & reqs) == reqs) {
@@ -122,19 +114,19 @@ public:
    }

    inline VkPhysicalDeviceLimits const& getPhysicalDeviceLimits() const noexcept {
-        return mPhysicalDeviceProperties.properties.limits;
+        return mPhysicalDeviceProperties.limits;
    }

    inline uint32_t getPhysicalDeviceVendorId() const noexcept {
-        return mPhysicalDeviceProperties.properties.vendorID;
+        return mPhysicalDeviceProperties.vendorID;
    }

    inline bool isImageCubeArraySupported() const noexcept {
-        return mPhysicalDeviceFeatures.features.imageCubeArray == VK_TRUE;
+        return mPhysicalDeviceFeatures.imageCubeArray == VK_TRUE;
    }

    inline bool isDepthClampSupported() const noexcept {
-        return mPhysicalDeviceFeatures.features.depthClamp == VK_TRUE;
+        return mPhysicalDeviceFeatures.depthClamp == VK_TRUE;
    }

    inline bool isDebugMarkersSupported() const noexcept {
@@ -150,30 +142,16 @@ public:
    }

    inline bool isClipDistanceSupported() const noexcept {
-        return mPhysicalDeviceFeatures.features.shaderClipDistance == VK_TRUE;
-    }
-
-    inline bool isLazilyAllocatedMemorySupported() const noexcept {
-        return mLazilyAllocatedMemorySupported;
-    }
-
-    inline bool isProtectedMemorySupported() const noexcept {
-        return mProtectedMemorySupported;
+        return mPhysicalDeviceFeatures.shaderClipDistance == VK_TRUE;
    }

 private:
    VkPhysicalDeviceMemoryProperties mMemoryProperties = {};
-    VkPhysicalDeviceProperties2 mPhysicalDeviceProperties = {
-        .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_PROPERTIES_2
-    };
-    VkPhysicalDeviceFeatures2 mPhysicalDeviceFeatures = {
-        .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_FEATURES_2
-    };
+    VkPhysicalDeviceProperties mPhysicalDeviceProperties = {};
+    VkPhysicalDeviceFeatures mPhysicalDeviceFeatures = {};
    bool mDebugMarkersSupported = false;
    bool mDebugUtilsSupported = false;
    bool mMultiviewEnabled = false;
-    bool mLazilyAllocatedMemorySupported = false;
-    bool mProtectedMemorySupported = false;

    VkFormatList mDepthStencilFormats;
    VkFormatList mBlittableDepthStencilFormats;
--- a/filament/backend/src/vulkan/VulkanDriver.cpp
+++ b/filament/backend/src/vulkan/VulkanDriver.cpp
--- a/filament/backend/src/vulkan/VulkanDriver.h
+++ b/filament/backend/src/vulkan/VulkanDriver.h
@@ -24,14 +24,13 @@
 #include "VulkanHandles.h"
 #include "VulkanPipelineCache.h"
 #include "VulkanReadPixels.h"
+#include "VulkanResourceAllocator.h"
 #include "VulkanSamplerCache.h"
 #include "VulkanStagePool.h"
 #include "VulkanUtility.h"
 #include "backend/DriverEnums.h"
 #include "caching/VulkanDescriptorSetManager.h"
 #include "caching/VulkanPipelineLayoutCache.h"
-#include "memory/ResourceManager.h"
-#include "memory/ResourcePointer.h"

 #include "DriverBase.h"
 #include "private/backend/Driver.h"
@@ -48,6 +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,
@@ -78,9 +92,6 @@ public:
 #endif // FVK_ENABLED(FVK_DEBUG_DEBUG_UTILS)

 private:
-    template<typename D>
-    using resource_ptr = fvkmemory::resource_ptr<D>;
-
    static constexpr uint8_t MAX_SAMPLER_BINDING_COUNT = Program::SAMPLER_BINDING_COUNT;

    void debugCommandBegin(CommandStream* cmds, bool synchronous,
@@ -117,16 +128,25 @@ private:
    void collectGarbage();

    VulkanPlatform* mPlatform = nullptr;
-    fvkmemory::ResourceManager mResourceManager;
    std::unique_ptr<VulkanTimestamps> mTimestamps;

-    resource_ptr<VulkanSwapChain> mCurrentSwapChain;
-    resource_ptr<VulkanRenderTarget> mDefaultRenderTarget;
+    // Placeholder resources
+    VulkanTexture* mEmptyTexture;
+    VulkanBufferObject* mEmptyBufferObject;
+
+    VulkanSwapChain* mCurrentSwapChain = nullptr;
+    VulkanRenderTarget* mDefaultRenderTarget = nullptr;
    VulkanRenderPass mCurrentRenderPass = {};
    VmaAllocator mAllocator = VK_NULL_HANDLE;
    VkDebugReportCallbackEXT mDebugCallback = VK_NULL_HANDLE;

    VulkanContext mContext = {};
+    VulkanResourceAllocator mResourceAllocator;
+    VulkanResourceManager mResourceManager;
+
+    // Used for resources that are created synchronously and used and destroyed on the backend
+    // thread.
+    VulkanThreadSafeResourceManager mThreadSafeResourceManager;

    VulkanCommands mCommands;
    VulkanPipelineLayoutCache mPipelineLayoutCache;
@@ -139,19 +159,15 @@ private:
    VulkanReadPixels mReadPixels;
    VulkanDescriptorSetManager mDescriptorSetManager;

-    // This is necessary for us to write to push constants after binding a pipeline.
-    struct {
-        resource_ptr<VulkanProgram> program;
-        VkPipelineLayout pipelineLayout;
-        DescriptorSetMask descriptorSetMask;
-    } mBoundPipeline = {};
+    VulkanDescriptorSetManager::GetPipelineLayoutFunction mGetPipelineFunction;

-    // 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 = {};
+    // This is necessary for us to write to push constants after binding a pipeline.
+    struct BoundPipeline {
+        VulkanProgram* program;
+        VkPipelineLayout pipelineLayout;
+    };
+    BoundPipeline mBoundPipeline = {};
+    RenderPassFboBundle mRenderPassFboInfo;

    bool const mIsSRGBSwapChainSupported;
    backend::StereoscopicType const mStereoscopicType;
--- a/filament/backend/src/vulkan/VulkanFboCache.cpp
+++ b/filament/backend/src/vulkan/VulkanFboCache.cpp
@@ -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;
@@ -69,8 +69,8 @@ VulkanFboCache::~VulkanFboCache() {
            << "Please explicitly call terminate() while the VkDevice is still alive.";
 }

-VkFramebuffer VulkanFboCache::getFramebuffer(FboKey const& config) noexcept {
-    FboMap::iterator iter = mFramebufferCache.find(config);
+VkFramebuffer VulkanFboCache::getFramebuffer(FboKey config) noexcept {
+    auto iter = mFramebufferCache.find(config);
    if (UTILS_LIKELY(iter != mFramebufferCache.end() && iter->second.handle != VK_NULL_HANDLE)) {
        iter.value().timestamp = mCurrentTime;
        return iter->second.handle;
@@ -121,7 +121,7 @@ VkFramebuffer VulkanFboCache::getFramebuffer(FboKey const& config) noexcept {
    return framebuffer;
 }

-VkRenderPass VulkanFboCache::getRenderPass(RenderPassKey const& config) noexcept {
+VkRenderPass VulkanFboCache::getRenderPass(RenderPassKey config) noexcept {
    auto iter = mRenderPassCache.find(config);
    if (UTILS_LIKELY(iter != mRenderPassCache.end() && iter->second.handle != VK_NULL_HANDLE)) {
        iter.value().timestamp = mCurrentTime;
@@ -255,10 +255,12 @@ VkRenderPass VulkanFboCache::getRenderPass(RenderPassKey const& 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),
        };
    }
@@ -362,7 +364,7 @@ void VulkanFboCache::gc() noexcept {
    }
    const uint32_t evictTime = mCurrentTime - TIME_BEFORE_EVICTION;

-    for (FboMap::iterator iter = mFramebufferCache.begin(); iter != mFramebufferCache.end(); ++iter) {
+    for (auto iter = mFramebufferCache.begin(); iter != mFramebufferCache.end(); ++iter) {
        const FboVal fbo = iter->second;
        if (fbo.timestamp < evictTime && fbo.handle) {
            mRenderPassRefCount[iter->first.renderPass]--;
--- a/filament/backend/src/vulkan/VulkanFboCache.h
+++ b/filament/backend/src/vulkan/VulkanFboCache.h
@@ -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.");
@@ -98,10 +109,10 @@ public:
    ~VulkanFboCache();

    // Retrieves or creates a VkFramebuffer handle.
-    VkFramebuffer getFramebuffer(FboKey const& config) noexcept;
+    VkFramebuffer getFramebuffer(FboKey config) noexcept;

    // Retrieves or creates a VkRenderPass handle.
-    VkRenderPass getRenderPass(RenderPassKey const& config) noexcept;
+    VkRenderPass getRenderPass(RenderPassKey config) noexcept;

    // Evicts old unused Vulkan objects. Call this once per frame.
    void gc() noexcept;
@@ -111,9 +122,7 @@ public:

 private:
    VkDevice mDevice;
-    using FboMap = tsl::robin_map<FboKey, FboVal, FboKeyHashFn, FboKeyEqualFn>;
-    FboMap mFramebufferCache;
-
+    tsl::robin_map<FboKey, FboVal, FboKeyHashFn, FboKeyEqualFn> mFramebufferCache;
    tsl::robin_map<RenderPassKey, RenderPassVal, RenderPassHash, RenderPassEq> mRenderPassCache;
    tsl::robin_map<VkRenderPass, uint32_t> mRenderPassRefCount;
    uint32_t mCurrentTime = 0;
--- a/filament/backend/src/vulkan/VulkanHandles.cpp
+++ b/filament/backend/src/vulkan/VulkanHandles.cpp
@@ -16,15 +16,13 @@

 #include "VulkanHandles.h"

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

 #include <backend/platforms/VulkanPlatform.h>

@@ -36,12 +34,15 @@ namespace filament::backend {

 namespace {

+void flipVertically(VkRect2D* rect, uint32_t framebufferHeight) {
+    rect->offset.y = framebufferHeight - rect->offset.y - rect->extent.height;
+}
+
 void flipVertically(VkViewport* rect, uint32_t framebufferHeight) {
    rect->y = framebufferHeight - rect->y - rect->height;
 }

 void clampToFramebuffer(VkRect2D* rect, uint32_t fbWidth, uint32_t fbHeight) {
-    rect->offset.y = fbHeight - rect->offset.y - rect->extent.height;
    int32_t x = std::max(rect->offset.x, 0);
    int32_t y = std::max(rect->offset.y, 0);
    int32_t right = std::min(rect->offset.x + (int32_t) rect->extent.width, (int32_t) fbWidth);
@@ -53,14 +54,62 @@ 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) {
@@ -74,72 +123,22 @@ 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;
-            }
-            // TODO: properly handle external sampler
-            case DescriptorType::SAMPLER_EXTERNAL:
-            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;
-}
-
-fvkmemory::resource_ptr<VulkanTexture> initMsaaTexture(
-        fvkmemory::resource_ptr<VulkanTexture> texture, VkDevice device,
-        VkPhysicalDevice physicalDevice, VulkanContext const& context, VmaAllocator allocator,
-        VulkanCommands* commands, fvkmemory::ResourceManager* resManager, uint8_t levels,
-        uint8_t samples, VulkanStagePool& stagePool) {
-    assert_invariant(texture);
-    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);
-
-        msTexture = resource_ptr<VulkanTexture>::construct(resManager, device, physicalDevice,
-                context, allocator, resManager, commands, texture->target, levels, texture->format,
-                samples, texture->width, texture->height, texture->depth, usage, stagePool);
-        texture->setSidecar(msTexture);
-    }
-    return msTexture;
-}
-
 } // anonymous namespace

-void VulkanDescriptorSet::acquire(fvkmemory::resource_ptr<VulkanTexture> texture) {
-    mResources.push_back(texture);
-}

-void VulkanDescriptorSet::acquire(fvkmemory::resource_ptr<VulkanBufferObject> obj) {
-    mResources.push_back(obj);
-}
-
-VulkanDescriptorSetLayout::VulkanDescriptorSetLayout(DescriptorSetLayout const& layout)
-    : bitmask(fromBackendLayout(layout)),
+VulkanDescriptorSetLayout::VulkanDescriptorSetLayout(VkDevice device,
+        VkDescriptorSetLayoutCreateInfo const& info, Bitmask const& bitmask)
+    : VulkanResource(VulkanResourceType::DESCRIPTOR_SET_LAYOUT),
+      mDevice(device),
+      vklayout(createDescriptorSetLayout(device, info)),
+      bitmask(bitmask),
+      bindings(getBindings(bitmask)),
      count(Count::fromLayoutBitmask(bitmask)) {}

+VulkanDescriptorSetLayout::~VulkanDescriptorSetLayout() {
+    vkDestroyDescriptorSetLayout(mDevice, vklayout, VKALLOC);
+}
+
 PushConstantDescription::PushConstantDescription(backend::Program const& program) noexcept {
    mRangeCount = 0;
    for (auto stage : { ShaderStage::VERTEX, ShaderStage::FRAGMENT, ShaderStage::COMPUTE }) {
@@ -163,9 +162,9 @@ PushConstantDescription::PushConstantDescription(backend::Program const& program
    }
 }

-void PushConstantDescription::write(VkCommandBuffer cmdbuf, VkPipelineLayout layout,
+void PushConstantDescription::write(VulkanCommands* commands, VkPipelineLayout layout,
        backend::ShaderStage stage, uint8_t index, backend::PushConstantVariant const& value) {
-
+    VulkanCommandBuffer* cmdbuf = &(commands->get());
    uint32_t binaryValue = 0;
    UTILS_UNUSED_IN_RELEASE auto const& types = mTypes[(uint8_t) stage];
    if (std::holds_alternative<bool>(value)) {
@@ -181,20 +180,34 @@ void PushConstantDescription::write(VkCommandBuffer cmdbuf, VkPipelineLayout lay
        int const ival = std::get<int>(value);
        binaryValue = *reinterpret_cast<uint32_t const*>(&ival);
    }
-    vkCmdPushConstants(cmdbuf, layout, getVkStage(stage), index * ENTRY_SIZE, ENTRY_SIZE,
+    vkCmdPushConstants(cmdbuf->buffer(), layout, getVkStage(stage), index * ENTRY_SIZE, ENTRY_SIZE,
            &binaryValue);
 }

 VulkanProgram::VulkanProgram(VkDevice device, Program const& builder) noexcept
    : HwProgram(builder.getName()),
+      VulkanResource(VulkanResourceType::PROGRAM),
      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);
@@ -211,6 +224,12 @@ 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,
@@ -238,6 +257,40 @@ 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;
@@ -252,239 +305,150 @@ VulkanProgram::~VulkanProgram() {
 }

 // Creates a special "default" render target (i.e. associated with the swap chain)
-VulkanRenderTarget::VulkanRenderTarget()
-    : HwRenderTarget(0, 0),
-      mOffscreen(false),
-      mProtected(false),
-      mInfo(std::make_unique<Auxiliary>()) {
-    mInfo->rpkey.samples = mInfo->fbkey.samples = 1;
-}
+VulkanRenderTarget::VulkanRenderTarget() :
+    HwRenderTarget(0, 0),
+    VulkanResource(VulkanResourceType::RENDER_TARGET),
+    mOffscreen(false), mSamples(1) {}

-VulkanRenderTarget::~VulkanRenderTarget() = default;
-
-void VulkanRenderTarget::bindToSwapChain(fvkmemory::resource_ptr<VulkanSwapChain> swapchain) {
+void VulkanRenderTarget::bindToSwapChain(VulkanSwapChain& swapChain) {
    assert_invariant(!mOffscreen);
-
-    VkExtent2D const extent = swapchain->getExtent();
+    VkExtent2D const extent = swapChain.getExtent();
+    mColor[0] = { .texture = swapChain.getCurrentColor() };
+    mDepth = { .texture = swapChain.getDepth() };
    width = extent.width;
    height = extent.height;
-    mProtected = swapchain->isProtected();
-
-    VulkanAttachment color = {};
-    color.texture = swapchain->getCurrentColor();
-    mInfo->attachments = {color};
-
-    auto& fbkey = mInfo->fbkey;
-    auto& rpkey = mInfo->rpkey;
-
-    rpkey.colorFormat[0] = color.getFormat();
-    fbkey.width = width;
-    fbkey.height = height;
-    fbkey.color[0] = color.getImageView();
-    fbkey.resolve[0] = VK_NULL_HANDLE;
-
-    if (swapchain->getDepth()) {
-        VulkanAttachment depth = {};
-        depth.texture = swapchain->getDepth();
-        mInfo->attachments.push_back(depth);
-        mInfo->depthIndex = 1;
-
-        rpkey.depthFormat = depth.getFormat();
-        fbkey.depth = depth.getImageView();
-    } else {
-        rpkey.depthFormat = VK_FORMAT_UNDEFINED;
-        fbkey.depth = VK_NULL_HANDLE;
-    }
-    mInfo->colors.set(0);
 }

 VulkanRenderTarget::VulkanRenderTarget(VkDevice device, VkPhysicalDevice physicalDevice,
-        VulkanContext const& context, fvkmemory::ResourceManager* resourceManager,
-        VmaAllocator allocator, VulkanCommands* commands, uint32_t width, uint32_t height,
-        uint8_t samples, VulkanAttachment color[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT],
+        VulkanContext const& context, VmaAllocator allocator, 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)
    : HwRenderTarget(width, height),
+      VulkanResource(VulkanResourceType::RENDER_TARGET),
      mOffscreen(true),
-      mProtected(false),
-      mInfo(std::make_unique<Auxiliary>()) {
-    auto& depth = depthStencil[0];
+      mSamples(samples),
+      mLayerCount(layerCount) {
+    for (int index = 0; index < MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT; index++) {
+        mColor[index] = color[index];
+    }
+    mDepth = depthStencil[0];
+    VulkanTexture* depthTexture = (VulkanTexture*) mDepth.texture;
+
+    if (samples == 1) {
+        return;
+    }

    // Constrain the sample count according to both kinds of sample count masks obtained from
    // VkPhysicalDeviceProperties. This is consistent with the VulkanTexture constructor.
    auto const& limits = context.getPhysicalDeviceLimits();
-    samples = reduceSampleCount(samples, limits.framebufferDepthSampleCounts &
+    mSamples = samples = reduceSampleCount(samples, limits.framebufferDepthSampleCounts &
            limits.framebufferColorSampleCounts);

-    auto& rpkey = mInfo->rpkey;
-    rpkey.samples = samples;
-    rpkey.depthFormat = depth.getFormat();
-    rpkey.viewCount = layerCount;
-
-    auto& fbkey = mInfo->fbkey;
-    fbkey.width = width;
-    fbkey.height = height;
-    fbkey.samples = samples;
-
-    std::vector<VulkanAttachment>& attachments = mInfo->attachments;
-    std::vector<VulkanAttachment> msaa;
-
+    // Create sidecar MSAA textures for color attachments if they don't already exist.
    for (int index = 0; index < MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT; index++) {
-        VulkanAttachment& attachment = color[index];
-        auto texture = attachment.texture;
-        if (!texture) {
-            rpkey.colorFormat[index] = VK_FORMAT_UNDEFINED;
-            continue;
-        }
-
-        mProtected |= texture->getIsProtected();
-
-        attachments.push_back(attachment);
-        mInfo->colors.set(index);
-
-        rpkey.colorFormat[index] = attachment.getFormat();
-        fbkey.color[index] = attachment.getImageView();
-        fbkey.resolve[index] = VK_NULL_HANDLE;
-
-        if (samples > 1) {
-            VulkanAttachment msaaAttachment = {};
-            if (texture->samples == 1) {
-                auto msaaTexture = initMsaaTexture(texture, device, physicalDevice, context,
-                        allocator, commands, resourceManager, texture->levels, samples, stagePool);
-                if (msaaTexture && msaaTexture->isTransientAttachment()) {
-                    rpkey.usesLazilyAllocatedMemory |= (1 << index);
-                }
-                if (attachment.texture->samples == 1) {
-                    rpkey.needsResolveMask |= (1 << index);
-                }
-                msaaAttachment = {
-                    .texture = msaaTexture,
-                    .layerCount = layerCount,
-                };
-
-                fbkey.resolve[index] = attachment.getImageView();
-            } else {
-                msaaAttachment = {
-                    .texture = texture,
-                    .layerCount = layerCount,
-                };
+        VulkanAttachment const& spec = color[index];
+        VulkanTexture* texture = (VulkanTexture*) spec.texture;
+        if (texture && texture->samples == 1) {
+            auto msTexture = texture->getSidecar();
+            if (UTILS_UNLIKELY(!msTexture)) {
+                // TODO: This should be allocated with the ResourceAllocator.
+                msTexture = new VulkanTexture(device, physicalDevice, context, allocator, commands,
+                        texture->target, ((VulkanTexture const*) texture)->levels, texture->format,
+                        samples, texture->width, texture->height, texture->depth, texture->usage,
+                        stagePool, true /* heap allocated */);
+                texture->setSidecar(msTexture);
            }
-            fbkey.color[index] = msaaAttachment.getImageView();
-            msaa.push_back(msaaAttachment);
+            mMsaaAttachments[index] = {.texture = msTexture};
+        }
+        if (texture && texture->samples > 1) {
+            mMsaaAttachments[index] = mColor[index];
        }
    }

-    if (attachments.size() > 0 && samples > 1 && msaa.size() > 0) {
-        mInfo->msaaIndex = (uint8_t) attachments.size();
-        attachments.insert(attachments.end(), msaa.begin(), msaa.end());
+    if (!depthTexture) {
+        return;
    }

-    if (depth.texture) {
-        auto depthTexture = depth.texture;
-        mInfo->depthIndex = (uint8_t) attachments.size();
-        attachments.push_back(depth);
-        fbkey.depth = depth.getImageView();
-        if (samples > 1) {
-            mInfo->msaaDepthIndex = mInfo->depthIndex;
-            if (depthTexture->samples == 1) {
-                // MSAA depth texture must have the mipmap count of 1
-                uint8_t const msLevel = 1;
-                // Create sidecar MSAA texture for the depth attachment if it does not already
-                // exist.
-                auto msaa = initMsaaTexture(depthTexture, device, physicalDevice, context,
-                        allocator, commands, resourceManager, msLevel, samples, stagePool);
-                mInfo->msaaDepthIndex = (uint8_t) attachments.size();
-                attachments.push_back({ .texture = msaa, .layerCount = layerCount });
-            }
-        }
+    // There is no need for sidecar depth if the depth texture is already MSAA.
+    if (depthTexture->samples > 1) {
+        mMsaaDepthAttachment = mDepth;
+        return;
    }
+
+    // MSAA depth texture must have the mipmap count of 1
+    uint8_t const msLevel = 1;
+
+    // Create sidecar MSAA texture for the depth attachment if it does not already exist.
+    VulkanTexture* msTexture = depthTexture->getSidecar();
+    if (UTILS_UNLIKELY(!msTexture)) {
+        msTexture = new VulkanTexture(device, physicalDevice, context, allocator,
+                commands, depthTexture->target, msLevel, depthTexture->format, samples,
+                depthTexture->width, depthTexture->height, depthTexture->depth, depthTexture->usage,
+                stagePool, true /* heap allocated */);
+        depthTexture->setSidecar(msTexture);
+    }
+
+    mMsaaDepthAttachment = {
+        .texture = msTexture,
+        .level = msLevel,
+        .layer = mDepth.layer,
+    };
 }

 void VulkanRenderTarget::transformClientRectToPlatform(VkRect2D* bounds) const {
-    auto const& extent = getExtent();
+    const auto& extent = getExtent();
+    flipVertically(bounds, extent.height);
    clampToFramebuffer(bounds, extent.width, extent.height);
 }

-void VulkanRenderTarget::transformViewportToPlatform(VkViewport* bounds) const {
+void VulkanRenderTarget::transformClientRectToPlatform(VkViewport* bounds) const {
    flipVertically(bounds, getExtent().height);
 }

+VkExtent2D VulkanRenderTarget::getExtent() const {
+    return {width, height};
+}
+
+VulkanAttachment& VulkanRenderTarget::getColor(int target) {
+    return mColor[target];
+}
+
+VulkanAttachment& VulkanRenderTarget::getMsaaColor(int target) {
+    return mMsaaAttachments[target];
+}
+
+VulkanAttachment& VulkanRenderTarget::getDepth() {
+    return mDepth;
+}
+
+VulkanAttachment& VulkanRenderTarget::getMsaaDepth() {
+    return mMsaaDepthAttachment;
+}
+
 uint8_t VulkanRenderTarget::getColorTargetCount(const VulkanRenderPass& pass) const {
    if (!mOffscreen) {
        return 1;
    }
-    if (pass.currentSubpass == 1) {
-        return mInfo->colors.count();
-    }
    uint8_t count = 0;
-    mInfo->colors.forEachSetBit([&count, &pass](size_t index) {
-        if (!(pass.params.subpassMask & (1 << index))) {
+    for (uint8_t i = 0; i < MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT; i++) {
+        if (!mColor[i].texture) {
+            continue;
+        }
+        // NOTE: This must be consistent with VkRenderPass construction (see VulkanFboCache).
+        if (!(pass.params.subpassMask & (1 << i)) || pass.currentSubpass == 1) {
            count++;
        }
-    });
+    }
    return count;
 }

-void VulkanRenderTarget::emitBarriersBeginRenderPass(VulkanCommandBuffer& commands) {
-    auto& attachments = mInfo->attachments;
-    auto samples = mInfo->fbkey.samples;
-    auto barrier = [&commands](VulkanAttachment& attachment, VulkanLayout const layout) {
-        auto tex = attachment.texture;
-        auto const& range = attachment.getSubresourceRange();
-        if (tex->getLayout(range.baseMipLevel, range.baseArrayLayer) != layout &&
-                !tex->transitionLayout(&commands, range, layout)) {
-            // If the layout transition did not emit a barrier, we do it manually here.
-            tex->samplerToAttachmentBarrier(&commands, range);
-        }
-    };
-
-    for (size_t i = 0, count = mInfo->colors.count(); i < count; ++i) {
-        auto& attachment = attachments[i];
-        auto tex = attachment.texture;
-        if (samples == 1 || tex->samples == 1) {
-            barrier(attachment, VulkanLayout::COLOR_ATTACHMENT);
-        }
-    }
-    if (mInfo->msaaIndex != Auxiliary::UNDEFINED_INDEX) {
-        for (size_t i = mInfo->msaaIndex, count = mInfo->msaaIndex + mInfo->colors.count();
-                i < count; ++i) {
-            barrier(attachments[i], VulkanLayout::COLOR_ATTACHMENT);
-        }
-    }
-    if (mInfo->depthIndex != Auxiliary::UNDEFINED_INDEX) {
-        barrier(attachments[mInfo->depthIndex], VulkanLayout::DEPTH_ATTACHMENT);
-    }
-    if (mInfo->msaaDepthIndex != Auxiliary::UNDEFINED_INDEX) {
-        barrier(attachments[mInfo->msaaDepthIndex], VulkanLayout::DEPTH_ATTACHMENT);
-    }
-}
-
-void VulkanRenderTarget::emitBarriersEndRenderPass(VulkanCommandBuffer& commands) {
-    if (isSwapChain()) {
-        return;
-    }
-
-    for (auto& attachment: mInfo->attachments) {
-        auto const& range = attachment.getSubresourceRange();
-        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);
-            }
-        }
-    }
-}
-
 VulkanVertexBufferInfo::VulkanVertexBufferInfo(
        uint8_t bufferCount, uint8_t attributeCount, AttributeArray const& attributes)
    : HwVertexBufferInfo(bufferCount, attributeCount),
+      VulkanResource(VulkanResourceType::VERTEX_BUFFER_INFO),
      mInfo(attributes.size()) {
+
    auto attribDesc = mInfo.mSoa.data<PipelineInfo::ATTRIBUTE_DESCRIPTION>();
    auto bufferDesc = mInfo.mSoa.data<PipelineInfo::BUFFER_DESCRIPTION>();
    auto offsets = mInfo.mSoa.data<PipelineInfo::OFFSETS>();
@@ -522,15 +486,19 @@ VulkanVertexBufferInfo::VulkanVertexBufferInfo(
 }

 VulkanVertexBuffer::VulkanVertexBuffer(VulkanContext& context, VulkanStagePool& stagePool,
-        uint32_t vertexCount, fvkmemory::resource_ptr<VulkanVertexBufferInfo> vbi)
+        VulkanResourceAllocator* allocator,
+        uint32_t vertexCount, Handle<HwVertexBufferInfo> vbih)
    : HwVertexBuffer(vertexCount),
-      vbi(vbi),
-      // TODO: Seems a bit wasteful. can we do better here?
-      mBuffers(MAX_VERTEX_BUFFER_COUNT) {
+      VulkanResource(VulkanResourceType::VERTEX_BUFFER),
+      vbih(vbih),
+      mBuffers(MAX_VERTEX_BUFFER_COUNT), // TODO: can we do better here?
+      mResources(allocator) {
 }

-void VulkanVertexBuffer::setBuffer(fvkmemory::resource_ptr<VulkanBufferObject> bufferObject,
-        uint32_t index) {
+void VulkanVertexBuffer::setBuffer(VulkanResourceAllocator const& allocator,
+        VulkanBufferObject* bufferObject, uint32_t index) {
+    VulkanVertexBufferInfo const* const vbi =
+            const_cast<VulkanResourceAllocator&>(allocator).handle_cast<VulkanVertexBufferInfo*>(vbih);
    size_t const count = vbi->getAttributeCount();
    VkBuffer* const vkbuffers = getVkBuffers();
    int8_t const* const attribToBuffer = vbi->getAttributeToBuffer();
@@ -539,20 +507,87 @@ void VulkanVertexBuffer::setBuffer(fvkmemory::resource_ptr<VulkanBufferObject> b
            vkbuffers[attribIndex] = bufferObject->buffer.getGpuBuffer();
        }
    }
-    mResources.push_back(bufferObject);
+    mResources.acquire(bufferObject);
 }

 VulkanBufferObject::VulkanBufferObject(VmaAllocator allocator, VulkanStagePool& stagePool,
        uint32_t byteCount, BufferObjectBinding bindingType)
    : HwBufferObject(byteCount),
+      VulkanResource(VulkanResourceType::BUFFER_OBJECT),
      buffer(allocator, stagePool, getBufferObjectUsage(bindingType), byteCount),
      bindingType(bindingType) {}

-VulkanRenderPrimitive::VulkanRenderPrimitive(PrimitiveType pt,
-        fvkmemory::resource_ptr<VulkanVertexBuffer> vb,
-        fvkmemory::resource_ptr<VulkanIndexBuffer> ib)
-    : HwRenderPrimitive{.type = pt},
-      vertexBuffer(vb),
-      indexBuffer(ib) {}
+VulkanTimerQuery::VulkanTimerQuery(std::tuple<uint32_t, uint32_t> indices)
+    : VulkanThreadSafeResource(VulkanResourceType::TIMER_QUERY),
+      mStartingQueryIndex(std::get<0>(indices)),
+      mStoppingQueryIndex(std::get<1>(indices)) {}
+
+void VulkanTimerQuery::setFence(std::shared_ptr<VulkanCmdFence> fence) noexcept {
+    std::unique_lock<utils::Mutex> lock(mFenceMutex);
+    mFence = fence;
+}
+
+bool VulkanTimerQuery::isCompleted() noexcept {
+    std::unique_lock<utils::Mutex> lock(mFenceMutex);
+    // QueryValue is a synchronous call and might occur before beginTimerQuery has written anything
+    // into the command buffer, which is an error according to the validation layer that ships in
+    // the Android NDK.  Even when AVAILABILITY_BIT is set, validation seems to require that the
+    // timestamp has at least been written into a processed command buffer.
+
+    // This fence indicates that the corresponding buffer has been completed.
+    if (!mFence) {
+        return false;
+    }
+    VkResult status = mFence->status.load(std::memory_order_relaxed);
+    if (status != VK_SUCCESS) {
+        return false;
+    }
+
+    return true;
+}
+
+VulkanTimerQuery::~VulkanTimerQuery() = default;
+
+VulkanRenderPrimitive::VulkanRenderPrimitive(VulkanResourceAllocator* resourceAllocator,
+        PrimitiveType pt, Handle<HwVertexBuffer> vbh, Handle<HwIndexBuffer> ibh)
+        : VulkanResource(VulkanResourceType::RENDER_PRIMITIVE),
+          mResources(resourceAllocator) {
+    type = pt;
+    vertexBuffer = resourceAllocator->handle_cast<VulkanVertexBuffer*>(vbh);
+    indexBuffer = resourceAllocator->handle_cast<VulkanIndexBuffer*>(ibh);
+    mResources.acquire(vertexBuffer);
+    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
--- a/filament/backend/src/vulkan/VulkanHandles.h
+++ b/filament/backend/src/vulkan/VulkanHandles.h
@@ -20,64 +20,48 @@
 // This needs to be at the top
 #include "DriverBase.h"

-#include "VulkanAsyncHandles.h"
 #include "VulkanBuffer.h"
-#include "VulkanFboCache.h"
+#include "VulkanResources.h"
 #include "VulkanSwapChain.h"
 #include "VulkanTexture.h"
 #include "VulkanUtility.h"
-#include "vulkan/memory/Resource.h"

+#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>

-#include <array>
-
 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 HwDescriptorSetLayout, fvkmemory::Resource {
-    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.
@@ -87,10 +71,6 @@ struct VulkanDescriptorSetLayout : public HwDescriptorSetLayout, fvkmemory::Reso
        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;
@@ -98,10 +78,10 @@ struct VulkanDescriptorSetLayout : public HwDescriptorSetLayout, fvkmemory::Reso

        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)),
            };
        }

@@ -117,71 +97,101 @@ struct VulkanDescriptorSetLayout : public HwDescriptorSetLayout, fvkmemory::Reso
        }
    };

-    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 HwDescriptorSet, fvkmemory::Resource {
+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(VkDescriptorSet rawSet,
-            UniformBufferBitmask const& dynamicUboMask,
-            uint8_t uniqueDynamicUboCount,
-            OnRecycle&& onRecycleFn)
-        : vkSet(rawSet),
-          dynamicUboMask(dynamicUboMask),
-          uniqueDynamicUboCount(uniqueDynamicUboCount),
+    VulkanDescriptorSet(VulkanResourceAllocator* allocator,
+            VkDescriptorSet rawSet, OnRecycle&& onRecycleFn)
+        : VulkanResource(VulkanResourceType::DESCRIPTOR_SET),
+          resources(allocator),
+          vkSet(rawSet),
          mOnRecycleFn(std::move(onRecycleFn)) {}

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

-    void setOffsets(backend::DescriptorSetOffsetArray&& offsets) noexcept {
-        mOffsets = std::move(offsets);
-    }
-
-    backend::DescriptorSetOffsetArray const* getOffsets() {
-        return &mOffsets;
-    }
-
-    void acquire(fvkmemory::resource_ptr<VulkanTexture> texture);
-    void acquire(fvkmemory::resource_ptr<VulkanBufferObject> buffer);
-
+    // TODO: maybe change to fixed size for performance.
+    VulkanAcquireOnlyResourceManager resources;
    VkDescriptorSet const vkSet;
-    UniformBufferBitmask const dynamicUboMask;
-    uint8_t const uniqueDynamicUboCount;

 private:
-    backend::DescriptorSetOffsetArray mOffsets;
-    std::vector<fvkmemory::resource_ptr<fvkmemory::Resource>> 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>;

 struct PushConstantDescription {
+
    explicit PushConstantDescription(backend::Program const& program) noexcept;

    VkPushConstantRange const* getVkRanges() const noexcept { return mRanges; }
+
    uint32_t getVkRangeCount() const noexcept { return mRangeCount; }
-    void write(VkCommandBuffer cmdbuf, VkPipelineLayout layout, backend::ShaderStage stage,
+
+    void write(VulkanCommands* commands, VkPipelineLayout layout, backend::ShaderStage stage,
            uint8_t index, backend::PushConstantVariant const& value);

 private:
@@ -192,10 +202,12 @@ private:
    uint32_t mRangeCount;
 };

-struct VulkanProgram : public HwProgram, fvkmemory::Resource {
+struct VulkanProgram : public HwProgram, VulkanResource {
+
    using BindingList = CappedArray<uint16_t, MAX_SAMPLER_COUNT>;

    VulkanProgram(VkDevice device, Program const& builder) noexcept;
+
    ~VulkanProgram();

    inline VkShaderModule getVertexShader() const {
@@ -204,6 +216,24 @@ struct VulkanProgram : public HwProgram, fvkmemory::Resource {

    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();
    }
@@ -212,9 +242,9 @@ struct VulkanProgram : public HwProgram, fvkmemory::Resource {
        return mInfo->pushConstantDescription.getVkRanges();
    }

-    inline void writePushConstant(VkCommandBuffer cmdbuf, VkPipelineLayout layout,
+    inline void writePushConstant(VulkanCommands* commands, VkPipelineLayout layout,
            backend::ShaderStage stage, uint8_t index, backend::PushConstantVariant const& value) {
-        mInfo->pushConstantDescription.write(cmdbuf, layout, stage, index, value);
+        mInfo->pushConstantDescription.write(commands, layout, stage, index, value);
    }

 #if FVK_ENABLED_DEBUG_SAMPLER_NAME
@@ -230,11 +260,30 @@ struct VulkanProgram : public HwProgram, fvkmemory::Resource {
 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
            {}

+        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
+        // We store the sampler name mapped from binding index (only for debug purposes).
+        utils::FixedCapacityVector<std::string> bindingToName;
+#endif
+
    };

    PipelineInfo* mInfo;
@@ -249,88 +298,45 @@ private:
 //
 // We use private inheritance to shield clients from the width / height fields in HwRenderTarget,
 // which are not representative when this is the default render target.
-struct VulkanRenderTarget : private HwRenderTarget, fvkmemory::Resource {
+struct VulkanRenderTarget : private HwRenderTarget, VulkanResource {
    // Creates an offscreen render target.
    VulkanRenderTarget(VkDevice device, VkPhysicalDevice physicalDevice,
-            VulkanContext const& context, fvkmemory::ResourceManager* resourceManager,
-            VmaAllocator allocator, VulkanCommands* commands, uint32_t width, uint32_t height,
+            VulkanContext const& context, VmaAllocator allocator,
+            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);

-    ~VulkanRenderTarget();
-
    // Creates a special "default" render target (i.e. associated with the swap chain)
    explicit VulkanRenderTarget();

    void transformClientRectToPlatform(VkRect2D* bounds) const;
-
-    void transformViewportToPlatform(VkViewport* bounds) const;
-
-    inline VkExtent2D getExtent() const {
-        return {width, height};
-    }
-
-    inline VulkanAttachment& getColor0() const {
-        assert_invariant(mInfo->colors[0]);
-        return mInfo->attachments[0];
-    }
-
-    inline VulkanAttachment& getDepth() const {
-        assert_invariant(hasDepth());
-        if (mInfo->fbkey.samples == 1) {
-            return mInfo->attachments[mInfo->depthIndex];
-        }
-        return mInfo->attachments[mInfo->msaaDepthIndex];
-    }
-
-    inline VulkanFboCache::RenderPassKey const& getRenderPassKey() const {
-        return mInfo->rpkey;
-    }
-
-    inline VulkanFboCache::FboKey const& getFboKey() const {
-        return mInfo->fbkey;
-    }
-
-    inline uint8_t getSamples() const {
-        return mInfo->fbkey.samples;
-    }
-
-    uint8_t getColorTargetCount(VulkanRenderPass const& pass) const;
-
-    inline bool hasDepth() const { return mInfo->depthIndex != Auxiliary::UNDEFINED_INDEX; }
-
-    inline bool isSwapChain() const { return !mOffscreen; }
-    inline bool isProtected() const { return mProtected; }
-
-    void bindToSwapChain(fvkmemory::resource_ptr<VulkanSwapChain> swapchain);
-
-    void emitBarriersBeginRenderPass(VulkanCommandBuffer& commands);
-
-    void emitBarriersEndRenderPass(VulkanCommandBuffer& commands);
+    void transformClientRectToPlatform(VkViewport* bounds) const;
+    VkExtent2D getExtent() const;
+    // We return references in the following methods to avoid a copy.
+    VulkanAttachment& getColor(int target);
+    VulkanAttachment& getMsaaColor(int target);
+    VulkanAttachment& getDepth();
+    VulkanAttachment& getMsaaDepth();
+    uint8_t getColorTargetCount(const VulkanRenderPass& pass) const;
+    uint8_t getSamples() const { return mSamples; }
+    uint8_t getLayerCount() const { return mLayerCount; }
+    bool hasDepth() const { return mDepth.texture; }
+    bool isSwapChain() const { return !mOffscreen; }
+    void bindToSwapChain(VulkanSwapChain& surf);

 private:
-    struct Auxiliary {
-        static constexpr int8_t UNDEFINED_INDEX = -1;
-
-        explicit Auxiliary() noexcept = default;
-
-        VulkanFboCache::RenderPassKey rpkey = {};
-        VulkanFboCache::FboKey fbkey = {};
-        std::vector<VulkanAttachment> attachments;
-        utils::bitset32 colors;
-        int8_t depthIndex = UNDEFINED_INDEX;
-        int8_t msaaDepthIndex = UNDEFINED_INDEX;
-        int8_t msaaIndex = UNDEFINED_INDEX;
-    };
-    bool const mOffscreen;
-    bool mProtected;
-
-    std::unique_ptr<Auxiliary> mInfo;
+    VulkanAttachment mColor[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT] = {};
+    VulkanAttachment mDepth = {};
+    VulkanAttachment mMsaaAttachments[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT] = {};
+    VulkanAttachment mMsaaDepthAttachment = {};
+    const bool mOffscreen : 1;
+    uint8_t mSamples : 7;
+    uint8_t mLayerCount = 1;
 };

 struct VulkanBufferObject;

-struct VulkanVertexBufferInfo : public HwVertexBufferInfo, fvkmemory::Resource {
+struct VulkanVertexBufferInfo : public HwVertexBufferInfo, VulkanResource {
    VulkanVertexBufferInfo(uint8_t bufferCount, uint8_t attributeCount,
            AttributeArray const& attributes);

@@ -377,24 +383,33 @@ private:
    PipelineInfo mInfo;
 };

-struct VulkanVertexBuffer : public HwVertexBuffer, fvkmemory::Resource {
-    VulkanVertexBuffer(VulkanContext& context, VulkanStagePool& stagePool, uint32_t vertexCount,
-            fvkmemory::resource_ptr<VulkanVertexBufferInfo> vbi);
-    void setBuffer(fvkmemory::resource_ptr<VulkanBufferObject> bufferObject, uint32_t index);
+struct VulkanVertexBuffer : public HwVertexBuffer, VulkanResource {
+    VulkanVertexBuffer(VulkanContext& context, VulkanStagePool& stagePool,
+            VulkanResourceAllocator* allocator,
+            uint32_t vertexCount, Handle<HwVertexBufferInfo> vbih);

-    inline VkBuffer const* getVkBuffers() const { return mBuffers.data(); }
-    inline VkBuffer* getVkBuffers() { return mBuffers.data(); }
-    fvkmemory::resource_ptr<VulkanVertexBufferInfo> vbi;
+    void setBuffer(VulkanResourceAllocator const& allocator,
+            VulkanBufferObject* bufferObject, uint32_t index);

+    inline VkBuffer const* getVkBuffers() const {
+        return mBuffers.data();
+    }
+
+    inline VkBuffer* getVkBuffers() {
+        return mBuffers.data();
+    }
+
+    Handle<HwVertexBufferInfo> vbih;
 private:
    utils::FixedCapacityVector<VkBuffer> mBuffers;
-    std::vector<fvkmemory::resource_ptr<VulkanBufferObject>> mResources;
+    FixedSizeVulkanResourceManager<MAX_VERTEX_BUFFER_COUNT> mResources;
 };

-struct VulkanIndexBuffer : public HwIndexBuffer, fvkmemory::Resource {
+struct VulkanIndexBuffer : public HwIndexBuffer, VulkanResource {
    VulkanIndexBuffer(VmaAllocator allocator, VulkanStagePool& stagePool, uint8_t elementSize,
            uint32_t indexCount)
        : HwIndexBuffer(elementSize, indexCount),
+          VulkanResource(VulkanResourceType::INDEX_BUFFER),
          buffer(allocator, stagePool, VK_BUFFER_USAGE_INDEX_BUFFER_BIT, elementSize * indexCount),
          indexType(elementSize == 2 ? VK_INDEX_TYPE_UINT16 : VK_INDEX_TYPE_UINT32) {}

@@ -402,7 +417,7 @@ struct VulkanIndexBuffer : public HwIndexBuffer, fvkmemory::Resource {
    const VkIndexType indexType;
 };

-struct VulkanBufferObject : public HwBufferObject, fvkmemory::Resource {
+struct VulkanBufferObject : public HwBufferObject, VulkanResource {
    VulkanBufferObject(VmaAllocator allocator, VulkanStagePool& stagePool, uint32_t byteCount,
            BufferObjectBinding bindingType);

@@ -410,13 +425,63 @@ struct VulkanBufferObject : public HwBufferObject, fvkmemory::Resource {
    const BufferObjectBinding bindingType;
 };

-struct VulkanRenderPrimitive : public HwRenderPrimitive, fvkmemory::Resource {
-    VulkanRenderPrimitive(PrimitiveType pt, fvkmemory::resource_ptr<VulkanVertexBuffer> vb,
-            fvkmemory::resource_ptr<VulkanIndexBuffer> ib);
-    ~VulkanRenderPrimitive() = default;
+struct VulkanSamplerGroup : public HwSamplerGroup, VulkanResource {
+    // NOTE: we have to use out-of-line allocation here because the size of a Handle<> is limited
+    std::unique_ptr<SamplerGroup> sb;// FIXME: this shouldn't depend on filament::SamplerGroup
+    explicit VulkanSamplerGroup(size_t size) noexcept
+        : VulkanResource(VulkanResourceType::SAMPLER_GROUP),
+          sb(new SamplerGroup(size)) {}
+};

-    fvkmemory::resource_ptr<VulkanVertexBuffer> vertexBuffer;
-    fvkmemory::resource_ptr<VulkanIndexBuffer> indexBuffer;
+struct VulkanRenderPrimitive : public HwRenderPrimitive, VulkanResource {
+    VulkanRenderPrimitive(VulkanResourceAllocator* resourceAllocator,
+            PrimitiveType pt, Handle<HwVertexBuffer> vbh, Handle<HwIndexBuffer> ibh);
+
+    ~VulkanRenderPrimitive() {
+        mResources.clear();
+    }
+
+    VulkanVertexBuffer* vertexBuffer = nullptr;
+    VulkanIndexBuffer* indexBuffer = nullptr;
+
+private:
+    // Keep references to the vertex buffer and the index buffer.
+    FixedSizeVulkanResourceManager<2> mResources;
+};
+
+struct VulkanFence : public HwFence, VulkanResource {
+    VulkanFence()
+        : VulkanResource(VulkanResourceType::FENCE) {}
+
+    explicit VulkanFence(std::shared_ptr<VulkanCmdFence> fence)
+        : VulkanResource(VulkanResourceType::FENCE),
+          fence(fence) {}
+
+    std::shared_ptr<VulkanCmdFence> fence;
+};
+
+struct VulkanTimerQuery : public HwTimerQuery, VulkanThreadSafeResource {
+    explicit VulkanTimerQuery(std::tuple<uint32_t, uint32_t> indices);
+    ~VulkanTimerQuery();
+
+    void setFence(std::shared_ptr<VulkanCmdFence> fence) noexcept;
+
+    bool isCompleted() noexcept;
+
+    uint32_t getStartingQueryIndex() const {
+        return mStartingQueryIndex;
+    }
+
+    uint32_t getStoppingQueryIndex() const {
+        return mStoppingQueryIndex;
+    }
+
+private:
+    uint32_t mStartingQueryIndex;
+    uint32_t mStoppingQueryIndex;
+
+    std::shared_ptr<VulkanCmdFence> mFence;
+    utils::Mutex mFenceMutex;
 };

 inline constexpr VkBufferUsageFlagBits getBufferObjectUsage(
--- a/filament/backend/src/vulkan/VulkanImageUtility.cpp
+++ b/filament/backend/src/vulkan/VulkanImageUtility.cpp
@@ -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
--- a/filament/backend/src/vulkan/VulkanImageUtility.h
+++ b/filament/backend/src/vulkan/VulkanImageUtility.h
@@ -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

--- a/Show More
+++ b/Show More