Merge branch 'rc/1.56.4' into release

renderdiff: allow for explicit (compile-time) linking of osmesa (#8301 )
If the shared osmesa lib is not found, then we assume that the library has been compile-time linked via the linker. This is to accommodate build frameworks where compile-time linking is preferred.
2024-12-17 16:39:38 -08:00 · 2024-12-12 10:56:29 -08:00 · 2024-12-11 02:17:56 +00:00 · 2024-12-11 02:17:56 +00:00 · 2024-12-11 02:17:39 +00:00 · 2024-12-10 14:22:57 -08:00
334 changed files with 15263 additions and 8702 deletions
@@ -0,0 +1,17 @@
+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
@@ -0,0 +1,9 @@
+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
@@ -10,30 +10,13 @@ on:
 jobs:
  build-android:
    name: build-android
-    runs-on: macos-14
+    # 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

    steps:
      - uses: actions/checkout@v4.1.6
-      - uses: actions/setup-java@v3
+      - name: Run Android Continuous
+        uses: ./.github/actions/android-continuous
        with:
-          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
+          build-abi: armeabi-v7a,arm64-v8a,x86_64
@@ -10,14 +10,14 @@ on:
 jobs:
  build-ios:
    name: build-ios
-    runs-on: macos-14
+    runs-on: macos-14-xlarge

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

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

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

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

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

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

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

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

    steps:
      - uses: actions/checkout@v4.1.6
@@ -49,12 +49,14 @@ 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
+          cd build/android && printf "y" | ./build.sh presubmit arm64-v8a

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

    steps:
      - uses: actions/checkout@v4.1.6
@@ -67,10 +69,25 @@ jobs:

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

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

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

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

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

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

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

    steps:
@@ -120,7 +120,7 @@ jobs:
        env:
          TAG: ${{ steps.git_ref.outputs.tag }}
        run: |
-          cd build/android && printf "y" | ./build.sh release
+          cd build/android && printf "y" | ./build.sh release armeabi-v7a,arm64-v8a,x86,x86_64
          cd ../..
          mv out/filament-android-release.aar out/filament-${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
+    runs-on: macos-14-xlarge
    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
+    runs-on: windows-2019-32core
    if: github.event_name == 'release' || github.event.inputs.platform == 'windows'

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

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

    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@v1.0.0
+      - uses: actions/upload-artifact@v4
        with:
          name: filament-windows
          path: out/filament-windows.tgz
@@ -45,6 +45,8 @@ 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."
 )
@@ -73,6 +75,10 @@ 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)

@@ -132,12 +138,22 @@ 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)
@@ -7,5 +7,3 @@ for next branch cut* header.
 appropriate header in [RELEASE_NOTES.md](./RELEASE_NOTES.md).

 ## Release notes for next branch cut
-
- Add a `name` API to Filament objects for debugging handle use-after-free assertions
@@ -31,7 +31,7 @@ repositories {
 }

 dependencies {
-    implementation 'com.google.android.filament:filament-android:1.54.1'
+    implementation 'com.google.android.filament:filament-android:1.56.4'
 }
 ```

@@ -51,19 +51,9 @@ 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', '~> 1.54.1'
+pod 'Filament', '~> 1.56.4'
 ```

-### 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
@@ -7,6 +7,42 @@ 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).

+## v1.56.4
+
+
+## v1.56.3
+
+
+## v1.56.2
+
+- vk: fix stage pool gc logic
+
+## 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


@@ -634,7 +670,7 @@ 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 passsed to `Stream::SetAcquiredImage` is ignored and leaked.
+- engine: Fix, first imaged passed 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.
@@ -83,12 +83,12 @@ buildscript {
        'minSdk': 21,
        'targetSdk': 34,
        'compileSdk': 34,
-        'kotlin': '2.0.0',
-        'kotlin_coroutines': '1.9.0-RC',
-        'buildTools': '34.0.0',
+        'kotlin': '2.0.21',
+        'kotlin_coroutines': '1.9.0',
+        'buildTools': '35.0.0',
        'ndk': '27.0.11718014',
        'androidx_core': '1.13.1',
-        'androidx_annotations': '1.8.0'
+        'androidx_annotations': '1.9.0'
    ]

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

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

@@ -499,6 +499,37 @@ 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{};
@@ -520,13 +551,12 @@ 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,
-        jlong textureUseAfterFreePoolSize, jboolean disableParallelShaderCompile,
+        jlong jobSystemThreadCount, jboolean disableParallelShaderCompile,
        jint stereoscopicType, jlong stereoscopicEyeCount,
        jlong resourceAllocatorCacheSizeMB, jlong resourceAllocatorCacheMaxAge,
        jboolean disableHandleUseAfterFreeCheck,
        jint preferredShaderLanguage,
-        jboolean forceGLES2Context) {
+        jboolean forceGLES2Context, jboolean assertNativeWindowIsValid) {
    Engine::Builder* builder = (Engine::Builder*) nativeBuilder;
    Engine::Config config = {
            .commandBufferSizeMB = (uint32_t) commandBufferSizeMB,
@@ -535,7 +565,6 @@ 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,
@@ -544,6 +573,7 @@ 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);
 }
@@ -566,6 +596,16 @@ 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;
@@ -38,7 +38,7 @@ Java_com_google_android_filament_EntityManager_nCreateArray(JNIEnv* env, jclass,
    // (which it is), but still.
    em->create((size_t) n, reinterpret_cast<Entity *>(entities));

-    env->ReleaseIntArrayElements(entities_, entities, JNI_ABORT);
+    env->ReleaseIntArrayElements(entities_, entities, 0);
 }

 extern "C" JNIEXPORT jint JNICALL
@@ -167,7 +167,7 @@ Java_com_google_android_filament_IndirectLight_nGetDirectionEstimateStatic(JNIEn
    jfloat *outDirection = env->GetFloatArrayElements(outDirection_, NULL);
    *reinterpret_cast<filament::math::float3*>(outDirection) = IndirectLight::getDirectionEstimate((filament::math::float3*)sh);
    env->ReleaseFloatArrayElements(outDirection_, outDirection, 0);
-    env->ReleaseFloatArrayElements(sh_, sh, JNI_ABORT);
+    env->ReleaseFloatArrayElements(sh_, sh, 0);
 }

 extern "C" JNIEXPORT void JNICALL
@@ -178,5 +178,5 @@ Java_com_google_android_filament_IndirectLight_nGetColorEstimateStatic(JNIEnv *e
    *reinterpret_cast<filament::math::float4*>(outColor) =
            IndirectLight::getColorEstimate((filament::math::float3*)sh, math::float3{x, y, z});
    env->ReleaseFloatArrayElements(outColor_, outColor, 0);
-    env->ReleaseFloatArrayElements(sh_, sh, JNI_ABORT);
+    env->ReleaseFloatArrayElements(sh_, sh, 0);
 }
@@ -222,6 +222,20 @@ 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;
@@ -224,13 +224,12 @@ public class Engine {
            nSetBuilderConfig(mNativeBuilder, config.commandBufferSizeMB,
                    config.perRenderPassArenaSizeMB, config.driverHandleArenaSizeMB,
                    config.minCommandBufferSizeMB, config.perFrameCommandsSizeMB,
-                    config.jobSystemThreadCount,
-                    config.textureUseAfterFreePoolSize, config.disableParallelShaderCompile,
+                    config.jobSystemThreadCount, config.disableParallelShaderCompile,
                    config.stereoscopicType.ordinal(), config.stereoscopicEyeCount,
                    config.resourceAllocatorCacheSizeMB, config.resourceAllocatorCacheMaxAge,
                    config.disableHandleUseAfterFreeCheck,
                    config.preferredShaderLanguage.ordinal(),
-                    config.forceGLES2Context);
+                    config.forceGLES2Context, config.assertNativeWindowIsValid);
            return this;
        }

@@ -259,6 +258,17 @@ 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
         *
@@ -394,6 +404,7 @@ 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;

@@ -419,12 +430,12 @@ 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.
@@ -432,12 +443,13 @@ 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
@@ -459,12 +471,20 @@ 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) {
@@ -687,11 +707,11 @@ 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
-     * Engine#Config#stereoscopicEyeCount} setting.
+     * eyes rendered is set at Engine creation time with the {@link Config#stereoscopicEyeCount}
+     * setting.
     *
     * @return the max number of stereoscopic eyes supported
-     * @see Engine#Config#stereoscopicEyeCount
+     * @see Config#stereoscopicEyeCount
     */
    public long getMaxStereoscopicEyes() {
        return nGetMaxStereoscopicEyes(getNativeObject());
@@ -888,7 +908,8 @@ public class Engine {

    /**
     * Returns whether the object is valid.
-     * @param object Object to check for validity
+     * @param ma Material
+     * @param mi MaterialInstance to check for validity
     * @return returns true if the specified object is valid.
     */
    public boolean isValidMaterialInstance(@NonNull Material ma, MaterialInstance mi) {
@@ -1310,6 +1331,39 @@ 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) {
@@ -1399,6 +1453,9 @@ 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);
@@ -1406,14 +1463,14 @@ public class Engine {
    private static native void nSetBuilderConfig(long nativeBuilder, long commandBufferSizeMB,
            long perRenderPassArenaSizeMB, long driverHandleArenaSizeMB,
            long minCommandBufferSizeMB, long perFrameCommandsSizeMB, long jobSystemThreadCount,
-            long textureUseAfterFreePoolSize, boolean disableParallelShaderCompile,
-            int stereoscopicType, long stereoscopicEyeCount,
+            boolean disableParallelShaderCompile, int stereoscopicType, long stereoscopicEyeCount,
            long resourceAllocatorCacheSizeMB, long resourceAllocatorCacheMaxAge,
            boolean disableHandleUseAfterFreeCheck,
            int preferredShaderLanguage,
-            boolean forceGLES2Context);
+            boolean forceGLES2Context, boolean assertNativeWindowIsValid);
    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);
 }
@@ -745,6 +745,33 @@ 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.
     *
@@ -1281,6 +1308,8 @@ 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);
@@ -1,5 +1,5 @@
 GROUP=com.google.android.filament
-VERSION_NAME=1.54.1
+VERSION_NAME=1.56.4

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

@@ -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-8.6-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.8-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
@@ -6,6 +6,10 @@ 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")
@@ -13,7 +17,7 @@ filamentTools {
 }

 // don't forget to update MainACtivity.kt when/if changing this.
-task copyMesh(type: Copy) {
+tasks.register('copyMesh', Copy) {
    from "../../../third_party/models/BusterDrone"
    into "src/main/assets/models"
 }
@@ -112,7 +112,13 @@ class MainActivity : Activity() {
    }

    private fun setupFilament() {
-        engine = Engine.Builder().featureLevel(Engine.FeatureLevel.FEATURE_LEVEL_0).build()
+        val config = Engine.Config()
+        //config.forceGLES2Context = true
+
+        engine = Engine.Builder()
+            .config(config)
+            .featureLevel(Engine.FeatureLevel.FEATURE_LEVEL_0)
+            .build()
        renderer = engine.createRenderer()
        scene = engine.createScene()
        view = engine.createView()
@@ -123,7 +129,9 @@ 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
-        view.isPostProcessingEnabled = false
+        if (engine.activeFeatureLevel == Engine.FeatureLevel.FEATURE_LEVEL_0) {
+            view.isPostProcessingEnabled = false
+        }

        // Tell the view which camera we want to use
        view.camera = camera
@@ -64,6 +64,9 @@ 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."
@@ -180,6 +183,8 @@ BACKEND_DEBUG_FLAG_OPTION=""

 STEREOSCOPIC_OPTION=""

+OSMESA_OPTION=""
+
 IOS_BUILD_SIMULATOR=false
 BUILD_UNIVERSAL_LIBRARIES=false

@@ -240,6 +245,7 @@ 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" \
@@ -796,7 +802,7 @@ function check_debug_release_build {

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

-while getopts ":hacCfgijmp:q:uvslwedk:bx:S:" opt; do
+while getopts ":hacCfgijmp:q:uvslwedk:bx:S:X:" opt; do
    case ${opt} in
        h)
            print_help
@@ -950,6 +956,8 @@ while getopts ":hacCfgijmp:q:uvslwedk:bx:S:" opt; do
                    exit 1
            esac
            ;;
+        X)  OSMESA_OPTION="-DFILAMENT_OSMESA_PATH=${OPTARG}"
+            ;;
        \?)
            echo "Invalid option: -${OPTARG}" >&2
            echo ""
@@ -60,13 +60,7 @@ if [[ ! -d "${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=
@@ -74,5 +68,19 @@ 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 $0`/../.. > /dev/null
-FILAMENT_NDK_VERSION=${FILAMENT_NDK_VERSION} ./build.sh -p android $ANDROID_ABIS -c $BUILD_SAMPLES $GENERATE_ARCHIVES $BUILD_DEBUG $BUILD_RELEASE
+build_android $2
@@ -1,7 +1,6 @@
 #!/bin/bash
 if [ `uname` == "Linux" ];then
-    curl -OL https://github.com/ninja-build/ninja/releases/download/v1.10.2/ninja-linux.zip
-    unzip -q ninja-linux.zip
+    source `dirname $0`/../linux/ci-common.sh
 elif [ `uname` == "Darwin" ];then
    curl -OL https://github.com/ninja-build/ninja/releases/download/v1.10.2/ninja-mac.zip
    unzip -q ninja-mac.zip
@@ -13,9 +12,6 @@ fi
 chmod +x ninja
 export PATH="$PWD:$PATH"

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

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

 echo Disk info after building variant: %variant%
@@ -1787,7 +1787,12 @@ non-shader data.
      declare a variable called <code>eyeDirection</code> you can access it in the fragment shader using
      <code>variable_eyeDirection</code>. In the vertex shader, the interpolant name is simply a member of
      the <code>MaterialVertexInputs</code> structure (<code>material.eyeDirection</code> in your example). Each
-      interpolant is of type <code>float4</code> (<code>vec4</code>) in the shaders.
+      interpolant is of type <code>float4</code> (<code>vec4</code>) in the shaders. By default the precision of the
+      interpolant is <code>highp</code> in <em class="asterisk">both</em> 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 <code>default</code> is specified the default precision is used is the fragment shader
+      (<code>mediump</code>) and in the vertex shader (<code>highp</code>).

 </p></dd></dl><p></p><pre class="listing tilde"><code><span class="line">material {</span>
 <span class="line">    name : Skybox,</span>
@@ -1798,7 +1803,11 @@ non-shader data.
 <span class="line">        }</span>
 <span class="line">    ],</span>
 <span class="line">    variables : [</span>
-<span class="line">         eyeDirection</span>
+<span class="line">         eyeDirection,</span>
+<span class="line">         {</span>
+<span class="line">            name : eyeColor,</span>
+<span class="line">            precision : medium</span>
+<span class="line">         }</span>
 <span class="line">    ],</span>
 <span class="line">    vertexDomain : device,</span>
 <span class="line">    depthWrite : <span class="hljs-literal">false</span>,</span>
@@ -1308,7 +1308,12 @@ 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.
+      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`).

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ JSON
 material {
@@ -1320,7 +1325,11 @@ material {
        }
    ],
    variables : [
-         eyeDirection
+         eyeDirection,
+         {
+            name : eyeColor,
+            precision : medium
+         }
    ],
    vertexDomain : device,
    depthWrite : false,
@@ -66,6 +66,7 @@ set(SRCS
        src/FrameSkipper.cpp
        src/Froxelizer.cpp
        src/Frustum.cpp
+        src/HwDescriptorSetLayoutFactory.cpp
        src/HwRenderPrimitiveFactory.cpp
        src/HwVertexBufferInfoFactory.cpp
        src/IndexBuffer.cpp
@@ -76,8 +77,6 @@ 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
@@ -126,6 +125,12 @@ 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
@@ -149,23 +154,21 @@ 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
@@ -193,6 +196,14 @@ 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
@@ -210,7 +221,6 @@ 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
@@ -298,6 +308,11 @@ 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
 # ==================================================================================================
@@ -597,6 +612,13 @@ 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
@@ -12,6 +12,7 @@ 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
@@ -69,9 +70,13 @@ 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
@@ -114,6 +119,8 @@ 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)
@@ -172,11 +179,18 @@ 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
@@ -207,9 +221,6 @@ 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
@@ -361,6 +372,11 @@ 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()
@@ -372,6 +388,9 @@ else()
            -Wover-aligned
            -Werror
    )
+    if (CMAKE_CXX_STANDARD EQUAL 20)
+        list(APPEND FILAMENT_WARNINGS -Wno-deprecated-this-capture)
+    endif()
 endif()

 if (APPLE)
@@ -381,6 +400,7 @@ endif()

 target_compile_options(${TARGET} PRIVATE
        ${FILAMENT_WARNINGS}
+        ${OSMESA_COMPILE_FLAGS}
        $<$<CONFIG:Release>:${OPTIMIZATION_FLAGS}>
        $<$<AND:$<PLATFORM_ID:Darwin>,$<CONFIG:Release>>:${DARWIN_OPTIMIZATION_FLAGS}>
 )
@@ -390,6 +410,7 @@ if (FILAMENT_SUPPORTS_METAL)
 endif()

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

@@ -424,6 +445,7 @@ 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
@@ -495,21 +517,40 @@ 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()

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

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

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

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

 endif()
@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef TNT_FILAMENT_BACKEND_COMMANDSTREAMVECTOR_H
+#define TNT_FILAMENT_BACKEND_COMMANDSTREAMVECTOR_H
+
+#include <backend/DriverApiForward.h>
+
+#include <initializer_list>
+#include <memory>
+
+#include <stddef.h>
+#include <stdint.h>
+
+
+namespace filament::backend {
+
+void* allocateFromCommandStream(DriverApi& driver, size_t size, size_t alignment) noexcept;
+
+class DescriptorSetOffsetArray {
+public:
+    using value_type = uint32_t;
+    using reference = value_type&;
+    using const_reference = value_type const&;
+    using size_type = uint32_t;
+    using difference_type = int32_t;
+    using pointer = value_type*;
+    using const_pointer = value_type const*;
+    using iterator = pointer;
+    using const_iterator = const_pointer;
+
+    DescriptorSetOffsetArray() noexcept = default;
+
+    ~DescriptorSetOffsetArray() noexcept = default;
+
+    DescriptorSetOffsetArray(size_type size, DriverApi& driver) noexcept {
+        mOffsets = (value_type *)allocateFromCommandStream(driver,
+                size * sizeof(value_type), alignof(value_type));
+        std::uninitialized_fill_n(mOffsets, size, 0);
+    }
+
+    DescriptorSetOffsetArray(std::initializer_list<uint32_t> list, DriverApi& driver) noexcept {
+        mOffsets = (value_type *)allocateFromCommandStream(driver,
+                list.size() * sizeof(value_type), alignof(value_type));
+        std::uninitialized_copy(list.begin(), list.end(), mOffsets);
+    }
+
+    DescriptorSetOffsetArray(DescriptorSetOffsetArray const&) = delete;
+    DescriptorSetOffsetArray& operator=(DescriptorSetOffsetArray const&) = delete;
+
+    DescriptorSetOffsetArray(DescriptorSetOffsetArray&& rhs) noexcept
+            : mOffsets(rhs.mOffsets) {
+        rhs.mOffsets = nullptr;
+    }
+
+    DescriptorSetOffsetArray& operator=(DescriptorSetOffsetArray&& rhs) noexcept {
+        if (this != &rhs) {
+            mOffsets = rhs.mOffsets;
+            rhs.mOffsets = nullptr;
+        }
+        return *this;
+    }
+
+    bool empty() const noexcept { return mOffsets == nullptr; }
+
+    value_type* data() noexcept { return mOffsets; }
+    const value_type* data() const noexcept { return mOffsets; }
+
+
+    reference operator[](size_type n) noexcept {
+        return *(data() + n);
+    }
+
+    const_reference operator[](size_type n) const noexcept {
+        return *(data() + n);
+    }
+
+    void clear() noexcept {
+        mOffsets = nullptr;
+    }
+
+private:
+    value_type *mOffsets = nullptr;
+};
+
+} // namespace filament::backend
+
+#endif //TNT_FILAMENT_BACKEND_COMMANDSTREAMVECTOR_H
@@ -19,13 +19,16 @@
 #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>
@@ -97,6 +100,8 @@ 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
@@ -191,6 +196,71 @@ 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
 */
@@ -249,8 +319,19 @@ 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.
@@ -270,15 +351,6 @@ 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);

 /**
@@ -368,6 +440,18 @@ 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
@@ -693,9 +777,27 @@ 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
+    DEFAULT             = UPLOADABLE | SAMPLEABLE,   //!< Default texture usage
+    ALL_ATTACHMENTS     = COLOR_ATTACHMENT | DEPTH_ATTACHMENT | STENCIL_ATTACHMENT | SUBPASS_INPUT,   //!< Mask of all attachments
 };

+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,
@@ -887,6 +989,9 @@ 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;
@@ -895,6 +1000,9 @@ 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;
@@ -902,6 +1010,12 @@ 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);
    }
@@ -1058,7 +1172,7 @@ struct RasterState {
            bool inverseFrontFaces                      : 1;        // 31

            //! padding, must be 0
-            uint8_t padding                             : 1;        // 32
+            bool depthClamp                             : 1;        // 32
        };
        uint32_t u = 0;
    };
@@ -1069,32 +1183,6 @@ 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.
@@ -1259,6 +1347,8 @@ template<> struct utils::EnableBitMaskOperators<filament::backend::ShaderStageFl
        : public std::true_type {};
 template<> struct utils::EnableBitMaskOperators<filament::backend::TargetBufferFlags>
        : public std::true_type {};
+template<> struct utils::EnableBitMaskOperators<filament::backend::DescriptorFlags>
+        : public std::true_type {};
 template<> struct utils::EnableBitMaskOperators<filament::backend::TextureUsage>
        : public std::true_type {};
 template<> struct utils::EnableBitMaskOperators<filament::backend::StencilFace>
@@ -23,6 +23,7 @@
 #include <utils/debug.h>

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

 #include <stdint.h>

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

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

-    Handle& operator=(Handle const& rhs) noexcept = default;
-    Handle& operator=(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;
+    }

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

@@ -130,19 +143,21 @@ 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 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>;

 } // namespace filament::backend

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

 #include <utils/ostream.h>

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

 namespace filament::backend {

 //! \privatesection

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

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

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

 #include <backend/DriverEnums.h>

-#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 <array>
+#include <unordered_map>
+#include <tuple>
+#include <utility>
+#include <variant>

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

-    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 Descriptor {
+        utils::CString name;
+        backend::DescriptorType type;
+        backend::descriptor_binding_t binding;
    };

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

-    struct Uniform {
+    struct Uniform { // For ES2 support
        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 UniformBlockInfo = std::array<utils::CString, UNIFORM_BINDING_COUNT>;
-    using UniformInfo = utils::FixedCapacityVector<Uniform>;
-    using SamplerGroupInfo = std::array<SamplerGroupData, SAMPLER_BINDING_COUNT>;
+    using DescriptorBindingsInfo = utils::FixedCapacityVector<Descriptor>;
+    using DescriptorSetInfo = std::array<DescriptorBindingsInfo, MAX_DESCRIPTOR_SET_COUNT>;
+    using SpecializationConstantsInfo = utils::FixedCapacityVector<SpecializationConstant>;
    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;
@@ -79,43 +88,19 @@ 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);

-    // 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;
+    // Descriptor binding (set, binding, type -> shader name) info
+    Program& descriptorBindings(backend::descriptor_set_t set,
+            DescriptorBindingsInfo descriptorBindings) 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;
+    Program& specializationConstants(SpecializationConstantsInfo specConstants) noexcept;

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

-    utils::FixedCapacityVector<SpecializationConstant> const& getSpecializationConstants() const noexcept {
+    uint64_t getCacheId() const noexcept { return mCacheId; }
+
+    bool isMultiview() const noexcept { return mMultiview; }
+
+    CompilerPriorityQueue getPriorityQueue() const noexcept { return mPriorityQueue; }
+
+    SpecializationConstantsInfo const& getSpecializationConstants() const noexcept {
        return mSpecializationConstants;
    }
-    utils::FixedCapacityVector<SpecializationConstant>& getSpecializationConstants() noexcept {
+
+    SpecializationConstantsInfo& 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)];
@@ -165,27 +157,29 @@ public:
        return mPushConstants[static_cast<uint8_t>(stage)];
    }

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

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

 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{};
-    utils::Invocable<utils::io::ostream&(utils::io::ostream& out)> mLogger;
-    utils::FixedCapacityVector<SpecializationConstant> mSpecializationConstants;
-    std::array<utils::FixedCapacityVector<PushConstant>, SHADER_TYPE_COUNT> mPushConstants;
-    utils::FixedCapacityVector<std::pair<utils::CString, uint8_t>> mAttributes;
-    std::array<UniformInfo, Program::UNIFORM_BINDING_COUNT> mBindingUniformInfo;
    CompilerPriorityQueue mPriorityQueue = CompilerPriorityQueue::HIGH;
+    utils::Invocable<utils::io::ostream&(utils::io::ostream& out)> mLogger;
+    SpecializationConstantsInfo mSpecializationConstants;
+    std::array<utils::FixedCapacityVector<PushConstant>, SHADER_TYPE_COUNT> mPushConstants;
+    DescriptorSetInfo mDescriptorBindings;
+
+    // For ES2 support only
+    AttributesInfo mAttributes;
+    BindingUniformsInfo mBindingUniformsInfo;
+
    // Indicates the current engine was initialized with multiview stereo, and the variant for this
    // program contains STE flag. This will be referred later for the OpenGL shader compiler to
    // determine whether shader code replacement for the num_views should be performed.
@@ -30,10 +30,6 @@ 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) {
    }
@@ -51,14 +47,15 @@ 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 cubemaps and 3D textures. See TextureCubemapFace for the face->layer mapping
+    // - 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.
    uint16_t layer = 0;
 };

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

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

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

+protected:
+    bool makeCurrent(ContextType type,
+            SwapChain* drawSwapChain,
+            SwapChain* readSwapChain) noexcept override;
+
 private:
    struct InitializeJvmForPerformanceManagerIfNeeded {
        InitializeJvmForPerformanceManagerIfNeeded();
@@ -102,6 +107,10 @@ 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
@@ -0,0 +1,64 @@
+/*
+ * 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
@@ -88,6 +88,7 @@ public:
        VkFormat colorFormat = VK_FORMAT_UNDEFINED;
        VkFormat depthFormat = VK_FORMAT_UNDEFINED;
        VkExtent2D extent = {0, 0};
+        bool isProtected = false;
    };

    struct ImageSyncData {
@@ -199,6 +200,13 @@ 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()
@@ -267,6 +275,23 @@ 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();

@@ -18,6 +18,7 @@
 #define TNT_FILAMENT_BACKEND_PRIVATE_DRIVER_H

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

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

-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,
+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,
        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,
@@ -225,9 +239,6 @@ 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,
@@ -261,25 +272,53 @@ 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(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)
+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)

 /*
 * Synchronous APIs
@@ -309,6 +348,7 @@ DECL_DRIVER_API_SYNCHRONOUS_0(bool, isParallelShaderCompileSupported)
 DECL_DRIVER_API_SYNCHRONOUS_0(bool, isDepthStencilResolveSupported)
 DECL_DRIVER_API_SYNCHRONOUS_N(bool, isDepthStencilBlitSupported, backend::TextureFormat, format)
 DECL_DRIVER_API_SYNCHRONOUS_0(bool, isProtectedTexturesSupported)
+DECL_DRIVER_API_SYNCHRONOUS_0(bool, isDepthClampSupported)
 DECL_DRIVER_API_SYNCHRONOUS_0(uint8_t, getMaxDrawBuffers)
 DECL_DRIVER_API_SYNCHRONOUS_0(size_t, getMaxUniformBufferSize)
 DECL_DRIVER_API_SYNCHRONOUS_0(math::float2, getClipSpaceParams)
@@ -345,15 +385,6 @@ 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,
@@ -368,10 +399,12 @@ 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,
@@ -418,37 +451,16 @@ 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,
-        uint32_t, len = 0)
+        const char*, string)

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

 DECL_DRIVER_API_0(popGroupMarker)

@@ -18,6 +18,17 @@
 #define TNT_FILAMENT_BACKEND_PRIVATE_DRIVERAPI_H

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

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

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

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

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

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

    template<typename B>
    bool is_valid(Handle<B>& handle) {
-        if (handle && isPoolHandle(handle.getId())) {
-            auto [p, tag] = handleToPointer(handle.getId());
+        if (!handle) {
+            // null handles are invalid
+            return false;
+        }
+        auto [p, tag] = handleToPointer(handle.getId());
+        if (isPoolHandle(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 true;
+        return p != nullptr;
    }

    template<typename Dp, typename B>
@@ -208,14 +228,8 @@ public:
        // TODO: for now, only pool handles check for use-after-free, so we only keep tags for
        // those
        if (isPoolHandle(id)) {
-            // Truncate the tag's age to N bits.
-            constexpr uint8_t N = 2; // support a history of 4 tags
-            constexpr uint8_t mask = (1 << N) - 1;
-
-            uint8_t const age = (id & HANDLE_AGE_MASK) >> HANDLE_AGE_SHIFT;
-            uint8_t const newAge = age & mask;
-            uint32_t const key = (id & ~HANDLE_AGE_MASK) | (newAge << HANDLE_AGE_SHIFT);
-
+            // 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);
@@ -226,7 +240,8 @@ public:
        if (!isPoolHandle(id)) {
            return "(no tag)";
        }
-        if (auto pos = mDebugTags.find(id); pos != mDebugTags.end()) {
+        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)";
@@ -349,12 +364,24 @@ private:
        }
    }

-    // 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;
+    // 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);

    static bool isPoolHandle(HandleBase::HandleId id) noexcept {
        return (id & HANDLE_HEAP_FLAG) == 0u;
@@ -369,7 +396,7 @@ private:
        // a non-pool handle.
        if (UTILS_LIKELY(isPoolHandle(id))) {
            char* const base = (char*)mHandleArena.getArea().begin();
-            uint32_t const tag = id & HANDLE_TAG_MASK;
+            uint32_t const tag = id & HANDLE_AGE_MASK;
            size_t const offset = (id & HANDLE_INDEX_MASK) * Allocator::getAlignment();
            return { static_cast<void*>(base + offset), tag };
        }
@@ -384,7 +411,7 @@ private:
        size_t const offset = (char*)p - base;
        assert_invariant((offset % Allocator::getAlignment()) == 0);
        auto id = HandleBase::HandleId(offset / Allocator::getAlignment());
-        id |= tag & HANDLE_TAG_MASK;
+        id |= tag & HANDLE_AGE_MASK;
        assert_invariant((id & HANDLE_HEAP_FLAG) == 0);
        return id;
    }
@@ -24,7 +24,7 @@
 #include <utils/debug.h>
 #include <utils/ostream.h>

-#if !defined(WIN32) && !defined(__EMSCRIPTEN__) && !defined(IOS)
+#if !defined(WIN32) && !defined(__EMSCRIPTEN__)
 #    include <sys/mman.h>
 #    include <unistd.h>
 #    define HAS_MMAP 1
@@ -20,11 +20,16 @@
 #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>
@@ -74,8 +79,8 @@ CommandStream::CommandStream(Driver& driver, CircularBuffer& buffer) noexcept
 }

 void CommandStream::execute(void* buffer) {
-    SYSTRACE_CALL();
-    SYSTRACE_CONTEXT();
+    // 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.

    Profiler profiler;

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

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

-#include "backend/Program.h"
+#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>

 namespace filament::backend {

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

-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;
-    }
+Program& Program::descriptorBindings(backend::descriptor_set_t set,
+        DescriptorBindingsInfo descriptorBindings) noexcept {
+    mDescriptorBindings[set] = std::move(descriptorBindings);
    return *this;
 }

-Program& Program::uniforms(uint32_t index, UniformInfo const& uniforms) noexcept {
-    assert_invariant(index < UNIFORM_BINDING_COUNT);
-    mBindingUniformInfo[index] = uniforms;
+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));
    return *this;
 }

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

-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 {
+Program& Program::specializationConstants(SpecializationConstantsInfo specConstants) noexcept {
    mSpecializationConstants = std::move(specConstants);
    return *this;
 }
@@ -0,0 +1,28 @@
+/*
+ * 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
+
@@ -73,10 +73,11 @@ public:
    enum class Type {
        NONE = 0,
        GENERIC = 1,
-        RING = 2,
+        RING = 2,       // deprecated
        STAGING = 3,
+        DESCRIPTOR_SET = 4,
    };
-    static constexpr size_t TypeCount = 3;
+    static constexpr size_t TypeCount = 4;

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

@@ -160,6 +163,8 @@ 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;

@@ -169,8 +174,10 @@ 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.
     */
-    void copyIntoBuffer(void* src, size_t size, size_t byteOffset);
-    void copyIntoBufferUnsynchronized(void* src, size_t size, size_t byteOffset);
+    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);

    /**
     * Denotes that this buffer is used for a draw call ensuring that its allocation remains valid
@@ -180,7 +187,7 @@ public:
     * is no device allocation.
     *
     */
-    id<MTLBuffer> getGpuBufferForDraw(id<MTLCommandBuffer> cmdBuffer) noexcept;
+    id<MTLBuffer> getGpuBufferForDraw() noexcept;

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

@@ -209,8 +216,10 @@ private:
        BUMP_ALLOCATOR,
    };

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

    UploadStrategy mUploadStrategy;
    TrackedMetalBuffer mBuffer;
@@ -40,12 +40,15 @@ 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.
    {
@@ -53,8 +56,8 @@ MetalBuffer::MetalBuffer(MetalContext& context, BufferObjectBinding bindingType,
        mBuffer = { [context.device newBufferWithLength:size options:MTLResourceStorageModePrivate],
            TrackedMetalBuffer::Type::GENERIC };
    }
-    FILAMENT_CHECK_POSTCONDITION(mBuffer)
-            << "Could not allocate Metal buffer of size " << size << ".";
+    // mBuffer might fail to be allocated. Clients can check for this by calling
+    // wasAllocationSuccessful().
 }

 MetalBuffer::~MetalBuffer() {
@@ -63,15 +66,20 @@ MetalBuffer::~MetalBuffer() {
    }
 }

-void MetalBuffer::copyIntoBuffer(void* src, size_t size, size_t byteOffset) {
+void MetalBuffer::copyIntoBuffer(
+        void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag) {
    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;
+            << " at offset " << byteOffset << ", tag=" << getHandleTag();
    // The copy blit requires that byteOffset be a multiple of 4.
-    FILAMENT_CHECK_PRECONDITION(!(byteOffset & 0x3)) << "byteOffset must be a multiple of 4";
+    FILAMENT_CHECK_PRECONDITION(!(byteOffset & 0x3))
+            << "byteOffset must be a multiple of 4, tag=" << getHandleTag();

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

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

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

-id<MTLBuffer> MetalBuffer::getGpuBufferForDraw(id<MTLCommandBuffer> cmdBuffer) noexcept {
+id<MTLBuffer> MetalBuffer::getGpuBufferForDraw() noexcept {
    // If there's a CPU buffer, then we return nil here, as the CPU-side buffer will be bound
    // separately.
    if (mCpuBuffer) {
@@ -137,7 +146,7 @@ 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(cmdBuffer);
+        id<MTLBuffer> gpuBuffer = buffer->getGpuBufferForDraw();
        if (!gpuBuffer) {
            continue;
        }
@@ -197,9 +206,13 @@ void MetalBuffer::bindBuffers(id<MTLCommandBuffer> cmdBuffer, id<MTLCommandEncod
    }
 }

-void MetalBuffer::uploadWithPoolBuffer(void* src, size_t size, size_t byteOffset) const {
+void MetalBuffer::uploadWithPoolBuffer(
+        void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag) 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.
@@ -217,10 +230,18 @@ void MetalBuffer::uploadWithPoolBuffer(void* src, size_t size, size_t byteOffset
    }];
 }

-void MetalBuffer::uploadWithBumpAllocator(void* src, size_t size, size_t byteOffset) const {
+void MetalBuffer::uploadWithBumpAllocator(
+        void* src, size_t size, size_t byteOffset, TagResolver&& getHandleTag) const {
    MetalBumpAllocator& allocator = *mContext.bumpAllocator;
    auto [buffer, offset] = allocator.allocateStagingArea(size);
-    memcpy(static_cast<char*>(buffer.contents) + offset, src, 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);

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

+#include <backend/DriverEnums.h>
+
 #include <CoreVideo/CVMetalTextureCache.h>
 #include <Metal/Metal.h>
 #include <QuartzCore/QuartzCore.h>
@@ -46,13 +48,13 @@ 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

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

-struct MetalContext {
-    explicit MetalContext(size_t metalFreedTextureListSize)
-        : texturesToDestroy(metalFreedTextureListSize) {}
+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 {
    MetalDriver* driver;
    id<MTLDevice> device = nullptr;
    id<MTLCommandQueue> commandQueue = nullptr;

-    id<MTLCommandBuffer> pendingCommandBuffer = nullptr;
-    id<MTLRenderCommandEncoder> currentRenderPassEncoder = 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;

    std::atomic<bool> memorylessLimitsReached = false;

@@ -85,6 +135,7 @@ struct MetalContext {
    bool supportsTextureSwizzling = false;
    bool supportsAutoDepthResolve = false;
    bool supportsMemorylessRenderTargets = false;
+    bool supportsDepthClamp = false;
    uint8_t maxColorRenderTargets = 4;
    struct {
        uint8_t common;
@@ -108,10 +159,10 @@ 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.
@@ -124,23 +175,17 @@ struct MetalContext {

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

-    MetalSamplerGroup* samplerBindings[Program::SAMPLER_BINDING_COUNT] = {};
+    // 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;

-    // 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;
+    // Keeps track of all alive textures.
    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;

@@ -153,6 +198,7 @@ struct MetalContext {

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

    MetalBlitter* blitter = nullptr;

@@ -101,9 +101,14 @@ 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) {
@@ -125,6 +130,7 @@ void submitPendingCommands(MetalContext* context) {
    assert_invariant(context->pendingCommandBuffer.status != MTLCommandBufferStatusCommitted);
    [context->pendingCommandBuffer commit];
    context->pendingCommandBuffer = nil;
+    context->pendingCommandBufferId++;
 }

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

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

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

 namespace filament {
 namespace backend {
@@ -57,11 +58,11 @@ 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;
@@ -73,10 +74,23 @@ 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;
-    std::mutex mTickOpsLock;
+
+    // Tasks regularly executed on the driver thread after a command buffer has completed
+    struct DeferredTask {
+        DeferredTask(uint64_t commandBufferId, utils::Invocable<void()>&& fn) noexcept
+            : commandBufferId(commandBufferId), fn(std::move(fn)) {}
+        uint64_t commandBufferId;     // after this command buffer completes
+        utils::Invocable<void()> fn;  // execute this task
+    };
+    void executeAfterCurrentCommandBufferCompletes(utils::Invocable<void()>&& fn) noexcept;
+    void executeDeferredOps() noexcept;
+    std::deque<DeferredTask> mDeferredTasks;

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

@@ -71,7 +71,8 @@ constexpr inline MTLIndexType getIndexType(size_t elementSize) noexcept {
    } else if (elementSize == 4) {
        return MTLIndexTypeUInt32;
    }
-    FILAMENT_CHECK_POSTCONDITION(false) << "Index element size not supported.";
+    assert_invariant(false);
+    return MTLIndexTypeUInt16;
 }

 constexpr inline MTLVertexFormat getMetalFormat(ElementType type, bool normalized) noexcept {
@@ -32,100 +32,75 @@ struct MetalContext;
 * texture.
 */
 class MetalExternalImage {
-
 public:
+    MetalExternalImage() = default;

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

    /**
-     * @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.
+     * While the texture is used for rendering, this MetalExternalImage must be kept alive.
     */
-    bool isValid() const noexcept;
+    id<MTLTexture> getMtlTexture() const noexcept;
+
+    bool isValid() const noexcept {
+        return mImage != nil || mRgbTexture != nullptr;
+    }
+
+    NSUInteger getWidth() const noexcept;
+    NSUInteger getHeight() const noexcept;

    /**
-     * 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.
+     * Create an external image with the passed-in CVPixelBuffer.
     *
-     * Calling set with a YCbCr image will encode a compute pass to convert the image from YCbCr to
-     * RGB.
+     * 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.
     */
-    void set(CVPixelBufferRef image) noexcept;
+    static MetalExternalImage createFromImage(MetalContext& context, CVPixelBufferRef image);

    /**
-     * 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.
+     * 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.
     */
-    void set(CVPixelBufferRef image, size_t plane) noexcept;
+    static MetalExternalImage createFromImagePlane(
+            MetalContext& context, CVPixelBufferRef image, uint32_t plane);

-    /**
-     * 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;
+    static void assertWritableImage(CVPixelBufferRef image);

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

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

-    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 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);

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

-    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.
+    // TODO: this could probably be a union.
    CVPixelBufferRef mImage = nullptr;
    CVMetalTextureRef mTexture = nullptr;
-    id<MTLTexture> mTextureView = nullptr;
-    size_t mWidth = 0;
-    size_t mHeight = 0;
-
-    // If the external image is in the YCbCr format, this holds the result of the converted RGB
-    // texture.
    id<MTLTexture> mRgbTexture = nil;
-
-    struct {
-        TextureSwizzle r, g, b, a;
-    } mSwizzle;
 };

 } // namespace backend
@@ -34,10 +34,6 @@
 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>
@@ -71,18 +67,30 @@ ycbcrToRgb(texture2d<half, access::read>  inYTexture    [[texture(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::getWidth() const noexcept {
+    if (mImage) {
+        return CVPixelBufferGetWidth(mImage);
+    }
+    if (mRgbTexture) {
+        return mRgbTexture.width;
+    }
+    return 0;
 }

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

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

    OSType formatType = CVPixelBufferGetPixelFormatType(image);
@@ -96,30 +104,29 @@ void MetalExternalImage::set(CVPixelBufferRef image) noexcept {
            << ".";

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

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

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

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

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

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

-void MetalExternalImage::set(CVPixelBufferRef image, size_t plane) noexcept {
-    unset();
-
+MetalExternalImage MetalExternalImage::createFromImagePlane(
+        MetalContext& context, CVPixelBufferRef image, uint32_t plane) {
    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.";

-    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;
+    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;
    };

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

-id<MTLTexture> MetalExternalImage::getMetalTextureForDraw() const noexcept {
+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 {
    if (mRgbTexture) {
        return mRgbTexture;
    }
-
-    // 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);
+    if (mTexture) {
+        return CVMetalTextureGetTexture(mTexture);
    }
-    if (tracker.trackResource((__bridge void*) commandBuffer, mTexture, cvBufferDeleter)) {
-        CVBufferRetain(mTexture);
-    }
-
-    assert_invariant(mTextureView);
-    return mTextureView;
+    return nil;
 }

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

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

-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) {
+id<MTLTexture> MetalExternalImage::createRgbTexture(
+        id<MTLDevice> device, size_t width, size_t height) {
    MTLTextureDescriptor *descriptor =
            [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatRGBA8Unorm
                                                               width:width
                                                              height:height
                                                           mipmapped:NO];
    descriptor.usage = MTLTextureUsageShaderWrite | MTLTextureUsageShaderRead;
-    return [mContext.device newTextureWithDescriptor:descriptor];
+    return [device newTextureWithDescriptor:descriptor];
 }

-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) {
+void MetalExternalImage::ensureComputePipelineState(MetalContext& context) {
+    if (context.externalImageComputePipelineState != nil) {
        return;
    }

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

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

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

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

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

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

    id<MTLComputeCommandEncoder> computeEncoder = [commandBuffer computeCommandEncoder];

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

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

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

    void releaseDrawable();

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

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

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

    enum class SwapChainType {
@@ -93,7 +97,6 @@ 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();
@@ -121,6 +124,7 @@ private:
    struct {
        CallbackHandler* handler = nullptr;
        std::shared_ptr<FrameScheduledCallback> callback = nullptr;
+        uint64_t flags = 0;
    } frameScheduled;

    struct {
@@ -131,19 +135,17 @@ 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);
-    void updateBufferUnsynchronized(void* data, size_t size, uint32_t byteOffset);
+    void updateBuffer(void* data, size_t size, uint32_t byteOffset, TagResolver&& getHandleTag);
+    void updateBufferUnsynchronized(
+            void* data, size_t size, uint32_t byteOffset, TagResolver&& getHandleTag);
    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;
 };
@@ -200,12 +202,11 @@ public:
    MetalProgram(MetalContext& context, Program&& program) noexcept;

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

 private:
    void initialize();

-    Program::SamplerGroupInfo samplerGroupInfo;
    MetalContext& mContext;
    MetalShaderCompiler::MetalFunctionBundle mFunctionBundle;
    MetalShaderCompiler::program_token_t mToken;
@@ -227,43 +228,42 @@ 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,
-            TextureSwizzle r, TextureSwizzle g, TextureSwizzle b, TextureSwizzle a)
-            noexcept;
+            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;

    // 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;

-    ~MetalTexture();
+    // 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;

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

    // Returns the id<MTLTexture> for attaching to a render pass.
-    id<MTLTexture> getMtlTextureForWrite() noexcept {
+    id<MTLTexture> getMtlTextureForWrite() const 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
@@ -272,26 +272,6 @@ 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;
@@ -302,95 +282,12 @@ 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 {
@@ -541,12 +438,67 @@ struct MetalTimerQuery : public HwTimerQuery {

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

@@ -74,7 +74,6 @@ 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) {
@@ -100,17 +99,15 @@ 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(context),
+      externalImage(MetalExternalImage::createFromImage(context, pixelBuffer)),
      type(SwapChainType::CVPIXELBUFFERREF) {
    assert_invariant(flags & SWAP_CHAIN_CONFIG_APPLE_CVPIXELBUFFER);
    MetalExternalImage::assertWritableImage(pixelBuffer);
-    externalImage.set(pixelBuffer);
    assert_invariant(externalImage.isValid());
 }

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

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

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

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

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

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

 void MetalSwapChain::setFrameCompletedCallback(
@@ -257,10 +254,6 @@ void MetalSwapChain::present() {
    }
 }

-#ifndef FILAMENT_RELEASE_PRESENT_DRAWABLE_MAIN_THREAD
-#define FILAMENT_RELEASE_PRESENT_DRAWABLE_MAIN_THREAD 1
-#endif
-
 class PresentDrawableData {
 public:
    PresentDrawableData() = delete;
@@ -268,10 +261,10 @@ public:
    PresentDrawableData& operator=(const PresentDrawableData&) = delete;

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

    static void maybePresentAndDestroyAsync(PresentDrawableData* that, bool shouldPresent) {
@@ -279,20 +272,23 @@ public:
           [that->mDrawable present];
        }

-#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
+        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);
+            });
+        }
    }

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

    static void cleanupAndDestroy(PresentDrawableData *that) {
        if (that->mDrawable) {
@@ -307,6 +303,7 @@ private:
    id<CAMetalDrawable> mDrawable;
    std::shared_ptr<std::mutex> mDrawableMutex;
    MetalDriver* mDriver = nullptr;
+    uint64_t mFlags = 0;
 };

 void presentDrawable(bool presentFrame, void* user) {
@@ -323,8 +320,8 @@ void MetalSwapChain::scheduleFrameScheduledCallback() {

    struct Callback {
        Callback(std::shared_ptr<FrameScheduledCallback> callback, id<CAMetalDrawable> drawable,
-                 std::shared_ptr<std::mutex> drawableMutex, MetalDriver* driver)
-            : f(callback), data(PresentDrawableData::create(drawable, drawableMutex, driver)) {}
+                 std::shared_ptr<std::mutex> drawableMutex, MetalDriver* driver, uint64_t flags)
+            : f(callback), data(PresentDrawableData::create(drawable, drawableMutex, driver, flags)) {}
        std::shared_ptr<FrameScheduledCallback> f;
        // PresentDrawableData* is destroyed by maybePresentAndDestroyAsync() later.
        std::unique_ptr<PresentDrawableData> data;
@@ -339,14 +336,19 @@ 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);
+            frameScheduled.callback, drawable, layerDrawableMutex, context.driver, flags);

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

@@ -381,12 +383,14 @@ 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) {
-    buffer.copyIntoBuffer(data, size, byteOffset);
+void MetalBufferObject::updateBuffer(
+        void* data, size_t size, uint32_t byteOffset, TagResolver&& getHandleTag) {
+    buffer.copyIntoBuffer(data, size, byteOffset, std::move(getHandleTag));
 }

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

 MetalVertexBufferInfo::MetalVertexBufferInfo(MetalContext& context, uint8_t bufferCount,
@@ -482,11 +486,6 @@ 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);
 }
@@ -496,6 +495,10 @@ const MetalShaderCompiler::MetalFunctionBundle& MetalProgram::getFunctions() {
    return mFunctionBundle;
 }

+const MetalShaderCompiler::MetalFunctionBundle& MetalProgram::getFunctionsIfPresent() const {
+    return mFunctionBundle;
+}
+
 void MetalProgram::initialize() {
    if (!mToken) {
        return;
@@ -506,10 +509,9 @@ 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, 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) {
+        TextureUsage usage) noexcept
+    : HwTexture(target, levels, samples, width, height, depth, format, usage), context(context) {
+    assert_invariant(target != SamplerType::SAMPLER_EXTERNAL);

    devicePixelFormat = decidePixelFormat(&context, format);
    FILAMENT_CHECK_POSTCONDITION(devicePixelFormat != MTLPixelFormatInvalid)
@@ -595,16 +597,28 @@ MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t le
            << ", levels = " << int(levels) << ", MTLPixelFormat = " << int(devicePixelFormat)
            << ", width = " << width << ", height = " << height << ", depth = " << depth
            << "). Out of memory?";
+}

-    // 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) {
+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) {
        // 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.
@@ -618,44 +632,30 @@ MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t le
 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),
-        externalImage(context) {
+    : HwTexture(target, levels, samples, width, height, depth, format, usage), context(context) {
    texture = metalTexture;
-    setLodRange(0, levels - 1);
 }

-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) 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();
 }

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

-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;
+id<MTLTexture> MetalTexture::getMtlTextureForRead() const noexcept {
+    return swizzledTextureView ? swizzledTextureView : texture;
 }

 MTLPixelFormat MetalTexture::decidePixelFormat(MetalContext* context, TextureFormat format) {
@@ -774,15 +774,12 @@ 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,
@@ -906,98 +903,6 @@ 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) :
@@ -1343,5 +1248,195 @@ 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
@@ -83,6 +83,10 @@ 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{});
        }
@@ -226,9 +226,11 @@ MetalShaderCompiler::program_token_t MetalShaderCompiler::createProgram(
            CompilerPriorityQueue const priorityQueue = program.getPriorityQueue();
            mCompilerThreadPool.queue(priorityQueue, token,
                    [this, name, device = mDevice, program = std::move(program), token]() {
-                        MetalFunctionBundle compiledProgram = compileProgram(program, device);
-                        token->set(compiledProgram);
-                        mCallbackManager.put(token->handle);
+                        @autoreleasepool {
+                            MetalFunctionBundle compiledProgram = compileProgram(program, device);
+                            token->set(compiledProgram);
+                            mCallbackManager.put(token->handle);
+                        }
                    });

            break;
@@ -28,37 +28,35 @@

 #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
-//   17-25       Uniform buffers                          9   Program::UNIFORM_BINDING_COUNT
-//   26          Push constants                           1
-//   27-30       Sampler groups (argument buffers)        4   Program::SAMPLER_BINDING_COUNT
+//   20          Push constants                           1
+//   21-24       Descriptor sets (argument buffers)       4   limited by MAX_DESCRIPTOR_SET_COUNT
+//   25          Dynamic offset buffer                    1
 //
-//   Total                                               31
+//   Total                                               23

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

 // 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.
@@ -71,10 +69,11 @@ 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 UNIFORM_BUFFER_BINDING_START = 17u;
-static constexpr uint32_t SSBO_BINDING_START = 0u;
-static constexpr uint32_t SAMPLER_GROUP_BINDING_START = 27u;
+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;

 // Forward declarations necessary here, definitions at end of file.
 inline bool operator==(const MTLViewport& lhs, const MTLViewport& rhs);
@@ -163,6 +162,8 @@ template<typename StateType,
         typename HashFn = utils::hash::MurmurHashFn<StateType>>
 class StateCache {

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

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

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

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

 };

@@ -207,9 +220,8 @@ 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>
+template <typename StateType, typename StateEqual = std::equal_to<StateType>>
 class StateTracker {
-
 public:

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

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

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

 // Pipeline state
@@ -346,6 +357,16 @@ 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;
@@ -382,18 +403,22 @@ using SamplerStateCache = StateCache<SamplerState, id<MTLSamplerState>, SamplerS

 using CullModeStateTracker = StateTracker<MTLCullMode>;
 using WindingStateTracker = StateTracker<MTLWinding>;
+using DepthClampStateTracker = StateTracker<MTLDepthClipMode>;

 // Argument encoder

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

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

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

    bool operator!=(const ArgumentEncoderState& rhs) const noexcept {
@@ -415,6 +440,30 @@ struct ArgumentEncoderCreator {
 using ArgumentEncoderCache = StateCache<ArgumentEncoderState, id<MTLArgumentEncoder>,
        ArgumentEncoderCreator, ArgumentEncoderHasher>;

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

@@ -166,28 +166,40 @@ 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& count = textureTypes.size();
-    assert_invariant(count > 0);
+    const auto& textureCount = textureTypes.size();
+    const auto& bufferCount = state.bufferCount;
+    assert_invariant(textureCount > 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:(count * 2)];
-    for (size_t i = 0; i < count; i++) {
+            [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++) {
        MTLArgumentDescriptor* textureArgument = [MTLArgumentDescriptor argumentDescriptor];
-        textureArgument.index = i * 2 + 0;
+        textureArgument.index = i++;
        textureArgument.dataType = MTLDataTypeTexture;
        textureArgument.textureType = textureTypes[i];
        textureArgument.access = MTLArgumentAccessReadOnly;
        [arguments addObject:textureArgument];

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

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

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

 }

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

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

@@ -111,6 +108,12 @@ 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 {};
 }
@@ -202,6 +205,10 @@ bool NoopDriver::isProtectedTexturesSupported() {
    return true;
 }

+bool NoopDriver::isDepthClampSupported() {
+    return false;
+}
+
 bool NoopDriver::isWorkaroundNeeded(Workaround) {
    return false;
 }
@@ -244,9 +251,6 @@ 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,
@@ -272,11 +276,6 @@ 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) {
@@ -299,27 +298,14 @@ 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, uint32_t len) {
+void NoopDriver::insertEventMarker(char const* string) {
 }

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

 void NoopDriver::popGroupMarker(int) {
@@ -388,6 +374,27 @@ 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) {
 }

@@ -0,0 +1,91 @@
+/*
+ * 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
@@ -0,0 +1,364 @@
+/*
+ * 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
@@ -0,0 +1,175 @@
+/*
+ * 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
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSETLAYOUT_H
+#define TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSETLAYOUT_H
+
+#include "DriverBase.h"
+
+#include <backend/DriverEnums.h>
+
+#include <algorithm>
+#include <utility>
+
+#include <stdint.h>
+
+namespace filament::backend {
+
+struct GLDescriptorSetLayout : public HwDescriptorSetLayout, public DescriptorSetLayout {
+    using HwDescriptorSetLayout::HwDescriptorSetLayout;
+    explicit GLDescriptorSetLayout(DescriptorSetLayout&& layout) noexcept
+            : DescriptorSetLayout(std::move(layout)) {
+
+        std::sort(bindings.begin(), bindings.end(),
+                [](auto&& lhs, auto&& rhs){
+            return lhs.binding < rhs.binding;
+        });
+
+        auto p = std::max_element(bindings.cbegin(), bindings.cend(),
+                [](auto const& lhs, auto const& rhs) {
+            return lhs.binding < rhs.binding;
+        });
+        maxDescriptorBinding = p->binding;
+    }
+    uint8_t maxDescriptorBinding = 0;
+};
+
+} // namespace filament::backend
+
+#endif //TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSETLAYOUT_H
@@ -21,12 +21,32 @@

 #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 {
@@ -44,8 +64,14 @@ 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;
 };

@@ -500,11 +500,13 @@ void OpenGLContext::initBugs(Bugs* bugs, Extensions const& exts,
            // qualcomm seems to have no problem with this (which is good for us)
            bugs->allow_read_only_ancillary_feedback_loop = true;

+#ifndef __EMSCRIPTEN__
            // Older Adreno devices that support ES3.0 only tend to be extremely buggy, so we
            // fall back to ES2.0.
            if (major == 3 && minor == 0) {
                bugs->force_feature_level0 = true;
            }
+#endif
        } else if (strstr(renderer, "Mali")) {
            // ARM GPU
            bugs->vao_doesnt_store_element_array_buffer_binding = true;
@@ -541,9 +543,6 @@ void OpenGLContext::initBugs(Bugs* bugs, Extensions const& exts,
            bugs->delay_fbo_destruction = true;
            // PowerVR seems to have no problem with this (which is good for us)
            bugs->allow_read_only_ancillary_feedback_loop = true;
-            // PowerVR doesn't respect lengths passed to glShaderSource, so concatenate them into a
-            // single string.
-            bugs->concatenate_shader_strings = true;
        } else if (strstr(renderer, "Apple")) {
            // Apple GPU
        } else if (strstr(renderer, "Tegra") ||
@@ -555,6 +554,14 @@ 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;
        }
@@ -609,7 +616,7 @@ 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;
                }
            }
@@ -618,15 +625,13 @@ 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
-#       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
+        // 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
        featureLevel = FeatureLevel::FEATURE_LEVEL_0;
    }
 #   endif // IOS
@@ -679,6 +684,7 @@ void OpenGLContext::initExtensionsGLES(Extensions* ext, GLint major, GLint minor
 #ifndef __EMSCRIPTEN__
    ext->EXT_debug_marker = exts.has("GL_EXT_debug_marker"sv);
 #endif
+    ext->EXT_depth_clamp = exts.has("GL_EXT_depth_clamp"sv);
    ext->EXT_discard_framebuffer = exts.has("GL_EXT_discard_framebuffer"sv);
 #ifndef __EMSCRIPTEN__
    ext->EXT_disjoint_timer_query = exts.has("GL_EXT_disjoint_timer_query"sv);
@@ -749,6 +755,7 @@ void OpenGLContext::initExtensionsGL(Extensions* ext, GLint major, GLint minor)
    ext->EXT_color_buffer_half_float = true;  // Assumes core profile.
    ext->EXT_clip_cull_distance = true;
    ext->EXT_debug_marker = exts.has("GL_EXT_debug_marker"sv);
+    ext->EXT_depth_clamp = true;
    ext->EXT_discard_framebuffer = false;
    ext->EXT_disjoint_timer_query = true;
    ext->EXT_multisampled_render_to_texture = false;
@@ -930,15 +937,19 @@ void OpenGLContext::unbindSampler(GLuint sampler) noexcept {
    }
 }

-void OpenGLContext::deleteBuffers(GLsizei n, const GLuint* buffers, GLenum target) noexcept {
-    glDeleteBuffers(n, buffers);
+void OpenGLContext::deleteBuffer(GLuint buffer, GLenum target) noexcept {
+    glDeleteBuffers(1, &buffer);
+
    // bindings of bound buffers are reset to 0
-    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;
+    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);
        }
    }

@@ -947,16 +958,13 @@ void OpenGLContext::deleteBuffers(GLsizei n, const GLuint* buffers, GLenum targe
            (target != GL_UNIFORM_BUFFER && target != GL_TRANSFORM_FEEDBACK_BUFFER));

    if (target == GL_UNIFORM_BUFFER || target == GL_TRANSFORM_FEEDBACK_BUFFER) {
-        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;
-                }
+        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;
            }
        }
    }
@@ -60,10 +60,19 @@ public:
    struct RenderPrimitive {
        static_assert(MAX_VERTEX_ATTRIBUTE_COUNT <= 16);

-        GLuint vao[2] = {};                                     // 4
+        GLuint vao[2] = {};                                     // 8
        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
@@ -76,16 +85,11 @@ public:
        // See OpenGLContext::bindVertexArray()
        uint8_t nameVersion = 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
+        // Size in bytes of indices in the index buffer (1 or 2)
+        uint8_t indicesShift = 0;                                // 1

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

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

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

    void destroyWithContext(size_t index, std::function<void(OpenGLContext&)> const& closure) noexcept;
@@ -220,8 +224,9 @@ public:
        bool EXT_color_buffer_float;
        bool EXT_color_buffer_half_float;
        bool EXT_debug_marker;
-        bool EXT_disjoint_timer_query;
+        bool EXT_depth_clamp;
        bool EXT_discard_framebuffer;
+        bool EXT_disjoint_timer_query;
        bool EXT_multisampled_render_to_texture2;
        bool EXT_multisampled_render_to_texture;
        bool EXT_protected_textures;
@@ -239,10 +244,10 @@ public:
        bool KHR_parallel_shader_compile;
        bool KHR_texture_compression_astc_hdr;
        bool KHR_texture_compression_astc_ldr;
-        bool OES_depth_texture;
-        bool OES_depth24;
-        bool OES_packed_depth_stencil;
        bool OES_EGL_image_external_essl3;
+        bool OES_depth24;
+        bool OES_depth_texture;
+        bool OES_packed_depth_stencil;
        bool OES_rgb8_rgba8;
        bool OES_standard_derivatives;
        bool OES_texture_npot;
@@ -311,15 +316,14 @@ 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;

-        // Some drivers don't respect the length argument of glShaderSource() and (apparently)
-        // require each shader source string to be null-terminated. This works around the issue by
-        // concatenating the strings into a single null-terminated string before passing it to
-        // glShaderSource().
-        bool concatenate_shader_strings;

    } bugs = {};

@@ -479,12 +483,6 @@ 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;
@@ -511,9 +509,6 @@ 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;

@@ -564,12 +559,12 @@ private:
            {   bugs.delay_fbo_destruction,
                    "delay_fbo_destruction",
                    ""},
+            {   bugs.rebind_buffer_after_deletion,
+                    "rebind_buffer_after_deletion",
+                    ""},
            {   bugs.force_feature_level0,
                    "force_feature_level0",
                    ""},
-            {   bugs.concatenate_shader_strings,
-                    "concatenate_shader_strings",
-                    ""},
    }};

    // this is chosen to minimize code size
@@ -636,6 +631,7 @@ constexpr size_t OpenGLContext::getIndexForCap(GLenum cap) noexcept { //NOLINT
 #ifdef BACKEND_OPENGL_VERSION_GL
        case GL_PROGRAM_POINT_SIZE:             index = 10; break;
 #endif
+        case GL_DEPTH_CLAMP:                    index = 11; break;
        default: break;
    }
    assert_invariant(index < state.enables.caps.size());
@@ -21,6 +21,8 @@
 #include "OpenGLContext.h"
 #include "OpenGLTimerQuery.h"
 #include "GLBufferObject.h"
+#include "GLDescriptorSet.h"
+#include "GLDescriptorSetLayout.h"
 #include "GLTexture.h"
 #include "ShaderCompilerService.h"

@@ -36,6 +38,7 @@
 #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>
@@ -52,6 +55,7 @@
 #include <tuple>
 #include <type_traits>
 #include <utility>
+#include <variant>
 #include <vector>

 #include <stddef.h>
@@ -123,16 +127,6 @@ 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;
@@ -145,6 +139,10 @@ 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 {
@@ -317,10 +315,6 @@ 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;
@@ -333,8 +327,16 @@ 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;
@@ -346,9 +348,6 @@ 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;

@@ -359,8 +358,6 @@ 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;
@@ -384,6 +381,7 @@ private:
    bool mRec709OutputColorspace = false;

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

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

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

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

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

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

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

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

 OpenGLProgram::OpenGLProgram(OpenGLDriver& gld, Program&& program) noexcept
-        : HwProgram(std::move(program.getName())) {
+        : HwProgram(std::move(program.getName())), mRec709Location(-1) {
    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));
@@ -124,36 +124,87 @@ 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 (!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);
-                }
-                CHECK_GL_ERROR(utils::slog.e)
-            }
-        }
-    } else
+                        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;
+                }
+                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)
+        }
+    }
+
+    if (context.isES2()) {
        // ES2 initialization of (fake) UBOs
        UniformsRecord* const uniformsRecords = new(std::nothrow) UniformsRecord[Program::UNIFORM_BINDING_COUNT];
        UTILS_NOUNROLL
-        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 (auto&& [index, name, uniforms] : lazyInitializationData.bindingUniformInfo) {
+            uniformsRecords[index].locations.reserve(uniforms.size());
+            uniformsRecords[index].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[binding].locations[j] = loc;
-                if (UTILS_UNLIKELY(binding == 0)) {
+                uniformsRecords[index].locations[j] = loc;
+                if (UTILS_UNLIKELY(index == 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.
@@ -165,51 +216,11 @@ void OpenGLProgram::initializeProgramState(OpenGLContext& context, GLuint progra
                    }
                }
            }
-            uniformsRecords[binding].uniforms = std::move(uniforms);
+            uniformsRecords[index].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;

@@ -226,41 +237,8 @@ void OpenGLProgram::initializeProgramState(OpenGLContext& context, GLuint progra
    }
 }

-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 {
+void OpenGLProgram::updateUniforms(
+        uint32_t index, GLuint id, void const* buffer, uint16_t age) const noexcept {
    assert_invariant(mUniformsRecords);
    assert_invariant(buffer);

@@ -277,7 +255,9 @@ void OpenGLProgram::updateUniforms(uint32_t index, GLuint id, void const* buffer
    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];
-        if (loc < 0) {
+        // 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) {
            continue;
        }
        // u.offset is in 'uint32_t' units
@@ -19,17 +19,20 @@

 #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>
@@ -69,31 +72,24 @@ 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;
    }

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

-    struct {
-        GLuint program = 0;
-    } gl;                                               // 4 bytes
+    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 setRec709ColorSpace(bool rec709) const noexcept;

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

-    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
+    BindingMap mBindingMap;     // 8 bytes + out-of-line 256 bytes

    ShaderCompilerService::program_token_t mToken{};    // 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
+    // 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

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

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

 } // namespace filament::backend

@@ -597,40 +597,30 @@ void ShaderCompilerService::compileShaders(OpenGLContext& context,
                version = "#version 310 es\n";
            }

-            const std::array<const char*, 5> sources = {
-                    version.data(),
-                    prolog.data(),
-                    specializationConstantString.c_str(),
-                    packingFunctions.data(),
-                    body.data()
+            std::array<std::string_view, 5> sources = {
+                version,
+                prolog,
+                specializationConstantString,
+                packingFunctions,
+                { body.data(), body.size() - 1 }  // null-terminated
            };

-            const std::array<GLint, 5> lengths = {
-                    (GLint)version.length(),
-                    (GLint)prolog.length(),
-                    (GLint)specializationConstantString.length(),
-                    (GLint)packingFunctions.length(),
-                    (GLint)body.length() - 1 // null terminated
-            };
+            // Some of the sources may be zero-length. Remove them as to avoid passing lengths of
+            // zero to glShaderSource(). glShaderSource should work with lengths of zero, but some
+            // drivers instead interpret zero as a sentinel for a null-terminated string.
+            auto partitionPoint = std::stable_partition(
+                    sources.begin(), sources.end(), [](std::string_view s) { return !s.empty(); });
+            size_t count = std::distance(sources.begin(), partitionPoint);
+
+            std::array<const char*, 5> shaderStrings;
+            std::array<GLint, 5> lengths;
+            for (size_t i = 0; i < count; i++) {
+                shaderStrings[i] = sources[i].data();
+                lengths[i] = sources[i].size();
+            }

            GLuint const shaderId = glCreateShader(glShaderType);
-
-            if (UTILS_UNLIKELY(context.bugs.concatenate_shader_strings)) {
-                size_t totalSize = 0;
-                for (size_t i = 0; i < sources.size(); i++) {
-                    totalSize += lengths[i];
-                }
-                std::string concatenatedShaderSource;
-                concatenatedShaderSource.reserve(totalSize);
-                for (size_t i = 0; i < sources.size(); i++) {
-                    concatenatedShaderSource.append(sources[i], lengths[i]);
-                }
-                const GLchar* ptr = concatenatedShaderSource.c_str();
-                GLint length = concatenatedShaderSource.length();
-                glShaderSource(shaderId, 1, &ptr, &length);
-            } else {
-                glShaderSource(shaderId, sources.size(), sources.data(), lengths.data());
-            }
+            glShaderSource(shaderId, count, shaderStrings.data(), lengths.data());

            glCompileShader(shaderId);

@@ -201,6 +201,12 @@ using namespace glext;
 #   define GL_CLIP_DISTANCE1                        0x3001
 #endif

+#if defined(GL_EXT_depth_clamp)
+#   define GL_DEPTH_CLAMP                           GL_DEPTH_CLAMP_EXT
+#else
+#   define GL_DEPTH_CLAMP                           0x864F
+#endif
+
 #if defined(GL_KHR_debug)
 #   define GL_DEBUG_OUTPUT                          GL_DEBUG_OUTPUT_KHR
 #   define GL_DEBUG_OUTPUT_SYNCHRONOUS              GL_DEBUG_OUTPUT_SYNCHRONOUS_KHR
@@ -155,10 +155,6 @@ 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");
@@ -557,6 +553,8 @@ 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/Show More
+++ b/Show More