Throw an NSException on Apple platforms when panicking

2024-03-27 16:04:49 -07:00
692 changed files with 33233 additions and 52139 deletions
@@ -1,17 +0,0 @@
-name: 'Android Continuous'
-inputs:
-  build-abi:
-    description: 'The target platform ABI'
-    required: true
-    default: 'armeabi-v7a'
-runs:
-  using: "composite"
-  steps:
-    - uses: actions/setup-java@v3
-      with:
-        distribution: 'temurin'
-        java-version: '17'
-    - name: Run build script
-      run: |
-        cd build/android && printf "y" | ./build.sh continuous ${{ inputs.build-abi }}
-      shell: bash
@@ -8,35 +8,32 @@ on:
      - rc/**

 jobs:
-  build-android-armv7:
-    name: build-android-armv7
+  build-android:
+    name: build-android
    runs-on: macos-14

    steps:
-      - uses: actions/checkout@v4.1.6
-      - name: Run Android Continuous
-        uses: ./.github/actions/android-continuous
+      - uses: actions/checkout@v3.3.0
+      - uses: actions/setup-java@v3
        with:
-          build-abi: armeabi-v7a
-
-  build-android-armv8a:
-    name: build-android-armv8a
-    runs-on: macos-14
-
-    steps:
-      - uses: actions/checkout@v4.1.6
-      - name: Run Android Continuous
-        uses: ./.github/actions/android-continuous
+          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:
-          build-abi: arm64-v8a
-
-  build-android-x86_64:
-    name: build-android-x86_64
-    runs-on: macos-14
-
-    steps:
-      - uses: actions/checkout@v4.1.6
-      - name: Run Android Continuous
-        uses: ./.github/actions/android-continuous
+          name: filament-android
+          path: out/filament-android-release.aar
+      - uses: actions/upload-artifact@v1.0.0
        with:
-          build-abi: x86_64
+          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
@@ -13,7 +13,7 @@ jobs:
    runs-on: macos-14

    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
      - name: Run build script
        run: |
          cd build/ios && printf "y" | ./build.sh continuous
@@ -13,7 +13,7 @@ jobs:
    runs-on: ubuntu-22.04

    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
      - name: Run build script
        run: |
          cd build/linux && printf "y" | ./build.sh continuous
@@ -13,7 +13,7 @@ jobs:
    runs-on: macos-14

    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
      - name: Run build script
        run: |
          cd build/mac && printf "y" | ./build.sh continuous
@@ -13,7 +13,7 @@ jobs:
    name: npm-deploy
    runs-on: macos-14
    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
        with:
          ref: ${{ github.event.inputs.release_tag }}
      # Setup .npmrc file to publish to npm
@@ -18,7 +18,7 @@ jobs:
        os: [macos-14, ubuntu-22.04]

    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
      - name: Run build script
        run: |
          WORKFLOW_OS=`echo \`uname\` | sed "s/Darwin/mac/" | tr [:upper:] [:lower:]`
@@ -32,7 +32,7 @@ jobs:
    runs-on: windows-2019

    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
      - name: Run build script
        run: |
          build\windows\build-github.bat presubmit
@@ -43,23 +43,21 @@ jobs:
    runs-on: macos-14

    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
      - uses: actions/setup-java@v3
        with:
          distribution: 'temurin'
          java-version: '17'
      - name: Run build script
-        # Only build 1 64 bit target during presubmit to cut down build times during presubmit
-        # Continuous builds will build everything
        run: |
-          cd build/android && printf "y" | ./build.sh presubmit arm64-v8a
+          cd build/android && printf "y" | ./build.sh presubmit

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

    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
      - name: Run build script
        run: |
          cd build/ios && printf "y" | ./build.sh presubmit
@@ -72,7 +70,7 @@ jobs:
    runs-on: macos-14

    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
      - name: Run build script
        run: |
          cd build/web && printf "y" | ./build.sh presubmit
@@ -41,7 +41,7 @@ jobs:
          TAG=${REF##*/}
          echo "ref=${REF}" >> $GITHUB_OUTPUT
          echo "tag=${TAG}" >> $GITHUB_OUTPUT
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
        with:
          ref: ${{ steps.git_ref.outputs.ref }}
      - name: Run build script
@@ -76,7 +76,7 @@ jobs:
          TAG=${REF##*/}
          echo "ref=${REF}" >> $GITHUB_OUTPUT
          echo "tag=${TAG}" >> $GITHUB_OUTPUT
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
        with:
          ref: ${{ steps.git_ref.outputs.ref }}
      - name: Run build script
@@ -109,7 +109,7 @@ jobs:
          TAG=${REF##*/}
          echo "ref=${REF}" >> $GITHUB_OUTPUT
          echo "tag=${TAG}" >> $GITHUB_OUTPUT
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
        with:
          ref: ${{ steps.git_ref.outputs.ref }}
      - uses: actions/setup-java@v3
@@ -120,7 +120,7 @@ jobs:
        env:
          TAG: ${{ steps.git_ref.outputs.tag }}
        run: |
-          cd build/android && printf "y" | ./build.sh release armeabi-v7a,arm64-v8a,x86,x86_64
+          cd build/android && printf "y" | ./build.sh release
          cd ../..
          mv out/filament-android-release.aar out/filament-${TAG}-android.aar
          mv out/filamat-android-release.aar out/filamat-${TAG}-android.aar
@@ -163,7 +163,7 @@ jobs:
          TAG=${REF##*/}
          echo "ref=${REF}" >> $GITHUB_OUTPUT
          echo "tag=${TAG}" >> $GITHUB_OUTPUT
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
        with:
          ref: ${{ steps.git_ref.outputs.ref }}
      - name: Run build script
@@ -197,7 +197,7 @@ jobs:
          echo "ref=${REF}" >> $GITHUB_OUTPUT
          echo "tag=${TAG}" >> $GITHUB_OUTPUT
        shell: bash
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
        with:
          ref: ${{ steps.git_ref.outputs.ref }}
      - name: Run build script
@@ -13,7 +13,7 @@ jobs:
    runs-on: macos-14

    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
      - name: Run build script
        run: |
          cd build/web && printf "y" | ./build.sh continuous
@@ -13,7 +13,7 @@ jobs:
    runs-on: windows-2019

    steps:
-      - uses: actions/checkout@v4.1.6
+      - uses: actions/checkout@v3.3.0
      - name: Run build script
        run: |
          build\windows\build-github.bat continuous
@@ -73,6 +73,7 @@ The following CMake options are boolean options specific to Filament:
 - `FILAMENT_SUPPORTS_VULKAN`:      Include the Vulkan backend
 - `FILAMENT_INSTALL_BACKEND_TEST`: Install the backend test library so it can be consumed on iOS
 - `FILAMENT_USE_EXTERNAL_GLES3`:   Experimental: Compile Filament against OpenGL ES 3
+- `FILAMENT_USE_SWIFTSHADER`:      Compile Filament against SwiftShader
 - `FILAMENT_SKIP_SAMPLES`:         Don't build sample apps

 To turn an option on or off:
@@ -425,7 +426,7 @@ value is the desired roughness between 0 and 1.

 ## Generating C++ documentation

-To generate the documentation you must first install `doxygen` and `graphviz`, then run the
+To generate the documentation you must first install `doxygen` and `graphviz`, then run the 
 following commands:

 ```shell
@@ -435,62 +436,32 @@ doxygen docs/doxygen/filament.doxygen

 Finally simply open `docs/html/index.html` in your web browser.

-## Software Rasterization
+## SwiftShader

-We have tested swiftshader and Mesa for software rasterization on the Vulkan/GL backends.
-
-To use this for Vulkan, please first make sure that the [Vulkan SDK](https://www.lunarg.com/vulkan-sdk/) is
-installed on your machine. If you are doing a manual installation of the SDK on Linux, you will have
-to source `setup-env.sh` in the SDK's root folder to make sure the Vulkan loader is the first lib loaded.
-
-### Swiftshader (Vulkan) [tested on macOS and Linux]
-
-First, build SwiftShader
+To try out Filament's Vulkan support with SwiftShader, first build SwiftShader and set the
+`SWIFTSHADER_LD_LIBRARY_PATH` variable to the folder that contains `libvk_swiftshader.dylib`:

 ```shell
 git clone https://github.com/google/swiftshader.git
 cd swiftshader/build
 cmake .. &&  make -j
+export SWIFTSHADER_LD_LIBRARY_PATH=`pwd`
 ```

-and then set `VK_ICD_FILENAMES` to the ICD json produced in the build. For example,
-```shell
-export VK_ICD_FILENAMES=/Users/user/swiftshader/build/Darwin/vk_swiftshader_icd.json
-```
+Next, go to your Filament repo and use the [easy build](#easy-build) script with `-t`.

-Build and run Filament as usual and specify the Vulkan backend when creating the Engine.
+## SwiftShader for CI

-### Mesa's LLVMPipe (GL) and Lavapipe (Vulkan) [tested on Linux]
-
-We will only cover steps that build Mesa from source. The official documentation of Mesa mentioned
-that in general precompiled libraries [are **not** made available](https://docs.mesa3d.org/precompiled.html).
-
-Download the repo and make sure you have the build depedencies. For example (assuming an Ubuntu/Debian distro),
-```shell
-git clone https://gitlab.freedesktop.org/mesa/mesa.git
-sudo apt-get build-dep mesa
-```
-
-To build both the GL and Vulkan rasterizers,
+Continuous testing turnaround can be quite slow if you need to build SwiftShader from scratch, so we
+provide an Ubuntu-based Docker image that has it already built. The Docker image also includes
+everything necessary for building Filament. You can fetch and run the image as follows:

 ```shell
-cd mesa
-mkdir -p out
-meson setup builddir/ -Dprefix=$(pwd)/out -Dglx=xlib -Dgallium-drivers=swrast -Dvulkan-drivers=swrast
-meson install -C builddir/
+docker pull ghcr.io/filament-assets/swiftshader
+docker run -it ghcr.io/filament-assets/swiftshader
 ```

-For GL, we need to ensure that we load the GL lib from the mesa output directory.  For example, to run
-the debug `gltf_viewer`, we would execute
-```shell
-LD_LIBRARY_PATH=/Users/user/mesa/out/lib/x86_64-linux-gnu \
-    ./out/cmake-debug/samples/gltf_viewer -a opengl
-```
+To do more with the container, see the helper script at `build/swiftshader/test.sh`.

-For Vulkan, we need to set the path to the ICD json, which tells the loader where to find the driver
-library. To run `gltf_viewer`, we would execute
-```shell
-VK_ICD_FILENAMES=/Users/user/mesa/out/share/vulkan/icd.d/lvp_icd.x86_64.json \
-    ./out/cmake-debug/samples/gltf_viewer -a vulkan
-
-```
+If you are a team member, you can update the public image to the latest SwiftShader by
+following the instructions at the top of `build/swiftshader/Dockerfile`.
@@ -21,6 +21,8 @@ project(TNT)
 # ==================================================================================================
 option(FILAMENT_USE_EXTERNAL_GLES3 "Experimental: Compile Filament against OpenGL ES 3" OFF)

+option(FILAMENT_USE_SWIFTSHADER "Compile Filament against SwiftShader" OFF)
+
 option(FILAMENT_ENABLE_LTO "Enable link-time optimizations if supported by the compiler" OFF)

 option(FILAMENT_SKIP_SAMPLES "Don't build samples" OFF)
@@ -69,10 +71,6 @@ set(FILAMENT_METAL_HANDLE_ARENA_SIZE_IN_MB "8" CACHE STRING
    "Size of the Metal handle arena, default 8."
 )

-set(FILAMENT_BACKEND_DEBUG_FLAG "" CACHE STRING
-    "A debug flag meant for enabling/disabling backend debugging paths"
-)
-
 # Enable exceptions by default in spirv-cross.
 set(SPIRV_CROSS_EXCEPTIONS_TO_ASSERTIONS OFF)

@@ -143,6 +141,11 @@ if (LINUX)
            add_definitions(-DFILAMENT_SUPPORTS_XCB)
        endif()

+        # Default Swiftshader build does not enable the xlib extension
+        if (FILAMENT_SUPPORTS_XLIB AND FILAMENT_USE_SWIFTSHADER)
+            set(FILAMENT_SUPPORTS_XLIB OFF)
+        endif()
+
        if (FILAMENT_SUPPORTS_XLIB)
            add_definitions(-DFILAMENT_SUPPORTS_XLIB)
        endif()
@@ -166,6 +169,15 @@ if (NOT ANDROID AND NOT WEBGL AND NOT IOS AND NOT FILAMENT_LINUX_IS_MOBILE)
    set(IS_HOST_PLATFORM TRUE)
 endif()

+if (IOS)
+    # Remove the headerpad_max_install_names linker flag on iOS. It causes warnings when linking
+    # executables with bitcode.
+    string(REPLACE "-Wl,-headerpad_max_install_names" "" CMAKE_C_LINK_FLAGS ${CMAKE_C_LINK_FLAGS})
+    string(REPLACE "-Wl,-headerpad_max_install_names" "" CMAKE_CXX_LINK_FLAGS ${CMAKE_CXX_LINK_FLAGS})
+    string(REPLACE "-Wl,-headerpad_max_install_names" "" CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS ${CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS})
+    string(REPLACE "-Wl,-headerpad_max_install_names" "" CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS ${CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS})
+endif()
+
 if (WIN32)
    # Link statically against c/c++ lib to avoid missing redistriburable such as
    # "VCRUNTIME140.dll not found. Try reinstalling the app.", but give users
@@ -320,6 +332,10 @@ if (FILAMENT_SUPPORTS_EGL_ON_LINUX)
  set(EGL TRUE)
 endif()

+if (FILAMENT_USE_SWIFTSHADER)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DFILAMENT_USE_SWIFTSHADER")
+endif()
+
 if (WIN32)
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -D_USE_MATH_DEFINES=1")
 endif()
@@ -373,9 +389,8 @@ endif()
 if (NOT MSVC AND NOT IOS)
    # Omitting stack frame pointers prevents the generation of readable stack traces in crash reports on iOS
    set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -fomit-frame-pointer")
-endif()

-if (NOT MSVC)
+    # These aren't compatible with -fembed-bitcode (and seem to have no effect on Apple platforms anyway)
    set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -ffunction-sections -fdata-sections")
 endif()

@@ -440,13 +455,8 @@ endif()
 if (NOT WEBGL)
    set(GC_SECTIONS "-Wl,--gc-sections")
 endif()
-
 set(B_SYMBOLIC_FUNCTIONS "-Wl,-Bsymbolic-functions")

-if (ANDROID)
-set(BINARY_ALIGNMENT "-Wl,-z,max-page-size=16384")
-endif()
-
 if (APPLE)
    set(GC_SECTIONS "-Wl,-dead_strip")
    set(B_SYMBOLIC_FUNCTIONS "")
@@ -460,7 +470,7 @@ if (APPLE)
 endif()

 set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${GC_SECTIONS}")
-set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${GC_SECTIONS} ${B_SYMBOLIC_FUNCTIONS} ${BINARY_ALIGNMENT}")
+set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${GC_SECTIONS} ${B_SYMBOLIC_FUNCTIONS}")

 if (WEBGL_PTHREADS)
    set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -pthread")
@@ -524,15 +534,13 @@ else()
 endif()

 # This only affects the prebuilt shader files in gltfio and samples, not filament library.
-# The value can be either "instanced", "multiview", or "none"
-set(FILAMENT_SAMPLES_STEREO_TYPE "none" CACHE STRING
+# The value can be either "instanced" or "multiview".
+set(FILAMENT_SAMPLES_STEREO_TYPE "instanced" CACHE STRING
    "Stereoscopic type that shader files in gltfio and samples are built for."
 )
 string(TOLOWER "${FILAMENT_SAMPLES_STEREO_TYPE}" FILAMENT_SAMPLES_STEREO_TYPE)
-if (NOT FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "instanced"
-    AND NOT FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "multiview"
-    AND NOT FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "none")
-    message(FATAL_ERROR "Invalid stereo type: \"${FILAMENT_SAMPLES_STEREO_TYPE}\" choose either \"instanced\",  \"multiview\", or \"none\" ")
+if (NOT FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "instanced" AND NOT FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "multiview")
+    message(FATAL_ERROR "Invalid stereo type: \"${FILAMENT_SAMPLES_STEREO_TYPE}\" choose either \"instanced\" or \"multiview\" ")
 endif ()

 # Compiling samples for multiview implies enabling multiview feature as well.
@@ -540,12 +548,6 @@ if (FILAMENT_SAMPLES_STEREO_TYPE STREQUAL "multiview")
    set(FILAMENT_ENABLE_MULTIVIEW ON)
 endif ()

-# Define backend flag for debug only
-if (CMAKE_BUILD_TYPE STREQUAL "Debug" AND NOT FILAMENT_BACKEND_DEBUG_FLAG STREQUAL "")
-    add_definitions(-DFILAMENT_BACKEND_DEBUG_FLAG=${FILAMENT_BACKEND_DEBUG_FLAG})
-    unset(FILAMENT_BACKEND_DEBUG_FLAG)
-endif()
-
 # ==================================================================================================
 # Material compilation flags
 # ==================================================================================================
@@ -674,6 +676,21 @@ else()
    set(IMPORT_EXECUTABLES ${FILAMENT}/${IMPORT_EXECUTABLES_DIR}/ImportExecutables-${CMAKE_BUILD_TYPE}.cmake)
 endif()

+# ==================================================================================================
+# Try to find Vulkan if the SDK is installed, otherwise fall back to the bundled version.
+# This needs to stay in our top-level CMakeLists because it sets up variables that are used by the
+# "bluevk" and "samples" targets.
+# ==================================================================================================
+
+if (FILAMENT_USE_SWIFTSHADER)
+    if (NOT FILAMENT_SUPPORTS_VULKAN)
+        message(ERROR "SwiftShader is only useful when Vulkan is enabled.")
+    endif()
+    find_library(SWIFTSHADER_VK NAMES vk_swiftshader HINTS "$ENV{SWIFTSHADER_LD_LIBRARY_PATH}")
+    message(STATUS "Found SwiftShader VK library in: ${SWIFTSHADER_VK}.")
+    add_definitions(-DFILAMENT_VKLIBRARY_PATH=\"${SWIFTSHADER_VK}\")
+endif()
+
 # ==================================================================================================
 # Common Functions
 # ==================================================================================================
@@ -735,6 +752,7 @@ add_subdirectory(${FILAMENT}/filament)
 add_subdirectory(${FILAMENT}/shaders)
 add_subdirectory(${EXTERNAL}/basisu/tnt)
 add_subdirectory(${EXTERNAL}/civetweb/tnt)
+add_subdirectory(${EXTERNAL}/hat-trie/tnt)
 add_subdirectory(${EXTERNAL}/imgui/tnt)
 add_subdirectory(${EXTERNAL}/robin-map/tnt)
 add_subdirectory(${EXTERNAL}/smol-v/tnt)
@@ -801,9 +819,6 @@ if (IS_HOST_PLATFORM)
    add_subdirectory(${TOOLS}/glslminifier)
    add_subdirectory(${TOOLS}/matc)
    add_subdirectory(${TOOLS}/matinfo)
-    if (NOT WIN32)  # matedit not yet supported on Windows
-        add_subdirectory(${TOOLS}/matedit)
-    endif()
    add_subdirectory(${TOOLS}/mipgen)
    add_subdirectory(${TOOLS}/normal-blending)
    add_subdirectory(${TOOLS}/resgen)
@@ -8,4 +8,4 @@ appropriate header in [RELEASE_NOTES.md](./RELEASE_NOTES.md).

 ## Release notes for next branch cut

- Add support for multi-layered render target with array textures.
+- engine: Add experimental APIs `Engine::builder::paused()` and `Engine::setPaused()`
@@ -31,7 +31,7 @@ repositories {
 }

 dependencies {
-    implementation 'com.google.android.filament:filament-android:1.54.2'
+    implementation 'com.google.android.filament:filament-android:1.51.0'
 }
 ```

@@ -51,9 +51,19 @@ Here are all the libraries available in the group `com.google.android.filament`:
 iOS projects can use CocoaPods to install the latest release:

 ```shell
-pod 'Filament', '~> 1.54.2'
+pod 'Filament', '~> 1.51.0'
 ```

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

 - [Filament](https://google.github.io/filament/Filament.html), an in-depth explanation of
@@ -166,7 +176,6 @@ pod 'Filament', '~> 1.54.2'
  - [x] KHR_materials_unlit
  - [x] KHR_materials_variants
  - [x] KHR_materials_volume
-  - [x] KHR_materials_specular
  - [x] KHR_mesh_quantization
  - [x] KHR_texture_basisu
  - [x] KHR_texture_transform
@@ -7,88 +7,6 @@ A new header is inserted each time a *tag* is created.
 Instead, if you are authoring a PR for the main branch, add your release note to
 [NEW_RELEASE_NOTES.md](./NEW_RELEASE_NOTES.md).

-## v1.54.3
-
-
-## v1.54.2
-
- Add a `name` API to Filament objects for debugging handle use-after-free assertions
-
-## v1.54.1
-
-
-## v1.54.0
-
- materials: add a new `stereoscopicType` material parameter. [⚠️ **New Material Version**]
- Fix a crash when compiling shaders on IMG devices
-
-## v1.53.5
-
- engine: Fix bug causing certain sampler parameters to not be applied correctly in GLES 2.0 and on
-  certain GLES 3.0 drivers.
-
-## v1.53.4
-
-
-## v1.53.3
-
- Add drag and drop support for IBL files for desktop gltf_viewer.
-
-## v1.53.2
-
-
-## v1.53.1
-
-
-## v1.53.0
-
- engine: fix skinning normals with large transforms (b/342459864) [⚠️ **New Material Version**]
-
-## v1.52.3
-
-
-## v1.52.2
-
-
-## v1.52.1
-
- Add instructions for using Mesa for software rasterization
-
-## v1.51.9
-
-
-## v1.51.8
-
- filagui: Fix regression which broke WebGL
- Add a new Engine::Config setting to control preferred shader language
- Add `getEyeIndex` vertex API
- ios: Remove bitcode from iOS builds
-
-## v1.51.7
-
- Add new matedit tool
- filagui: Support rendering `GL_TEXTURE_EXTERNAL_OES` textures.
- `setFrameScheduledCallback` now takes a `utils::Invocable`.
- engine: Add `isPaused()`
-
-## v1.51.6
-
- Add new matedit tool
- filagui: Support rendering `GL_TEXTURE_EXTERNAL_OES` textures.
-
-## v1.51.5
-
-
-## v1.51.4
-
-
-## v1.51.3
-
-
-## v1.51.2
-
- engine: Add experimental APIs `Engine::builder::paused()` and `Engine::setPaused()`
-
 ## v1.51.1


@@ -83,12 +83,12 @@ buildscript {
        'minSdk': 21,
        'targetSdk': 34,
        'compileSdk': 34,
-        'kotlin': '2.0.0',
-        'kotlin_coroutines': '1.9.0-RC',
+        'kotlin': '1.9.21',
+        'kotlin_coroutines': '1.7.3',
        'buildTools': '34.0.0',
-        'ndk': '27.0.11718014',
-        'androidx_core': '1.13.1',
-        'androidx_annotations': '1.8.0'
+        'ndk': '26.1.10909125',
+        'androidx_core': '1.12.0',
+        'androidx_annotations': '1.7.0'
    ]

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

    dependencies {
-        classpath 'com.android.tools.build:gradle:8.4.1'
+        classpath 'com.android.tools.build:gradle:8.2.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:${versions.kotlin}"
    }

@@ -38,7 +38,6 @@ set(FILAMAT_INCLUDE_DIRS
 include_directories(${FILAMENT_DIR}/include)

 set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "${CMAKE_SHARED_LINKER_FLAGS_RELEASE} -Wl,--version-script=${CMAKE_SOURCE_DIR}/libfilamat-jni.map")
-set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-z,max-page-size=16384")

 add_library(filamat-jni SHARED src/main/cpp/MaterialBuilder.cpp)
 target_include_directories(filamat-jni PRIVATE ${FILAMAT_INCLUDE_DIRS})
@@ -59,7 +59,6 @@ endif()

 set(VERSION_SCRIPT "${CMAKE_CURRENT_SOURCE_DIR}/libfilament-jni.map")
 set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "${CMAKE_SHARED_LINKER_FLAGS_RELEASE} -Wl,--version-script=${VERSION_SCRIPT}")
-set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-z,max-page-size=16384")

 add_library(filament-jni SHARED
    src/main/cpp/BufferObject.cpp
@@ -342,21 +342,6 @@ Java_com_google_android_filament_Engine_nIsValidMaterial(JNIEnv*, jclass,
    return (jboolean)engine->isValid((Material*)nativeMaterial);
 }

-extern "C" JNIEXPORT jboolean JNICALL
-Java_com_google_android_filament_Engine_nIsValidMaterialInstance(JNIEnv*, jclass,
-        jlong nativeEngine, jlong nativeMaterial, jlong nativeMaterialInstance) {
-    Engine* engine = (Engine *)nativeEngine;
-    return (jboolean)engine->isValid((Material*)nativeMaterial,
-            (MaterialInstance*)nativeMaterialInstance);
-}
-
-extern "C" JNIEXPORT jboolean JNICALL
-        Java_com_google_android_filament_Engine_nIsValidExpensiveMaterialInstance(JNIEnv*, jclass,
-        jlong nativeEngine, jlong nativeMaterialInstance) {
-    Engine* engine = (Engine *)nativeEngine;
-    return (jboolean)engine->isValidExpensive((MaterialInstance*)nativeMaterialInstance);
-}
-
 extern "C" JNIEXPORT jboolean JNICALL
 Java_com_google_android_filament_Engine_nIsValidSkybox(JNIEnv*, jclass,
        jlong nativeEngine, jlong nativeSkybox) {
@@ -406,13 +391,6 @@ Java_com_google_android_filament_Engine_nFlush(JNIEnv*, jclass,
    engine->flush();
 }

-extern "C" JNIEXPORT jboolean JNICALL
-Java_com_google_android_filament_Engine_nIsPaused(JNIEnv*, jclass,
-        jlong nativeEngine) {
-    Engine* engine = (Engine*) nativeEngine;
-    return (jboolean)engine->isPaused();
-}
-
 extern "C" JNIEXPORT void JNICALL
 Java_com_google_android_filament_Engine_nSetPaused(JNIEnv*, jclass,
        jlong nativeEngine, jboolean paused) {
@@ -420,13 +398,6 @@ Java_com_google_android_filament_Engine_nSetPaused(JNIEnv*, jclass,
    engine->setPaused(paused);
 }

-extern "C" JNIEXPORT void JNICALL
-Java_com_google_android_filament_Engine_nUnprotected(JNIEnv*, jclass,
-        jlong nativeEngine, jboolean paused) {
-    Engine* engine = (Engine*) nativeEngine;
-    engine->unprotected();
-}
-
 // Managers...

 extern "C" JNIEXPORT jlong JNICALL
@@ -524,9 +495,7 @@ extern "C" JNIEXPORT void JNICALL Java_com_google_android_filament_Engine_nSetBu
        jlong textureUseAfterFreePoolSize, jboolean disableParallelShaderCompile,
        jint stereoscopicType, jlong stereoscopicEyeCount,
        jlong resourceAllocatorCacheSizeMB, jlong resourceAllocatorCacheMaxAge,
-        jboolean disableHandleUseAfterFreeCheck,
-        jint preferredShaderLanguage,
-        jboolean forceGLES2Context) {
+        jboolean disableHandleUseAfterFreeCheck) {
    Engine::Builder* builder = (Engine::Builder*) nativeBuilder;
    Engine::Config config = {
            .commandBufferSizeMB = (uint32_t) commandBufferSizeMB,
@@ -542,8 +511,6 @@ extern "C" JNIEXPORT void JNICALL Java_com_google_android_filament_Engine_nSetBu
            .resourceAllocatorCacheSizeMB = (uint32_t) resourceAllocatorCacheSizeMB,
            .resourceAllocatorCacheMaxAge = (uint8_t) resourceAllocatorCacheMaxAge,
            .disableHandleUseAfterFreeCheck = (bool) disableHandleUseAfterFreeCheck,
-            .preferredShaderLanguage = (Engine::Config::ShaderLanguage) preferredShaderLanguage,
-            .forceGLES2Context = (bool) forceGLES2Context,
    };
    builder->config(&config);
 }
@@ -571,9 +538,3 @@ Java_com_google_android_filament_Engine_nBuilderBuild(JNIEnv*, jclass, jlong nat
    Engine::Builder* builder = (Engine::Builder*) nativeBuilder;
    return (jlong) builder->build();
 }
-
-extern "C"
-JNIEXPORT jlong JNICALL
-Java_com_google_android_filament_Engine_getSteadyClockTimeNano(JNIEnv *env, jclass clazz) {
-    return (jlong)Engine::getSteadyClockTimeNano();
-}
@@ -25,17 +25,12 @@ using namespace filament;

 extern "C" JNIEXPORT jlong JNICALL
 Java_com_google_android_filament_Material_nBuilderBuild(JNIEnv *env, jclass,
-        jlong nativeEngine, jobject buffer_, jint size, jint shBandCount) {
+        jlong nativeEngine, jobject buffer_, jint size) {
    Engine* engine = (Engine*) nativeEngine;
    AutoBuffer buffer(env, buffer_, size);
-    auto builder = Material::Builder();
-    if (shBandCount) {
-        builder.sphericalHarmonicsBandCount(shBandCount);
-    }
-    Material* material = builder
+    Material* material = Material::Builder()
            .package(buffer.getData(), buffer.getSize())
            .build(*engine);
-
    return (jlong) material;
 }

@@ -245,18 +245,12 @@ Java_com_google_android_filament_RenderableManager_nBuilderMorphing(JNIEnv*, jcl
 }

 extern "C" JNIEXPORT void JNICALL
-Java_com_google_android_filament_RenderableManager_nBuilderMorphingStandard(JNIEnv*, jclass,
-        jlong nativeBuilder, jlong nativeMorphTargetBuffer) {
+Java_com_google_android_filament_RenderableManager_nBuilderSetMorphTargetBufferAt(JNIEnv*, jclass,
+        jlong nativeBuilder, int level, int primitiveIndex, jlong nativeMorphTargetBuffer,
+        int offset, int count) {
    RenderableManager::Builder *builder = (RenderableManager::Builder *) nativeBuilder;
    MorphTargetBuffer *morphTargetBuffer = (MorphTargetBuffer *) nativeMorphTargetBuffer;
-    builder->morphing(morphTargetBuffer);
-}
-
-extern "C" JNIEXPORT void JNICALL
-Java_com_google_android_filament_RenderableManager_nBuilderSetMorphTargetBufferOffsetAt(JNIEnv*, jclass,
-        jlong nativeBuilder, int level, int primitiveIndex, int offset) {
-    RenderableManager::Builder *builder = (RenderableManager::Builder *) nativeBuilder;
-    builder->morphing(level, primitiveIndex, offset);
+    builder->morphing(level, primitiveIndex, morphTargetBuffer, offset, count);
 }

 extern "C" JNIEXPORT void JNICALL
@@ -328,12 +322,13 @@ Java_com_google_android_filament_RenderableManager_nSetMorphWeights(JNIEnv* env,
 }

 extern "C" JNIEXPORT void JNICALL
-Java_com_google_android_filament_RenderableManager_nSetMorphTargetBufferOffsetAt(JNIEnv*,
+Java_com_google_android_filament_RenderableManager_nSetMorphTargetBufferAt(JNIEnv*,
        jclass, jlong nativeRenderableManager, jint i, int level, jint primitiveIndex,
-        jlong, jint offset) {
+        jlong nativeMorphTargetBuffer, jint offset, jint count) {
    RenderableManager *rm = (RenderableManager *) nativeRenderableManager;
-    rm->setMorphTargetBufferOffsetAt((RenderableManager::Instance) i, (uint8_t) level,
-            (size_t) primitiveIndex, (size_t) offset);
+    MorphTargetBuffer *morphTargetBuffer = (MorphTargetBuffer *) nativeMorphTargetBuffer;
+    rm->setMorphTargetBufferAt((RenderableManager::Instance) i, (uint8_t) level,
+            (size_t) primitiveIndex, morphTargetBuffer, (size_t) offset, (size_t) count);
 }

 extern "C" JNIEXPORT jint JNICALL
@@ -28,14 +28,6 @@
 using namespace filament;
 using namespace backend;

-
-extern "C" JNIEXPORT void JNICALL
-Java_com_google_android_filament_Renderer_nSkipFrame(JNIEnv *, jclass, jlong nativeRenderer,
-        jlong vsyncSteadyClockTimeNano) {
-    Renderer *renderer = (Renderer *) nativeRenderer;
-    renderer->skipFrame(uint64_t(vsyncSteadyClockTimeNano));
-}
-
 extern "C" JNIEXPORT jboolean JNICALL
 Java_com_google_android_filament_Renderer_nBeginFrame(JNIEnv *, jclass, jlong nativeRenderer,
        jlong nativeSwapChain, jlong frameTimeNanos) {
@@ -195,10 +187,3 @@ Java_com_google_android_filament_Renderer_nSetPresentationTime(JNIEnv *, jclass
    Renderer *renderer = (Renderer *) nativeRenderer;
    renderer->setPresentationTime(monotonicClockNanos);
 }
-
-extern "C" JNIEXPORT void JNICALL
-Java_com_google_android_filament_Renderer_nSetVsyncTime(JNIEnv *, jclass,
-    jlong nativeRenderer, jlong steadyClockTimeNano) {
-    Renderer *renderer = (Renderer *) nativeRenderer;
-    renderer->setVsyncTime(steadyClockTimeNano);
-}
@@ -49,12 +49,6 @@ Java_com_google_android_filament_View_nSetCamera(JNIEnv*, jclass,
    view->setCamera(camera);
 }

-extern "C" JNIEXPORT jboolean JNICALL
-Java_com_google_android_filament_View_nHasCamera(JNIEnv*, jclass, jlong nativeView) {
-    View* view = (View*) nativeView;
-    return (jboolean)view->hasCamera();
-}
-
 extern "C" JNIEXPORT void JNICALL
 Java_com_google_android_filament_View_nSetColorGrading(JNIEnv*, jclass,
        jlong nativeView, jlong nativeColorGrading) {
@@ -531,12 +525,3 @@ Java_com_google_android_filament_View_nGetFogEntity(JNIEnv *env, jclass clazz,
    View *view = (View *) nativeView;
    return (jint)view->getFogEntity().getId();
 }
-
-extern "C"
-JNIEXPORT void JNICALL
-Java_com_google_android_filament_View_nClearFrameHistory(JNIEnv *env, jclass clazz,
-        jlong nativeView, jlong nativeEngine) {
-    View *view = (View *) nativeView;
-    Engine *engine = (Engine *) nativeEngine;
-    view->clearFrameHistory(*engine);
-}
@@ -159,12 +159,9 @@ public class Engine {
    };

    /**
-     * The type of technique for stereoscopic rendering. (Note that the materials used will need to be
-     * compatible with the chosen technique.)
+     * The type of technique for stereoscopic rendering
     */
    public enum StereoscopicType {
-        /** No stereoscopic rendering. */
-        NONE,
        /** Stereoscopic rendering is performed using instanced rendering technique. */
        INSTANCED,
        /** Stereoscopic rendering is performed using the multiview feature from the graphics backend. */
@@ -228,9 +225,7 @@ public class Engine {
                    config.textureUseAfterFreePoolSize, config.disableParallelShaderCompile,
                    config.stereoscopicType.ordinal(), config.stereoscopicEyeCount,
                    config.resourceAllocatorCacheSizeMB, config.resourceAllocatorCacheMaxAge,
-                    config.disableHandleUseAfterFreeCheck,
-                    config.preferredShaderLanguage.ordinal(),
-                    config.forceGLES2Context);
+                    config.disableHandleUseAfterFreeCheck);
            return this;
        }

@@ -408,7 +403,7 @@ public class Engine {
         *
         * @see View#setStereoscopicOptions
         */
-        public StereoscopicType stereoscopicType = StereoscopicType.NONE;
+        public StereoscopicType stereoscopicType = StereoscopicType.INSTANCED;

        /**
         * The number of eyes to render when stereoscopic rendering is enabled. Supported values are
@@ -425,46 +420,14 @@ public class Engine {
        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.
-         * The default is 1.
+         * This value determines for how many frames are texture entries kept in the cache.
         */
-        public long resourceAllocatorCacheMaxAge = 1;
+        public long resourceAllocatorCacheMaxAge = 2;

        /*
         * Disable backend handles use-after-free checks.
         */
        public boolean disableHandleUseAfterFreeCheck = false;
-
-        /*
-         * Sets a preferred shader language for Filament to use.
-         *
-         * The Metal backend supports two shader languages: MSL (Metal Shading Language) and
-         * METAL_LIBRARY (precompiled .metallib). This option controls which shader language is
-         * used when materials contain both.
-         *
-         * By default, when preferredShaderLanguage is unset, Filament will prefer METAL_LIBRARY
-         * shaders if present within a material, falling back to MSL. Setting
-         * preferredShaderLanguage to ShaderLanguage::MSL will instead instruct Filament to check
-         * for the presence of MSL in a material first, falling back to METAL_LIBRARY if MSL is not
-         * present.
-         *
-         * When using a non-Metal backend, setting this has no effect.
-         */
-        public enum ShaderLanguage {
-            DEFAULT,
-            MSL,
-            METAL_LIBRARY,
-        };
-        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;
    }

    private Engine(long nativeEngine, Config config) {
@@ -886,24 +849,6 @@ public class Engine {
        return nIsValidMaterial(getNativeObject(), object.getNativeObject());
    }

-    /**
-     * Returns whether the object is valid.
-     * @param object Object to check for validity
-     * @return returns true if the specified object is valid.
-     */
-    public boolean isValidMaterialInstance(@NonNull Material ma, MaterialInstance mi) {
-        return nIsValidMaterialInstance(getNativeObject(), ma.getNativeObject(), mi.getNativeObject());
-    }
-
-    /**
-     * Returns whether the object is valid.
-     * @param object Object to check for validity
-     * @return returns true if the specified object is valid.
-     */
-    public boolean isValidExpensiveMaterialInstance(@NonNull MaterialInstance object) {
-        return nIsValidExpensiveMaterialInstance(getNativeObject(), object.getNativeObject());
-    }
-
    /**
     * Returns whether the object is valid.
     * @param object Object to check for validity
@@ -1264,17 +1209,6 @@ public class Engine {
        nFlush(getNativeObject());
    }

-    /**
-     * Get paused state of rendering thread.
-     *
-     * <p>Warning: This is an experimental API.
-     *
-     * @see #setPaused
-     */
-    public boolean isPaused() {
-        return nIsPaused(getNativeObject());
-    }
-
    /**
     * Pause or resume the rendering thread.
     *
@@ -1292,24 +1226,6 @@ public class Engine {
        nSetPaused(getNativeObject(), paused);
    }

-    /**
-     * Switch the command queue to unprotected mode. Protected mode can be activated via
-     * Renderer::beginFrame() using a protected SwapChain.
-     * @see Renderer
-     * @see SwapChain
-     */
-    public void unprotected() {
-        nUnprotected(getNativeObject());
-    }
-
-    /**
-     * Get the current time. This is a convenience function that simply returns the
-     * time in nanosecond since epoch of std::chrono::steady_clock.
-     * @return current time in nanosecond since epoch of std::chrono::steady_clock.
-     * @see Renderer#beginFrame
-     */
-    public static native long getSteadyClockTimeNano();
-
    @UsedByReflection("TextureHelper.java")
    public long getNativeObject() {
        if (mNativeObject == 0) {
@@ -1375,8 +1291,6 @@ public class Engine {
    private static native boolean nIsValidSkinningBuffer(long nativeEngine, long nativeSkinningBuffer);
    private static native boolean nIsValidIndirectLight(long nativeEngine, long nativeIndirectLight);
    private static native boolean nIsValidMaterial(long nativeEngine, long nativeMaterial);
-    private static native boolean nIsValidMaterialInstance(long nativeEngine, long nativeMaterial, long nativeMaterialInstance);
-    private static native boolean nIsValidExpensiveMaterialInstance(long nativeEngine, long nativeMaterialInstance);
    private static native boolean nIsValidSkybox(long nativeEngine, long nativeSkybox);
    private static native boolean nIsValidColorGrading(long nativeEngine, long nativeColorGrading);
    private static native boolean nIsValidTexture(long nativeEngine, long nativeTexture);
@@ -1385,9 +1299,7 @@ public class Engine {
    private static native void nDestroyEntity(long nativeEngine, int entity);
    private static native void nFlushAndWait(long nativeEngine);
    private static native void nFlush(long nativeEngine);
-    private static native boolean nIsPaused(long nativeEngine);
    private static native void nSetPaused(long nativeEngine, boolean paused);
-    private static native void nUnprotected(long nativeEngine);
    private static native long nGetTransformManager(long nativeEngine);
    private static native long nGetLightManager(long nativeEngine);
    private static native long nGetRenderableManager(long nativeEngine);
@@ -1409,9 +1321,7 @@ public class Engine {
            long textureUseAfterFreePoolSize, boolean disableParallelShaderCompile,
            int stereoscopicType, long stereoscopicEyeCount,
            long resourceAllocatorCacheSizeMB, long resourceAllocatorCacheMaxAge,
-            boolean disableHandleUseAfterFreeCheck,
-            int preferredShaderLanguage,
-            boolean forceGLES2Context);
+            boolean disableHandleUseAfterFreeCheck);
    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);
@@ -346,7 +346,6 @@ public class Material {
    public static class Builder {
        private Buffer mBuffer;
        private int mSize;
-        private int mShBandCount = 0;

        /**
         * Specifies the material data. The material data is a binary blob produced by
@@ -362,22 +361,6 @@ public class Material {
            return this;
        }

-        /**
-         * Sets the quality of the indirect lights computations. This is only taken into account
-         * if this material is lit and in the surface domain. This setting will affect the
-         * IndirectLight computation if one is specified on the Scene and Spherical Harmonics
-         * are used for the irradiance.
-         *
-         * @param shBandCount Number of spherical harmonic bands. Must be 1, 2 or 3 (default).
-         * @return Reference to this Builder for chaining calls.
-         * @see IndirectLight
-         */
-        @NonNull
-        public Builder sphericalHarmonicsBandCount(@IntRange(from = 0) int shBandCount) {
-            mShBandCount = shBandCount;
-            return this;
-        }
-
        /**
         * Creates and returns the Material object.
         *
@@ -389,8 +372,7 @@ public class Material {
         */
        @NonNull
        public Material build(@NonNull Engine engine) {
-            long nativeMaterial = nBuilderBuild(engine.getNativeObject(),
-                mBuffer, mSize, mShBandCount);
+            long nativeMaterial = nBuilderBuild(engine.getNativeObject(), mBuffer, mSize);
            if (nativeMaterial == 0) throw new IllegalStateException("Couldn't create Material");
            return new Material(nativeMaterial);
        }
@@ -1041,7 +1023,7 @@ public class Material {
        mNativeObject = 0;
    }

-    private static native long nBuilderBuild(long nativeEngine, @NonNull Buffer buffer, int size, int shBandCount);
+    private static native long nBuilderBuild(long nativeEngine, @NonNull Buffer buffer, int size);
    private static native long nCreateInstance(long nativeMaterial);
    private static native long nCreateInstanceWithName(long nativeMaterial, @NonNull String name);
    private static native long nGetDefaultInstance(long nativeMaterial);
@@ -74,7 +74,7 @@ public class MorphTargetBuffer {
         *
         * @exception IllegalStateException if the MorphTargetBuffer could not be created
         *
-         * @see #setMorphTargetBufferOffsetAt
+         * @see #setMorphTargetBufferAt
         */
        @NonNull
        public MorphTargetBuffer build(@NonNull Engine engine) {
@@ -524,7 +524,14 @@ public class RenderableManager {
        }

        /**
-         * Controls if the renderable has legacy vertex morphing targets, zero by default.
+         * Controls if the renderable has vertex morphing targets, zero by default. This is
+         * required to enable GPU morphing.
+         *
+         * <p>Filament supports two morphing modes: standard (default) and legacy.</p>
+         *
+         * <p>For standard morphing, A {@link MorphTargetBuffer} must be created and provided via
+         * {@link RenderableManager#setMorphTargetBufferAt}. Standard morphing supports up to
+         * <code>CONFIG_MAX_MORPH_TARGET_COUNT</code> morph targets.</p>
         *
         * For legacy morphing, the attached {@link VertexBuffer} must provide data in the
         * appropriate {@link VertexBuffer.VertexAttribute} slots (<code>MORPH_POSITION_0</code> etc).
@@ -542,22 +549,6 @@ public class RenderableManager {
            return this;
        }

-        /**
-         * Controls if the renderable has vertex morphing targets, zero by default.
-         *
-         * <p>For standard morphing, A {@link MorphTargetBuffer} must be provided.
-         * Standard morphing supports up to
-         * <code>CONFIG_MAX_MORPH_TARGET_COUNT</code> morph targets.</p>
-         *
-         * <p>See also {@link RenderableManager#setMorphWeights}, which can be called on a per-frame basis
-         * to advance the animation.</p>
-         */
-        @NonNull
-        public Builder morphing(@NonNull MorphTargetBuffer morphTargetBuffer) {
-            nBuilderMorphingStandard(mNativeBuilder, morphTargetBuffer.getNativeObject());
-            return this;
-        }
-
        /**
         * Specifies the morph target buffer for a primitive.
         *
@@ -569,13 +560,31 @@ public class RenderableManager {
         *
         * @param level the level of detail (lod), only 0 can be specified
         * @param primitiveIndex zero-based index of the primitive, must be less than the count passed to Builder constructor
+         * @param morphTargetBuffer specifies the morph target buffer
         * @param offset specifies where in the morph target buffer to start reading (expressed as a number of vertices)
+         * @param count number of vertices in the morph target buffer to read, must equal the geometry's count (for triangles, this should be a multiple of 3)
         */
        @NonNull
        public Builder morphing(@IntRange(from = 0) int level,
                                @IntRange(from = 0) int primitiveIndex,
-                                @IntRange(from = 0) int offset) {
-            nBuilderSetMorphTargetBufferOffsetAt(mNativeBuilder, level, primitiveIndex, offset);
+                                @NonNull MorphTargetBuffer morphTargetBuffer,
+                                @IntRange(from = 0) int offset,
+                                @IntRange(from = 0) int count) {
+            nBuilderSetMorphTargetBufferAt(mNativeBuilder, level, primitiveIndex,
+                    morphTargetBuffer.getNativeObject(), offset, count);
+            return this;
+        }
+
+        /**
+         * Utility method to specify morph target buffer for a primitive.
+         * For details, see the {@link RenderableManager.Builder#morphing}.
+         */
+        @NonNull
+        public Builder morphing(@IntRange(from = 0) int level,
+                                @IntRange(from = 0) int primitiveIndex,
+                                @NonNull MorphTargetBuffer morphTargetBuffer) {
+            nBuilderSetMorphTargetBufferAt(mNativeBuilder, level, primitiveIndex,
+                    morphTargetBuffer.getNativeObject(), 0, morphTargetBuffer.getVertexCount());
            return this;
        }

@@ -678,11 +687,26 @@ public class RenderableManager {
     *
     * @see Builder#morphing
     */
-    public void setMorphTargetBufferOffsetAt(@EntityInstance int i,
+    public void setMorphTargetBufferAt(@EntityInstance int i,
                                       @IntRange(from = 0) int level,
                                       @IntRange(from = 0) int primitiveIndex,
-                                       @IntRange(from = 0) int offset) {
-        nSetMorphTargetBufferOffsetAt(mNativeObject, i, level, primitiveIndex, 0, offset);
+                                       @NonNull MorphTargetBuffer morphTargetBuffer,
+                                       @IntRange(from = 0) int offset,
+                                       @IntRange(from = 0) int count) {
+        nSetMorphTargetBufferAt(mNativeObject, i, level, primitiveIndex,
+                morphTargetBuffer.getNativeObject(), offset, count);
+    }
+
+    /**
+     * Utility method to change morph target buffer for the given primitive.
+     * For details, see the {@link RenderableManager#setMorphTargetBufferAt}.
+     */
+    public void setMorphTargetBufferAt(@EntityInstance int i,
+                                       @IntRange(from = 0) int level,
+                                       @IntRange(from = 0) int primitiveIndex,
+                                       @NonNull MorphTargetBuffer morphTargetBuffer) {
+        nSetMorphTargetBufferAt(mNativeObject, i, level, primitiveIndex,
+                morphTargetBuffer.getNativeObject(), 0, morphTargetBuffer.getVertexCount());
    }

    /**
@@ -982,8 +1006,7 @@ public class RenderableManager {
    private static native int nBuilderSkinningBones(long nativeBuilder, int boneCount, Buffer bones, int remaining);
    private static native void nBuilderSkinningBuffer(long nativeBuilder, long nativeSkinningBuffer, int boneCount, int offset);
    private static native void nBuilderMorphing(long nativeBuilder, int targetCount);
-    private static native void nBuilderMorphingStandard(long nativeBuilder, long nativeMorphTargetBuffer);
-    private static native void nBuilderSetMorphTargetBufferOffsetAt(long nativeBuilder, int level, int primitiveIndex, int offset);
+    private static native void nBuilderSetMorphTargetBufferAt(long nativeBuilder, int level, int primitiveIndex, long nativeMorphTargetBuffer, int offset, int count);
    private static native void nBuilderEnableSkinningBuffers(long nativeBuilder, boolean enabled);
    private static native void nBuilderFog(long nativeBuilder, boolean enabled);
    private static native void nBuilderLightChannel(long nativeRenderableManager, int channel, boolean enable);
@@ -993,7 +1016,7 @@ public class RenderableManager {
    private static native int nSetBonesAsMatrices(long nativeObject, int i, Buffer matrices, int remaining, int boneCount, int offset);
    private static native int nSetBonesAsQuaternions(long nativeObject, int i, Buffer quaternions, int remaining, int boneCount, int offset);
    private static native void nSetMorphWeights(long nativeObject, int instance, float[] weights, int offset);
-    private static native void nSetMorphTargetBufferOffsetAt(long nativeObject, int i, int level, int primitiveIndex, long nativeMorphTargetBuffer, int offset);
+    private static native void nSetMorphTargetBufferAt(long nativeObject, int i, int level, int primitiveIndex, long nativeMorphTargetBuffer, int offset, int count);
    private static native int nGetMorphTargetCount(long nativeObject, int i);
    private static native void nSetAxisAlignedBoundingBox(long nativeRenderableManager, int i, float cx, float cy, float cz, float ex, float ey, float ez);
    private static native void nSetLayerMask(long nativeRenderableManager, int i, int select, int value);
@@ -284,33 +284,6 @@ public class Renderer {
        nSetPresentationTime(getNativeObject(), monotonicClockNanos);
    }

-    /**
-     * The use of this method is optional. It sets the VSYNC time expressed as the duration in
-     * nanosecond since epoch of std::chrono::steady_clock.
-     * If called, passing 0 to frameTimeNanos in Renderer.BeginFrame will use this
-     * time instead.
-     * @param steadyClockTimeNano duration in nanosecond since epoch of std::chrono::steady_clock
-     * @see Engine#getSteadyClockTimeNano
-     * @see Renderer#beginFrame
-     */
-    public void setVsyncTime(long steadyClockTimeNano) {
-        nSetVsyncTime(getNativeObject(), steadyClockTimeNano);
-    }
-
-    /**
-     * Call skipFrame when momentarily skipping frames, for instance if the content of the
-     * scene doesn't change.
-     *
-     * @param vsyncSteadyClockTimeNano The time in nanoseconds when the frame started being rendered,
-     *                       in the {@link System#nanoTime()} timebase. Divide this value by 1000000 to
-     *                       convert it to the {@link android.os.SystemClock#uptimeMillis()}
-     *                       time base. This typically comes from
-     *                       {@link android.view.Choreographer.FrameCallback}.
-     */
-    public void skipFrame(long vsyncSteadyClockTimeNano) {
-        nSkipFrame(getNativeObject(), vsyncSteadyClockTimeNano);
-    }
-
    /**
     * Sets up a frame for this <code>Renderer</code>.
     * <p><code>beginFrame</code> manages frame pacing, and returns whether or not a frame should be
@@ -729,8 +702,6 @@ public class Renderer {
    }

    private static native void nSetPresentationTime(long nativeObject, long monotonicClockNanos);
-    private static native void nSetVsyncTime(long nativeObject, long steadyClockTimeNano);
-    private static native void nSkipFrame(long nativeObject, long vsyncSteadyClockTimeNano);
    private static native boolean nBeginFrame(long nativeRenderer, long nativeSwapChain, long frameTimeNanos);
    private static native void nEndFrame(long nativeRenderer);
    private static native void nRender(long nativeRenderer, long nativeView);
@@ -241,15 +241,6 @@ public class View {
        nSetCamera(getNativeObject(), camera == null ? 0 : camera.getNativeObject());
    }

-    /**
-     * Query whether a camera is set.
-     * @return true if a camera is set, false otherwise
-     * @see #setCamera
-     */
-    public boolean hasCamera() {
-        return nHasCamera(getNativeObject());
-    }
-
    /**
     * Gets this View's associated Camera, or null if none has been assigned.
     *
@@ -1233,18 +1224,6 @@ public class View {
        return nGetFogEntity(getNativeObject());
    }

-    /**
-     * When certain temporal features are used (e.g.: TAA or Screen-space reflections), the view
-     * keeps a history of previous frame renders associated with the Renderer the view was last
-     * used with. When switching Renderer, it may be necessary to clear that history by calling
-     * this method. Similarly, if the whole content of the screen change, like when a cut-scene
-     * starts, clearing the history might be needed to avoid artifacts due to the previous frame
-     * being very different.
-     */
-    public void clearFrameHistory(Engine engine) {
-        nClearFrameHistory(getNativeObject(), engine.getNativeObject());
-    }
-
    public long getNativeObject() {
        if (mNativeObject == 0) {
            throw new IllegalStateException("Calling method on destroyed View");
@@ -1259,7 +1238,6 @@ public class View {
    private static native void nSetName(long nativeView, String name);
    private static native void nSetScene(long nativeView, long nativeScene);
    private static native void nSetCamera(long nativeView, long nativeCamera);
-    private static native boolean nHasCamera(long nativeView);
    private static native void nSetViewport(long nativeView, int left, int bottom, int width, int height);
    private static native void nSetVisibleLayers(long nativeView, int select, int value);
    private static native void nSetShadowingEnabled(long nativeView, boolean enabled);
@@ -1306,7 +1284,7 @@ public class View {
    private static native void nSetMaterialGlobal(long nativeView, int index, float x, float y, float z, float w);
    private static native void nGetMaterialGlobal(long nativeView, int index, float[] out);
    private static native int nGetFogEntity(long nativeView);
-    private static native void nClearFrameHistory(long nativeView, long nativeEngine);
+

    /**
     * List of available ambient occlusion techniques.
@@ -31,7 +31,6 @@ set_target_properties(iblprefilter PROPERTIES IMPORTED_LOCATION
        ${FILAMENT_DIR}/lib/${ANDROID_ABI}/libfilament-iblprefilter.a)

 set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "${CMAKE_SHARED_LINKER_FLAGS_RELEASE} -Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/libfilament-utils-jni.map")
-set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-z,max-page-size=16384")

 add_library(filament-utils-jni SHARED
        src/main/cpp/AutomationEngine.cpp
@@ -125,11 +125,6 @@ extern "C" JNIEXPORT void Java_com_google_android_filament_utils_Manipulator_nBu
    builder->groundPlane(a, b, c, d);
 }

-extern "C" JNIEXPORT void Java_com_google_android_filament_utils_Manipulator_nBuilderPanning(JNIEnv*, jclass, jlong nativeBuilder, jboolean enabled) {
-    Builder* builder = (Builder*) nativeBuilder;
-    builder->panning(enabled);
-}
-
 extern "C" JNIEXPORT long Java_com_google_android_filament_utils_Manipulator_nBuilderBuild(JNIEnv*, jclass, jlong nativeBuilder, jint mode) {
    Builder* builder = (Builder*) nativeBuilder;
    return (jlong) builder->build((Mode) mode);
@@ -274,17 +274,6 @@ public class Manipulator {
            return this;
        }

-        /**
-         * Sets whether panning is enabled in the manipulator.
-         *
-         * @return this <code>Builder</code> object for chaining calls
-         */
-        @NonNull
-        public Builder panning(Boolean enabled) {
-            nBuilderPanning(mNativeBuilder, enabled);
-            return this;
-        }
-
        /**
         * Creates and returns the <code>Manipulator</code> object.
         *
@@ -494,7 +483,6 @@ public class Manipulator {
    private static native void nBuilderFlightPanSpeed(long nativeBuilder, float x, float y);
    private static native void nBuilderFlightMoveDamping(long nativeBuilder, float damping);
    private static native void nBuilderGroundPlane(long nativeBuilder, float a, float b, float c, float d);
-    private static native void nBuilderPanning(long nativeBuilder, Boolean enabled);
    private static native long nBuilderBuild(long nativeBuilder, int mode);

    private static native void nDestroyManipulator(long nativeManip);
@@ -44,7 +44,6 @@ set_target_properties(uberarchive PROPERTIES IMPORTED_LOCATION
        ${FILAMENT_DIR}/lib/${ANDROID_ABI}/libuberarchive.a)

 set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "${CMAKE_SHARED_LINKER_FLAGS_RELEASE} -Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/libgltfio-jni.map")
-set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-z,max-page-size=16384")

 set(GLTFIO_SRCS
        ${GLTFIO_DIR}/include/gltfio/Animator.h
@@ -87,10 +86,7 @@ set(GLTFIO_SRCS
        ${GLTFIO_DIR}/src/Wireframe.cpp
        ${GLTFIO_DIR}/src/Wireframe.h
        ${GLTFIO_DIR}/src/downcast.h
-        ${GLTFIO_DIR}/src/extended/AssetLoaderExtended.cpp
        ${GLTFIO_DIR}/src/extended/AssetLoaderExtended.h
-        ${GLTFIO_DIR}/src/extended/ResourceLoaderExtended.cpp
-        ${GLTFIO_DIR}/src/extended/ResourceLoaderExtended.h
        ${GLTFIO_DIR}/src/extended/TangentsJobExtended.cpp
        ${GLTFIO_DIR}/src/extended/TangentsJobExtended.h
        ${GLTFIO_DIR}/src/extended/TangentSpaceMeshWrapper.cpp
@@ -120,6 +116,7 @@ set(GLTFIO_INCLUDE_DIRS
        ../../third_party/cgltf
        ../../third_party/meshoptimizer/src
        ../../third_party/robin-map
+        ../../third_party/hat-trie
        ../../third_party/stb
        ../../libs/utils/include
        ../../libs/ktxreader/include
@@ -1,5 +1,5 @@
 GROUP=com.google.android.filament
-VERSION_NAME=1.54.2
+VERSION_NAME=1.51.0

 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-8.2-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
@@ -321,7 +321,7 @@ class MainActivity : Activity() {
            var flags = uiHelper.swapChainFlags
            if (engine.activeFeatureLevel == Engine.FeatureLevel.FEATURE_LEVEL_0) {
                if (SwapChain.isSRGBSwapChainSupported(engine)) {
-                    flags = flags or SwapChainFlags.CONFIG_SRGB_COLORSPACE
+                    flags = flags or SwapChain.CONFIG_SRGB_COLORSPACE
                }
            }

@@ -44,6 +44,8 @@ function print_help {
    echo "        Exclude Vulkan support from the Android build."
    echo "    -s"
    echo "        Add iOS simulator support to the iOS build."
+    echo "    -t"
+    echo "        Enable SwiftShader support for Vulkan in desktop builds."
    echo "    -e"
    echo "        Enable EGL on Linux support for desktop builds."
    echo "    -l"
@@ -59,14 +61,6 @@ function print_help {
    echo "    -b"
    echo "        Enable Address and Undefined Behavior Sanitizers (asan/ubsan) for debugging."
    echo "        This is only for the desktop build."
-    echo "    -x value"
-    echo "        Define a preprocessor flag FILAMENT_BACKEND_DEBUG_FLAG with [value]. This is useful for"
-    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 "    -S type"
-    echo "        Enable stereoscopic rendering where type is one of [instanced|multiview]. This is only"
-    echo "        meant for building the samples."
    echo ""
    echo "Build types:"
    echo "    release"
@@ -166,6 +160,8 @@ INSTALL_COMMAND=
 VULKAN_ANDROID_OPTION="-DFILAMENT_SUPPORTS_VULKAN=ON"
 VULKAN_ANDROID_GRADLE_OPTION=""

+SWIFTSHADER_OPTION="-DFILAMENT_USE_SWIFTSHADER=OFF"
+
 EGL_ON_LINUX_OPTION="-DFILAMENT_SUPPORTS_EGL_ON_LINUX=OFF"

 MATDBG_OPTION="-DFILAMENT_ENABLE_MATDBG=OFF"
@@ -176,10 +172,6 @@ MATOPT_GRADLE_OPTION=""

 ASAN_UBSAN_OPTION=""

-BACKEND_DEBUG_FLAG_OPTION=""
-
-STEREOSCOPIC_OPTION=""
-
 IOS_BUILD_SIMULATOR=false
 BUILD_UNIVERSAL_LIBRARIES=false

@@ -234,12 +226,11 @@ function build_desktop_target {
            -DIMPORT_EXECUTABLES_DIR=out \
            -DCMAKE_BUILD_TYPE="$1" \
            -DCMAKE_INSTALL_PREFIX="../${lc_target}/filament" \
+            ${SWIFTSHADER_OPTION} \
            ${EGL_ON_LINUX_OPTION} \
            ${MATDBG_OPTION} \
            ${MATOPT_OPTION} \
            ${ASAN_UBSAN_OPTION} \
-            ${BACKEND_DEBUG_FLAG_OPTION} \
-            ${STEREOSCOPIC_OPTION} \
            ${architectures} \
            ../..
        ln -sf "out/cmake-${lc_target}/compile_commands.json" \
@@ -298,7 +289,6 @@ function build_webgl_with_target {
            -DCMAKE_BUILD_TYPE="$1" \
            -DCMAKE_INSTALL_PREFIX="../webgl-${lc_target}/filament" \
            -DWEBGL=1 \
-            ${BACKEND_DEBUG_FLAG_OPTION} \
            ../..
        ln -sf "out/cmake-webgl-${lc_target}/compile_commands.json" \
           ../../compile_commands.json
@@ -373,8 +363,6 @@ function build_android_target {
            ${MATDBG_OPTION} \
            ${MATOPT_OPTION} \
            ${VULKAN_ANDROID_OPTION} \
-            ${BACKEND_DEBUG_FLAG_OPTION} \
-            ${STEREOSCOPIC_OPTION} \
            ../..
        ln -sf "out/cmake-android-${lc_target}-${arch}/compile_commands.json" \
           ../../compile_commands.json
@@ -609,7 +597,6 @@ function build_ios_target {
            -DCMAKE_TOOLCHAIN_FILE=../../third_party/clang/iOS.cmake \
            ${MATDBG_OPTION} \
            ${MATOPT_OPTION} \
-            ${STEREOSCOPIC_OPTION} \
            ../..
        ln -sf "out/cmake-ios-${lc_target}-${arch}/compile_commands.json" \
           ../../compile_commands.json
@@ -743,13 +730,6 @@ function validate_build_command {
            exit 1
        fi
    fi
-
-    # Make sure FILAMENT_BACKEND_DEBUG_FLAG is only meant for debug builds
-    if [[ "${ISSUE_DEBUG_BUILD}" != "true" ]] && [[ ! -z "${BACKEND_DEBUG_FLAG_OPTION}" ]]; then
-        echo "Error: cannot specify FILAMENT_BACKEND_DEBUG_FLAG in non-debug build"
-        exit 1
-    fi
-
    set -e
 }

@@ -796,7 +776,7 @@ function check_debug_release_build {

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

-while getopts ":hacCfgijmp:q:uvslwedk:bx:S:" opt; do
+while getopts ":hacCfgijmp:q:uvslwtedk:b" opt; do
    case ${opt} in
        h)
            print_help
@@ -860,7 +840,7 @@ while getopts ":hacCfgijmp:q:uvslwedk:bx:S:" opt; do
                        echo "Platform must be one of [desktop|android|ios|webgl|all]"
                        echo ""
                        exit 1
-                    ;;
+                    ;;    
                esac
            done
            ;;
@@ -915,6 +895,10 @@ while getopts ":hacCfgijmp:q:uvslwedk:bx:S:" opt; do
            IOS_BUILD_SIMULATOR=true
            echo "iOS simulator support enabled."
            ;;
+        t)
+            SWIFTSHADER_OPTION="-DFILAMENT_USE_SWIFTSHADER=ON"
+            echo "SwiftShader support enabled."
+            ;;
        e)
            EGL_ON_LINUX_OPTION="-DFILAMENT_SUPPORTS_EGL_ON_LINUX=ON -DFILAMENT_SKIP_SDL2=ON -DFILAMENT_SKIP_SAMPLES=ON"
            echo "EGL on Linux support enabled; skipping SDL2."
@@ -934,22 +918,6 @@ while getopts ":hacCfgijmp:q:uvslwedk:bx:S:" opt; do
        b)  ASAN_UBSAN_OPTION="-DFILAMENT_ENABLE_ASAN_UBSAN=ON"
            echo "Enabled ASAN/UBSAN"
            ;;
-        x)  BACKEND_DEBUG_FLAG_OPTION="-DFILAMENT_BACKEND_DEBUG_FLAG=${OPTARG}"
-            ;;
-        S)  case $(echo "${OPTARG}" | tr '[:upper:]' '[:lower:]') in
-                instanced)
-                    STEREOSCOPIC_OPTION="-DFILAMENT_SAMPLES_STEREO_TYPE=instanced"
-                    ;;
-                multiview)
-                    STEREOSCOPIC_OPTION="-DFILAMENT_SAMPLES_STEREO_TYPE=multiview"
-                    ;;
-                *)
-                    echo "Unknown stereoscopic type ${OPTARG}"
-                    echo "Type must be one of [instanced|multiview]"
-                    echo ""
-                    exit 1
-            esac
-            ;;
        \?)
            echo "Invalid option: -${OPTARG}" >&2
            echo ""
@@ -57,10 +57,15 @@ FILAMENT_NDK_VERSION=${FILAMENT_NDK_VERSION:-$(cat `dirname $0`/ndk.version)}

 # Install the required NDK version specifically (if not present)
 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"
+    ${ANDROID_HOME}/cmdline-tools/latest/bin/sdkmanager "ndk;$FILAMENT_NDK_VERSION" > /dev/null
 fi
+
+# Only build 1 64 bit target during presubmit to cut down build times during presubmit
+# Continuous builds will build everything
 ANDROID_ABIS=
+if [[ "$TARGET" == "presubmit" ]]; then
+  ANDROID_ABIS="-q arm64-v8a"
+fi

 # Build the Android sample-gltf-viewer APK during release.
 BUILD_SAMPLES=
@@ -68,19 +73,5 @@ if [[ "$TARGET" == "release" ]]; then
    BUILD_SAMPLES="-k sample-gltf-viewer"
 fi

-function build_android() {
-    local ABI=$1
-
-    # Do the following in two steps so that we do not run out of space
-    if [[ -n "${BUILD_DEBUG}" ]]; then
-        FILAMENT_NDK_VERSION=${FILAMENT_NDK_VERSION} ./build.sh -p android -q ${ABI} -c ${BUILD_SAMPLES} ${GENERATE_ARCHIVES} ${BUILD_DEBUG}
-        rm -rf out/cmake-android-debug-*
-    fi
-    if [[ -n "${BUILD_RELEASE}" ]]; then
-        FILAMENT_NDK_VERSION=${FILAMENT_NDK_VERSION} ./build.sh -p android -q ${ABI} -c ${BUILD_SAMPLES} ${GENERATE_ARCHIVES} ${BUILD_RELEASE}
-        rm -rf out/cmake-android-release-*
-    fi
-}
-
 pushd `dirname $0`/../.. > /dev/null
-build_android $2
+FILAMENT_NDK_VERSION=${FILAMENT_NDK_VERSION} ./build.sh -p android $ANDROID_ABIS -c $BUILD_SAMPLES $GENERATE_ARCHIVES $BUILD_DEBUG $BUILD_RELEASE
@@ -1 +1 @@
-27.0.11718014
+26.1.10909125
@@ -0,0 +1,53 @@
+# Build the image:
+#   docker build --no-cache --tag ssfilament -f build/swiftshader/Dockerfile .
+#   docker tag ssfilament ghcr.io/filament-assets/swiftshader
+#
+# Publish the image:
+#   docker login ghcr.io --username <user> --password <token>
+#   docker push ghcr.io/filament-assets/swiftshader
+#
+# Run the image and mount the current directory:
+#   docker run -it -v `pwd`:/trees/filament -t ssfilament
+
+FROM ubuntu:focal
+WORKDIR /trees
+ARG DEBIAN_FRONTEND=noninteractive
+ENV SWIFTSHADER_LD_LIBRARY_PATH=/trees/swiftshader/build
+ENV CXXFLAGS='-fno-builtin -Wno-pass-failed'
+
+RUN apt-get update && \
+    apt-get --no-install-recommends install -y \
+	apt-transport-https \
+	apt-utils \
+	build-essential \
+	cmake \
+	ca-certificates \
+	git \
+	ninja-build \
+	python \
+	python3 \
+	xorg-dev \
+	clang-7 \
+	libc++-7-dev \
+	libc++abi-7-dev \
+	lldb
+
+# Ensure that clang is used instead of gcc.
+RUN set -eux ;\
+    update-alternatives --install /usr/bin/clang clang /usr/bin/clang-7 100 ;\
+    update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-7 100 ;\
+    update-alternatives --install /usr/bin/cc cc /usr/bin/clang 100 ;\
+    update-alternatives --install /usr/bin/c++ c++ /usr/bin/clang++ 100
+
+# Get patch files from the local Filament tree.
+COPY build/swiftshader/*.diff .
+
+# Clone SwiftShader, apply patches, and build it.
+RUN set -eux ;\
+	git clone https://swiftshader.googlesource.com/SwiftShader swiftshader ;\
+    cd swiftshader ;\
+	git checkout 139f5c3 ;\
+	git apply /trees/*.diff ;\
+    cd build ;\
+    cmake .. -GNinja -DCMAKE_BUILD_TYPE=Release ;\
+    ninja
@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+
+from pathlib import Path
+import os
+
+spath = os.path.dirname(os.path.realpath(__file__))
+
+path = Path(spath)
+
+folder = "../../results/"
+
+images = list(path.glob(folder + '*.png'))
+
+images.sort()
+
+gallery = open(path.absolute().joinpath(folder + 'index.html'), 'w')
+
+gallery.write("""<html>
+<head>
+<script type="module" src="https://unpkg.com/img-comparison-slider@latest/dist/component/component.esm.js"></script>
+<script nomodule="" src="https://unpkg.com/img-comparison-slider@latest/dist/component/component.js"></script>
+<link rel="stylesheet" href="https://unpkg.com/img-comparison-slider@latest/dist/collection/styles/initial.css"/>
+<style>
+    h2 {
+        font-weight: normal;
+        margin-top: 150px;
+        margin-bottom: 20px;
+    }
+    a {
+        text-decoration: none;
+        font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
+        color: blue;
+    }
+    a:hover {
+        font-weight: bold;
+    }
+</style>
+</head>
+<body>
+""")
+
+tag = ''
+
+for image in images:
+    group = image.stem.rstrip('0123456789')
+    before = f'https://filament-assets.github.io/golden/{group}/{image.name}'
+    after = image.name
+    gallery.write('\n')
+    gallery.write(f'<h2><a href="{image.stem}.json">{image.stem}.json</a></h2>\n')
+    gallery.write('<img-comparison-slider>\n')
+    gallery.write(f'<img slot="before" src="{before}" /> <img slot="after" src="{after}" />\n')
+    gallery.write('</img-comparison-slider>\n')
+
+gallery.write("""</body>
+</html>
+""")
@@ -0,0 +1,62 @@
+diff --git a/src/Vulkan/VkPipeline.cpp b/src/Vulkan/VkPipeline.cpp
+index 86913ec72..3b35345af 100644
+--- a/src/Vulkan/VkPipeline.cpp
+++ b/src/Vulkan/VkPipeline.cpp
+@@ -71,7 +71,56 @@ std::vector<uint32_t> preprocessSpirv(
+ 	if(optimize)
+ 	{
+ 		// Full optimization list taken from spirv-opt.
+-		opt.RegisterPerformancePasses();
+
+		// We have removed CreateRedundancyEliminationPass because it segfaults when encountering:
+		//     %389 = OpCompositeConstruct %7 %386 %387 %388 %86
+		// When inserting an entry into instruction_to_value_ (which is an unordered_map)
+		// This could perhaps be investigated further with help from asan.
+
+		using namespace spvtools;
+		opt.RegisterPass(CreateWrapOpKillPass())
+			.RegisterPass(CreateDeadBranchElimPass())
+			.RegisterPass(CreateMergeReturnPass())
+			.RegisterPass(CreateInlineExhaustivePass())
+			.RegisterPass(CreateAggressiveDCEPass())
+			.RegisterPass(CreatePrivateToLocalPass())
+			.RegisterPass(CreateLocalSingleBlockLoadStoreElimPass())
+			.RegisterPass(CreateLocalSingleStoreElimPass())
+			.RegisterPass(CreateAggressiveDCEPass())
+			.RegisterPass(CreateScalarReplacementPass())
+			.RegisterPass(CreateLocalAccessChainConvertPass())
+			.RegisterPass(CreateLocalSingleBlockLoadStoreElimPass())
+			.RegisterPass(CreateLocalSingleStoreElimPass())
+			.RegisterPass(CreateAggressiveDCEPass())
+			.RegisterPass(CreateLocalMultiStoreElimPass())
+			.RegisterPass(CreateAggressiveDCEPass())
+			.RegisterPass(CreateCCPPass())
+			.RegisterPass(CreateAggressiveDCEPass())
+			.RegisterPass(CreateLoopUnrollPass(true))
+			.RegisterPass(CreateDeadBranchElimPass())
+			.RegisterPass(CreateRedundancyEliminationPass()) // workaround for SEGFAULT
+			.RegisterPass(CreateCombineAccessChainsPass())
+			.RegisterPass(CreateSimplificationPass())
+			.RegisterPass(CreateScalarReplacementPass())
+			.RegisterPass(CreateLocalAccessChainConvertPass())
+			.RegisterPass(CreateLocalSingleBlockLoadStoreElimPass())
+			.RegisterPass(CreateLocalSingleStoreElimPass())
+			.RegisterPass(CreateAggressiveDCEPass())
+			.RegisterPass(CreateSSARewritePass())
+			.RegisterPass(CreateAggressiveDCEPass())
+			.RegisterPass(CreateVectorDCEPass())
+			.RegisterPass(CreateDeadInsertElimPass())
+			.RegisterPass(CreateDeadBranchElimPass())
+			.RegisterPass(CreateSimplificationPass())
+			.RegisterPass(CreateIfConversionPass())
+			.RegisterPass(CreateCopyPropagateArraysPass())
+			.RegisterPass(CreateReduceLoadSizePass())
+			.RegisterPass(CreateAggressiveDCEPass())
+			.RegisterPass(CreateBlockMergePass())
+			.RegisterPass(CreateRedundancyEliminationPass()) // workaround for SEGFAULT
+			.RegisterPass(CreateDeadBranchElimPass())
+			.RegisterPass(CreateBlockMergePass())
+			.RegisterPass(CreateSimplificationPass());
+ 	}
+ 
+ 	std::vector<uint32_t> optimized;
@@ -0,0 +1,127 @@
+#!/bin/bash
+set -e
+
+function print_help {
+    local self_name=$(basename "$0")
+    echo "This script issues docker commands for testing Filament with SwiftShader."
+    echo "The usual sequence of commands is: fetch, start, build filament release, and run."
+    echo ""
+    echo "Usage:"
+    echo "    $self_name [command]"
+    echo ""
+    echo "Commands:"
+    echo "    build filament [debug | release]"
+    echo "        Use the container to build Filament."
+    echo "    build swiftshader [debug | release]"
+    echo "        Use the container to do a clean rebuild of SwiftShader."
+    echo "        (Note that the container already has SwiftShader built.)"
+    echo "    fetch"
+    echo "        Download the docker image from the central repository."
+    echo "    help"
+    echo "        Print this help message."
+    echo "    logs"
+    echo "        Print messages from the container's kernel ring buffer."
+    echo "        This is useful for diagnosing OOM issues."
+    echo "    run [lldb]"
+    echo "        Launch a test inside the container, optionally via lldb."
+    echo "    shell"
+    echo "        Interact with a bash prompt in the container."
+    echo "    start"
+    echo "        Start a container from the image."
+    echo "    stop"
+    echo "        Stop the container."
+    echo ""
+}
+
+# Change the current working directory to the Filament root.
+pushd "$(dirname "$0")/../.." > /dev/null
+
+if [[ "$1" == "build" ]] && [[ "$2" == "filament" ]]; then
+    docker exec runner filament/build.sh -t $3 gltf_viewer
+    exit $?
+fi
+
+if [[ "$1" == "build" ]] && [[ "$2" == "swiftshader" ]]; then
+    BUILD_TYPE="$3"
+    BUILD_TYPE="$(tr '[:lower:]' '[:upper:]' <<< ${BUILD_TYPE:0:1})${BUILD_TYPE:1}"
+    docker exec --workdir /trees/swiftshader runner rm -rf build
+    docker exec --workdir /trees/swiftshader runner mkdir build
+    docker exec --workdir /trees/swiftshader/build runner cmake -GNinja -DCMAKE_BUILD_TYPE="$BUILD_TYPE" ..
+    docker exec --workdir /trees/swiftshader/build runner ninja
+    exit $?
+fi
+
+if [[ "$1" == "fetch" ]]; then
+    docker pull ghcr.io/filament-assets/swiftshader:latest
+    docker tag ghcr.io/filament-assets/swiftshader:latest ssfilament
+    exit $?
+fi
+
+if [[ "$1" == "help" ]]; then
+    print_help
+    exit 0
+fi
+
+if [[ "$1" == "logs" ]]; then
+    docker exec runner dmesg --human --read-clear
+    exit $?
+fi
+
+if [[ "$1" == "run" ]] && [[ "$2" == "lldb" ]]; then
+    docker exec -i --workdir /trees/filament/results runner \
+          lldb --batch -o run -o bt -- \
+          ../out/cmake-release/samples/gltf_viewer \
+          --headless \
+          --batch ../libs/viewer/tests/basic.json \
+          --api vulkan
+    docker exec runner /trees/filament/build/swiftshader/gallery.py
+    exit $?
+fi
+
+if [[ "$1" == "run" ]]; then
+    docker exec --tty  --workdir /trees/filament/results runner \
+          /usr/bin/catchsegv \
+          ../out/cmake-release/samples/gltf_viewer \
+          --headless \
+          --batch ../libs/viewer/tests/basic.json \
+          --api vulkan
+    docker exec runner /trees/filament/build/swiftshader/gallery.py
+    exit $?
+fi
+
+if [[ "$1" == "shell" ]]; then
+    docker exec --interactive --tty runner /bin/bash
+    exit $?
+fi
+
+# Notes on options being passed to docker's run command:
+#
+# - The memory constraint seems to prevent an OOM signal in GitHub Actions.
+# - The cap / security args allow use of lldb and creation of core dumps.
+# - The privileged arg allows use of dmesg for examining OOM logs.
+#
+# Currently, a GitHub Actions VM has 2 CPUs, 7 GB RAM, and 14 GB of SSD disk space.
+#
+# Please be aware that Docker Desktop might impose additional resource constraints, and that those
+# settings can only be controlled with its GUI. We recommend at least 7 GB of memory and 2 GB swap.
+if [[ "$1" == "start" ]]; then
+    mkdir -p results
+    docker run --tty --rm --detach --privileged \
+          --memory 6.5g \
+          --name runner \
+          --cap-add=SYS_PTRACE \
+          --security-opt seccomp=unconfined \
+          --security-opt apparmor=unconfined \
+          --volume `pwd`:/trees/filament \
+          --workdir /trees \
+          ssfilament
+    exit $?
+fi
+
+if [[ "$1" == "stop" ]]; then
+    docker container rm runner --force
+    exit $?
+fi
+
+print_help
+exit 1
@@ -476,7 +476,7 @@ Energy conservation is one of the key components of a good BRDF for physically b
 <p>


-For the specular term, \(f_r\) is a mirror BRDF that can be modeled with the Fresnel law, noted \(F\) in the Cook-Torrance approximation of the microfacet model integration:
+For the specular term, \(f_m\) is a mirror BRDF that can be modeled with the Fresnel law, noted \(F\) in the Cook-Torrance approximation of the microfacet model integration:

 </p><p>

@@ -857,7 +857,7 @@ The full GLSL implementation of the standard model is shown in <a href="#listing
 <span class="line">    <span class="hljs-comment">// perceptually linear roughness to roughness (see parameterization)</span></span>
 <span class="line">    <span class="hljs-type">float</span> roughness = perceptualRoughness * perceptualRoughness;</span>
 <span class="line"></span>
-<span class="line">    <span class="hljs-type">float</span> D = D_GGX(NoH, roughness);</span>
+<span class="line">    <span class="hljs-type">float</span> D = D_GGX(NoH, a);</span>
 <span class="line">    <span class="hljs-type">vec3</span>  F = F_Schlick(LoH, f0);</span>
 <span class="line">    <span class="hljs-type">float</span> V = V_SmithGGXCorrelated(NoV, NoL, roughness);</span>
 <span class="line"></span>
@@ -1308,12 +1308,7 @@ Description
      declare a variable called `eyeDirection` you can access it in the fragment shader using
      `variable_eyeDirection`. In the vertex shader, the interpolant name is simply a member of
      the `MaterialVertexInputs` structure (`material.eyeDirection` in your example). Each
-      interpolant is of type `float4` (`vec4`) in the shaders. By default the precision of the
-      interpolant is `highp` in *both* the vertex and fragment shaders.
-      An alternate syntax can be used to specify both the name and precision of the interpolant.
-      In this case the specified precision is used as-is in both fragment and vertex stages, in
-      particular if `default` is specified the default precision is used is the fragment shader
-      (`mediump`) and in the vertex shader (`highp`).
+      interpolant is of type `float4` (`vec4`) in the shaders.

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ JSON
 material {
@@ -1325,11 +1320,7 @@ material {
        }
    ],
    variables : [
-         eyeDirection,
-         {
-            name : eyeColor,
-            precision : medium
-         }
+         eyeDirection
    ],
    vertexDomain : device,
    depthWrite : false,
@@ -1406,7 +1397,7 @@ Type
 :    `string`

 Value
-:     Any of `opaque`, `transparent`, `fade`, `add`, `masked`, `multiply`, `screen`, `custom`. Defaults to `opaque`.
+:     Any of `opaque`, `transparent`, `fade`, `add`, `masked`, `multiply`, `screen`. Defaults to `opaque`.

 Description
 :     Defines how/if the rendered object is blended with the content of the render target.
@@ -1429,7 +1420,6 @@ Description
      of the material's output defines whether a fragment is discarded or not. Additionally,
      ALPHA_TO_COVERAGE is enabled for non-translucent views. See the maskThreshold section for more
      information.
-    - **Custom**: blending is enabled. But the blending function is user specified. See `blendFunction`.

 !!! Note
    When `blending` is set to `masked`, alpha to coverage is automatically enabled for the material.
@@ -1442,36 +1432,6 @@ material {
 }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

-### Blending and transparency: blendFunction
-
-Type
-:    `object`
-
-Fields
-:     `srcRGB`, `srcA`, `dstRGB`, `dstA`
-
-Description
-:       - *srcRGB*: source function applied to the RGB channels
-        - *srcA*: source function applied to the alpha channel
-        - *srcRGB*: destination function applied to the RGB channels
-        - *srcRGB*: destination function applied to the alpha channel
-        The values possible for each functions are one of `zero`, `one`, `srcColor`, `oneMinusSrcColor`,
-               `dstColor`, `oneMinusDstColor`, `srcAlpha`, `oneMinusSrcAlpha`, `dstAlpha`,
-               `oneMinusDstAlpha`, `srcAlphaSaturate`
-
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ JSON
-material {
-    blending : custom,
-    blendFunction :
-    {
-        srcRGB: one,
-        srcA: one,
-        dstRGB: oneMinusSrcColor,
-        dstA: oneMinusSrcAlpha
-    }
- }
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
 ### Blending and transparency: postLightingBlending

 Type
@@ -2434,7 +2394,6 @@ The following APIs are only available from the vertex block:
 **getWorldFromModelMatrix()**        | float4x4 |  Matrix that converts from model (object) space to world space
 **getWorldFromModelNormalMatrix()**  | float3x3 |  Matrix that converts normals from model (object) space to world space
 **getVertexIndex()**                 | int      |  Index of the current vertex
-**getEyeIndex()**                    | int      |  Index of the eye being rendered, starting at 0

 ### Fragment only

@@ -43,7 +43,7 @@ filament-viewer::part(canvas) {
 </p>

 </main>
-<script src="https://unpkg.com/filament@1.51.6/filament.js"></script>
+<script src="https://unpkg.com/filament@1.44.0/filament.js"></script>
 <script src="https://unpkg.com/gltumble"></script>
 <script src="filament-viewer.js" type="module"></script>
 </body>
@@ -61,7 +61,6 @@ set(SRCS
        src/Engine.cpp
        src/Exposure.cpp
        src/Fence.cpp
-        src/FilamentBuilder.cpp
        src/FrameInfo.cpp
        src/FrameSkipper.cpp
        src/Froxelizer.cpp
@@ -76,6 +75,8 @@ set(SRCS
        src/MaterialInstance.cpp
        src/MaterialParser.cpp
        src/MorphTargetBuffer.cpp
+        src/PerViewUniforms.cpp
+        src/PerShadowMapUniforms.cpp
        src/PostProcessManager.cpp
        src/RenderPass.cpp
        src/RenderPrimitive.cpp
@@ -124,12 +125,6 @@ set(SRCS
        src/details/Texture.cpp
        src/details/VertexBuffer.cpp
        src/details/View.cpp
-        src/ds/ColorPassDescriptorSet.cpp
-        src/ds/DescriptorSet.cpp
-        src/ds/DescriptorSetLayout.cpp
-        src/ds/PostProcessDescriptorSet.cpp
-        src/ds/ShadowMapDescriptorSet.cpp
-        src/ds/SsrPassDescriptorSet.cpp
        src/fg/Blackboard.cpp
        src/fg/DependencyGraph.cpp
        src/fg/FrameGraph.cpp
@@ -157,16 +152,18 @@ set(PRIVATE_HDRS
        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
@@ -194,14 +191,6 @@ set(PRIVATE_HDRS
        src/details/Texture.h
        src/details/VertexBuffer.h
        src/details/View.h
-        src/downcast.h
-        src/ds/ColorPassDescriptorSet.h
-        src/ds/DescriptorSetLayout.h
-        src/ds/PostProcessDescriptorSet.h
-        src/ds/ShadowMapDescriptorSet.h
-        src/ds/SsrPassDescriptorSet.h
-        src/ds/TypedBuffer.h
-        src/ds/TypedUniformBuffer.h
        src/fg/Blackboard.h
        src/fg/FrameGraph.h
        src/fg/FrameGraphId.h
@@ -219,12 +208,12 @@ 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
        src/materials/antiAliasing/fxaa.mat
        src/materials/antiAliasing/taa.mat
-        src/materials/blitDepth.mat
        src/materials/blitLow.mat
        src/materials/blitArray.mat
        src/materials/bloom/bloomDownsample.mat
@@ -12,7 +12,6 @@ set(PUBLIC_HDRS
        include/backend/AcquiredImage.h
        include/backend/BufferDescriptor.h
        include/backend/CallbackHandler.h
-        include/backend/DescriptorSetOffsetArray.h
        include/backend/DriverApiForward.h
        include/backend/DriverEnums.h
        include/backend/Handle.h
@@ -67,17 +66,11 @@ set(PRIVATE_HDRS
 # OpenGL / OpenGL ES Sources
 # ==================================================================================================

-if (FILAMENT_SUPPORTS_OPENGL AND NOT FILAMENT_USE_EXTERNAL_GLES3)
+if (FILAMENT_SUPPORTS_OPENGL AND NOT FILAMENT_USE_EXTERNAL_GLES3 AND NOT FILAMENT_USE_SWIFTSHADER)
    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
            src/opengl/OpenGLBlobCache.cpp
@@ -173,10 +166,8 @@ endif()
 if (FILAMENT_SUPPORTS_VULKAN)
    list(APPEND SRCS
            include/backend/platforms/VulkanPlatform.h
-            src/vulkan/caching/VulkanDescriptorSetManager.cpp
-            src/vulkan/caching/VulkanDescriptorSetManager.h
-            src/vulkan/caching/VulkanPipelineLayoutCache.cpp
-            src/vulkan/caching/VulkanPipelineLayoutCache.h
+            src/vulkan/caching/VulkanDescriptorSet.cpp
+            src/vulkan/caching/VulkanDescriptorSet.h
            src/vulkan/platform/VulkanPlatform.cpp
            src/vulkan/platform/VulkanPlatformSwapChainImpl.cpp
            src/vulkan/platform/VulkanPlatformSwapChainImpl.h
@@ -422,9 +413,7 @@ if (APPLE OR LINUX)
        test/test_MissingRequiredAttributes.cpp
        test/test_ReadPixels.cpp
        test/test_BufferUpdates.cpp
-        test/test_Callbacks.cpp
        test/test_MRT.cpp
-        test/test_PushConstants.cpp
        test/test_LoadImage.cpp
        test/test_StencilBuffer.cpp
        test/test_Scissor.cpp
@@ -485,10 +474,6 @@ if (APPLE)
       # linker from removing "unused" symbols.
       target_link_libraries(backend_test_mac PRIVATE -force_load backend_test)
       set_target_properties(backend_test_mac PROPERTIES FOLDER Tests)
-
-       # This is needed after XCode 15.3
-       set_target_properties(backend_test_mac PROPERTIES BUILD_WITH_INSTALL_RPATH TRUE)
-       set_target_properties(backend_test_mac PROPERTIES INSTALL_RPATH /usr/local/lib)
    endif()
 endif()

@@ -500,38 +485,21 @@ endif()

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

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

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

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

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

 endif()
@@ -1,101 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_COMMANDSTREAMVECTOR_H
-#define TNT_FILAMENT_BACKEND_COMMANDSTREAMVECTOR_H
-
-#include <backend/DriverApiForward.h>
-
-#include <initializer_list>
-#include <memory>
-
-#include <stddef.h>
-#include <stdint.h>
-
-
-namespace filament::backend {
-
-void* allocateFromCommandStream(DriverApi& driver, size_t size, size_t alignment) noexcept;
-
-class DescriptorSetOffsetArray {
-public:
-    using value_type = uint32_t;
-    using reference = value_type&;
-    using const_reference = value_type const&;
-    using size_type = uint32_t;
-    using difference_type = int32_t;
-    using pointer = value_type*;
-    using const_pointer = value_type const*;
-    using iterator = pointer;
-    using const_iterator = const_pointer;
-
-    DescriptorSetOffsetArray() noexcept = default;
-
-    ~DescriptorSetOffsetArray() noexcept = default;
-
-    DescriptorSetOffsetArray(size_type size, DriverApi& driver) noexcept {
-        mOffsets = (value_type *)allocateFromCommandStream(driver,
-                size * sizeof(value_type), alignof(value_type));
-        std::uninitialized_fill_n(mOffsets, size, 0);
-    }
-
-    DescriptorSetOffsetArray(std::initializer_list<uint32_t> list, DriverApi& driver) noexcept {
-        mOffsets = (value_type *)allocateFromCommandStream(driver,
-                list.size() * sizeof(value_type), alignof(value_type));
-        std::uninitialized_copy(list.begin(), list.end(), mOffsets);
-    }
-
-    DescriptorSetOffsetArray(DescriptorSetOffsetArray const&) = delete;
-    DescriptorSetOffsetArray& operator=(DescriptorSetOffsetArray const&) = delete;
-
-    DescriptorSetOffsetArray(DescriptorSetOffsetArray&& rhs) noexcept
-            : mOffsets(rhs.mOffsets) {
-        rhs.mOffsets = nullptr;
-    }
-
-    DescriptorSetOffsetArray& operator=(DescriptorSetOffsetArray&& rhs) noexcept {
-        if (this != &rhs) {
-            mOffsets = rhs.mOffsets;
-            rhs.mOffsets = nullptr;
-        }
-        return *this;
-    }
-
-    bool empty() const noexcept { return mOffsets == nullptr; }
-
-    value_type* data() noexcept { return mOffsets; }
-    const value_type* data() const noexcept { return mOffsets; }
-
-
-    reference operator[](size_type n) noexcept {
-        return *(data() + n);
-    }
-
-    const_reference operator[](size_type n) const noexcept {
-        return *(data() + n);
-    }
-
-    void clear() noexcept {
-        mOffsets = nullptr;
-    }
-
-private:
-    value_type *mOffsets = nullptr;
-};
-
-} // namespace filament::backend
-
-#endif //TNT_FILAMENT_BACKEND_COMMANDSTREAMVECTOR_H
@@ -19,23 +19,17 @@
 #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>

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

 #include <stddef.h>
 #include <stdint.h>
@@ -96,16 +90,11 @@ static constexpr uint64_t SWAP_CHAIN_HAS_STENCIL_BUFFER         = SWAP_CHAIN_CON
 */
 static constexpr uint64_t SWAP_CHAIN_CONFIG_PROTECTED_CONTENT   = 0x40;

+
 static constexpr size_t MAX_VERTEX_ATTRIBUTE_COUNT  = 16;   // This is guaranteed by OpenGL ES.
 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
-                                                            // types).

 // Per feature level caps
 // Use (int)FeatureLevel to index this array
@@ -123,7 +112,7 @@ static_assert(MAX_VERTEX_BUFFER_COUNT <= MAX_VERTEX_ATTRIBUTE_COUNT,
        "The number of buffer objects that can be attached to a VertexBuffer must be "
        "less than or equal to the maximum number of vertex attributes.");

-static constexpr size_t CONFIG_UNIFORM_BINDING_COUNT = 9;   // This is guaranteed by OpenGL ES.
+static constexpr size_t CONFIG_UNIFORM_BINDING_COUNT = 10;  // This is guaranteed by OpenGL ES.
 static constexpr size_t CONFIG_SAMPLER_BINDING_COUNT = 4;   // This is guaranteed by OpenGL ES.

 /**
@@ -169,16 +158,14 @@ static constexpr const char* backendToString(Backend backend) {
 }

 /**
- * Defines the shader language. Similar to the above backend enum, with some differences:
- * - The OpenGL backend can select between two shader languages: ESSL 1.0 and ESSL 3.0.
- * - The Metal backend can prefer precompiled Metal libraries, while falling back to MSL.
+ * Defines the shader language. Similar to the above backend enum, but the OpenGL backend can select
+ * between two shader languages: ESSL 1.0 and ESSL 3.0.
 */
 enum class ShaderLanguage {
    ESSL1 = 0,
    ESSL3 = 1,
    SPIRV = 2,
    MSL = 3,
-    METAL_LIBRARY = 4,
 };

 static constexpr const char* shaderLanguageToString(ShaderLanguage shaderLanguage) {
@@ -191,66 +178,9 @@ static constexpr const char* shaderLanguageToString(ShaderLanguage shaderLanguag
            return "SPIR-V";
        case ShaderLanguage::MSL:
            return "MSL";
-        case ShaderLanguage::METAL_LIBRARY:
-            return "Metal precompiled library";
    }
 }

-enum class ShaderStage : uint8_t {
-    VERTEX = 0,
-    FRAGMENT = 1,
-    COMPUTE = 2
-};
-
-static constexpr size_t PIPELINE_STAGE_COUNT = 2;
-enum class ShaderStageFlags : uint8_t {
-    NONE        =    0,
-    VERTEX      =    0x1,
-    FRAGMENT    =    0x2,
-    COMPUTE     =    0x4,
-    ALL_SHADER_STAGE_FLAGS = VERTEX | FRAGMENT | COMPUTE
-};
-
-static inline constexpr bool hasShaderType(ShaderStageFlags flags, ShaderStage type) noexcept {
-    switch (type) {
-        case ShaderStage::VERTEX:
-            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::VERTEX));
-        case ShaderStage::FRAGMENT:
-            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::FRAGMENT));
-        case ShaderStage::COMPUTE:
-            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::COMPUTE));
-    }
-}
-
-enum class DescriptorType : uint8_t {
-    UNIFORM_BUFFER,
-    SHADER_STORAGE_BUFFER,
-    SAMPLER,
-    INPUT_ATTACHMENT,
-};
-
-enum class DescriptorFlags : uint8_t {
-    NONE = 0x00,
-    DYNAMIC_OFFSET = 0x01
-};
-
-using descriptor_set_t = uint8_t;
-
-using descriptor_binding_t = uint8_t;
-
-struct DescriptorSetLayoutBinding {
-    DescriptorType type;
-    ShaderStageFlags stageFlags;
-    descriptor_binding_t binding;
-    DescriptorFlags flags;
-    uint16_t count;
-};
-
-struct DescriptorSetLayout {
-    utils::FixedCapacityVector<DescriptorSetLayoutBinding> bindings;
-};
-
-
 /**
 * Bitmask for selecting render buffers
 */
@@ -330,6 +260,15 @@ enum class FenceStatus : int8_t {
    TIMEOUT_EXPIRED = 1,        //!< wait()'s timeout expired. The Fence condition is not satisfied.
 };

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

 /**
@@ -388,7 +327,7 @@ enum class UniformType : uint8_t {
 /**
 * Supported constant parameter types
 */
-enum class ConstantType : uint8_t {
+ enum class ConstantType : uint8_t {
  INT,
  FLOAT,
  BOOL
@@ -419,18 +358,6 @@ enum class SamplerType : uint8_t {
    SAMPLER_CUBEMAP_ARRAY,  //!< Cube map array texture (feature level 2)
 };

-inline const char* stringify(SamplerType samplerType) {
-    switch (samplerType) {
-        case SamplerType::SAMPLER_2D: return "SAMPLER_2D";
-        case SamplerType::SAMPLER_2D_ARRAY: return "SAMPLER_2D_ARRAY";
-        case SamplerType::SAMPLER_CUBEMAP: return "SAMPLER_CUBEMAP";
-        case SamplerType::SAMPLER_EXTERNAL: return "SAMPLER_EXTERNAL";
-        case SamplerType::SAMPLER_3D: return "SAMPLER_3D";
-        case SamplerType::SAMPLER_CUBEMAP_ARRAY: return "SAMPLER_CUBEMAP_ARRAY";
-    }
-    return "UNKNOWN";
-}
-
 //! Subpass type
 enum class SubpassType : uint8_t {
    SUBPASS_INPUT
@@ -755,27 +682,10 @@ enum class TextureUsage : uint16_t {
    SUBPASS_INPUT       = 0x0020,            //!< Texture can be used as a subpass input
    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
+    PROTECTED           = 0x0100,            //!< Texture can be used the destination of a blit()
    DEFAULT             = UPLOADABLE | SAMPLEABLE   //!< Default texture usage
 };

-inline const char* stringify(TextureUsage usage) {
-    switch (usage) {
-        case TextureUsage::NONE: return "NONE";
-        case TextureUsage::COLOR_ATTACHMENT: return "COLOR_ATTACHMENT";
-        case TextureUsage::DEPTH_ATTACHMENT: return "DEPTH_ATTACHMENT";
-        case TextureUsage::STENCIL_ATTACHMENT: return "STENCIL_ATTACHMENT";
-        case TextureUsage::UPLOADABLE: return "UPLOADABLE";
-        case TextureUsage::SAMPLEABLE: return "SAMPLEABLE";
-        case TextureUsage::SUBPASS_INPUT: return "SUBPASS_INPUT";
-        case TextureUsage::BLIT_SRC: return "BLIT_SRC";
-        case TextureUsage::BLIT_DST: return "BLIT_DST";
-        case TextureUsage::PROTECTED: return "PROTECTED";
-        case TextureUsage::DEFAULT: return "DEFAULT";
-        default: return "UNKNOWN";
-    }
-}
-
 //! Texture swizzle
 enum class TextureSwizzle : uint8_t {
    SUBSTITUTE_ZERO,
@@ -967,9 +877,6 @@ struct SamplerParams { // NOLINT

    struct EqualTo {
        bool operator()(SamplerParams lhs, SamplerParams rhs) const noexcept {
-            assert_invariant(lhs.padding0 == 0);
-            assert_invariant(lhs.padding1 == 0);
-            assert_invariant(lhs.padding2 == 0);
            auto* pLhs = reinterpret_cast<uint32_t const*>(reinterpret_cast<char const*>(&lhs));
            auto* pRhs = reinterpret_cast<uint32_t const*>(reinterpret_cast<char const*>(&rhs));
            return *pLhs == *pRhs;
@@ -978,9 +885,6 @@ struct SamplerParams { // NOLINT

    struct LessThan {
        bool operator()(SamplerParams lhs, SamplerParams rhs) const noexcept {
-            assert_invariant(lhs.padding0 == 0);
-            assert_invariant(lhs.padding1 == 0);
-            assert_invariant(lhs.padding2 == 0);
            auto* pLhs = reinterpret_cast<uint32_t const*>(reinterpret_cast<char const*>(&lhs));
            auto* pRhs = reinterpret_cast<uint32_t const*>(reinterpret_cast<char const*>(&rhs));
            return *pLhs == *pRhs;
@@ -988,12 +892,6 @@ struct SamplerParams { // NOLINT
    };

 private:
-    friend inline bool operator == (SamplerParams lhs, SamplerParams rhs) noexcept {
-        return SamplerParams::EqualTo{}(lhs, rhs);
-    }
-    friend inline bool operator != (SamplerParams lhs, SamplerParams rhs) noexcept {
-        return  !SamplerParams::EqualTo{}(lhs, rhs);
-    }
    friend inline bool operator < (SamplerParams lhs, SamplerParams rhs) noexcept {
        return SamplerParams::LessThan{}(lhs, rhs);
    }
@@ -1150,7 +1048,7 @@ struct RasterState {
            bool inverseFrontFaces                      : 1;        // 31

            //! padding, must be 0
-            bool depthClamp                             : 1;        // 32
+            uint8_t padding                             : 1;        // 32
        };
        uint32_t u = 0;
    };
@@ -1161,6 +1059,32 @@ struct RasterState {
 * \privatesection
 */

+enum class ShaderStage : uint8_t {
+    VERTEX = 0,
+    FRAGMENT = 1,
+    COMPUTE = 2
+};
+
+static constexpr size_t PIPELINE_STAGE_COUNT = 2;
+enum class ShaderStageFlags : uint8_t {
+    NONE        =    0,
+    VERTEX      =    0x1,
+    FRAGMENT    =    0x2,
+    COMPUTE     =    0x4,
+    ALL_SHADER_STAGE_FLAGS = VERTEX | FRAGMENT | COMPUTE
+};
+
+static inline constexpr bool hasShaderType(ShaderStageFlags flags, ShaderStage type) noexcept {
+    switch (type) {
+        case ShaderStage::VERTEX:
+            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::VERTEX));
+        case ShaderStage::FRAGMENT:
+            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::FRAGMENT));
+        case ShaderStage::COMPUTE:
+            return bool(uint8_t(flags) & uint8_t(ShaderStageFlags::COMPUTE));
+    }
+}
+
 /**
 * Selects which buffers to clear at the beginning of the render pass, as well as which buffers
 * can be discarded at the beginning and end of the render pass.
@@ -1290,15 +1214,13 @@ struct StencilState {
    uint8_t padding = 0;
 };

-using PushConstantVariant = std::variant<int32_t, float, bool>;
-
 static_assert(sizeof(StencilState::StencilOperations) == 5u,
        "StencilOperations size not what was intended");

 static_assert(sizeof(StencilState) == 12u,
        "StencilState size not what was intended");

-using FrameScheduledCallback = utils::Invocable<void(backend::PresentCallable)>;
+using FrameScheduledCallback = void(*)(PresentCallable callable, void* user);

 enum class Workaround : uint16_t {
    // The EASU pass must split because shader compiler flattens early-exit branch
@@ -1310,14 +1232,23 @@ enum class Workaround : uint16_t {
    ADRENO_UNIFORM_ARRAY_CRASH,
    // Workaround a Metal pipeline compilation error with the message:
    // "Could not statically determine the target of a texture". See light_indirect.fs
-    METAL_STATIC_TEXTURE_TARGET_ERROR,
+    A8X_STATIC_TEXTURE_TARGET_ERROR,
    // Adreno drivers sometimes aren't able to blit into a layer of a texture array.
    DISABLE_BLIT_INTO_TEXTURE_ARRAY,
    // Multiple workarounds needed for PowerVR GPUs
    POWER_VR_SHADER_WORKAROUNDS,
+    // The driver has some threads pinned, and we can't easily know on which core, it can hurt
+    // performance more if we end-up pinned on the same one.
+    DISABLE_THREAD_AFFINITY
 };

-using StereoscopicType = backend::Platform::StereoscopicType;
+//! The type of technique for stereoscopic rendering
+enum class StereoscopicType : uint8_t {
+    // Stereoscopic rendering is performed using instanced rendering technique.
+    INSTANCED,
+    // Stereoscopic rendering is performed using the multiview feature from the graphics backend.
+    MULTIVIEW,
+};

 } // namespace filament::backend

@@ -1325,8 +1256,6 @@ template<> struct utils::EnableBitMaskOperators<filament::backend::ShaderStageFl
        : public std::true_type {};
 template<> struct utils::EnableBitMaskOperators<filament::backend::TargetBufferFlags>
        : public std::true_type {};
-template<> struct utils::EnableBitMaskOperators<filament::backend::DescriptorFlags>
-        : public std::true_type {};
 template<> struct utils::EnableBitMaskOperators<filament::backend::TextureUsage>
        : public std::true_type {};
 template<> struct utils::EnableBitMaskOperators<filament::backend::StencilFace>
@@ -41,8 +41,6 @@ struct HwTexture;
 struct HwTimerQuery;
 struct HwVertexBufferInfo;
 struct HwVertexBuffer;
-struct HwDescriptorSetLayout;
-struct HwDescriptorSet;

 /*
 * A handle to a backend resource. HandleBase is for internal use only.
@@ -77,19 +75,6 @@ protected:
    HandleBase(HandleBase const& rhs) noexcept = default;
    HandleBase& operator=(HandleBase const& rhs) noexcept = default;

-    HandleBase(HandleBase&& rhs) noexcept
-            : object(rhs.object) {
-        rhs.object = nullid;
-    }
-
-    HandleBase& operator=(HandleBase&& rhs) noexcept {
-        if (this != &rhs) {
-            object = rhs.object;
-            rhs.object = nullid;
-        }
-        return *this;
-    }
-
 private:
    HandleId object;
 };
@@ -104,10 +89,8 @@ struct Handle : public HandleBase {
    Handle() noexcept = default;

    Handle(Handle const& rhs) noexcept = default;
-    Handle(Handle&& rhs) noexcept = default;

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

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

@@ -132,21 +115,19 @@ private:

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

 } // namespace filament::backend

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

 #include <utils/ostream.h>

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

 namespace filament::backend {

 //! \privatesection

-struct PipelineLayout {
-    using SetLayout = std::array<Handle<HwDescriptorSetLayout>, MAX_DESCRIPTOR_SET_COUNT>;
-    SetLayout setLayout;      // 16
-};
-
 struct PipelineState {
    Handle<HwProgram> program;                                              //  4
    Handle<HwVertexBufferInfo> vertexBufferInfo;                            //  4
-    PipelineLayout pipelineLayout;                                          // 16
    RasterState rasterState;                                                //  4
    StencilState stencilState;                                              // 12
    PolygonOffset polygonOffset;                                            //  8
@@ -41,26 +41,6 @@ public:
    struct Fence {};
    struct Stream {};

-    /**
-     * The type of technique for stereoscopic rendering. (Note that the materials used will need to
-     * be compatible with the chosen technique.)
-     */
-    enum class StereoscopicType : uint8_t {
-        /**
-         * No stereoscopic rendering
-         */
-        NONE,
-        /**
-         * Stereoscopic rendering is performed using instanced rendering technique.
-         */
-        INSTANCED,
-        /**
-         * Stereoscopic rendering is performed using the multiview feature from the graphics
-         * backend.
-         */
-        MULTIVIEW,
-    };
-
    struct DriverConfig {
        /**
         * Size of handle arena in bytes. Setting to 0 indicates default value is to be used.
@@ -75,8 +55,6 @@ public:
         */
        size_t textureUseAfterFreePoolSize = 0;

-        size_t metalUploadBufferSizeBytes = 512 * 1024;
-
        /**
         * Set to `true` to forcibly disable parallel shader compilation in the backend.
         * Currently only honored by the GL and Metal backends.
@@ -87,17 +65,6 @@ public:
         * Disable backend handles use-after-free checks.
         */
        bool disableHandleUseAfterFreeCheck = false;
-
-        /**
-         * Force GLES2 context if supported, or pretend the context is ES2. Only meaningful on
-         * GLES 3.x backends.
-         */
-        bool forceGLES2Context = false;
-
-        /**
-         * Sets the technique for stereoscopic rendering.
-         */
-        StereoscopicType stereoscopicType = StereoscopicType::NONE;
    };

    Platform() noexcept;
@@ -48,7 +48,7 @@ namespace filament::backend {
 * and optional user data:
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- * swapChain->setFrameScheduledCallback(nullptr, myFrameScheduledCallback);
+ * swapChain->setFrameScheduledCallback(myFrameScheduledCallback, nullptr);
 * if (renderer->beginFrame(swapChain)) {
 *     renderer->render(view);
 *     renderer->endFrame();
@@ -58,6 +58,8 @@ namespace filament::backend {
 * @remark Only Filament's Metal backend supports PresentCallables and frame callbacks. Other
 * backends ignore the callback (which will never be called) and proceed normally.
 *
+ * @remark The SwapChain::FrameScheduledCallback is called on an arbitrary thread.
+ *
 * Applications *must* call each PresentCallable they receive. Each PresentCallable represents a
 * frame that is waiting to be presented. If an application fails to call a PresentCallable, a
 * memory leak could occur. To "cancel" the presentation of a frame, pass false to the
@@ -24,11 +24,9 @@

 #include <backend/DriverEnums.h>

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

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

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

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

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

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

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

    Program(const Program& rhs) = delete;
@@ -88,47 +79,69 @@ 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)
-    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;

-    Program& specializationConstants(SpecializationConstantsInfo specConstants) noexcept;
+    // Note: This is only needed for GLES2.0.
+    Program& attributes(
+            utils::FixedCapacityVector<std::pair<utils::CString, uint8_t>> attributes) noexcept;

-    struct PushConstant {
-        utils::CString name;
-        ConstantType type;
+    // 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& pushConstants(ShaderStage stage,
-            utils::FixedCapacityVector<PushConstant> constants) noexcept;
+    Program& specializationConstants(
+            utils::FixedCapacityVector<SpecializationConstant> specConstants) noexcept;

    Program& cacheId(uint64_t cacheId) noexcept;

    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 {
+        return mSpecializationConstants;
+    }
+    utils::FixedCapacityVector<SpecializationConstant>& getSpecializationConstants() noexcept {
+        return mSpecializationConstants;
+    }

    uint64_t getCacheId() const noexcept { return mCacheId; }

@@ -136,50 +149,19 @@ public:

    CompilerPriorityQueue getPriorityQueue() const noexcept { return mPriorityQueue; }

-    SpecializationConstantsInfo const& getSpecializationConstants() const noexcept {
-        return mSpecializationConstants;
-    }
-
-    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)];
-    }
-
-    utils::FixedCapacityVector<PushConstant>& getPushConstants(ShaderStage stage) noexcept {
-        return mPushConstants[static_cast<uint8_t>(stage)];
-    }
-
-    auto const& getBindingUniformInfo() const { return mBindingUniformsInfo; }
-    auto& getBindingUniformInfo() { return mBindingUniformsInfo; }
-
-    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{};
-    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;
-
+    utils::FixedCapacityVector<SpecializationConstant> mSpecializationConstants;
+    utils::FixedCapacityVector<std::pair<utils::CString, uint8_t>> mAttributes;
+    std::array<UniformInfo, Program::UNIFORM_BINDING_COUNT> mBindingUniformInfo;
+    CompilerPriorityQueue mPriorityQueue = CompilerPriorityQueue::HIGH;
    // Indicates the current engine was initialized with multiview stereo, and the variant for this
    // program contains STE flag. This will be referred later for the OpenGL shader compiler to
    // determine whether shader code replacement for the num_views should be performed.
@@ -29,36 +29,17 @@ namespace filament::backend {
 //! \privatesection

 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) {
-    }
-
-    TargetBufferInfo(Handle<HwTexture> handle, uint8_t level) noexcept
-            : handle(handle), level(level) {
-    }
-
-    TargetBufferInfo(Handle<HwTexture> handle) noexcept // NOLINT(*-explicit-constructor)
-            : handle(handle) {
-    }
-
-    TargetBufferInfo() noexcept = default;
-
    // 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
+    // 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 cubemaps and 3D textures. See TextureCubemapFace for the face->layer mapping
    uint16_t layer = 0;
 };

@@ -83,7 +64,7 @@ public:

    MRT() noexcept = default;

-    MRT(TargetBufferInfo const& color) noexcept // NOLINT(hicpp-explicit-conversions, *-explicit-constructor)
+    MRT(TargetBufferInfo const& color) noexcept // NOLINT(hicpp-explicit-conversions)
            : mInfos{ color } {
    }

@@ -103,7 +84,7 @@ 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, 0, level, layer }} {
    }
 };

@@ -140,23 +140,6 @@ public:
     */
    virtual uint32_t getDefaultFramebufferObject() noexcept;

-    /**
-     * Called by the backend when a frame starts.
-     * @param steady_clock_ns vsync time point on the monotonic clock
-     * @param refreshIntervalNs refresh interval in nanosecond
-     * @param frameId a frame id
-     */
-    virtual void beginFrame(
-            int64_t monotonic_clock_ns,
-            int64_t refreshIntervalNs,
-            uint32_t frameId) noexcept;
-
-    /**
-     * Called by the backend when a frame ends.
-     * @param frameId the frame id used in beginFrame
-     */
-    virtual void endFrame(
-            uint32_t frameId) noexcept;

    /**
     * Type of contexts available
@@ -208,12 +191,6 @@ public:
            utils::Invocable<void()> preContextChange,
            utils::Invocable<void(size_t index)> postContextChange) noexcept;

-    /**
-     * Called by the backend just before calling commit()
-     * @see commit()
-     */
-    virtual void preCommit() noexcept;
-
    /**
     * Called by the driver once the current frame finishes drawing. Typically, this should present
     * the drawSwapChain. This is for example where `eglMakeCurrent()` would be called.
@@ -22,10 +22,6 @@
 #include <backend/platforms/OpenGLPlatform.h>
 #include <backend/platforms/PlatformEGL.h>

-#include <utils/android/PerformanceHintManager.h>
-
-#include <chrono>
-
 #include <stddef.h>
 #include <stdint.h>

@@ -62,13 +58,6 @@ protected:

    void terminate() noexcept override;

-    void beginFrame(
-            int64_t monotonic_clock_ns,
-            int64_t refreshIntervalNs,
-            uint32_t frameId) noexcept override;
-
-    void preCommit() noexcept override;
-
    /**
     * Set the presentation time using `eglPresentationTimeANDROID`
     * @param presentationTimeInNanosecond
@@ -90,18 +79,8 @@ protected:
    AcquiredImage transformAcquiredImage(AcquiredImage source) noexcept override;

 private:
-    struct InitializeJvmForPerformanceManagerIfNeeded {
-        InitializeJvmForPerformanceManagerIfNeeded();
-    };
-
    int mOSVersion;
    ExternalStreamManagerAndroid& mExternalStreamManager;
-    InitializeJvmForPerformanceManagerIfNeeded const mInitializeJvmForPerformanceManagerIfNeeded;
-    utils::PerformanceHintManager mPerformanceHintManager;
-    utils::PerformanceHintManager::Session mPerformanceHintSession;
-
-    using clock = std::chrono::high_resolution_clock;
-    clock::time_point mStartTimeOfActualWork;
 };

 } // namespace filament::backend
@@ -23,9 +23,9 @@

 #include <utils/CString.h>
 #include <utils/FixedCapacityVector.h>
-#include <utils/Hash.h>
 #include <utils/PrivateImplementation.h>

+#include <string_view>
 #include <tuple>
 #include <unordered_set>

@@ -47,14 +47,6 @@ struct VulkanPlatformPrivate;
 class VulkanPlatform : public Platform, utils::PrivateImplementation<VulkanPlatformPrivate> {
 public:

-    struct ExtensionHashFn {
-        std::size_t operator()(utils::CString const& s) const noexcept {
-            return std::hash<std::string>{}(s.data());
-        }
-    };
-    // Utility for managing device or instance extensions during initialization.
-    using ExtensionSet = std::unordered_set<utils::CString, ExtensionHashFn>;
-
    /**
     * A collection of handles to objects and metadata that comprises a Vulkan context. The client
     * can instantiate this struct and pass to Engine::Builder::sharedContext if they wishes to
@@ -90,20 +82,6 @@ public:
        VkExtent2D extent = {0, 0};
    };

-    struct ImageSyncData {
-        static constexpr uint32_t INVALID_IMAGE_INDEX = UINT32_MAX;
-
-        // The index of the next image as returned by vkAcquireNextImage or equivalent.
-        uint32_t imageIndex = INVALID_IMAGE_INDEX;
-
-        // Semaphore to be signaled once the image is available.
-        VkSemaphore imageReadySemaphore = VK_NULL_HANDLE;
-
-        // A function called right before vkQueueSubmit. After this call, the image must be 
-        // available. This pointer can be null if imageReadySemaphore is not VK_NULL_HANDLE.
-        std::function<void(SwapChainPtr handle)> explicitImageReadyWait = nullptr;
-    };
-
    VulkanPlatform();

    ~VulkanPlatform() override;
@@ -141,12 +119,6 @@ public:
         * before recreating the swapchain. Default is true.
         */
        bool flushAndWaitOnWindowResize = true;
-
-        /**
-         * Whether the swapchain image should be transitioned to a layout suitable for
-         * presentation. Default is true.
-         */
-        bool transitionSwapChainImageLayoutForPresent = true;
    };

    /**
@@ -175,10 +147,13 @@ public:
     * corresponding VkImage will be used as the output color attachment. The client should signal
     * the `clientSignal` semaphore when the image is ready to be used by the backend.
     * @param handle         The handle returned by createSwapChain()
-     * @param outImageSyncData The synchronization data used for image readiness
+     * @param clientSignal   The semaphore that the client will signal to indicate that the backend
+     *                       may render into the image.
+     * @param index          Pointer to memory that will be filled with the index that corresponding
+     *                       to an image in the `SwapChainBundle.colors` array.
     * @return               Result of acquire
     */
-    virtual VkResult acquire(SwapChainPtr handle, ImageSyncData* outImageSyncData);
+    virtual VkResult acquire(SwapChainPtr handle, VkSemaphore clientSignal, uint32_t* index);

    /**
     * Present the image corresponding to `index` to the display. The client should wait on
@@ -217,13 +192,6 @@ public:
    virtual SwapChainPtr createSwapChain(void* nativeWindow, uint64_t flags = 0,
            VkExtent2D extent = {0, 0});

-    /**
-     * Allows implementers to provide instance extensions that they'd like to include in the
-     * instance creation.
-     * @return          A set of extensions to enable for the instance.
-     */
-    virtual ExtensionSet getRequiredInstanceExtensions() { return {}; }
-
    /**
     * Destroy the swapchain.
     * @param handle    The handle returned by createSwapChain()
@@ -268,9 +236,10 @@ public:
    VkQueue getGraphicsQueue() const noexcept;

 private:
-    static ExtensionSet getSwapchainInstanceExtensions();
-
    // Platform dependent helper methods
+    using ExtensionSet = std::unordered_set<std::string_view>;
+    static ExtensionSet getRequiredInstanceExtensions();
+
    using SurfaceBundle = std::tuple<VkSurfaceKHR, VkExtent2D>;
    static SurfaceBundle createVkSurfaceKHR(void* nativeWindow, VkInstance instance,
            uint64_t flags) noexcept;
@@ -82,7 +82,6 @@ public:
    void requestExit();

    // suspend or unsuspend the queue.
-    bool isPaused() const noexcept;
    void setPaused(bool paused);

    bool isExitRequested() const;
@@ -134,7 +134,7 @@ struct CommandType<void (Driver::*)(ARGS...)> {

    public:
        template<typename M, typename D>
-        static inline void execute(M&& method, D&& driver, CommandBase* base, intptr_t* next) {
+        static inline void execute(M&& method, D&& driver, CommandBase* base, intptr_t* next) noexcept {
            Command* self = static_cast<Command*>(base);
            *next = align(sizeof(Command));
 #if DEBUG_COMMAND_STREAM
@@ -168,7 +168,7 @@ struct CommandType<void (Driver::*)(ARGS...)> {

 class CustomCommand : public CommandBase {
    std::function<void()> mCommand;
-    static void execute(Driver&, CommandBase* base, intptr_t* next);
+    static void execute(Driver&, CommandBase* base, intptr_t* next) noexcept;
 public:
    inline CustomCommand(CustomCommand&& rhs) = default;
    inline explicit CustomCommand(std::function<void()> cmd)
@@ -18,7 +18,6 @@
 #define TNT_FILAMENT_BACKEND_PRIVATE_DRIVER_H

 #include <backend/CallbackHandler.h>
-#include <backend/DescriptorSetOffsetArray.h>
 #include <backend/DriverApiForward.h>
 #include <backend/DriverEnums.h>
 #include <backend/Handle.h>
@@ -77,7 +76,7 @@ public:
    // the fn function will execute a batch of driver commands
    // this gives the driver a chance to wrap their execution in a meaningful manner
    // the default implementation simply calls fn
-    virtual void execute(std::function<void(void)> const& fn);
+    virtual void execute(std::function<void(void)> const& fn) noexcept;

    // This is called on debug build, or when enabled manually on the backend thread side.
    virtual void debugCommandBegin(CommandStream* cmds,
@@ -133,18 +133,18 @@ DECL_DRIVER_API_0(tick)

 DECL_DRIVER_API_N(beginFrame,
        int64_t, monotonic_clock_ns,
-        int64_t, refreshIntervalNs,
        uint32_t, frameId)

 DECL_DRIVER_API_N(setFrameScheduledCallback,
        backend::SwapChainHandle, sch,
-        backend::CallbackHandler*, handler,
-        backend::FrameScheduledCallback&&, callback)
+        backend::FrameScheduledCallback, callback,
+        void*, user)

 DECL_DRIVER_API_N(setFrameCompletedCallback,
        backend::SwapChainHandle, sch,
        backend::CallbackHandler*, handler,
-        utils::Invocable<void(void)>&&, callback)
+        backend::CallbackHandler::Callback, callback,
+        void*, user)

 DECL_DRIVER_API_N(setPresentationTime,
        int64_t, monotonic_clock_ns)
@@ -162,10 +162,6 @@ DECL_DRIVER_API_0(finish)
 // reset state tracking, if the driver does any state tracking (e.g. GL)
 DECL_DRIVER_API_0(resetState)

-DECL_DRIVER_API_N(setDebugTag,
-        backend::HandleBase::HandleId, handleId,
-        utils::CString, tag)
-
 /*
 * Creating driver objects
 * -----------------------
@@ -200,33 +196,20 @@ DECL_DRIVER_API_R_N(backend::TextureHandle, createTexture,
        uint32_t, depth,
        backend::TextureUsage, usage)

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

-DECL_DRIVER_API_R_N(backend::TextureHandle, createTextureExternalImage,
-        backend::TextureFormat, format,
-        uint32_t, width,
-        uint32_t, height,
-        backend::TextureUsage, usage,
-        void*, image)
-
-DECL_DRIVER_API_R_N(backend::TextureHandle, createTextureExternalImagePlane,
-        backend::TextureFormat, format,
-        uint32_t, width,
-        uint32_t, height,
-        backend::TextureUsage, usage,
-        void*, image,
-        uint32_t, plane)
-
 DECL_DRIVER_API_R_N(backend::TextureHandle, importTexture,
        intptr_t, id,
        backend::SamplerType, target,
@@ -238,6 +221,9 @@ DECL_DRIVER_API_R_N(backend::TextureHandle, importTexture,
        uint32_t, depth,
        backend::TextureUsage, usage)

+DECL_DRIVER_API_R_N(backend::SamplerGroupHandle, createSamplerGroup,
+        uint32_t, size, utils::FixedSizeString<32>, debugName)
+
 DECL_DRIVER_API_R_N(backend::RenderPrimitiveHandle, createRenderPrimitive,
        backend::VertexBufferHandle, vbh,
        backend::IndexBufferHandle, ibh,
@@ -271,53 +257,25 @@ DECL_DRIVER_API_R_N(backend::SwapChainHandle, createSwapChainHeadless,

 DECL_DRIVER_API_R_0(backend::TimerQueryHandle, createTimerQuery)

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

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

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

 /*
 * Synchronous APIs
@@ -342,12 +300,10 @@ DECL_DRIVER_API_SYNCHRONOUS_0(bool, isFrameTimeSupported)
 DECL_DRIVER_API_SYNCHRONOUS_0(bool, isAutoDepthResolveSupported)
 DECL_DRIVER_API_SYNCHRONOUS_0(bool, isSRGBSwapChainSupported)
 DECL_DRIVER_API_SYNCHRONOUS_0(bool, isProtectedContentSupported)
-DECL_DRIVER_API_SYNCHRONOUS_0(bool, isStereoSupported)
+DECL_DRIVER_API_SYNCHRONOUS_N(bool, isStereoSupported, backend::StereoscopicType, stereoscopicType)
 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)
@@ -384,6 +340,15 @@ DECL_DRIVER_API_N(updateBufferObjectUnsynchronized,
 DECL_DRIVER_API_N(resetBufferObject,
        backend::BufferObjectHandle, ibh)

+DECL_DRIVER_API_N(updateSamplerGroup,
+        backend::SamplerGroupHandle, ubh,
+        backend::BufferDescriptor&&, data)
+
+DECL_DRIVER_API_N(setMinMaxLevels,
+        backend::TextureHandle, th,
+        uint32_t, minLevel,
+        uint32_t, maxLevel)
+
 DECL_DRIVER_API_N(update3DImage,
        backend::TextureHandle, th,
        uint32_t, level,
@@ -398,12 +363,10 @@ DECL_DRIVER_API_N(update3DImage,
 DECL_DRIVER_API_N(generateMipmaps,
        backend::TextureHandle, th)

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

-// Deprecated
 DECL_DRIVER_API_N(setExternalImagePlane,
        backend::TextureHandle, th,
        void*, image,
@@ -450,16 +413,32 @@ DECL_DRIVER_API_N(commit,
 * -----------------------
 */

-DECL_DRIVER_API_N(setPushConstant,
-        backend::ShaderStage, stage,
-        uint8_t, index,
-        backend::PushConstantVariant, value)
+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(insertEventMarker,
-        const char*, string)
+        const char*, string,
+        uint32_t, len = 0)

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

 DECL_DRIVER_API_0(popGroupMarker)

@@ -516,7 +495,7 @@ DECL_DRIVER_API_N(blit,
        math::uint2, size)

 DECL_DRIVER_API_N(bindPipeline,
-        backend::PipelineState const&, state)
+        backend::PipelineState, state)

 DECL_DRIVER_API_N(bindRenderPrimitive,
        backend::RenderPrimitiveHandle, rph)
@@ -18,17 +18,6 @@
 #define TNT_FILAMENT_BACKEND_PRIVATE_DRIVERAPI_H

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

-#include <stddef.h>
-
-namespace filament::backend {
-
-inline void* allocateFromCommandStream(DriverApi& driver, size_t size, size_t alignment) noexcept {
-    return driver.allocate(size, alignment);
-}
-
-} // namespace filament::backend
-
 #endif // TNT_FILAMENT_BACKEND_PRIVATE_DRIVERAPI_H
@@ -20,12 +20,11 @@
 #include <backend/Handle.h>

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

 #include <tsl/robin_map.h>

@@ -38,9 +37,9 @@
 #include <stddef.h>
 #include <stdint.h>

-#define HandleAllocatorGL  HandleAllocator<32,  96, 136>    // ~4520 / pool / MiB
+#define HandleAllocatorGL  HandleAllocator<32,  64, 136>    // ~4520 / pool / MiB
 #define HandleAllocatorVK  HandleAllocator<64, 160, 312>    // ~1820 / pool / MiB
-#define HandleAllocatorMTL HandleAllocator<32,  64, 552>    // ~1660 / pool / MiB
+#define HandleAllocatorMTL HandleAllocator<32,  48, 552>    // ~1660 / pool / MiB

 namespace filament::backend {

@@ -66,7 +65,7 @@ public:
     *
     */
    template<typename D, typename ... ARGS>
-    Handle<D> allocateAndConstruct(ARGS&& ... args) {
+    Handle<D> allocateAndConstruct(ARGS&& ... args) noexcept {
        Handle<D> h{ allocateHandle<D>() };
        D* addr = handle_cast<D*>(h);
        new(addr) D(std::forward<ARGS>(args)...);
@@ -98,7 +97,7 @@ public:
     */
    template<typename D, typename B, typename ... ARGS>
    typename std::enable_if_t<std::is_base_of_v<B, D>, D>*
-    destroyAndConstruct(Handle<B> const& handle, ARGS&& ... args) {
+    destroyAndConstruct(Handle<B> const& handle, ARGS&& ... args) noexcept {
        assert_invariant(handle);
        D* addr = handle_cast<D*>(const_cast<Handle<B>&>(handle));
        assert_invariant(addr);
@@ -164,7 +163,7 @@ public:
    inline typename std::enable_if_t<
            std::is_pointer_v<Dp> &&
            std::is_base_of_v<B, typename std::remove_pointer_t<Dp>>, Dp>
-    handle_cast(Handle<B>& handle) {
+    handle_cast(Handle<B>& handle) noexcept {
        assert_invariant(handle);
        auto [p, tag] = handleToPointer(handle.getId());

@@ -174,59 +173,22 @@ public:
                uint8_t const age = (tag & HANDLE_AGE_MASK) >> HANDLE_AGE_SHIFT;
                auto const pNode = static_cast<typename Allocator::Node*>(p);
                uint8_t const expectedAge = pNode[-1].age;
-                // getHandleTag() is only called if the check fails.
-                FILAMENT_CHECK_POSTCONDITION(expectedAge == age)
-                        << "use-after-free of Handle with id=" << handle.getId()
-                        << ", tag=" << getHandleTag(handle.getId()).c_str_safe();
+                ASSERT_POSTCONDITION(expectedAge == age,
+                        "use-after-free of Handle with id=%d", handle.getId());
            }
        }

        return static_cast<Dp>(p);
    }

-    template<typename B>
-    bool is_valid(Handle<B>& handle) {
-        if (handle && isPoolHandle(handle.getId())) {
-            auto [p, tag] = handleToPointer(handle.getId());
-            uint8_t const age = (tag & HANDLE_AGE_MASK) >> HANDLE_AGE_SHIFT;
-            auto const pNode = static_cast<typename Allocator::Node*>(p);
-            uint8_t const expectedAge = pNode[-1].age;
-            return expectedAge == age;
-        }
-        return true;
-    }
-
    template<typename Dp, typename B>
    inline typename std::enable_if_t<
            std::is_pointer_v<Dp> &&
            std::is_base_of_v<B, typename std::remove_pointer_t<Dp>>, Dp>
-    handle_cast(Handle<B> const& handle) {
+    handle_cast(Handle<B> const& handle) noexcept {
        return handle_cast<Dp>(const_cast<Handle<B>&>(handle));
    }

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

    template<typename D>
@@ -278,8 +240,8 @@ private:
            Node* const pNode = static_cast<Node*>(p);
            uint8_t& expectedAge = pNode[-1].age;
            if (UTILS_UNLIKELY(!mUseAfterFreeCheckDisabled)) {
-                FILAMENT_CHECK_POSTCONDITION(expectedAge == age) <<
-                        "double-free of Handle of size " << size << " at " << p;
+                ASSERT_POSTCONDITION(expectedAge == age,
+                        "double-free of Handle of size %d at %p", size, p);
            }
            expectedAge = (expectedAge + 1) & 0xF; // fixme

@@ -344,30 +306,18 @@ private:
        }
    }

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

    static bool isPoolHandle(HandleBase::HandleId id) noexcept {
        return (id & HANDLE_HEAP_FLAG) == 0u;
    }

-    HandleBase::HandleId allocateHandleSlow(size_t size);
+    HandleBase::HandleId allocateHandleSlow(size_t size) noexcept;
    void deallocateHandleSlow(HandleBase::HandleId id, size_t size) noexcept;

    // We inline this because it's just 4 instructions in the fast case
@@ -376,7 +326,7 @@ private:
        // a non-pool handle.
        if (UTILS_LIKELY(isPoolHandle(id))) {
            char* const base = (char*)mHandleArena.getArea().begin();
-            uint32_t const tag = id & HANDLE_AGE_MASK;
+            uint32_t const tag = id & HANDLE_TAG_MASK;
            size_t const offset = (id & HANDLE_INDEX_MASK) * Allocator::getAlignment();
            return { static_cast<void*>(base + offset), tag };
        }
@@ -391,7 +341,7 @@ private:
        size_t const offset = (char*)p - base;
        assert_invariant((offset % Allocator::getAlignment()) == 0);
        auto id = HandleBase::HandleId(offset / Allocator::getAlignment());
-        id |= tag & HANDLE_AGE_MASK;
+        id |= tag & HANDLE_TAG_MASK;
        assert_invariant((id & HANDLE_HEAP_FLAG) == 0);
        return id;
    }
@@ -401,7 +351,6 @@ private:
    // Below is only used when running out of space in the HandleArena
    mutable utils::Mutex mLock;
    tsl::robin_map<HandleBase::HandleId, void*> mOverflowMap;
-    tsl::robin_map<HandleBase::HandleId, utils::CString> mDebugTags;
    HandleBase::HandleId mId = 0;
    bool mUseAfterFreeCheckDisabled = false;
 };
@@ -27,8 +27,8 @@ PresentCallable::PresentCallable(PresentFn fn, void* user) noexcept
 }

 void PresentCallable::operator()(bool presentFrame) noexcept {
-    FILAMENT_CHECK_PRECONDITION(mPresentFn) << "This PresentCallable was already called. "
-                                               "PresentCallables should be called exactly once.";
+    ASSERT_PRECONDITION(mPresentFn, "This PresentCallable was already called. " \
+            "PresentCallables should be called exactly once.");
    mPresentFn(presentFrame, mUser);
    // Set mPresentFn to nullptr to denote that the callable has been called.
    mPresentFn = nullptr;
@@ -24,7 +24,7 @@
 #include <utils/debug.h>
 #include <utils/ostream.h>

-#if !defined(WIN32) && !defined(__EMSCRIPTEN__)
+#if !defined(WIN32) && !defined(__EMSCRIPTEN__) && !defined(IOS)
 #    include <sys/mman.h>
 #    include <unistd.h>
 #    define HAS_MMAP 1
@@ -32,11 +32,10 @@
 #    define HAS_MMAP 0
 #endif

-#include <stddef.h>
 #include <stdint.h>
-#include <stdio.h>
+#include <stddef.h>
 #include <stdlib.h>
-#include <string.h>
+#include <stdio.h>

 using namespace utils;

@@ -82,9 +81,6 @@ void* CircularBuffer::alloc(size_t size) noexcept {
            // map the circular buffer once...
            vaddr = mmap(reserve_vaddr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
            if (vaddr != MAP_FAILED) {
-                // populate the address space with pages (because this is a circular buffer,
-                // all the pages will be allocated eventually, might as well do it now)
-                memset(vaddr, 0, size);
                // and map the circular buffer again, behind the previous copy...
                vaddr_shadow = mmap((char*)vaddr + size, size,
                        PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
@@ -105,7 +101,7 @@ void* CircularBuffer::alloc(size_t size) noexcept {
    if (UTILS_UNLIKELY(mAshmemFd < 0)) {
        // ashmem failed
        if (vaddr_guard != MAP_FAILED) {
-            munmap(vaddr_guard, BLOCK_SIZE);
+            munmap(vaddr_guard, size);
        }

        if (vaddr_shadow != MAP_FAILED) {
@@ -123,11 +119,12 @@ void* CircularBuffer::alloc(size_t size) noexcept {
        data = mmap(nullptr, size * 2 + BLOCK_SIZE,
                PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

-        FILAMENT_CHECK_POSTCONDITION(data != MAP_FAILED) <<
-                "couldn't allocate " << (size * 2 / 1024) <<
-                " KiB of virtual address space for the command buffer";
+        ASSERT_POSTCONDITION(data,
+                "couldn't allocate %u KiB of virtual address space for the command buffer",
+                (size * 2 / 1024));

-        slog.w << "Using 'soft' CircularBuffer (" << (size * 2 / 1024) << " KiB)" << io::endl;
+        slog.d << "WARNING: Using soft CircularBuffer (" << (size * 2 / 1024) << " KiB)"
+               << io::endl;

        // guard page at the end
        void* guard = (void*)(uintptr_t(data) + size * 2);
@@ -57,11 +57,6 @@ void CommandBufferQueue::requestExit() {
    mCondition.notify_one();
 }

-bool CommandBufferQueue::isPaused() const noexcept {
-    std::lock_guard<utils::Mutex> const lock(mLock);
-    return mPaused;
-}
-
 void CommandBufferQueue::setPaused(bool paused) {
    std::lock_guard<utils::Mutex> const lock(mLock);
    if (paused) {
@@ -74,6 +69,8 @@ void CommandBufferQueue::setPaused(bool paused) {

 bool CommandBufferQueue::isExitRequested() const {
    std::lock_guard<utils::Mutex> const lock(mLock);
+    ASSERT_PRECONDITION( mExitRequested == 0 || mExitRequested == EXIT_REQUESTED,
+            "mExitRequested is corrupted (value = 0x%08x)!", mExitRequested);
    return (bool)mExitRequested;
 }

@@ -101,23 +98,22 @@ void CommandBufferQueue::flush() noexcept {
    size_t const used = std::distance(
            static_cast<char const*>(begin), static_cast<char const*>(end));

-
    std::unique_lock<utils::Mutex> lock(mLock);
-
-    // circular buffer is too small, we corrupted the stream
-    FILAMENT_CHECK_POSTCONDITION(used <= mFreeSpace) <<
-            "Backend CommandStream overflow. Commands are corrupted and unrecoverable.\n"
-            "Please increase minCommandBufferSizeMB inside the Config passed to Engine::create.\n"
-            "Space used at this time: " << used <<
-            " bytes, overflow: " << used - mFreeSpace << " bytes";
-
-    mFreeSpace -= used;
    mCommandBuffersToExecute.push_back({ begin, end });
    mCondition.notify_one();

+    // circular buffer is too small, we corrupted the stream
+    ASSERT_POSTCONDITION(used <= mFreeSpace,
+            "Backend CommandStream overflow. Commands are corrupted and unrecoverable.\n"
+            "Please increase minCommandBufferSizeMB inside the Config passed to Engine::create.\n"
+            "Space used at this time: %u bytes, overflow: %u bytes",
+            (unsigned)used, unsigned(used - mFreeSpace));
+
    // wait until there is enough space in the buffer
+    mFreeSpace -= used;
    if (UTILS_UNLIKELY(mFreeSpace < requiredSize)) {

+
 #ifndef NDEBUG
        size_t const totalUsed = circularBuffer.size() - mFreeSpace;
        slog.d << "CommandStream used too much space (will block): "
@@ -130,11 +126,9 @@ void CommandBufferQueue::flush() noexcept {
 #endif

        SYSTRACE_NAME("waiting: CircularBuffer::flush()");
-
-        FILAMENT_CHECK_POSTCONDITION(!mPaused) <<
+        ASSERT_POSTCONDITION(!mPaused,
                "CommandStream is full, but since the rendering thread is paused, "
-                "the buffer cannot flush and we will deadlock. Instead, abort.";
-
+                "the buffer cannot flush and we will deadlock. Instead, abort.");
        mCondition.wait(lock, [this, requiredSize]() -> bool {
            // TODO: on macOS, we need to call pumpEvents from time to time
            return mFreeSpace >= requiredSize;
@@ -150,14 +144,16 @@ std::vector<CommandBufferQueue::Range> CommandBufferQueue::waitForCommands() con
    while ((mCommandBuffersToExecute.empty() || mPaused) && !mExitRequested) {
        mCondition.wait(lock);
    }
+
+    ASSERT_PRECONDITION( mExitRequested == 0 || mExitRequested == EXIT_REQUESTED,
+            "mExitRequested is corrupted (value = 0x%08x)!", mExitRequested);
+
    return std::move(mCommandBuffersToExecute);
 }

 void CommandBufferQueue::releaseBuffer(CommandBufferQueue::Range const& buffer) {
-    size_t const used = std::distance(
-            static_cast<char const*>(buffer.begin), static_cast<char const*>(buffer.end));
    std::lock_guard<utils::Mutex> const lock(mLock);
-    mFreeSpace += used;
+    mFreeSpace += uintptr_t(buffer.end) - uintptr_t(buffer.begin);
    mCondition.notify_one();
 }

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

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

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

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

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

    Profiler profiler;

@@ -105,7 +100,6 @@ void CommandStream::execute(void* buffer) {
            // we want to remove all this when tracing is completely disabled
            profiler.stop();
            UTILS_UNUSED Profiler::Counters const counters = profiler.readCounters();
-            SYSTRACE_CONTEXT();
            SYSTRACE_VALUE32("GLThread (I)", counters.getInstructions());
            SYSTRACE_VALUE32("GLThread (C)", counters.getCpuCycles());
            SYSTRACE_VALUE32("GLThread (CPI x10)", counters.getCPI() * 10);
@@ -155,7 +149,7 @@ void CommandType<void (Driver::*)(ARGS...)>::Command<METHOD>::log() noexcept  {

 // ------------------------------------------------------------------------------------------------

-void CustomCommand::execute(Driver&, CommandBase* base, intptr_t* next) {
+void CustomCommand::execute(Driver&, CommandBase* base, intptr_t* next) noexcept {
    *next = CustomCommand::align(sizeof(CustomCommand));
    static_cast<CustomCommand*>(base)->mCommand();
    static_cast<CustomCommand*>(base)->~CustomCommand();
@@ -214,7 +214,7 @@ size_t Driver::getElementTypeSize(ElementType type) noexcept {

 Driver::~Driver() noexcept = default;

-void Driver::execute(std::function<void(void)> const& fn) {
+void Driver::execute(std::function<void(void)> const& fn) noexcept {
    fn();
 }

@@ -101,14 +101,6 @@ struct HwProgram : public HwBase {
    HwProgram() noexcept = default;
 };

-struct HwDescriptorSetLayout : public HwBase {
-    HwDescriptorSetLayout() noexcept = default;
-};
-
-struct HwDescriptorSet : public HwBase {
-    HwDescriptorSet() noexcept = default;
-};
-
 struct HwSamplerGroup : public HwBase {
    HwSamplerGroup() noexcept = default;
 };
@@ -80,9 +80,6 @@ HandleAllocator<P0, P1, P2>::HandleAllocator(const char* name, size_t size,
        bool disableUseAfterFreeCheck) noexcept
    : mHandleArena(name, size, disableUseAfterFreeCheck),
      mUseAfterFreeCheckDisabled(disableUseAfterFreeCheck) {
-    // Reserve initial space for debug tags. This prevents excessive calls to malloc when the first
-    // few tags are set.
-    mDebugTags.reserve(512);
 }

 template <size_t P0, size_t P1, size_t P2>
@@ -110,15 +107,15 @@ void* HandleAllocator<P0, P1, P2>::handleToPointerSlow(HandleBase::HandleId id)
 }

 template <size_t P0, size_t P1, size_t P2>
-HandleBase::HandleId HandleAllocator<P0, P1, P2>::allocateHandleSlow(size_t size) {
+HandleBase::HandleId HandleAllocator<P0, P1, P2>::allocateHandleSlow(size_t size) noexcept {
    void* p = ::malloc(size);
    std::unique_lock lock(mLock);

    HandleBase::HandleId id = (++mId) | HANDLE_HEAP_FLAG;

-    FILAMENT_CHECK_POSTCONDITION(mId < HANDLE_HEAP_FLAG) <<
+    ASSERT_POSTCONDITION(mId < HANDLE_HEAP_FLAG,
            "No more Handle ids available! This can happen if HandleAllocator arena has been full"
-            " for a while. Please increase FILAMENT_OPENGL_HANDLE_ARENA_SIZE_IN_MB";
+            " for a while. Please increase FILAMENT_OPENGL_HANDLE_ARENA_SIZE_IN_MB");

    mOverflowMap.emplace(id, p);
    lock.unlock();
@@ -29,21 +29,21 @@
        #include "backend/platforms/PlatformCocoaTouchGL.h"
    #endif
 #elif defined(__APPLE__)
-    #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3)
+    #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3) && !defined(FILAMENT_USE_SWIFTSHADER)
        #include <backend/platforms/PlatformCocoaGL.h>
    #endif
 #elif defined(__linux__)
    #if defined(FILAMENT_SUPPORTS_X11)
-        #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3)
+        #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3) && !defined(FILAMENT_USE_SWIFTSHADER)
            #include "backend/platforms/PlatformGLX.h"
        #endif
    #elif defined(FILAMENT_SUPPORTS_EGL_ON_LINUX)
-        #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3)
+        #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3) && !defined(FILAMENT_USE_SWIFTSHADER)
            #include "backend/platforms/PlatformEGLHeadless.h"
        #endif
    #endif
 #elif defined(WIN32)
-    #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3)
+    #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3) && !defined(FILAMENT_USE_SWIFTSHADER)
        #include "backend/platforms/PlatformWGL.h"
    #endif
 #elif defined(__EMSCRIPTEN__)
@@ -111,7 +111,8 @@ Platform* PlatformFactory::create(Backend* backend) noexcept {
    }
    assert_invariant(*backend == Backend::OPENGL);
    #if defined(FILAMENT_SUPPORTS_OPENGL)
-        #if defined(FILAMENT_USE_EXTERNAL_GLES3)
+        #if defined(FILAMENT_USE_EXTERNAL_GLES3) || defined(FILAMENT_USE_SWIFTSHADER)
+            // Swiftshader OpenGLES support is deprecated and incomplete
            return nullptr;
        #elif defined(__ANDROID__)
            return new PlatformEGLAndroid();
@@ -14,25 +14,14 @@
 * limitations under the License.
 */

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

 namespace filament::backend {

 using namespace utils;

 // We want these in the .cpp file, so they're not inlined (not worth it)
-Program::Program() noexcept {  // NOLINT(modernize-use-equals-default)
+Program::Program() noexcept { // NOLINT(modernize-use-equals-default)
 }

 Program::Program(Program&& rhs) noexcept = default;
@@ -58,36 +47,42 @@ Program& Program::shader(ShaderStage shader, void const* data, size_t size) {
    return *this;
 }

-Program& Program::shaderLanguage(ShaderLanguage shaderLanguage) {
-    mShaderLanguage = shaderLanguage;
+Program& Program::uniformBlockBindings(
+        FixedCapacityVector<std::pair<utils::CString, uint8_t>> const& uniformBlockBindings) noexcept {
+    for (auto const& item : uniformBlockBindings) {
+        assert_invariant(item.second < UNIFORM_BINDING_COUNT);
+        mUniformBlocks[item.second] = item.first;
+    }
    return *this;
 }

-Program& Program::descriptorBindings(backend::descriptor_set_t set,
-        DescriptorBindingsInfo descriptorBindings) noexcept {
-    mDescriptorBindings[set] = std::move(descriptorBindings);
+Program& Program::uniforms(uint32_t index, UniformInfo const& uniforms) noexcept {
+    assert_invariant(index < UNIFORM_BINDING_COUNT);
+    mBindingUniformInfo[index] = uniforms;
    return *this;
 }

-Program& Program::uniforms(uint32_t index, utils::CString name, UniformInfo uniforms) noexcept {
-    mBindingUniformsInfo.reserve(mBindingUniformsInfo.capacity() + 1);
-    mBindingUniformsInfo.emplace_back(index, std::move(name), std::move(uniforms));
-    return *this;
-}

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

-Program& Program::specializationConstants(SpecializationConstantsInfo specConstants) noexcept {
-    mSpecializationConstants = std::move(specConstants);
+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::pushConstants(ShaderStage stage,
-        utils::FixedCapacityVector<PushConstant> constants) noexcept {
-    mPushConstants[static_cast<uint8_t>(stage)] = std::move(constants);
+Program& Program::specializationConstants(
+        FixedCapacityVector<SpecializationConstant> specConstants) noexcept {
+    mSpecializationConstants = std::move(specConstants);
    return *this;
 }

@@ -16,23 +16,13 @@

 #include "private/backend/VirtualMachineEnv.h"

-#include <utils/compiler.h>
 #include <utils/debug.h>

-#include <jni.h>
-
 namespace filament {

 JavaVM* VirtualMachineEnv::sVirtualMachine = nullptr;

-/*
- * This is typically called by filament_jni.so when it is loaded. If filament_jni.so is not used,
- * then this must be called manually -- however, this is a problem because VirtualMachineEnv.h
- * is currently private and part of backend.
- * For now, we authorize this usage, but we will need to fix it; by making a proper public
- * API for this.
- */
-UTILS_PUBLIC
+// This is called when the library is loaded. We need this to get a reference to the global VM
 UTILS_NOINLINE
 jint VirtualMachineEnv::JNI_OnLoad(JavaVM* vm) noexcept {
    JNIEnv* env = nullptr;
@@ -109,8 +109,9 @@ inline bool MTLSizeEqual(T a, T b) noexcept {
 MetalBlitter::MetalBlitter(MetalContext& context) noexcept : mContext(context) { }

 void MetalBlitter::blit(id<MTLCommandBuffer> cmdBuffer, const BlitArgs& args, const char* label) {
-    FILAMENT_CHECK_PRECONDITION(args.source.region.size.depth == args.destination.region.size.depth)
-            << "Blitting requires the source and destination regions to have the same depth.";
+
+    ASSERT_PRECONDITION(args.source.region.size.depth == args.destination.region.size.depth,
+            "Blitting requires the source and destination regions to have the same depth.");

    // Determine if the blit for color or depth are eligible to use a MTLBlitCommandEncoder.
    // blitFastPath returns true upon success.
@@ -326,8 +327,7 @@ id<MTLFunction> MetalBlitter::compileFragmentFunction(BlitFunctionKey key) const
            utils::slog.e << description << utils::io::endl;
        }
    }
-    FILAMENT_CHECK_POSTCONDITION(library && function)
-            << "Unable to compile fragment shader for MetalBlitter.";
+    ASSERT_POSTCONDITION(library && function, "Unable to compile fragment shader for MetalBlitter.");

    return function;
 }
@@ -352,8 +352,7 @@ id<MTLFunction> MetalBlitter::getBlitVertexFunction() {
            utils::slog.e << description << utils::io::endl;
        }
    }
-    FILAMENT_CHECK_POSTCONDITION(library && function)
-            << "Unable to compile vertex shader for MetalBlitter.";
+    ASSERT_POSTCONDITION(library && function, "Unable to compile vertex shader for MetalBlitter.");

    mVertexFunction = function;

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

 #include "MetalContext.h"
-#include "MetalPlatform.h"

 #include <backend/DriverEnums.h>

@@ -29,88 +28,20 @@
 #include <utility>
 #include <memory>
 #include <atomic>
-#include <chrono>

 namespace filament::backend {

-class ScopedAllocationTimer {
-public:
-    ScopedAllocationTimer(const char* name) : mBeginning(clock_t::now()), mName(name) {}
-    ~ScopedAllocationTimer() {
-        using namespace std::literals::chrono_literals;
-        static constexpr std::chrono::seconds LONG_TIME_THRESHOLD = 10s;
-
-        auto end = clock_t::now();
-        std::chrono::duration<double, std::micro> allocationTimeMicroseconds = end - mBeginning;
-
-        if (UTILS_UNLIKELY(allocationTimeMicroseconds > LONG_TIME_THRESHOLD)) {
-            if (platform && platform->hasDebugUpdateStatFunc()) {
-                char buffer[64];
-                snprintf(buffer, sizeof(buffer), "filament.metal.long_buffer_allocation_time.%s",
-                        mName);
-                platform->debugUpdateStat(
-                        buffer, static_cast<uint64_t>(allocationTimeMicroseconds.count()));
-            }
-        }
-    }
-
-    static void setPlatform(MetalPlatform* p) { platform = p; }
-
-private:
-    typedef std::chrono::steady_clock clock_t;
-
-    static MetalPlatform* platform;
-
-    std::chrono::time_point<clock_t> mBeginning;
-    const char* mName;
-};
-
 class TrackedMetalBuffer {
 public:
-
-    static constexpr size_t EXCESS_BUFFER_COUNT = 30000;
-
-    enum class Type {
-        NONE = 0,
-        GENERIC = 1,
-        RING = 2,
-        STAGING = 3,
-    };
-    static constexpr size_t TypeCount = 3;
-
-    static constexpr auto toIndex(Type t) {
-        assert_invariant(t != Type::NONE);
-        switch (t) {
-            case Type::NONE:
-            case Type::GENERIC:
-                return 0;
-            case Type::RING:
-                return 1;
-            case Type::STAGING:
-                return 2;
-        }
-    }
-
    TrackedMetalBuffer() noexcept : mBuffer(nil) {}
-    TrackedMetalBuffer(nullptr_t) noexcept : mBuffer(nil) {}
-    TrackedMetalBuffer(id<MTLBuffer> buffer, Type type) : mBuffer(buffer), mType(type) {
-        assert_invariant(type != Type::NONE);
+    TrackedMetalBuffer(id<MTLBuffer> buffer) noexcept : mBuffer(buffer) {
        if (buffer) {
-            aliveBuffers[toIndex(type)]++;
-            mType = type;
-            if (getAliveBuffers() >= EXCESS_BUFFER_COUNT) {
-                if (platform && platform->hasDebugUpdateStatFunc()) {
-                    platform->debugUpdateStat("filament.metal.excess_buffers_allocated",
-                            TrackedMetalBuffer::getAliveBuffers());
-                }
-            }
+            aliveBuffers++;
        }
    }
-
    ~TrackedMetalBuffer() {
        if (mBuffer) {
-            assert_invariant(mType != Type::NONE);
-            aliveBuffers[toIndex(mType)]--;
+            aliveBuffers--;
        }
    }

@@ -126,31 +57,18 @@ public:
    id<MTLBuffer> get() const noexcept { return mBuffer; }
    operator bool() const noexcept { return bool(mBuffer); }

-    static uint64_t getAliveBuffers() {
-        uint64_t sum = 0;
-        for (const auto& v : aliveBuffers) {
-            sum += v;
-        }
-        return sum;
-    }
-
-    static uint64_t getAliveBuffers(Type type) {
-        assert_invariant(type != Type::NONE);
-        return aliveBuffers[toIndex(type)];
-    }
-    static void setPlatform(MetalPlatform* p) { platform = p; }
+    static uint64_t getAliveBuffers() { return aliveBuffers; }

 private:
    void swap(TrackedMetalBuffer& other) noexcept {
-        std::swap(mBuffer, other.mBuffer);
-        std::swap(mType, other.mType);
+        id<MTLBuffer> temp = mBuffer;
+        mBuffer = other.mBuffer;
+        other.mBuffer = temp;
    }

    id<MTLBuffer> mBuffer;
-    Type mType = Type::NONE;

-    static MetalPlatform* platform;
-    static std::array<uint64_t, TypeCount> aliveBuffers;
+    static std::atomic<uint64_t> aliveBuffers;
 };

 class MetalBuffer {
@@ -160,8 +78,6 @@ public:
         size_t size, bool forceGpuBuffer = false);
    ~MetalBuffer();

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

@@ -182,7 +98,7 @@ public:
     * is no device allocation.
     *
     */
-    id<MTLBuffer> getGpuBufferForDraw() noexcept;
+    id<MTLBuffer> getGpuBufferForDraw(id<MTLCommandBuffer> cmdBuffer) noexcept;

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

@@ -206,15 +122,6 @@ public:

 private:

-    enum class UploadStrategy {
-        POOL,
-        BUMP_ALLOCATOR,
-    };
-
-    void uploadWithPoolBuffer(void* src, size_t size, size_t byteOffset) const;
-    void uploadWithBumpAllocator(void* src, size_t size, size_t byteOffset) const;
-
-    UploadStrategy mUploadStrategy;
    TrackedMetalBuffer mBuffer;
    size_t mBufferSize = 0;
    void* mCpuBuffer = nullptr;
@@ -264,9 +171,7 @@ public:
          mBufferOptions(options),
          mSlotSizeBytes(computeSlotSize(layout)),
          mSlotCount(slotCount) {
-        ScopedAllocationTimer timer("ring");
-        mBuffer = { [device newBufferWithLength:mSlotSizeBytes * mSlotCount options:mBufferOptions],
-            TrackedMetalBuffer::Type::RING };
+        mBuffer = [device newBufferWithLength:mSlotSizeBytes * mSlotCount options:mBufferOptions];
        assert_invariant(mBuffer);
    }

@@ -284,13 +189,9 @@ public:
            // If we already have an aux buffer, it will get freed here, unless it has been retained
            // by a MTLCommandBuffer. In that case, it will be freed when the command buffer
            // finishes executing.
-            {
-                ScopedAllocationTimer timer("ring");
-                mAuxBuffer = { [mDevice newBufferWithLength:mSlotSizeBytes options:mBufferOptions],
-                    TrackedMetalBuffer::Type::RING };
-            }
+            mAuxBuffer = [mDevice newBufferWithLength:mSlotSizeBytes options:mBufferOptions];
            assert_invariant(mAuxBuffer);
-            return { mAuxBuffer.get(), 0 };
+            return {mAuxBuffer.get(), 0};
        }
        mCurrentSlot = (mCurrentSlot + 1) % mSlotCount;
        mOccupiedSlots->fetch_add(1, std::memory_order_relaxed);
@@ -22,42 +22,23 @@
 namespace filament {
 namespace backend {

-std::array<uint64_t, TrackedMetalBuffer::TypeCount> TrackedMetalBuffer::aliveBuffers = { 0 };
-MetalPlatform* TrackedMetalBuffer::platform = nullptr;
-MetalPlatform* ScopedAllocationTimer::platform = nullptr;
+std::atomic<uint64_t> TrackedMetalBuffer::aliveBuffers = 0;

 MetalBuffer::MetalBuffer(MetalContext& context, BufferObjectBinding bindingType, BufferUsage usage,
-        size_t size, bool forceGpuBuffer)
-    : mBufferSize(size), mContext(context) {
-    const MetalBumpAllocator& allocator = *mContext.bumpAllocator;
-    // VERTEX is also used for index buffers
-    if (allocator.getCapacity() > 0 && bindingType == BufferObjectBinding::VERTEX) {
-        mUploadStrategy = UploadStrategy::BUMP_ALLOCATOR;
-    } else {
-        mUploadStrategy = UploadStrategy::POOL;
-    }
-
+        size_t size, bool forceGpuBuffer) : mBufferSize(size), mContext(context) {
    // 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.
-    {
-        ScopedAllocationTimer timer("generic");
-        mBuffer = { [context.device newBufferWithLength:size options:MTLResourceStorageModePrivate],
-            TrackedMetalBuffer::Type::GENERIC };
-    }
-    // mBuffer might fail to be allocated. Clients can check for this by calling
-    // wasAllocationSuccessful().
+    mBuffer = [context.device newBufferWithLength:size options:MTLResourceStorageModePrivate];
+    ASSERT_POSTCONDITION(mBuffer, "Could not allocate Metal buffer of size %zu.", size);
 }

 MetalBuffer::~MetalBuffer() {
@@ -70,26 +51,37 @@ void MetalBuffer::copyIntoBuffer(void* src, size_t size, size_t byteOffset) {
    if (size <= 0) {
        return;
    }
-    FILAMENT_CHECK_PRECONDITION(size + byteOffset <= mBufferSize)
-            << "Attempting to copy " << size << " bytes into a buffer of size " << mBufferSize
-            << " at offset " << byteOffset;
-    // The copy blit requires that byteOffset be a multiple of 4.
-    FILAMENT_CHECK_PRECONDITION(!(byteOffset & 0x3)) << "byteOffset must be a multiple of 4";
+    ASSERT_PRECONDITION(size + byteOffset <= mBufferSize,
+            "Attempting to copy %zu bytes into a buffer of size %zu at offset %zu",
+            size, mBufferSize, byteOffset);

-    // If we have a cpu buffer, we can directly copy into it.
+    // Either copy into the Metal buffer or into our cpu buffer.
    if (mCpuBuffer) {
        memcpy(static_cast<uint8_t*>(mCpuBuffer) + byteOffset, src, size);
        return;
    }

-    switch (mUploadStrategy) {
-        case UploadStrategy::BUMP_ALLOCATOR:
-            uploadWithBumpAllocator(src, size, byteOffset);
-            break;
-        case UploadStrategy::POOL:
-            uploadWithPoolBuffer(src, size, byteOffset);
-            break;
-    }
+    // Acquire a staging buffer to hold the contents of this update.
+    MetalBufferPool* bufferPool = mContext.bufferPool;
+    const MetalBufferPoolEntry* const staging = bufferPool->acquireBuffer(size);
+    memcpy(staging->buffer.get().contents, src, size);
+
+    // The blit below requires that byteOffset be a multiple of 4.
+    ASSERT_PRECONDITION(!(byteOffset & 0x3u), "byteOffset must be a multiple of 4");
+
+    // Encode a blit from the staging buffer into the private GPU buffer.
+    id<MTLCommandBuffer> cmdBuffer = getPendingCommandBuffer(&mContext);
+    id<MTLBlitCommandEncoder> blitEncoder = [cmdBuffer blitCommandEncoder];
+    blitEncoder.label = @"Buffer upload blit";
+    [blitEncoder copyFromBuffer:staging->buffer.get()
+                   sourceOffset:0
+                       toBuffer:mBuffer.get()
+              destinationOffset:byteOffset
+                           size:size];
+    [blitEncoder endEncoding];
+    [cmdBuffer addCompletedHandler:^(id<MTLCommandBuffer> cb) {
+        bufferPool->releaseBuffer(staging);
+    }];
 }

 void MetalBuffer::copyIntoBufferUnsynchronized(void* src, size_t size, size_t byteOffset) {
@@ -97,7 +89,7 @@ void MetalBuffer::copyIntoBufferUnsynchronized(void* src, size_t size, size_t by
    copyIntoBuffer(src, size, byteOffset);
 }

-id<MTLBuffer> MetalBuffer::getGpuBufferForDraw() noexcept {
+id<MTLBuffer> MetalBuffer::getGpuBufferForDraw(id<MTLCommandBuffer> cmdBuffer) noexcept {
    // If there's a CPU buffer, then we return nil here, as the CPU-side buffer will be bound
    // separately.
    if (mCpuBuffer) {
@@ -140,7 +132,7 @@ void MetalBuffer::bindBuffers(id<MTLCommandBuffer> cmdBuffer, id<MTLCommandEncod
        }
        // getGpuBufferForDraw() might return nil, which means there isn't a device allocation for
        // this buffer. In this case, we'll bind the buffer below with the CPU-side memory.
-        id<MTLBuffer> gpuBuffer = buffer->getGpuBufferForDraw();
+        id<MTLBuffer> gpuBuffer = buffer->getGpuBufferForDraw(cmdBuffer);
        if (!gpuBuffer) {
            continue;
        }
@@ -200,42 +192,5 @@ void MetalBuffer::bindBuffers(id<MTLCommandBuffer> cmdBuffer, id<MTLCommandEncod
    }
 }

-void MetalBuffer::uploadWithPoolBuffer(void* src, size_t size, size_t byteOffset) const {
-    MetalBufferPool* bufferPool = mContext.bufferPool;
-    const MetalBufferPoolEntry* const staging = bufferPool->acquireBuffer(size);
-    memcpy(staging->buffer.get().contents, src, size);
-
-    // Encode a blit from the staging buffer into the private GPU buffer.
-    id<MTLCommandBuffer> cmdBuffer = getPendingCommandBuffer(&mContext);
-    id<MTLBlitCommandEncoder> blitEncoder = [cmdBuffer blitCommandEncoder];
-    blitEncoder.label = @"Buffer upload blit - pool buffer";
-    [blitEncoder copyFromBuffer:staging->buffer.get()
-                   sourceOffset:0
-                       toBuffer:mBuffer.get()
-              destinationOffset:byteOffset
-                           size:size];
-    [blitEncoder endEncoding];
-    [cmdBuffer addCompletedHandler:^(id<MTLCommandBuffer> cb) {
-        bufferPool->releaseBuffer(staging);
-    }];
-}
-
-void MetalBuffer::uploadWithBumpAllocator(void* src, size_t size, size_t byteOffset) const {
-    MetalBumpAllocator& allocator = *mContext.bumpAllocator;
-    auto [buffer, offset] = allocator.allocateStagingArea(size);
-    memcpy(static_cast<char*>(buffer.contents) + offset, src, size);
-
-    // Encode a blit from the staging buffer into the private GPU buffer.
-    id<MTLCommandBuffer> cmdBuffer = getPendingCommandBuffer(&mContext);
-    id<MTLBlitCommandEncoder> blitEncoder = [cmdBuffer blitCommandEncoder];
-    blitEncoder.label = @"Buffer upload blit - bump allocator";
-    [blitEncoder copyFromBuffer:buffer
-                   sourceOffset:offset
-                       toBuffer:mBuffer.get()
-              destinationOffset:byteOffset
-                           size:size];
-    [blitEncoder endEncoding];
-}
-
 } // namespace backend
 } // namespace filament
@@ -38,28 +38,6 @@ struct MetalBufferPoolEntry {
    mutable uint32_t referenceCount;
 };

-class MetalBumpAllocator {
-public:
-    MetalBumpAllocator(id<MTLDevice> device, size_t capacity);
-
-    /**
-     * Allocates a staging area of the given size. Returns a pair of the buffer and the offset
-     * within the buffer. The buffer is guaranteed to be at least the given size, but may be larger.
-     * Clients must not write to the buffer beyond the returned offset + size.
-     * Clients are responsible for holding a reference to the returned buffer.
-     * Allocations are guaranteed to be aligned to 4 bytes.
-     */
-    std::pair<id<MTLBuffer>, size_t> allocateStagingArea(size_t size);
-
-    size_t getCapacity() const noexcept { return mCapacity; }
-
-private:
-    id<MTLDevice> mDevice;
-    TrackedMetalBuffer mCurrentUploadBuffer = nil;
-    size_t mHead = 0;
-    size_t mCapacity;
-};
-
 // Manages a pool of Metal buffers, periodically releasing ones that have been unused for awhile.
 class MetalBufferPool {
 public:
@@ -42,16 +42,11 @@ MetalBufferPoolEntry const* MetalBufferPool::acquireBuffer(size_t numBytes) {
    }

    // We were not able to find a sufficiently large stage, so create a new one.
-    id<MTLBuffer> buffer = nil;
-    {
-        ScopedAllocationTimer timer("staging");
-        buffer = [mContext.device newBufferWithLength:numBytes
-                                              options:MTLResourceStorageModeShared];
-    }
-    FILAMENT_CHECK_POSTCONDITION(buffer)
-            << "Could not allocate Metal staging buffer of size " << numBytes << ".";
+    id<MTLBuffer> buffer = [mContext.device newBufferWithLength:numBytes
+                                                        options:MTLResourceStorageModeShared];
+    ASSERT_POSTCONDITION(buffer, "Could not allocate Metal staging buffer of size %zu.", numBytes);
    MetalBufferPoolEntry* stage = new MetalBufferPoolEntry {
-        .buffer = { buffer, TrackedMetalBuffer::Type::STAGING },
+        .buffer = buffer,
        .capacity = numBytes,
        .lastAccessed = mCurrentFrame,
        .referenceCount = 1
@@ -116,39 +111,5 @@ void MetalBufferPool::reset() noexcept {
    mFreeStages.clear();
 }

-MetalBumpAllocator::MetalBumpAllocator(id<MTLDevice> device, size_t capacity)
-    : mDevice(device), mCapacity(capacity) {
-    if (mCapacity > 0) {
-        mCurrentUploadBuffer = { [device newBufferWithLength:capacity options:MTLStorageModeShared],
-            TrackedMetalBuffer::Type::STAGING };
-    }
-}
-
-std::pair<id<MTLBuffer>, size_t> MetalBumpAllocator::allocateStagingArea(size_t size) {
-    if (size == 0) {
-        return { nil, 0 };
-    }
-    if (size > mCapacity) {
-        return { [mDevice newBufferWithLength:size options:MTLStorageModeShared], 0 };
-    }
-    assert_invariant(mCurrentUploadBuffer);
-
-    // Align the head to a 4-byte boundary.
-    mHead = (mHead + 3) & ~3;
-
-    if (UTILS_LIKELY(mHead + size <= mCapacity)) {
-        const size_t oldHead = mHead;
-        mHead += size;
-        return { mCurrentUploadBuffer.get(), oldHead };
-    }
-
-    // We're finished with the current allocation.
-    mCurrentUploadBuffer = { [mDevice newBufferWithLength:mCapacity options:MTLStorageModeShared],
-        TrackedMetalBuffer::Type::STAGING };
-    mHead = size;
-
-    return { mCurrentUploadBuffer.get(), 0 };
-}
-
 } // namespace backend
 } // namespace filament
@@ -21,8 +21,6 @@
 #include "MetalShaderCompiler.h"
 #include "MetalState.h"

-#include <backend/DriverEnums.h>
-
 #include <CoreVideo/CVMetalTextureCache.h>
 #include <Metal/Metal.h>
 #include <QuartzCore/QuartzCore.h>
@@ -46,77 +44,17 @@ namespace backend {
 class MetalDriver;
 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

-class MetalPushConstantBuffer {
-public:
-    void setPushConstant(PushConstantVariant value, uint8_t index);
-    bool isDirty() const { return mDirty; }
-    void setBytes(id<MTLCommandEncoder> encoder, ShaderStage stage);
-    void clear();
-
-private:
-    std::vector<PushConstantVariant> mPushConstants;
-    bool mDirty = false;
-};
-
-class MetalDynamicOffsets {
-public:
-    void setOffsets(uint32_t set, const uint32_t* offsets, uint32_t count) {
-        assert(set < MAX_DESCRIPTOR_SET_COUNT);
-
-        auto getStartIndexForSet = [&](uint32_t s) {
-            uint32_t startIndex = 0;
-            for (uint32_t i = 0; i < s; i++) {
-                startIndex += mCounts[i];
-            }
-            return startIndex;
-        };
-
-        const bool resizeNecessary = mCounts[set] != count;
-        if (UTILS_UNLIKELY(resizeNecessary)) {
-            int delta = count - mCounts[set];
-
-            auto thisSetStart = mOffsets.begin() + getStartIndexForSet(set);
-            if (delta > 0) {
-                mOffsets.insert(thisSetStart, delta, 0);
-            } else {
-                mOffsets.erase(thisSetStart, thisSetStart - delta);
-            }
-
-            mCounts[set] = count;
-        }
-
-        if (resizeNecessary ||
-                !std::equal(
-                        offsets, offsets + count, mOffsets.begin() + getStartIndexForSet(set))) {
-            std::copy(offsets, offsets + count, mOffsets.begin() + getStartIndexForSet(set));
-            mDirty = true;
-        }
-    }
-    bool isDirty() const { return mDirty; }
-    void setDirty(bool dirty) { mDirty = dirty; }
-
-    std::pair<uint32_t, const uint32_t*> getOffsets() const {
-        return { mOffsets.size(), mOffsets.data() };
-    }
-
-private:
-    std::array<uint32_t, MAX_DESCRIPTOR_SET_COUNT> mCounts = { 0 };
-    std::vector<uint32_t> mOffsets;
-    bool mDirty = false;
-};
-
 struct MetalContext {
    explicit MetalContext(size_t metalFreedTextureListSize)
        : texturesToDestroy(metalFreedTextureListSize) {}
@@ -125,12 +63,8 @@ struct MetalContext {
    id<MTLDevice> device = nullptr;
    id<MTLCommandQueue> commandQueue = nullptr;

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

    std::atomic<bool> memorylessLimitsReached = false;

@@ -146,7 +80,7 @@ struct MetalContext {
    } highestSupportedGpuFamily;

    struct {
-        bool staticTextureTargetError;
+        bool a8xStaticTextureTargetError;
    } bugs;

    // sampleCountLookup[requestedSamples] gives a <= sample count supported by the device.
@@ -161,9 +95,10 @@ 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;
    Handle<HwRenderPrimitive> currentRenderPrimitive;

    // State caches.
@@ -174,17 +109,13 @@ struct MetalContext {

    PolygonOffset currentPolygonOffset = {0.0f, 0.0f};

-    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 textures.
+    // Keeps track of all alive sampler groups, textures.
+    tsl::robin_set<MetalSamplerGroup*> samplerGroups;
    tsl::robin_set<MetalTexture*> textures;

    // This circular buffer implements delayed destruction for Metal texture handles. It keeps a
@@ -196,7 +127,6 @@ struct MetalContext {
    utils::FixedCircularBuffer<Handle<HwTexture>> texturesToDestroy;

    MetalBufferPool* bufferPool;
-    MetalBumpAllocator* bumpAllocator;

    MetalSwapChain* currentDrawSwapChain = nil;
    MetalSwapChain* currentReadSwapChain = nil;
@@ -207,7 +137,6 @@ struct MetalContext {

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

    MetalBlitter* blitter = nullptr;

@@ -101,14 +101,9 @@ id<MTLCommandBuffer> getPendingCommandBuffer(MetalContext* context) {
    context->pendingCommandBuffer = [context->commandQueue commandBuffer];
    // It's safe for this block to capture the context variable. MetalDriver::terminate will ensure
    // all frames and their completion handlers finish before context is deallocated.
-    uint64_t thisCommandBufferId = context->pendingCommandBufferId;
    [context->pendingCommandBuffer addCompletedHandler:^(id <MTLCommandBuffer> buffer) {
        context->resourceTracker.clearResources((__bridge void*) buffer);
-
-        // Command buffers should complete in order, so latestCompletedCommandBufferId will only
-        // ever increase.
-        context->latestCompletedCommandBufferId = thisCommandBufferId;
-
+        
        auto errorCode = (MTLCommandBufferError)buffer.error.code;
        if (@available(macOS 11.0, *)) {
            if (errorCode == MTLCommandBufferErrorMemoryless) {
@@ -118,8 +113,7 @@ id<MTLCommandBuffer> getPendingCommandBuffer(MetalContext* context) {
            }
        }
    }];
-    FILAMENT_CHECK_POSTCONDITION(context->pendingCommandBuffer)
-            << "Could not obtain command buffer.";
+    ASSERT_POSTCONDITION(context->pendingCommandBuffer, "Could not obtain command buffer.");
    return context->pendingCommandBuffer;
 }

@@ -130,7 +124,6 @@ void submitPendingCommands(MetalContext* context) {
    assert_invariant(context->pendingCommandBuffer.status != MTLCommandBufferStatusCommitted);
    [context->pendingCommandBuffer commit];
    context->pendingCommandBuffer = nil;
-    context->pendingCommandBufferId++;
 }

 id<MTLTexture> getOrCreateEmptyTexture(MetalContext* context) {
@@ -160,67 +153,5 @@ bool isInRenderPass(MetalContext* context) {
    return context->currentRenderPassEncoder != nil;
 }

-void MetalPushConstantBuffer::setPushConstant(PushConstantVariant value, uint8_t index) {
-    if (mPushConstants.size() <= index) {
-        mPushConstants.resize(index + 1);
-        mDirty = true;
-    }
-    if (UTILS_LIKELY(mPushConstants[index] != value)) {
-        mDirty = true;
-        mPushConstants[index] = value;
-    }
-}
-
-void MetalPushConstantBuffer::setBytes(id<MTLCommandEncoder> encoder, ShaderStage stage) {
-    constexpr size_t PUSH_CONSTANT_SIZE_BYTES = 4;
-
-    static char buffer[MAX_PUSH_CONSTANT_COUNT * PUSH_CONSTANT_SIZE_BYTES];
-    assert_invariant(mPushConstants.size() <= MAX_PUSH_CONSTANT_COUNT);
-
-    size_t bufferSize = PUSH_CONSTANT_SIZE_BYTES * mPushConstants.size();
-    for (size_t i = 0; i < mPushConstants.size(); i++) {
-        const auto& constant = mPushConstants[i];
-        std::visit(
-                [i](auto arg) {
-                    if constexpr (std::is_same_v<decltype(arg), bool>) {
-                        // bool push constants are converted to uints in MSL.
-                        // We must ensure we write all the bytes for boolean values to work
-                        // correctly.
-                        uint32_t boolAsUint = arg ? 0x00000001 : 0x00000000;
-                        *(reinterpret_cast<uint32_t*>(buffer + PUSH_CONSTANT_SIZE_BYTES * i)) =
-                                boolAsUint;
-                    } else {
-                        *(decltype(arg)*)(buffer + PUSH_CONSTANT_SIZE_BYTES * i) = arg;
-                    }
-                },
-                constant);
-    }
-
-    switch (stage) {
-        case ShaderStage::VERTEX:
-            [(id<MTLRenderCommandEncoder>)encoder setVertexBytes:buffer
-                                                          length:bufferSize
-                                                         atIndex:PUSH_CONSTANT_BUFFER_INDEX];
-            break;
-        case ShaderStage::FRAGMENT:
-            [(id<MTLRenderCommandEncoder>)encoder setFragmentBytes:buffer
-                                                            length:bufferSize
-                                                           atIndex:PUSH_CONSTANT_BUFFER_INDEX];
-            break;
-        case ShaderStage::COMPUTE:
-            [(id<MTLComputeCommandEncoder>)encoder setBytes:buffer
-                                                     length:bufferSize
-                                                    atIndex:PUSH_CONSTANT_BUFFER_INDEX];
-            break;
-    }
-
-    mDirty = false;
-}
-
-void MetalPushConstantBuffer::clear() {
-    mPushConstants.clear();
-    mDirty = false;
-}
-
 } // namespace backend
 } // namespace filament
@@ -17,7 +17,6 @@
 #ifndef TNT_FILAMENT_DRIVER_METALDRIVER_H
 #define TNT_FILAMENT_DRIVER_METALDRIVER_H

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

@@ -32,7 +31,6 @@
 #include <functional>
 #include <mutex>
 #include <vector>
-#include <deque>

 namespace filament {
 namespace backend {
@@ -58,11 +56,11 @@ class MetalDriver final : public DriverBase {

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

 private:

    friend class MetalSwapChain;
-    friend struct MetalDescriptorSet;

    MetalPlatform& mPlatform;
    MetalContext* mContext;
@@ -74,23 +72,10 @@ private:

    /*
     * Tasks run regularly on the driver thread.
-     * Not thread-safe; tasks are run from the driver thead and must be enqueued from the driver
-     * thread.
     */
-    void runAtNextTick(const std::function<void()>& fn) noexcept;
    void executeTickOps() noexcept;
    std::vector<std::function<void()>> mTickOps;
-
-    // Tasks regularly executed on the driver thread after a command buffer has completed
-    struct DeferredTask {
-        DeferredTask(uint64_t commandBufferId, utils::Invocable<void()>&& fn) noexcept
-            : commandBufferId(commandBufferId), fn(std::move(fn)) {}
-        uint64_t commandBufferId;     // after this command buffer completes
-        utils::Invocable<void()> fn;  // execute this task
-    };
-    void executeAfterCurrentCommandBufferCompletes(utils::Invocable<void()>&& fn) noexcept;
-    void executeDeferredOps() noexcept;
-    std::deque<DeferredTask> mDeferredTasks;
+    std::mutex mTickOpsLock;

    /*
     * Driver interface
@@ -151,10 +136,10 @@ 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);

-    backend::StereoscopicType const mStereoscopicType;
 };

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

 constexpr inline MTLVertexFormat getMetalFormat(ElementType type, bool normalized) noexcept {
@@ -100,7 +100,7 @@ constexpr inline MTLVertexFormat getMetalFormat(ElementType type, bool normalize
            case ElementType::SHORT4: return MTLVertexFormatShort4Normalized;
            case ElementType::USHORT4: return MTLVertexFormatUShort4Normalized;
            default:
-                FILAMENT_CHECK_POSTCONDITION(false) << "Normalized format does not exist.";
+                ASSERT_POSTCONDITION(false, "Normalized format does not exist.");
                return MTLVertexFormatInvalid;
        }
    }
@@ -326,8 +326,7 @@ constexpr inline MTLCullMode getMetalCullMode(CullingMode cullMode) noexcept {
        case CullingMode::FRONT: return MTLCullModeFront;
        case CullingMode::BACK: return MTLCullModeBack;
        case CullingMode::FRONT_AND_BACK:
-            FILAMENT_CHECK_POSTCONDITION(false)
-                    << "FRONT_AND_BACK culling is not supported in Metal.";
+            ASSERT_POSTCONDITION(false, "FRONT_AND_BACK culling is not supported in Metal.");
    }
 }

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

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

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

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

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

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

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

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

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

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

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

 } // namespace backend
@@ -29,11 +29,15 @@
        auto description = [error.localizedDescription cStringUsingEncoding:NSUTF8StringEncoding]; \
        utils::slog.e << description << utils::io::endl;                                           \
    }                                                                                              \
-    FILAMENT_CHECK_POSTCONDITION(error == nil) << message;
+    ASSERT_POSTCONDITION(error == nil, message);

 namespace filament {
 namespace backend {

+static const auto cvBufferDeleter = [](const void* buffer) {
+    CVBufferRelease((CVMetalTextureRef) buffer);
+};
+
 static const char* kernel = R"(
 #include <metal_stdlib>
 #include <simd/simd.h>
@@ -67,66 +71,55 @@ ycbcrToRgb(texture2d<half, access::read>  inYTexture    [[texture(0)]],
 }
 )";

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

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

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

    OSType formatType = CVPixelBufferGetPixelFormatType(image);
-    FILAMENT_CHECK_POSTCONDITION(formatType == kCVPixelFormatType_32BGRA ||
-            formatType == kCVPixelFormatType_420YpCbCr8BiPlanarFullRange)
-            << "Metal external images must be in either 32BGRA or 420f format.";
+    ASSERT_POSTCONDITION(formatType == kCVPixelFormatType_32BGRA ||
+                         formatType == kCVPixelFormatType_420YpCbCr8BiPlanarFullRange,
+            "Metal external images must be in either 32BGRA or 420f format.");

    size_t planeCount = CVPixelBufferGetPlaneCount(image);
-    FILAMENT_CHECK_POSTCONDITION(planeCount == 0 || planeCount == 2)
-            << "The Metal backend does not support images with plane counts of " << planeCount
-            << ".";
+    ASSERT_POSTCONDITION(planeCount == 0 || planeCount == 2,
+            "The Metal backend does not support images with plane counts of %d.", planeCount);
+

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

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

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

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

+        mRgbTexture = createSwizzledTextureView(rgbTexture);
+
        [commandBuffer addCompletedHandler:^(id <MTLCommandBuffer> o) {
            CVBufferRelease(yPlane);
            CVBufferRelease(cbcrPlane);
@@ -134,85 +127,72 @@ MetalExternalImage MetalExternalImage::createFromImage(
        }];

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    id<MTLComputeCommandEncoder> computeEncoder = [commandBuffer computeCommandEncoder];

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

-void MetalExternalImage::assertWritableImage(CVPixelBufferRef image) {
-    OSType formatType = CVPixelBufferGetPixelFormatType(image);
-    FILAMENT_CHECK_PRECONDITION(formatType == kCVPixelFormatType_32BGRA)
-            << "Metal SwapChain images must be in the 32BGRA format.";
-}
-
 } // namespace backend
 } // namespace filament
@@ -31,8 +31,6 @@

 #include "private/backend/SamplerGroup.h"

-#include <backend/DriverEnums.h>
-
 #include <utils/bitset.h>
 #include <utils/CString.h>
 #include <utils/FixedCapacityVector.h>
@@ -44,7 +42,6 @@
 #include <condition_variable>
 #include <memory>
 #include <type_traits>
-#include <vector>

 namespace filament {
 namespace backend {
@@ -74,9 +71,9 @@ public:

    void releaseDrawable();

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

    // For CAMetalLayer-backed SwapChains, presents the drawable or schedules a
    // FrameScheduledCallback.
@@ -85,8 +82,6 @@ public:
    NSUInteger getSurfaceWidth() const;
    NSUInteger getSurfaceHeight() const;

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

    enum class SwapChainType {
@@ -96,6 +91,7 @@ private:
    };
    bool isCaMetalLayer() const { return type == SwapChainType::CAMETALLAYER; }
    bool isHeadless() const { return type == SwapChainType::HEADLESS; }
+    bool isPixelBuffer() const { return type == SwapChainType::CVPIXELBUFFERREF; }

    void scheduleFrameScheduledCallback();
    void scheduleFrameCompletedCallback();
@@ -111,23 +107,22 @@ private:
    NSUInteger headlessWidth = 0;
    NSUInteger headlessHeight = 0;
    CAMetalLayer* layer = nullptr;
-    std::shared_ptr<std::mutex> layerDrawableMutex;
    MetalExternalImage externalImage;
    SwapChainType type;

-    // These fields store a callback to notify the client that a frame is ready for presentation. If
-    // !frameScheduled.callback, then the Metal backend automatically calls presentDrawable when the
-    // frame is committed. Otherwise, the Metal backend will not automatically present the frame.
-    // Instead, clients bear the responsibility of presenting the frame by calling the
-    // PresentCallable object.
-    struct {
-        CallbackHandler* handler = nullptr;
-        std::shared_ptr<FrameScheduledCallback> callback = nullptr;
-    } frameScheduled;
+    // These two fields store a callback and user data to notify the client that a frame is ready
+    // for presentation.
+    // If frameScheduledCallback is nullptr, then the Metal backend automatically calls
+    // presentDrawable when the frame is committed.
+    // Otherwise, the Metal backend will not automatically present the frame. Instead, clients bear
+    // the responsibility of presenting the frame by calling the PresentCallable object.
+    FrameScheduledCallback frameScheduledCallback = nullptr;
+    void* frameScheduledUserData = nullptr;

    struct {
        CallbackHandler* handler = nullptr;
-        std::shared_ptr<utils::Invocable<void(void)>> callback = nullptr;
+        CallbackHandler::Callback callback = {};
+        void* user = nullptr;
    } frameCompleted;
 };

@@ -140,6 +135,12 @@ public:
    void updateBufferUnsynchronized(void* data, size_t size, uint32_t byteOffset);
    MetalBuffer* getBuffer() { return &buffer; }

+    // Tracks which uniform/ssbo buffers this buffer object is bound into.
+    static_assert(Program::UNIFORM_BINDING_COUNT <= 32);
+    static_assert(MAX_SSBO_COUNT <= 32);
+    utils::bitset32 boundUniformBuffers;
+    utils::bitset32 boundSsbos;
+
 private:
    MetalBuffer buffer;
 };
@@ -196,10 +197,12 @@ public:
    MetalProgram(MetalContext& context, Program&& program) noexcept;

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

 private:
    void initialize();

+    Program::SamplerGroupInfo samplerGroupInfo;
    MetalContext& mContext;
    MetalShaderCompiler::MetalFunctionBundle mFunctionBundle;
    MetalShaderCompiler::program_token_t mToken;
@@ -221,42 +224,43 @@ struct PixelBufferShape {
 class MetalTexture : public HwTexture {
 public:
    MetalTexture(MetalContext& context, SamplerType target, uint8_t levels, TextureFormat format,
-            uint8_t samples, uint32_t width, uint32_t height, uint32_t depth,
-            TextureUsage usage) noexcept;
-
-    // constructors for creating texture views
-    MetalTexture(MetalContext& context, MetalTexture const* src, uint8_t baseLevel,
-            uint8_t levelCount) noexcept;
-    MetalTexture(MetalContext& context, MetalTexture const* src, TextureSwizzle r, TextureSwizzle g,
-            TextureSwizzle b, TextureSwizzle a) noexcept;
+            uint8_t samples, uint32_t width, uint32_t height, uint32_t depth, TextureUsage usage,
+            TextureSwizzle r, TextureSwizzle g, TextureSwizzle b, TextureSwizzle a)
+            noexcept;

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

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

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

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

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

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

    MetalContext& context;
+    MetalExternalImage externalImage;

    // A "sidecar" texture used to implement automatic MSAA resolve.
    // This is created by MetalRenderTarget and stored here so it can be used with multiple
@@ -295,16 +299,97 @@ 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 {
 public:

@@ -459,61 +544,6 @@ struct MetalTimerQuery : public HwTimerQuery {
    std::shared_ptr<Status> status;
 };

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

@@ -73,7 +73,7 @@ MetalSwapChain::MetalSwapChain(MetalContext& context, CAMetalLayer* nativeWindow
    : context(context),
      depthStencilFormat(decideDepthStencilFormat(flags)),
      layer(nativeWindow),
-      layerDrawableMutex(std::make_shared<std::mutex>()),
+      externalImage(context),
      type(SwapChainType::CAMETALLAYER) {

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

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

@@ -118,6 +120,7 @@ MTLPixelFormat MetalSwapChain::decideDepthStencilFormat(uint64_t flags) {
 }

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

 NSUInteger MetalSwapChain::getSurfaceWidth() const {
@@ -167,28 +170,18 @@ id<MTLTexture> MetalSwapChain::acquireDrawable() {
    }

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

    assert_invariant(isCaMetalLayer());
+    drawable = [layer nextDrawable];

-    // CAMetalLayer's drawable pool is not thread safe. Use a mutex when
-    // calling -nextDrawable, or when releasing the last known reference
-    // to any CAMetalDrawable returned from a previous -nextDrawable.
-    {
-        std::lock_guard<std::mutex> lock(*layerDrawableMutex);
-        drawable = [layer nextDrawable];
-    }
-
-    FILAMENT_CHECK_POSTCONDITION(drawable != nil) << "Could not obtain drawable.";
+    ASSERT_POSTCONDITION(drawable != nil, "Could not obtain drawable.");
    return drawable.texture;
 }

 void MetalSwapChain::releaseDrawable() {
-    if (drawable) {
-        std::lock_guard<std::mutex> lock(*layerDrawableMutex);
-        drawable = nil;
-    }
+    drawable = nil;
 }

 id<MTLTexture> MetalSwapChain::acquireDepthTexture() {
@@ -228,16 +221,16 @@ void MetalSwapChain::ensureDepthStencilTexture() {
    depthStencilTexture = [context.device newTextureWithDescriptor:descriptor];
 }

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

-void MetalSwapChain::setFrameCompletedCallback(
-        CallbackHandler* handler, utils::Invocable<void(void)>&& callback) {
+void MetalSwapChain::setFrameCompletedCallback(CallbackHandler* handler,
+        CallbackHandler::Callback callback, void* user) {
    frameCompleted.handler = handler;
-    frameCompleted.callback = std::make_shared<utils::Invocable<void(void)>>(std::move(callback));
+    frameCompleted.callback = callback;
+    frameCompleted.user = user;
 }

 void MetalSwapChain::present() {
@@ -245,7 +238,7 @@ void MetalSwapChain::present() {
        scheduleFrameCompletedCallback();
    }
    if (drawable) {
-        if (frameScheduled.callback) {
+        if (frameScheduledCallback) {
            scheduleFrameScheduledCallback();
        } else  {
            [getPendingCommandBuffer(&context) presentDrawable:drawable];
@@ -253,17 +246,19 @@ void MetalSwapChain::present() {
    }
 }

+#ifndef FILAMENT_RELEASE_PRESENT_DRAWABLE_MAIN_THREAD
+#define FILAMENT_RELEASE_PRESENT_DRAWABLE_MAIN_THREAD 1
+#endif
+
 class PresentDrawableData {
 public:
    PresentDrawableData() = delete;
    PresentDrawableData(const PresentDrawableData&) = delete;
    PresentDrawableData& operator=(const PresentDrawableData&) = delete;

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

    static void maybePresentAndDestroyAsync(PresentDrawableData* that, bool shouldPresent) {
@@ -271,29 +266,27 @@ 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
    }

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

    static void cleanupAndDestroy(PresentDrawableData *that) {
-        if (that->mDrawable) {
-            std::lock_guard<std::mutex> lock(*(that->mDrawableMutex));
-            that->mDrawable = nil;
-        }
-        that->mDrawableMutex.reset();
+        that->mDrawable = nil;
        that->mDriver = nullptr;
        delete that;
    }

    id<CAMetalDrawable> mDrawable;
-    std::shared_ptr<std::mutex> mDrawableMutex;
    MetalDriver* mDriver = nullptr;
 };

@@ -303,38 +296,21 @@ void presentDrawable(bool presentFrame, void* user) {
 }

 void MetalSwapChain::scheduleFrameScheduledCallback() {
-    if (!frameScheduled.callback) {
+    if (!frameScheduledCallback) {
        return;
    }

    assert_invariant(drawable);

-    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<FrameScheduledCallback> f;
-        // PresentDrawableData* is destroyed by maybePresentAndDestroyAsync() later.
-        std::unique_ptr<PresentDrawableData> data;
-        static void func(void* user) {
-            auto* const c = reinterpret_cast<Callback*>(user);
-            PresentDrawableData* presentDrawableData = c->data.release();
-            PresentCallable presentCallable(presentDrawable, presentDrawableData);
-            c->f->operator()(presentCallable);
-            delete c;
-        }
-    };
+    // Destroy this by calling maybePresentAndDestroyAsync() later.
+    auto* presentData = PresentDrawableData::create(drawable, context.driver);

-    // 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.
-    __block auto callback = std::make_unique<Callback>(
-        frameScheduled.callback, drawable, layerDrawableMutex, context.driver);
+    FrameScheduledCallback userCallback = frameScheduledCallback;
+    void* userData = frameScheduledUserData;

-    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);
+        PresentCallable callable(presentDrawable, static_cast<void*>(presentData));
+        userCallback(callable, userData);
    }];
 }

@@ -343,25 +319,13 @@ void MetalSwapChain::scheduleFrameCompletedCallback() {
        return;
    }

-    struct Callback {
-        Callback(std::shared_ptr<utils::Invocable<void(void)>> callback) : f(callback) {}
-        std::shared_ptr<utils::Invocable<void(void)>> f;
-        static void func(void* user) {
-            auto* const c = reinterpret_cast<Callback*>(user);
-            c->f->operator()();
-            delete c;
-        }
-    };
-
-    // This callback pointer will be captured by the block. Even if the completed handler is never
-    // called, the unique_ptr will still ensure we don't leak memory.
-    __block auto callback = std::make_unique<Callback>(frameCompleted.callback);
-
    CallbackHandler* handler = frameCompleted.handler;
+    void* user = frameCompleted.user;
+    CallbackHandler::Callback callback = frameCompleted.callback;
+
    MetalDriver* driver = context.driver;
    [getPendingCommandBuffer(&context) addCompletedHandler:^(id<MTLCommandBuffer> cb) {
-        Callback* user = callback.release();
-        driver->scheduleCallback(handler, user, &Callback::func);
+        driver->scheduleCallback(handler, user, callback);
    }];
 }

@@ -470,6 +434,11 @@ void MetalRenderPrimitive::setBuffers(MetalVertexBufferInfo const* const vbi,

 MetalProgram::MetalProgram(MetalContext& context, Program&& program) noexcept
    : HwProgram(program.getName()), mContext(context) {
+
+    // Save this program's SamplerGroupInfo, it's used during draw calls to bind sampler groups to
+    // the appropriate stage(s).
+    samplerGroupInfo = program.getSamplerGroupInfo();
+
    mToken = context.shaderCompiler->createProgram(program.getName(), std::move(program));
    assert_invariant(mToken);
 }
@@ -489,21 +458,21 @@ void MetalProgram::initialize() {

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

    devicePixelFormat = decidePixelFormat(&context, format);
-    FILAMENT_CHECK_POSTCONDITION(devicePixelFormat != MTLPixelFormatInvalid)
-            << "Texture format not supported.";
+    ASSERT_POSTCONDITION(devicePixelFormat != MTLPixelFormatInvalid, "Texture format not supported.");

    const BOOL mipmapped = levels > 1;
    const BOOL multisampled = samples > 1;

 #if defined(IOS)
    const BOOL textureArray = target == SamplerType::SAMPLER_2D_ARRAY;
-    FILAMENT_CHECK_PRECONDITION(!textureArray || !multisampled)
-            << "iOS does not support multisampled texture arrays.";
+    ASSERT_PRECONDITION(!textureArray || !multisampled,
+            "iOS does not support multisampled texture arrays.");
 #endif

    const auto get2DTextureType = [](SamplerType target, bool isMultisampled) {
@@ -538,12 +507,12 @@ MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t le
            descriptor.usage = getMetalTextureUsage(usage);
            descriptor.storageMode = MTLStorageModePrivate;
            texture = [context.device newTextureWithDescriptor:descriptor];
+            ASSERT_POSTCONDITION(texture != nil, "Could not create Metal texture. Out of memory?");
            break;
        case SamplerType::SAMPLER_CUBEMAP:
        case SamplerType::SAMPLER_CUBEMAP_ARRAY:
-            FILAMENT_CHECK_POSTCONDITION(!multisampled)
-                    << "Multisampled cubemap faces not supported.";
-            FILAMENT_CHECK_POSTCONDITION(width == height) << "Cubemap faces must be square.";
+            ASSERT_POSTCONDITION(!multisampled, "Multisampled cubemap faces not supported.");
+            ASSERT_POSTCONDITION(width == height, "Cubemap faces must be square.");
            descriptor = [MTLTextureDescriptor textureCubeDescriptorWithPixelFormat:devicePixelFormat
                                                                               size:width
                                                                          mipmapped:mipmapped];
@@ -552,6 +521,7 @@ MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t le
            descriptor.usage = getMetalTextureUsage(usage);
            descriptor.storageMode = MTLStorageModePrivate;
            texture = [context.device newTextureWithDescriptor:descriptor];
+            ASSERT_POSTCONDITION(texture != nil, "Could not create Metal texture. Out of memory?");
            break;
        case SamplerType::SAMPLER_3D:
            descriptor = [MTLTextureDescriptor new];
@@ -564,6 +534,7 @@ MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t le
            descriptor.usage = getMetalTextureUsage(usage);
            descriptor.storageMode = MTLStorageModePrivate;
            texture = [context.device newTextureWithDescriptor:descriptor];
+            ASSERT_POSTCONDITION(texture != nil, "Could not create Metal texture. Out of memory?");
            break;
        case SamplerType::SAMPLER_EXTERNAL:
            // If we're using external textures (CVPixelBufferRefs), we don't need to make any
@@ -572,33 +543,15 @@ MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t le
            break;
    }

-    FILAMENT_CHECK_POSTCONDITION(target == SamplerType::SAMPLER_EXTERNAL || texture != nil)
-            << "Could not create Metal texture (SamplerType = " << int(target)
-            << ", levels = " << int(levels) << ", MTLPixelFormat = " << int(devicePixelFormat)
-            << ", width = " << width << ", height = " << height << ", depth = " << depth
-            << "). Out of memory?";
-}
-
-MetalTexture::MetalTexture(MetalContext& context, MetalTexture const* src, uint8_t baseLevel,
-        uint8_t levelCount) noexcept
-    : HwTexture(src->target, src->levels, src->samples, src->width, src->height, src->depth,
-              src->format, src->usage),
-      context(context),
-      devicePixelFormat(src->devicePixelFormat),
-      externalImage(src->externalImage) {
-    texture = createTextureViewWithLodRange(
-            src->getMtlTextureForRead(), baseLevel, baseLevel + levelCount - 1);
-}
-
-MetalTexture::MetalTexture(MetalContext& context, MetalTexture const* src, TextureSwizzle r,
-        TextureSwizzle g, TextureSwizzle b, TextureSwizzle a) noexcept
-    : HwTexture(src->target, src->levels, src->samples, src->width, src->height, src->depth,
-              src->format, src->usage),
-      context(context),
-      devicePixelFormat(src->devicePixelFormat),
-      externalImage(src->externalImage) {
-    texture = src->getMtlTextureForRead();
-    if (context.supportsTextureSwizzling) {
+    // If swizzling is set, set up a swizzled texture view that we'll use when sampling this texture.
+    const bool isDefaultSwizzle =
+            r == TextureSwizzle::CHANNEL_0 &&
+            g == TextureSwizzle::CHANNEL_1 &&
+            b == TextureSwizzle::CHANNEL_2 &&
+            a == TextureSwizzle::CHANNEL_3;
+    // If texture is nil, then it must be a SAMPLER_EXTERNAL texture.
+    // Swizzling for external textures is handled inside MetalExternalImage.
+    if (!isDefaultSwizzle && texture && context.supportsTextureSwizzling) {
        // Even though we've already checked context.supportsTextureSwizzling, we still need to
        // guard these calls with @availability, otherwise the API usage will generate compiler
        // warnings.
@@ -612,38 +565,44 @@ MetalTexture::MetalTexture(MetalContext& context, MetalTexture const* src, Textu
 MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t levels, TextureFormat format,
        uint8_t samples, uint32_t width, uint32_t height, uint32_t depth, TextureUsage usage,
        id<MTLTexture> metalTexture) noexcept
-    : HwTexture(target, levels, samples, width, height, depth, format, usage), context(context) {
+    : HwTexture(target, levels, samples, width, height, depth, format, usage), context(context),
+        externalImage(context) {
    texture = metalTexture;
-}
-
-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(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();
+    setLodRange(0, levels - 1);
 }

 void MetalTexture::terminate() noexcept {
    texture = nil;
    swizzledTextureView = nil;
+    lodTextureView = nil;
    msaaSidecar = nil;
-    externalImage = nullptr;
+    externalImage.set(nullptr);
    terminated = true;
 }

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

 MTLPixelFormat MetalTexture::decidePixelFormat(MetalContext* context, TextureFormat format) {
@@ -762,21 +721,24 @@ 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,
        PixelBufferDescriptor const& data) noexcept {
    const PixelBufferShape shape = PixelBufferShape::compute(data, format, region.size, byteOffset);

-    FILAMENT_CHECK_PRECONDITION(data.size >= shape.totalBytes)
-            << "Expected buffer size of at least " << shape.totalBytes
-            << " but received PixelBufferDescriptor with size " << data.size << ".";
+    ASSERT_PRECONDITION(data.size >= shape.totalBytes,
+            "Expected buffer size of at least %d but "
+            "received PixelBufferDescriptor with size %d.", shape.totalBytes, data.size);

    // Earlier versions of iOS don't have the maxBufferLength query, but 256 MB is a safe bet.
    NSUInteger deviceMaxBufferLength = 256 * 1024 * 1024;   // 256 MB
@@ -891,6 +853,98 @@ void MetalTexture::loadWithBlit(uint32_t level, uint32_t slice, MTLRegion region
    context.blitter->blit(getPendingCommandBuffer(&context), args, "Texture upload blit");
 }

+void MetalTexture::extendLodRangeTo(uint16_t level) {
+    assert_invariant(!isInRenderPass(&context));
+    minLod = std::min(minLod, level);
+    maxLod = std::max(maxLod, level);
+    lodTextureView = nil;
+}
+
+void MetalTexture::setLodRange(uint16_t min, uint16_t max) {
+    assert_invariant(!isInRenderPass(&context));
+    assert_invariant(min <= max);
+    minLod = min;
+    maxLod = max;
+    lodTextureView = nil;
+}
+
+void MetalSamplerGroup::finalize() {
+    assert_invariant(encoder);
+    // TODO: we should be able to encode textures and samplers inside setFinalizedTexture and
+    // setFinalizedSampler as they become available, but Metal doesn't seem to like this; the arg
+    // buffer gets encoded incorrectly. This warrants more investigation.
+
+    auto [buffer, offset] = argBuffer->getCurrentAllocation();
+    [encoder setArgumentBuffer:buffer offset:offset];
+
+    // Encode all textures and samplers.
+    for (size_t s = 0; s < size; s++) {
+        [encoder setTexture:textures[s] atIndex:(s * 2 + 0)];
+        [encoder setSamplerState:samplers[s] atIndex:(s * 2 + 1)];
+    }
+
+    finalized = true;
+}
+
+void MetalSamplerGroup::reset(id<MTLCommandBuffer> cmdBuffer, id<MTLArgumentEncoder> e,
+        id<MTLDevice> device) {
+    encoder = e;
+
+    // The number of slots in the ring buffer we use to manage argument buffer allocations.
+    // This number was chosen to avoid running out of slots and having to allocate a "fallback"
+    // buffer when SamplerGroups are updated multiple times a frame. This value can reduced after
+    // auditing Filament's calls to updateSamplerGroup, which should be as few times as possible.
+    // For example, the bloom downsample pass should be refactored to maintain two separate
+    // MaterialInstances instead of "ping ponging" between two texture bindings, which causes a
+    // single SamplerGroup to be updated many times a frame.
+    static constexpr auto METAL_ARGUMENT_BUFFER_SLOTS = 32;
+
+    MTLSizeAndAlign argBufferLayout;
+    argBufferLayout.size = encoder.encodedLength;
+    argBufferLayout.align = encoder.alignment;
+    // Chances are, even though the MTLArgumentEncoder might change, the required size and alignment
+    // probably won't. So we can re-use the previous ring buffer.
+    if (UTILS_UNLIKELY(!argBuffer || !argBuffer->canAccomodateLayout(argBufferLayout))) {
+        argBuffer = std::make_unique<MetalRingBuffer>(device, MTLResourceStorageModeShared,
+                argBufferLayout, METAL_ARGUMENT_BUFFER_SLOTS);
+    } else {
+        argBuffer->createNewAllocation(cmdBuffer);
+    }
+
+    // Clear all textures and samplers.
+    assert_invariant(textureHandles.size() == textures.size());
+    assert_invariant(textures.size() == samplers.size());
+    for (size_t s = 0; s < textureHandles.size(); s++) {
+        textureHandles[s] = {};
+        textures[s] = nil;
+        samplers[s] = nil;
+    }
+
+    finalized = false;
+}
+
+void MetalSamplerGroup::mutate(id<MTLCommandBuffer> cmdBuffer) {
+    assert_invariant(finalized);    // only makes sense to mutate if this sampler group is finalized
+    assert_invariant(argBuffer);
+    argBuffer->createNewAllocation(cmdBuffer);
+    finalized = false;
+}
+
+void MetalSamplerGroup::useResources(id<MTLRenderCommandEncoder> renderPassEncoder) {
+    assert_invariant(finalized);
+    if (@available(iOS 13, *)) {
+        // TODO: pass only the appropriate stages to useResources.
+        [renderPassEncoder useResources:textures.data()
+                                  count:textures.size()
+                                  usage:MTLResourceUsageRead | MTLResourceUsageSample
+                                 stages:MTLRenderStageFragment | MTLRenderStageVertex];
+    } else {
+        [renderPassEncoder useResources:textures.data()
+                                  count:textures.size()
+                                  usage:MTLResourceUsageRead | MTLResourceUsageSample];
+    }
+}
+
 MetalRenderTarget::MetalRenderTarget(MetalContext* context, uint32_t width, uint32_t height,
        uint8_t samples, Attachment colorAttachments[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT],
        Attachment depthAttachment, Attachment stencilAttachment) :
@@ -905,9 +959,9 @@ MetalRenderTarget::MetalRenderTarget(MetalContext* context, uint32_t width, uint
        }
        color[i] = colorAttachments[i];

-        FILAMENT_CHECK_PRECONDITION(color[i].getSampleCount() <= samples)
-                << "MetalRenderTarget was initialized with a MSAA COLOR" << i
-                << " texture, but sample count is " << samples << ".";
+        ASSERT_PRECONDITION(color[i].getSampleCount() <= samples,
+                "MetalRenderTarget was initialized with a MSAA COLOR%d texture, but sample count is %d.",
+                i, samples);

        auto t = color[i].metalTexture;
        const auto twidth = std::max(1u, t->width >> color[i].level);
@@ -930,10 +984,9 @@ MetalRenderTarget::MetalRenderTarget(MetalContext* context, uint32_t width, uint
    if (depthAttachment) {
        depth = depthAttachment;

-        FILAMENT_CHECK_PRECONDITION(depth.getSampleCount() <= samples)
-                << "MetalRenderTarget was initialized with a MSAA DEPTH texture, but sample count "
-                   "is "
-                << samples << ".";
+        ASSERT_PRECONDITION(depth.getSampleCount() <= samples,
+                "MetalRenderTarget was initialized with a MSAA DEPTH texture, but sample count is %d.",
+                samples);

        auto t = depth.metalTexture;
        const auto twidth = std::max(1u, t->width >> depth.level);
@@ -956,10 +1009,9 @@ MetalRenderTarget::MetalRenderTarget(MetalContext* context, uint32_t width, uint
    if (stencilAttachment) {
        stencil = stencilAttachment;

-        FILAMENT_CHECK_PRECONDITION(stencil.getSampleCount() <= samples)
-                << "MetalRenderTarget was initialized with a MSAA STENCIL texture, but sample "
-                   "count is "
-                << samples << ".";
+        ASSERT_PRECONDITION(stencil.getSampleCount() <= samples,
+                "MetalRenderTarget was initialized with a MSAA STENCIL texture, but sample count is %d.",
+                samples);

        auto t = stencil.metalTexture;
        const auto twidth = std::max(1u, t->width >> stencil.level);
@@ -1236,189 +1288,5 @@ FenceStatus MetalFence::wait(uint64_t timeoutNs) {
    return FenceStatus::ERROR;
 }

-MetalDescriptorSetLayout::MetalDescriptorSetLayout(DescriptorSetLayout&& l) noexcept
-    : mLayout(std::move(l)) {
-    size_t dynamicBindings = 0;
-    for (const auto& binding : mLayout.bindings) {
-        if (any(binding.flags & DescriptorFlags::DYNAMIC_OFFSET)) {
-            dynamicBindings++;
-        }
-    }
-    mDynamicOffsetCount = dynamicBindings;
-}
-
-id<MTLArgumentEncoder> MetalDescriptorSetLayout::getArgumentEncoder(id<MTLDevice> device, ShaderStage stage,
-        utils::FixedCapacityVector<MTLTextureType> const& textureTypes) {
-    auto const index = static_cast<size_t>(stage);
-    assert_invariant(index < mCachedArgumentEncoder.size());
-    if (mCachedArgumentEncoder[index] &&
-            std::equal(
-                    textureTypes.begin(), textureTypes.end(), mCachedTextureTypes[index].begin())) {
-        return mCachedArgumentEncoder[index];
-    }
-    mCachedArgumentEncoder[index] = getArgumentEncoderSlow(device, stage, textureTypes);
-    mCachedTextureTypes[index] = textureTypes;
-    return mCachedArgumentEncoder[index];
-}
-
-id<MTLArgumentEncoder> MetalDescriptorSetLayout::getArgumentEncoderSlow(id<MTLDevice> device,
-        ShaderStage stage, utils::FixedCapacityVector<MTLTextureType> const& textureTypes) {
-    auto const& bindings = getBindings();
-    NSMutableArray<MTLArgumentDescriptor*>* arguments = [NSMutableArray new];
-    // Important! The bindings must be sorted by binding number. This has already been done inside
-    // createDescriptorSetLayout.
-    size_t textureIndex = 0;
-    for (auto const& binding : bindings) {
-        if (!hasShaderType(binding.stageFlags, stage)) {
-            continue;
-        }
-        switch (binding.type) {
-            case DescriptorType::UNIFORM_BUFFER:
-            case DescriptorType::SHADER_STORAGE_BUFFER: {
-                MTLArgumentDescriptor* bufferArgument = [MTLArgumentDescriptor argumentDescriptor];
-                bufferArgument.index = binding.binding * 2;
-                bufferArgument.dataType = MTLDataTypePointer;
-                bufferArgument.access = MTLArgumentAccessReadOnly;
-                [arguments addObject:bufferArgument];
-                break;
-            }
-            case DescriptorType::SAMPLER: {
-                MTLArgumentDescriptor* textureArgument = [MTLArgumentDescriptor argumentDescriptor];
-                textureArgument.index = binding.binding * 2;
-                textureArgument.dataType = MTLDataTypeTexture;
-                MTLTextureType textureType = MTLTextureType2D;
-                if (textureIndex < textureTypes.size()) {
-                    textureType = textureTypes[textureIndex++];
-                }
-                textureArgument.textureType = textureType;
-                textureArgument.access = MTLArgumentAccessReadOnly;
-                [arguments addObject:textureArgument];
-
-                MTLArgumentDescriptor* samplerArgument = [MTLArgumentDescriptor argumentDescriptor];
-                samplerArgument.index = binding.binding * 2 + 1;
-                samplerArgument.dataType = MTLDataTypeSampler;
-                textureArgument.access = MTLArgumentAccessReadOnly;
-                [arguments addObject:samplerArgument];
-                break;
-            }
-            case DescriptorType::INPUT_ATTACHMENT:
-                // TODO: support INPUT_ATTACHMENT
-                assert_invariant(false);
-                break;
-        }
-    }
-    return [device newArgumentEncoderWithArguments:arguments];
-}
-
-MetalDescriptorSet::MetalDescriptorSet(MetalDescriptorSetLayout* layout) noexcept
-    : layout(layout) {}
-
-void MetalDescriptorSet::finalize(MetalDriver* driver) {
-    [driver->mContext->currentRenderPassEncoder useResource:driver->mContext->emptyBuffer
-                                                      usage:MTLResourceUsageRead];
-    [driver->mContext->currentRenderPassEncoder
-            useResource:getOrCreateEmptyTexture(driver->mContext)
-                  usage:MTLResourceUsageRead];
-
-    if (@available(iOS 13.0, *)) {
-        [driver->mContext->currentRenderPassEncoder useResources:vertexResources.data()
-                                                           count:vertexResources.size()
-                                                           usage:MTLResourceUsageRead
-                                                          stages:MTLRenderStageVertex];
-        [driver->mContext->currentRenderPassEncoder useResources:fragmentResources.data()
-                                                           count:fragmentResources.size()
-                                                           usage:MTLResourceUsageRead
-                                                          stages:MTLRenderStageFragment];
-    } else {
-        [driver->mContext->currentRenderPassEncoder useResources:vertexResources.data()
-                                                           count:vertexResources.size()
-                                                           usage:MTLResourceUsageRead];
-        [driver->mContext->currentRenderPassEncoder useResources:fragmentResources.data()
-                                                           count:fragmentResources.size()
-                                                           usage:MTLResourceUsageRead];
-    }
-}
-
-id<MTLBuffer> MetalDescriptorSet::finalizeAndGetBuffer(MetalDriver* driver, ShaderStage stage) {
-    auto const index = static_cast<size_t>(stage);
-    assert_invariant(index < cachedBuffer.size());
-    auto& buffer = cachedBuffer[index];
-
-    if (buffer) {
-        return buffer;
-    }
-
-    // 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);
-
-    buffer = [context.device newBufferWithLength:encoder.encodedLength
-                                         options:MTLResourceStorageModeShared];
-    [encoder setArgumentBuffer:buffer offset:0];
-
-    for (auto const& binding : bindings) {
-        if (!hasShaderType(binding.stageFlags, stage)) {
-            continue;
-        }
-        switch (binding.type) {
-            case DescriptorType::UNIFORM_BUFFER:
-            case DescriptorType::SHADER_STORAGE_BUFFER: {
-                auto found = buffers.find(binding.binding);
-                if (found == buffers.end()) {
-                    [encoder setBuffer:driver->mContext->emptyBuffer
-                                offset:0
-                               atIndex:binding.binding * 2];
-                    continue;
-                }
-
-                auto const& bufferBinding = buffers[binding.binding];
-                [encoder setBuffer:bufferBinding.buffer
-                            offset:bufferBinding.offset
-                           atIndex:binding.binding * 2];
-                break;
-            }
-            case DescriptorType::SAMPLER: {
-                auto found = textures.find(binding.binding);
-                if (found == textures.end()) {
-                    [encoder setTexture:driver->mContext->emptyTexture atIndex:binding.binding * 2];
-                    id<MTLSamplerState> sampler =
-                            driver->mContext->samplerStateCache.getOrCreateState({});
-                    [encoder setSamplerState:sampler atIndex:binding.binding * 2 + 1];
-                    continue;
-                }
-
-                auto const& textureBinding = textures[binding.binding];
-                [encoder setTexture:textureBinding.texture atIndex:binding.binding * 2];
-                SamplerState samplerState { .samplerParams = textureBinding.sampler };
-                id<MTLSamplerState> sampler =
-                        driver->mContext->samplerStateCache.getOrCreateState(samplerState);
-                [encoder setSamplerState:sampler atIndex:binding.binding * 2 + 1];
-                break;
-            }
-            case DescriptorType::INPUT_ATTACHMENT:
-                assert_invariant(false);
-                break;
-        }
-    }
-
-    return buffer;
-}
-
 } // namespace backend
 } // namespace filament
@@ -106,41 +106,26 @@ bool MetalShaderCompiler::isParallelShaderCompileSupported() const noexcept {
            continue;
        }

+        assert_invariant(source[source.size() - 1] == '\0');
+
+        // the shader string is null terminated and the length includes the null character
+        NSString* objcSource = [[NSString alloc] initWithBytes:source.data()
+                                                        length:source.size() - 1
+                                                      encoding:NSUTF8StringEncoding];
+
+        // By default, Metal uses the most recent language version.
+        MTLCompileOptions* options = [MTLCompileOptions new];
+
+        // Disable Fast Math optimizations.
+        // This ensures that operations adhere to IEEE standards for floating-point arithmetic,
+        // which is crucial for half precision floats in scenarios where fast math optimizations
+        // lead to inaccuracies, such as in handling special values like NaN or Infinity.
+        options.fastMathEnabled = NO;
+
        NSError* error = nil;
-        id<MTLLibrary> library = nil;
-        switch (program.getShaderLanguage()) {
-            case ShaderLanguage::MSL: {
-                // By default, Metal uses the most recent language version.
-                MTLCompileOptions* options = [MTLCompileOptions new];
-
-                // Disable Fast Math optimizations.
-                // This ensures that operations adhere to IEEE standards for floating-point
-                // arithmetic, which is crucial for half precision floats in scenarios where fast
-                // math optimizations lead to inaccuracies, such as in handling special values like
-                // NaN or Infinity.
-                options.fastMathEnabled = NO;
-
-                assert_invariant(source[source.size() - 1] == '\0');
-                // the shader string is null terminated and the length includes the null character
-                NSString* objcSource = [[NSString alloc] initWithBytes:source.data()
-                                                                length:source.size() - 1
-                                                              encoding:NSUTF8StringEncoding];
-                library = [device newLibraryWithSource:objcSource options:options error:&error];
-                break;
-            }
-            case ShaderLanguage::METAL_LIBRARY: {
-                dispatch_data_t data = dispatch_data_create(source.data(), source.size(),
-                        dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),
-                        DISPATCH_DATA_DESTRUCTOR_DEFAULT);
-                library = [device newLibraryWithData:data error:&error];
-                break;
-            }
-            case ShaderLanguage::ESSL1:
-            case ShaderLanguage::ESSL3:
-            case ShaderLanguage::SPIRV:
-                break;
-        }
-
+        id<MTLLibrary> library = [device newLibraryWithSource:objcSource
+                                                      options:options
+                                                        error:&error];
        if (library == nil) {
            NSString* errorMessage = @"unknown error";
            if (error) {
@@ -169,23 +154,6 @@ bool MetalShaderCompiler::isParallelShaderCompileSupported() const noexcept {
        id<MTLFunction> function = [library newFunctionWithName:@"main0"
                                                 constantValues:constants
                                                          error:&error];
-        if (function == nil) {
-            // If the library loads but functions within it fail to load, it usually means the
-            // GPU backend crashed. (This can happen if it's a Metallib shader that was compiled
-            // with a minimum iOS version that's newer than this device.)
-            NSString* errorMessage = @"unknown error";
-            if (error) {
-                auto description =
-                        [error.localizedDescription cStringUsingEncoding:NSUTF8StringEncoding];
-                utils::slog.w << description << utils::io::endl;
-                errorMessage = error.localizedDescription;
-            }
-            PANIC_LOG("Failed to load main0 in Metal program.");
-            NSString* programName =
-                [NSString stringWithFormat:@"%s::main0", program.getName().c_str_safe()];
-            return MetalFunctionBundle::error(errorMessage, programName);
-        }
-
        if (!program.getName().empty()) {
            function.label = @(program.getName().c_str());
        }
@@ -33,28 +33,30 @@
 namespace filament {
 namespace backend {

+inline bool operator==(const SamplerParams& lhs, const SamplerParams& rhs) {
+    return SamplerParams::EqualTo{}(lhs, rhs);
+}
+
 //   Rasterization Bindings
 //   ----------------------
 //   Bindings    Buffer name                          Count
 //   ------------------------------------------------------
 //   0           Zero buffer (placeholder vertex buffer)  1
 //   1-16        Filament vertex buffers                 16   limited by MAX_VERTEX_BUFFER_COUNT
-//   20          Push constants                           1
-//   21-24       Descriptor sets (argument buffers)       4   limited by MAX_DESCRIPTOR_SET_COUNT
-//   25          Dynamic offset buffer                    1
+//   17-26       Uniform buffers                         10   Program::UNIFORM_BINDING_COUNT
+//   27-30       Sampler groups (argument buffers)        4   Program::SAMPLER_BINDING_COUNT
 //
-//   Total                                               23
+//   Total                                               31

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

 // The total number of vertex buffer "slots" that the Metal backend can bind.
 // + 1 to account for the zero buffer, a placeholder buffer used internally by the Metal backend.
@@ -67,11 +69,10 @@ static constexpr uint32_t ZERO_VERTEX_BUFFER_BINDING = 0u;

 static constexpr uint32_t USER_VERTEX_BUFFER_BINDING_START = 1u;

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

 // Forward declarations necessary here, definitions at end of file.
 inline bool operator==(const MTLViewport& lhs, const MTLViewport& rhs);
@@ -379,22 +380,18 @@ 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(
-            NSUInteger bufferCount, utils::FixedCapacityVector<MTLTextureType>&& types)
-        : bufferCount(bufferCount), textureTypes(std::move(types)) {}
+    explicit ArgumentEncoderState(utils::FixedCapacityVector<MTLTextureType>&& types)
+        : textureTypes(std::move(types)) {}

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

    bool operator!=(const ArgumentEncoderState& rhs) const noexcept {
@@ -416,30 +413,6 @@ struct ArgumentEncoderCreator {
 using ArgumentEncoderCache = StateCache<ArgumentEncoderState, id<MTLArgumentEncoder>,
        ArgumentEncoderCreator, ArgumentEncoderHasher>;

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

@@ -90,17 +90,11 @@ id<MTLRenderPipelineState> PipelineStateCreator::operator()(id<MTLDevice> device
    NSError* error = nullptr;
    id<MTLRenderPipelineState> pipeline = [device newRenderPipelineStateWithDescriptor:descriptor
                                                                                 error:&error];
-    if (UTILS_UNLIKELY(pipeline == nil)) {
-        NSString *errorMessage =
-            [NSString stringWithFormat:@"Could not create Metal pipeline state: %@",
-                error ? error.localizedDescription : @"unknown error"];
-        auto description = [errorMessage cStringUsingEncoding:NSUTF8StringEncoding];
+    if (error) {
+        auto description = [error.localizedDescription cStringUsingEncoding:NSUTF8StringEncoding];
        utils::slog.e << description << utils::io::endl;
-        [[NSException exceptionWithName:@"MetalRenderPipelineFailure"
-                                 reason:errorMessage
-                               userInfo:nil] raise];
    }
-    FILAMENT_CHECK_POSTCONDITION(error == nil) << "Could not create Metal pipeline state.";
+    ASSERT_POSTCONDITION(error == nil, "Could not create Metal pipeline state.");

    return pipeline;
 }
@@ -166,40 +160,28 @@ id<MTLSamplerState> SamplerStateCreator::operator()(id<MTLDevice> device,
 id<MTLArgumentEncoder> ArgumentEncoderCreator::operator()(id<MTLDevice> device,
        const ArgumentEncoderState &state) noexcept {
    const auto& textureTypes = state.textureTypes;
-    const auto& textureCount = textureTypes.size();
-    const auto& bufferCount = state.bufferCount;
-    assert_invariant(textureCount > 0);
+    const auto& count = textureTypes.size();
+    assert_invariant(count > 0);

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

        MTLArgumentDescriptor* samplerArgument = [MTLArgumentDescriptor argumentDescriptor];
-        samplerArgument.index = i++;
+        samplerArgument.index = i * 2 + 1;
        samplerArgument.dataType = MTLDataTypeSampler;
        textureArgument.access = MTLArgumentAccessReadOnly;
        [arguments addObject:samplerArgument];
@@ -208,64 +190,5 @@ id<MTLArgumentEncoder> ArgumentEncoderCreator::operator()(id<MTLDevice> device,
    return [device newArgumentEncoderWithArguments:arguments];
 }

-template <NSUInteger N, ShaderStage stage>
-void MetalBufferBindings<N, stage>::setBuffer(const id<MTLBuffer> buffer, NSUInteger offset, NSUInteger index) {
-    assert_invariant(offset + 1 <= N);
-
-    if (mBuffers[index] != buffer) {
-        mBuffers[index] = buffer;
-        mDirtyBuffers.set(index);
-    }
-
-    if (mOffsets[index] != offset) {
-        mOffsets[index] = offset;
-        mDirtyOffsets.set(index);
-    }
-}
-
-template <NSUInteger N, ShaderStage stage>
-void MetalBufferBindings<N, stage>::bindBuffers(
-        id<MTLCommandEncoder> encoder, NSUInteger startIndex) {
-    if (mDirtyBuffers.none() && mDirtyOffsets.none()) {
-        return;
-    }
-
-    utils::bitset8 onlyOffsetDirty = mDirtyOffsets & ~mDirtyBuffers;
-    onlyOffsetDirty.forEachSetBit([&](size_t i) {
-        if constexpr (stage == ShaderStage::VERTEX) {
-            [(id<MTLRenderCommandEncoder>)encoder setVertexBufferOffset:mOffsets[i]
-                                                                atIndex:i + startIndex];
-        } else if constexpr (stage == ShaderStage::FRAGMENT) {
-            [(id<MTLRenderCommandEncoder>)encoder setFragmentBufferOffset:mOffsets[i]
-                                                                  atIndex:i + startIndex];
-        } else if constexpr (stage == ShaderStage::COMPUTE) {
-            [(id<MTLComputeCommandEncoder>)encoder setBufferOffset:mOffsets[i]
-                                                           atIndex:i + startIndex];
-        }
-    });
-    mDirtyOffsets.reset();
-
-    mDirtyBuffers.forEachSetBit([&](size_t i) {
-        if constexpr (stage == ShaderStage::VERTEX) {
-            [(id<MTLRenderCommandEncoder>)encoder setVertexBuffer:mBuffers[i]
-                                                           offset:mOffsets[i]
-                                                          atIndex:i + startIndex];
-        } else if constexpr (stage == ShaderStage::FRAGMENT) {
-            [(id<MTLRenderCommandEncoder>)encoder setFragmentBuffer:mBuffers[i]
-                                                             offset:mOffsets[i]
-                                                            atIndex:i + startIndex];
-        } else if constexpr (stage == ShaderStage::COMPUTE) {
-            [(id<MTLComputeCommandEncoder>)encoder setBuffer:mBuffers[i]
-                                                      offset:mOffsets[i]
-                                                     atIndex:i + startIndex];
-        }
-    });
-    mDirtyBuffers.reset();
-}
-
-template class MetalBufferBindings<MAX_DESCRIPTOR_SET_COUNT, ShaderStage::VERTEX>;
-template class MetalBufferBindings<MAX_DESCRIPTOR_SET_COUNT, ShaderStage::FRAGMENT>;
-template class MetalBufferBindings<MAX_DESCRIPTOR_SET_COUNT, ShaderStage::COMPUTE>;
-
 } // namespace backend
 } // namespace filament
@@ -49,17 +49,16 @@ void NoopDriver::terminate() {
 void NoopDriver::tick(int) {
 }

-void NoopDriver::beginFrame(int64_t monotonic_clock_ns,
-        int64_t refreshIntervalNs, uint32_t frameId) {
+void NoopDriver::beginFrame(int64_t monotonic_clock_ns, uint32_t frameId) {
 }

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

 }

 void NoopDriver::setFrameCompletedCallback(Handle<HwSwapChain> sch,
-        CallbackHandler* handler, utils::Invocable<void(void)>&& callback) {
+        CallbackHandler* handler, CallbackHandler::Callback callback, void* user) {

 }

@@ -99,6 +98,9 @@ void NoopDriver::destroyProgram(Handle<HwProgram> ph) {
 void NoopDriver::destroyRenderTarget(Handle<HwRenderTarget> rth) {
 }

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

@@ -108,12 +110,6 @@ void NoopDriver::destroyStream(Handle<HwStream> sh) {
 void NoopDriver::destroyTimerQuery(Handle<HwTimerQuery> tqh) {
 }

-void NoopDriver::destroyDescriptorSetLayout(Handle<HwDescriptorSetLayout> tqh) {
-}
-
-void NoopDriver::destroyDescriptorSet(Handle<HwDescriptorSet> tqh) {
-}
-
 Handle<HwStream> NoopDriver::createStreamNative(void* nativeStream) {
    return {};
 }
@@ -185,7 +181,7 @@ bool NoopDriver::isProtectedContentSupported() {
    return false;
 }

-bool NoopDriver::isStereoSupported() {
+bool NoopDriver::isStereoSupported(backend::StereoscopicType) {
    return false;
 }

@@ -197,18 +193,10 @@ bool NoopDriver::isDepthStencilResolveSupported() {
    return true;
 }

-bool NoopDriver::isDepthStencilBlitSupported(TextureFormat format) {
-    return true;
-}
-
 bool NoopDriver::isProtectedTexturesSupported() {
    return true;
 }

-bool NoopDriver::isDepthClampSupported() {
-    return false;
-}
-
 bool NoopDriver::isWorkaroundNeeded(Workaround) {
    return false;
 }
@@ -251,6 +239,9 @@ void NoopDriver::setVertexBufferObject(Handle<HwVertexBuffer> vbh, uint32_t inde
        Handle<HwBufferObject> boh) {
 }

+void NoopDriver::setMinMaxLevels(Handle<HwTexture> th, uint32_t minLevel, uint32_t maxLevel) {
+}
+
 void NoopDriver::update3DImage(Handle<HwTexture> th,
        uint32_t level, uint32_t xoffset, uint32_t yoffset, uint32_t zoffset,
        uint32_t width, uint32_t height, uint32_t depth,
@@ -276,6 +267,11 @@ void NoopDriver::setExternalStream(Handle<HwTexture> th, Handle<HwStream> sh) {

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

+void NoopDriver::updateSamplerGroup(Handle<HwSamplerGroup> sbh,
+        BufferDescriptor&& data) {
+    scheduleDestroy(std::move(data));
+}
+
 void NoopDriver::compilePrograms(CompilerPriorityQueue priority,
        CallbackHandler* handler, CallbackHandler::Callback callback, void* user) {
    if (callback) {
@@ -298,14 +294,23 @@ void NoopDriver::makeCurrent(Handle<HwSwapChain> drawSch, Handle<HwSwapChain> re
 void NoopDriver::commit(Handle<HwSwapChain> sch) {
 }

-void NoopDriver::setPushConstant(backend::ShaderStage stage, uint8_t index,
-        backend::PushConstantVariant value) {
+void NoopDriver::bindUniformBuffer(uint32_t index, Handle<HwBufferObject> ubh) {
 }

-void NoopDriver::insertEventMarker(char const* string) {
+void NoopDriver::bindBufferRange(BufferObjectBinding bindingType, uint32_t index,
+        Handle<HwBufferObject> ubh, uint32_t offset, uint32_t size) {
 }

-void NoopDriver::pushGroupMarker(char const* string) {
+void NoopDriver::unbindBuffer(BufferObjectBinding bindingType, uint32_t index) {
+}
+
+void NoopDriver::bindSamplers(uint32_t index, Handle<HwSamplerGroup> sbh) {
+}
+
+void NoopDriver::insertEventMarker(char const* string, uint32_t len) {
+}
+
+void NoopDriver::pushGroupMarker(char const* string,  uint32_t len) {
 }

 void NoopDriver::popGroupMarker(int) {
@@ -345,7 +350,7 @@ void NoopDriver::blit(
        math::uint2 size) {
 }

-void NoopDriver::bindPipeline(PipelineState const& pipelineState) {
+void NoopDriver::bindPipeline(PipelineState pipelineState) {
 }

 void NoopDriver::bindRenderPrimitive(Handle<HwRenderPrimitive> rph) {
@@ -374,28 +379,4 @@ void NoopDriver::endTimerQuery(Handle<HwTimerQuery> tqh) {
 void NoopDriver::resetState(int) {
 }

-void NoopDriver::updateDescriptorSetBuffer(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_binding_t binding,
-        backend::BufferObjectHandle boh,
-        uint32_t offset,
-        uint32_t size) {
-}
-
-void NoopDriver::updateDescriptorSetTexture(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_binding_t binding,
-        backend::TextureHandle th,
-        SamplerParams params) {
-}
-
-void NoopDriver::bindDescriptorSet(
-        backend::DescriptorSetHandle dsh,
-        backend::descriptor_set_t set,
-        backend::DescriptorSetOffsetArray&& offsets) {
-}
-
-void NoopDriver::setDebugTag(HandleBase::HandleId handleId, utils::CString tag) {
-}
-
 } // namespace filament
@@ -1,89 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_OPENGL_BINDINGMAP_H
-#define TNT_FILAMENT_BACKEND_OPENGL_BINDINGMAP_H
-
-#include <backend/DriverEnums.h>
-
-#include "gl_headers.h"
-
-#include <utils/bitset.h>
-#include <utils/debug.h>
-
-#include <new>
-
-#include <stddef.h>
-#include <stdint.h>
-#include <string.h>
-
-namespace filament::backend {
-
-class BindingMap {
-    struct CompressedBinding {
-        // this is in fact a GLuint, but we only want 8-bits
-        uint8_t binding : 7;
-        uint8_t sampler : 1;
-    };
-
-    CompressedBinding (*mStorage)[MAX_DESCRIPTOR_COUNT];
-
-    utils::bitset64 mActiveDescriptors[MAX_DESCRIPTOR_SET_COUNT];
-
-public:
-    BindingMap() noexcept
-            : mStorage(new (std::nothrow) CompressedBinding[MAX_DESCRIPTOR_SET_COUNT][MAX_DESCRIPTOR_COUNT]) {
-#ifndef NDEBUG
-        memset(mStorage, 0xFF, sizeof(CompressedBinding[MAX_DESCRIPTOR_SET_COUNT][MAX_DESCRIPTOR_COUNT]));
-#endif
-    }
-
-    ~BindingMap() noexcept {
-        delete [] mStorage;
-    }
-
-    BindingMap(BindingMap const&) noexcept = delete;
-    BindingMap(BindingMap&&) noexcept = delete;
-    BindingMap& operator=(BindingMap const&) noexcept = delete;
-    BindingMap& operator=(BindingMap&&) noexcept = delete;
-
-    struct Binding {
-        GLuint binding;
-        DescriptorType type;
-    };
-
-    void insert(descriptor_set_t set, descriptor_binding_t binding, Binding entry) noexcept {
-        assert_invariant(set < MAX_DESCRIPTOR_SET_COUNT);
-        assert_invariant(binding < MAX_DESCRIPTOR_COUNT);
-        assert_invariant(entry.binding < 128); // we reserve 1 bit for the type right now
-        mStorage[set][binding] = { (uint8_t)entry.binding, entry.type == DescriptorType::SAMPLER };
-        mActiveDescriptors[set].set(binding);
-    }
-
-    GLuint get(descriptor_set_t set, descriptor_binding_t binding) const noexcept {
-        assert_invariant(set < MAX_DESCRIPTOR_SET_COUNT);
-        assert_invariant(binding < MAX_DESCRIPTOR_COUNT);
-        return mStorage[set][binding].binding;
-    }
-
-    utils::bitset64 getActiveDescriptors(descriptor_set_t set) const noexcept {
-        return mActiveDescriptors[set];
-    }
-};
-
-} // namespace filament::backend
-
-#endif //TNT_FILAMENT_BACKEND_OPENGL_BINDINGMAP_H
@@ -1,51 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_OPENGL_GLBUFFEROBJECT_H
-#define TNT_FILAMENT_BACKEND_OPENGL_GLBUFFEROBJECT_H
-
-#include "DriverBase.h"
-
-#include "gl_headers.h"
-
-#include <backend/DriverEnums.h>
-
-#include <stdint.h>
-
-namespace filament::backend {
-
-struct GLBufferObject : public HwBufferObject {
-    using HwBufferObject::HwBufferObject;
-    GLBufferObject(uint32_t size,
-            BufferObjectBinding bindingType, BufferUsage usage) noexcept
-            : HwBufferObject(size), usage(usage), bindingType(bindingType) {
-    }
-
-    struct {
-        GLuint id;
-        union {
-            GLenum binding;
-            void* buffer;
-        };
-    } gl;
-    BufferUsage usage;
-    BufferObjectBinding bindingType;
-    uint16_t age = 0;
-};
-
-} // namespace filament::backend
-
-#endif //TNT_FILAMENT_BACKEND_OPENGL_GLBUFFEROBJECT_H
@@ -1,361 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "GLDescriptorSet.h"
-
-#include "GLBufferObject.h"
-#include "GLDescriptorSetLayout.h"
-#include "GLTexture.h"
-#include "GLUtils.h"
-#include "OpenGLDriver.h"
-#include "OpenGLContext.h"
-#include "OpenGLProgram.h"
-
-#include "gl_headers.h"
-
-#include <private/backend/HandleAllocator.h>
-
-#include <backend/DriverEnums.h>
-#include <backend/Handle.h>
-
-#include <utils/BitmaskEnum.h>
-#include <utils/Log.h>
-#include <utils/Panic.h>
-#include <utils/bitset.h>
-#include <utils/compiler.h>
-#include <utils/debug.h>
-#include <algorithm>
-
-#include <type_traits>
-#include <utility>
-#include <variant>
-
-#include <stddef.h>
-#include <stdint.h>
-
-namespace filament::backend {
-
-GLDescriptorSet::GLDescriptorSet(OpenGLContext& gl, DescriptorSetLayoutHandle dslh,
-        GLDescriptorSetLayout const* layout) noexcept
-        : descriptors(layout->maxDescriptorBinding + 1),
-          dslh(std::move(dslh)) {
-
-    // We have allocated enough storage for all descriptors. Now allocate the empty descriptor
-    // themselves.
-    for (auto const& entry : layout->bindings) {
-        size_t const index = entry.binding;
-
-        // now we'll initialize the alternative for each way we can handle this descriptor.
-        auto& desc = descriptors[index].desc;
-        switch (entry.type) {
-            case DescriptorType::UNIFORM_BUFFER: {
-                // A uniform buffer can have dynamic offsets or not and have special handling for
-                // ES2 (where we need to emulate it). That's four alternatives.
-                bool const dynamicOffset = any(entry.flags & DescriptorFlags::DYNAMIC_OFFSET);
-                dynamicBuffers.set(index, dynamicOffset);
-                if (UTILS_UNLIKELY(gl.isES2())) {
-                    dynamicBufferCount++;
-                    desc.emplace<BufferGLES2>(dynamicOffset);
-                } else {
-                    auto const type = GLUtils::getBufferBindingType(BufferObjectBinding::UNIFORM);
-                    if (dynamicOffset) {
-                        dynamicBufferCount++;
-                        desc.emplace<DynamicBuffer>(type);
-                    } else {
-                        desc.emplace<Buffer>(type);
-                    }
-                }
-                break;
-            }
-            case DescriptorType::SHADER_STORAGE_BUFFER: {
-                // shader storage buffers are not supported on ES2, So that's two alternatives.
-                bool const dynamicOffset = any(entry.flags & DescriptorFlags::DYNAMIC_OFFSET);
-                dynamicBuffers.set(index, dynamicOffset);
-                auto const type = GLUtils::getBufferBindingType(BufferObjectBinding::SHADER_STORAGE);
-                if (dynamicOffset) {
-                    dynamicBufferCount++;
-                    desc.emplace<DynamicBuffer>(type);
-                } else {
-                    desc.emplace<Buffer>(type);
-                }
-                break;
-            }
-            case DescriptorType::SAMPLER:
-                if (UTILS_UNLIKELY(gl.isES2())) {
-                    desc.emplace<SamplerGLES2>();
-                } else {
-                    const bool anisotropyWorkaround =
-                            gl.ext.EXT_texture_filter_anisotropic &&
-                            gl.bugs.texture_filter_anisotropic_broken_on_sampler;
-                    if (anisotropyWorkaround) {
-                        desc.emplace<SamplerWithAnisotropyWorkaround>();
-                    } else {
-                        desc.emplace<Sampler>();
-                    }
-                }
-                break;
-            case DescriptorType::INPUT_ATTACHMENT:
-                break;
-        }
-    }
-}
-
-void GLDescriptorSet::update(OpenGLContext&,
-        descriptor_binding_t binding, GLBufferObject* bo, size_t offset, size_t size) noexcept {
-    assert_invariant(binding < descriptors.size());
-    std::visit([=](auto&& arg) {
-        using T = std::decay_t<decltype(arg)>;
-        if constexpr (std::is_same_v<T, Buffer> || std::is_same_v<T, DynamicBuffer>) {
-            assert_invariant(arg.target != 0);
-            arg.id = bo ? bo->gl.id : 0;
-            arg.offset = uint32_t(offset);
-            arg.size = uint32_t(size);
-            assert_invariant(arg.id || (!arg.size && !offset));
-        } else if constexpr (std::is_same_v<T, BufferGLES2>) {
-            arg.bo = bo;
-            arg.offset = uint32_t(offset);
-        } else {
-            // API usage error. User asked to update the wrong type of descriptor.
-            PANIC_PRECONDITION("descriptor %d is not a buffer", +binding);
-        }
-    }, descriptors[binding].desc);
-}
-
-void GLDescriptorSet::update(OpenGLContext& gl,
-        descriptor_binding_t binding, GLTexture* t, SamplerParams params) noexcept {
-    assert_invariant(binding < descriptors.size());
-    std::visit([=, &gl](auto&& arg) mutable {
-        using T = std::decay_t<decltype(arg)>;
-        if constexpr (std::is_same_v<T, Sampler> ||
-                      std::is_same_v<T, SamplerWithAnisotropyWorkaround> ||
-                      std::is_same_v<T, SamplerGLES2>) {
-            if (UTILS_UNLIKELY(t && t->target == SamplerType::SAMPLER_EXTERNAL)) {
-                // From OES_EGL_image_external spec:
-                // "The default s and t wrap modes are CLAMP_TO_EDGE, and it is an INVALID_ENUM
-                //  error to set the wrap mode to any other value."
-                params.wrapS = SamplerWrapMode::CLAMP_TO_EDGE;
-                params.wrapT = SamplerWrapMode::CLAMP_TO_EDGE;
-                params.wrapR = SamplerWrapMode::CLAMP_TO_EDGE;
-            }
-            // GLES3.x specification forbids depth textures to be filtered.
-            if (t && isDepthFormat(t->format)
-                    && params.compareMode == SamplerCompareMode::NONE) {
-                params.filterMag = SamplerMagFilter::NEAREST;
-                switch (params.filterMin) {
-                    case SamplerMinFilter::LINEAR:
-                        params.filterMin = SamplerMinFilter::NEAREST;
-                        break;
-                    case SamplerMinFilter::LINEAR_MIPMAP_NEAREST:
-                    case SamplerMinFilter::NEAREST_MIPMAP_LINEAR:
-                    case SamplerMinFilter::LINEAR_MIPMAP_LINEAR:
-                        params.filterMin = SamplerMinFilter::NEAREST_MIPMAP_NEAREST;
-                        break;
-                    default:
-                        break;
-                }
-            }
-
-            arg.target = t ? t->gl.target : 0;
-            arg.id = t ? t->gl.id : 0;
-            if constexpr (std::is_same_v<T, Sampler> ||
-                          std::is_same_v<T, SamplerWithAnisotropyWorkaround>) {
-                if constexpr (std::is_same_v<T, SamplerWithAnisotropyWorkaround>) {
-                    arg.anisotropy = float(1u << params.anisotropyLog2);
-                }
-                if (t) {
-                    arg.ref = t->ref;
-                    arg.baseLevel = t->gl.baseLevel;
-                    arg.maxLevel = t->gl.maxLevel;
-                    arg.swizzle = t->gl.swizzle;
-                }
-#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
-                arg.sampler = gl.getSampler(params);
-#else
-                (void)gl;
-#endif
-            } else {
-                arg.params = params;
-            }
-        } else {
-            // API usage error. User asked to update the wrong type of descriptor.
-            PANIC_PRECONDITION("descriptor %d is not a texture", +binding);
-        }
-    }, descriptors[binding].desc);
-}
-
-template<typename T>
-void GLDescriptorSet::updateTextureView(OpenGLContext& gl,
-        HandleAllocatorGL& handleAllocator, GLuint unit, T const& desc) noexcept {
-    // The common case is that we don't have a ref handle (we only have one if
-    // the texture ever had a View on it).
-    assert_invariant(desc.ref);
-    GLTextureRef* const ref = handleAllocator.handle_cast<GLTextureRef*>(desc.ref);
-    if (UTILS_UNLIKELY((desc.baseLevel != ref->baseLevel || desc.maxLevel != ref->maxLevel))) {
-        // If we have views, then it's still uncommon that we'll switch often
-        // handle the case where we reset to the original texture
-        GLint baseLevel = GLint(desc.baseLevel); // NOLINT(*-signed-char-misuse)
-        GLint maxLevel = GLint(desc.maxLevel); // NOLINT(*-signed-char-misuse)
-        if (baseLevel > maxLevel) {
-            baseLevel = 0;
-            maxLevel = 1000; // per OpenGL spec
-        }
-        // that is very unfortunate that we have to call activeTexture here
-        gl.activeTexture(unit);
-        glTexParameteri(desc.target, GL_TEXTURE_BASE_LEVEL, baseLevel);
-        glTexParameteri(desc.target, GL_TEXTURE_MAX_LEVEL,  maxLevel);
-        ref->baseLevel = desc.baseLevel;
-        ref->maxLevel = desc.maxLevel;
-    }
-    if (UTILS_UNLIKELY(desc.swizzle != ref->swizzle)) {
-        using namespace GLUtils;
-        gl.activeTexture(unit);
-#if !defined(__EMSCRIPTEN__)  && !defined(FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2)
-        glTexParameteri(desc.target, GL_TEXTURE_SWIZZLE_R, (GLint)getSwizzleChannel(desc.swizzle[0]));
-        glTexParameteri(desc.target, GL_TEXTURE_SWIZZLE_G, (GLint)getSwizzleChannel(desc.swizzle[1]));
-        glTexParameteri(desc.target, GL_TEXTURE_SWIZZLE_B, (GLint)getSwizzleChannel(desc.swizzle[2]));
-        glTexParameteri(desc.target, GL_TEXTURE_SWIZZLE_A, (GLint)getSwizzleChannel(desc.swizzle[3]));
-#endif
-        ref->swizzle = desc.swizzle;
-    }
-}
-
-void GLDescriptorSet::bind(
-        OpenGLContext& gl,
-        HandleAllocatorGL& handleAllocator,
-        OpenGLProgram const& p,
-        descriptor_set_t set, uint32_t const* offsets, bool offsetsOnly) const noexcept {
-    // TODO: check that offsets is sized correctly
-    size_t dynamicOffsetIndex = 0;
-
-    utils::bitset64 activeDescriptorBindings = p.getActiveDescriptors(set);
-    if (offsetsOnly) {
-        activeDescriptorBindings &= dynamicBuffers;
-    }
-
-    // loop only over the active indices for this program
-    activeDescriptorBindings.forEachSetBit(
-            [this,&gl, &handleAllocator, &p, set, offsets, &dynamicOffsetIndex]
-            (size_t binding) {
-
-        // This would fail here if we're trying to set a descriptor that doesn't exist in the
-        // program. In other words, a mismatch between the program's layout and this descriptor-set.
-        assert_invariant(binding < descriptors.size());
-
-        auto const& entry = descriptors[binding];
-        std::visit(
-                [&gl, &handleAllocator, &p, &dynamicOffsetIndex, set, binding, offsets]
-                (auto&& arg) {
-            using T = std::decay_t<decltype(arg)>;
-            if constexpr (std::is_same_v<T, Buffer>) {
-                GLuint const bindingPoint = p.getBufferBinding(set, binding);
-                GLintptr const offset = arg.offset;
-                assert_invariant(arg.id || (!arg.size && !offset));
-                gl.bindBufferRange(arg.target, bindingPoint, arg.id, offset, arg.size);
-            } else if constexpr (std::is_same_v<T, DynamicBuffer>) {
-                GLuint const bindingPoint = p.getBufferBinding(set, binding);
-                GLintptr const offset = arg.offset + offsets[dynamicOffsetIndex++];
-                assert_invariant(arg.id || (!arg.size && !offset));
-                gl.bindBufferRange(arg.target, bindingPoint, arg.id, offset, arg.size);
-            } else if constexpr (std::is_same_v<T, BufferGLES2>) {
-                GLuint const bindingPoint = p.getBufferBinding(set, binding);
-                GLintptr offset = arg.offset;
-                if (arg.dynamicOffset) {
-                    offset += offsets[dynamicOffsetIndex++];
-                }
-                if (arg.bo) {
-                    auto buffer = static_cast<char const*>(arg.bo->gl.buffer) + offset;
-                    p.updateUniforms(bindingPoint, arg.bo->gl.id, buffer, arg.bo->age);
-                }
-            } else if constexpr (std::is_same_v<T, Sampler>) {
-                GLuint const unit = p.getTextureUnit(set, binding);
-                if (arg.target) {
-                    gl.bindTexture(unit, arg.target, arg.id);
-                    gl.bindSampler(unit, arg.sampler);
-                    if (UTILS_UNLIKELY(arg.ref)) {
-                        updateTextureView(gl, handleAllocator, unit, arg);
-                    }
-                } else {
-                    gl.unbindTextureUnit(unit);
-                }
-            } else if constexpr (std::is_same_v<T, SamplerWithAnisotropyWorkaround>) {
-                GLuint const unit = p.getTextureUnit(set, binding);
-                if (arg.target) {
-                    gl.bindTexture(unit, arg.target, arg.id);
-                    gl.bindSampler(unit, arg.sampler);
-                    if (UTILS_UNLIKELY(arg.ref)) {
-                        updateTextureView(gl, handleAllocator, unit, arg);
-                    }
-#if defined(GL_EXT_texture_filter_anisotropic)
-                    // Driver claims to support anisotropic filtering, but it fails when set on
-                    // the sampler, we have to set it on the texture instead.
-                    glTexParameterf(arg.target, GL_TEXTURE_MAX_ANISOTROPY_EXT,
-                            std::min(gl.gets.max_anisotropy, float(arg.anisotropy)));
-#endif
-                } else {
-                    gl.unbindTextureUnit(unit);
-                }
-            } else if constexpr (std::is_same_v<T, SamplerGLES2>) {
-                // in ES2 the sampler parameters need to be set on the texture itself
-                GLuint const unit = p.getTextureUnit(set, binding);
-                if (arg.target) {
-                    gl.bindTexture(unit, arg.target, arg.id);
-                    SamplerParams const params = arg.params;
-                    glTexParameteri(arg.target, GL_TEXTURE_MIN_FILTER,
-                            (GLint)GLUtils::getTextureFilter(params.filterMin));
-                    glTexParameteri(arg.target, GL_TEXTURE_MAG_FILTER,
-                            (GLint)GLUtils::getTextureFilter(params.filterMag));
-                    glTexParameteri(arg.target, GL_TEXTURE_WRAP_S,
-                            (GLint)GLUtils::getWrapMode(params.wrapS));
-                    glTexParameteri(arg.target, GL_TEXTURE_WRAP_T,
-                            (GLint)GLUtils::getWrapMode(params.wrapT));
-#if defined(GL_EXT_texture_filter_anisotropic)
-                    glTexParameterf(arg.target, GL_TEXTURE_MAX_ANISOTROPY_EXT,
-                            std::min(gl.gets.max_anisotropy, arg.anisotropy));
-#endif
-                } else {
-                    gl.unbindTextureUnit(unit);
-                }
-            }
-        }, entry.desc);
-    });
-    CHECK_GL_ERROR(utils::slog.e)
-}
-
-void GLDescriptorSet::validate(HandleAllocatorGL& allocator,
-        DescriptorSetLayoutHandle pipelineLayout) const {
-
-    if (UTILS_UNLIKELY(dslh != pipelineLayout)) {
-        auto* const dsl = allocator.handle_cast < GLDescriptorSetLayout const * > (dslh);
-        auto* const cur = allocator.handle_cast < GLDescriptorSetLayout const * > (pipelineLayout);
-
-        UTILS_UNUSED_IN_RELEASE
-        bool const pipelineLayoutMatchesDescriptorSetLayout = std::equal(
-                dsl->bindings.begin(), dsl->bindings.end(),
-                cur->bindings.begin(),
-                [](DescriptorSetLayoutBinding const& lhs,
-                        DescriptorSetLayoutBinding const& rhs) {
-                    return lhs.type == rhs.type &&
-                           lhs.stageFlags == rhs.stageFlags &&
-                           lhs.binding == rhs.binding &&
-                           lhs.flags == rhs.flags &&
-                           lhs.count == rhs.count;
-                });
-
-        assert_invariant(pipelineLayoutMatchesDescriptorSetLayout);
-    }
-}
-
-} // namespace filament::backend
@@ -1,171 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSET_H
-#define TNT_FILAMENT_BACKEND_OPENGL_GLDESCRIPTORSET_H
-
-#include "DriverBase.h"
-
-#include "gl_headers.h"
-
-#include <private/backend/HandleAllocator.h>
-
-#include <backend/DriverEnums.h>
-#include <backend/Handle.h>
-
-#include <utils/bitset.h>
-#include <utils/FixedCapacityVector.h>
-
-#include <math/half.h>
-
-#include <array>
-#include <variant>
-
-#include <stddef.h>
-#include <stdint.h>
-
-namespace filament::backend {
-
-struct GLBufferObject;
-struct GLTexture;
-struct GLTextureRef;
-struct GLDescriptorSetLayout;
-class OpenGLProgram;
-class OpenGLContext;
-class OpenGLDriver;
-
-struct GLDescriptorSet : public HwDescriptorSet {
-
-    using HwDescriptorSet::HwDescriptorSet;
-
-    GLDescriptorSet(OpenGLContext& gl, DescriptorSetLayoutHandle dslh,
-            GLDescriptorSetLayout const* layout) noexcept;
-
-    // update a buffer descriptor in the set
-    void update(OpenGLContext& gl,
-            descriptor_binding_t binding, GLBufferObject* bo, size_t offset, size_t size) noexcept;
-
-    // update a sampler descriptor in the set
-    void update(OpenGLContext& gl,
-            descriptor_binding_t binding, GLTexture* t, SamplerParams params) noexcept;
-
-    // conceptually bind the set to the command buffer
-    void bind(
-            OpenGLContext& gl,
-            HandleAllocatorGL& handleAllocator,
-            OpenGLProgram const& p,
-            descriptor_set_t set, uint32_t const* offsets, bool offsetsOnly) const noexcept;
-
-    uint32_t getDynamicBufferCount() const noexcept {
-        return dynamicBufferCount;
-    }
-
-    void validate(HandleAllocatorGL& allocator, DescriptorSetLayoutHandle pipelineLayout) const;
-
-private:
-    // a Buffer Descriptor such as SSBO or UBO with static offset
-    struct Buffer {
-        Buffer() = default;
-        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
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