renderdiff: Use single lib for osmesa (#8255 )

Previously, we linked against libOSMesa through the linker and then used dlopen to link against libGL. This is not how libOSMesa is intended to be used. Instead, we use dlopen on libOSMesa (via bluegl), which then will map the correct GL methods for us, and for the OSMesa functions, we also map those functions from libOSMesa (instead of relying on compile-time linker).
2024-11-07 15:42:44 -08:00
207 changed files with 3254 additions and 5876 deletions
@@ -525,14 +525,11 @@ else()
    option(FILAMENT_BUILD_FILAMAT "Build filamat and JNI buildings" OFF)
 endif()

-# By default, link in matdbg/fgviewer for Desktop + Debug only since it pulls in filamat and a web server.
+# By default, link in matdbg for Desktop + Debug only since it pulls in filamat and a web server.
 if (CMAKE_BUILD_TYPE STREQUAL "Debug" AND IS_HOST_PLATFORM)
    option(FILAMENT_ENABLE_MATDBG "Enable the material debugger" ON)
-    # TODO: Uncomment below when fgviewer is ready
-    # option(FILAMENT_ENABLE_FGVIEWER "Enable the frame graph viewer" ON)
 else()
    option(FILAMENT_ENABLE_MATDBG "Enable the material debugger" OFF)
-    option(FILAMENT_ENABLE_FGVIEWER "Enable the frame graph viewer" OFF)
 endif()

 # Only optimize materials in Release mode (so error message lines match the source code)
@@ -781,11 +778,6 @@ if (FILAMENT_BUILD_FILAMAT OR IS_HOST_PLATFORM)
    if (FILAMENT_ENABLE_MATDBG OR IS_HOST_PLATFORM)
        add_subdirectory(${LIBRARIES}/matdbg)
    endif()
-
-    # TODO: Uncomment below when fgviewer is ready
-    # if (FILAMENT_ENABLE_FGVIEWER OR IS_HOST_PLATFORM)
-    #     add_subdirectory(${LIBRARIES}/fgviewer)
-    # endif()
 endif()

 if (FILAMENT_SUPPORTS_VULKAN)
@@ -31,7 +31,7 @@ repositories {
 }

 dependencies {
-    implementation 'com.google.android.filament:filament-android:1.56.6'
+    implementation 'com.google.android.filament:filament-android:1.55.1'
 }
 ```

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

 ```shell
-pod 'Filament', '~> 1.56.6'
+pod 'Filament', '~> 1.55.1'
 ```

 ## Documentation
@@ -7,29 +7,6 @@ A new header is inserted each time a *tag* is created.
 Instead, if you are authoring a PR for the main branch, add your release note to
 [NEW_RELEASE_NOTES.md](./NEW_RELEASE_NOTES.md).

-## v1.56.6
-
-fix crash: the 'target_node' of Animation Channel may be nullpointer.
-
-## v1.56.5
-
-
-## v1.56.4
-
-
-## v1.56.3
-
-
-## v1.56.2
-
- vk: fix stage pool gc logic
-
-## v1.56.1
-
-## v1.56.0
-
- backend: descriptor layouts distinguish samplers and external samplers (b/376089915) [⚠️ **New Material Version**]
-
 ## v1.55.1


@@ -677,7 +654,7 @@ fix crash: the 'target_node' of Animation Channel may be nullpointer.

 - engine: Binary size improvements.
 - engine: Add basic support for instanced renderables [**NEW API**].
- engine: Fix, first imaged passed to `Stream::SetAcquiredImage` is ignored and leaked.
+- engine: Fix, first imaged passsed to `Stream::SetAcquiredImage` is ignored and leaked.
 - Vulkan: Robustness improvements.
 - Java: Fix, lookAt z axis negated.
 - gltfio: Be graceful when model has > 4 weights per vert.
@@ -11,9 +11,6 @@
 // com.google.android.filament.exclude-vulkan
 //     When set, support for Vulkan will be excluded.
 //
-// com.google.android.filament.fgviewer
-//     When set, enables fgviewer
-//
 // com.google.android.filament.matdbg
 //     When set, enables matdbg
 //
@@ -64,11 +61,6 @@ buildscript {
            .gradleProperty("com.google.android.filament.exclude-vulkan")
            .isPresent()

-    // TODO: Uncomment below when fgviewer is ready
-    // def fgviewer = providers
-    //         .gradleProperty("com.google.android.filament.fgviewer")
-    //         .isPresent()
-
    def matdbg = providers
            .gradleProperty("com.google.android.filament.matdbg")
            .isPresent()
@@ -91,12 +83,12 @@ buildscript {
        'minSdk': 21,
        'targetSdk': 34,
        'compileSdk': 34,
-        'kotlin': '2.0.21',
-        'kotlin_coroutines': '1.9.0',
-        'buildTools': '35.0.0',
+        'kotlin': '2.0.0',
+        'kotlin_coroutines': '1.9.0-RC',
+        'buildTools': '34.0.0',
        'ndk': '27.0.11718014',
        'androidx_core': '1.13.1',
-        'androidx_annotations': '1.9.0'
+        'androidx_annotations': '1.8.0'
    ]

    ext.deps = [
@@ -112,7 +104,7 @@ buildscript {
    ]

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

@@ -123,8 +115,6 @@ buildscript {
        "-DANDROID_STL=c++_static",
        "-DFILAMENT_DIST_DIR=${filamentPath}".toString(),
        "-DFILAMENT_SUPPORTS_VULKAN=${excludeVulkan ? 'OFF' : 'ON'}".toString(),
-        // TODO: Uncomment below when fgviewer is ready
-        // "-DFILAMENT_ENABLE_FGVIEWER=${fgviewer ? 'ON' : 'OFF'}".toString(),
        "-DFILAMENT_ENABLE_MATDBG=${matdbg ? 'ON' : 'OFF'}".toString(),
        "-DFILAMENT_DISABLE_MATOPT=${matnopt ? 'ON' : 'OFF'}".toString()
    ]
@@ -2,8 +2,6 @@ cmake_minimum_required(VERSION 3.19)
 project(filament-android)

 option(FILAMENT_SUPPORTS_VULKAN "Enables Vulkan on Android" OFF)
-# TODO: Uncomment below when fgviewer is ready
-# option(FILAMENT_ENABLE_FGVIEWER "Enables Frame Graph Viewer" OFF)
 option(FILAMENT_ENABLE_MATDBG "Enables Material debugger" OFF)
 option(FILAMENT_DISABLE_MATOPT "Disables material optimizations" OFF)

@@ -53,13 +51,6 @@ add_library(smol-v STATIC IMPORTED)
 set_target_properties(smol-v PROPERTIES IMPORTED_LOCATION
        ${FILAMENT_DIR}/lib/${ANDROID_ABI}/libsmol-v.a)

-# TODO: Uncomment below when fgviewer is ready
-# if (FILAMENT_ENABLE_FGVIEWER)
-#     add_library(fgviewer STATIC IMPORTED)
-#     set_target_properties(fgviewer PROPERTIES IMPORTED_LOCATION
-#             ${FILAMENT_DIR}/lib/${ANDROID_ABI}/libfgviewer.a)
-# endif()
-
 if (FILAMENT_ENABLE_MATDBG)
    add_library(matdbg STATIC IMPORTED)
    set_target_properties(matdbg PROPERTIES IMPORTED_LOCATION
@@ -126,8 +117,6 @@ target_link_libraries(filament-jni
    # libgeometry is PUBLIC because gltfio uses it.
    PUBLIC geometry

-    # TODO: Uncomment below when fgviewer is ready
-    # $<$<STREQUAL:${FILAMENT_ENABLE_FGVIEWER},ON>:fgviewer>
    $<$<STREQUAL:${FILAMENT_ENABLE_MATDBG},ON>:matdbg>
    $<$<STREQUAL:${FILAMENT_ENABLE_MATDBG},ON>:filamat>
    $<$<STREQUAL:${FILAMENT_SUPPORTS_VULKAN},ON>:bluevk>
@@ -499,37 +499,6 @@ Java_com_google_android_filament_Engine_nGetActiveFeatureLevel(JNIEnv *, jclass,
    return (jint)engine->getActiveFeatureLevel();
 }

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

-extern "C"
-JNIEXPORT void JNICALL
-Java_com_google_android_filament_Engine_nSetBuilderFeature(JNIEnv *env, jclass clazz,
-        jlong nativeBuilder, jstring name_, jboolean value) {
-    Engine::Builder* builder = (Engine::Builder*) nativeBuilder;
-    const char *name = env->GetStringUTFChars(name_, 0);
-    builder->feature(name, (bool)value);
-    env->ReleaseStringUTFChars(name_, name);
-}
-
 extern "C" JNIEXPORT jlong JNICALL
 Java_com_google_android_filament_Engine_nBuilderBuild(JNIEnv*, jclass, jlong nativeBuilder) {
    Engine::Builder* builder = (Engine::Builder*) nativeBuilder;
@@ -38,7 +38,7 @@ Java_com_google_android_filament_EntityManager_nCreateArray(JNIEnv* env, jclass,
    // (which it is), but still.
    em->create((size_t) n, reinterpret_cast<Entity *>(entities));

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

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

 extern "C" JNIEXPORT void JNICALL
@@ -178,5 +178,5 @@ Java_com_google_android_filament_IndirectLight_nGetColorEstimateStatic(JNIEnv *e
    *reinterpret_cast<filament::math::float4*>(outColor) =
            IndirectLight::getColorEstimate((filament::math::float3*)sh, math::float3{x, y, z});
    env->ReleaseFloatArrayElements(outColor_, outColor, 0);
-    env->ReleaseFloatArrayElements(sh_, sh, 0);
+    env->ReleaseFloatArrayElements(sh_, sh, JNI_ABORT);
 }
@@ -25,14 +25,13 @@ 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, jint shadowQuality) {
+        jlong nativeEngine, jobject buffer_, jint size, jint shBandCount) {
    Engine* engine = (Engine*) nativeEngine;
    AutoBuffer buffer(env, buffer_, size);
    auto builder = Material::Builder();
    if (shBandCount) {
        builder.sphericalHarmonicsBandCount(shBandCount);
    }
-    builder.shadowSamplingQuality((Material::Builder::ShadowSamplingQuality)shadowQuality);
    Material* material = builder
            .package(buffer.getData(), buffer.getSize())
            .build(*engine);
@@ -138,13 +138,6 @@ Java_com_google_android_filament_Texture_nBuilderImportTexture(JNIEnv*, jclass,
    builder->import((intptr_t)id);
 }

-extern "C"
-JNIEXPORT void JNICALL
-Java_com_google_android_filament_Texture_nBuilderExternal(JNIEnv*, jclass, jlong nativeBuilder) {
-    Texture::Builder *builder = (Texture::Builder *) nativeBuilder;
-    builder->external();
-}
-
 extern "C" JNIEXPORT jlong JNICALL
 Java_com_google_android_filament_Texture_nBuilderBuild(JNIEnv*, jclass,
        jlong nativeBuilder, jlong nativeEngine) {
@@ -222,20 +222,6 @@ Java_com_google_android_filament_View_nIsFrontFaceWindingInverted(JNIEnv*,
    return static_cast<jboolean>(view->isFrontFaceWindingInverted());
 }

-extern "C" JNIEXPORT void JNICALL
-Java_com_google_android_filament_View_nSetTransparentPickingEnabled(JNIEnv*,
-        jclass, jlong nativeView, jboolean enabled) {
-    View* view = (View*) nativeView;
-    view->setTransparentPickingEnabled(enabled);
-}
-
-extern "C" JNIEXPORT jboolean JNICALL
-Java_com_google_android_filament_View_nIsTransparentPickingEnabled(JNIEnv*,
-        jclass, jlong nativeView) {
-    View* view = (View*) nativeView;
-    return static_cast<jboolean>(view->isTransparentPickingEnabled());
-}
-
 extern "C" JNIEXPORT void JNICALL
 Java_com_google_android_filament_View_nSetAmbientOcclusion(JNIEnv*, jclass, jlong nativeView, jint ordinal) {
    View* view = (View*) nativeView;
@@ -258,17 +258,6 @@ public class Engine {
            return this;
        }

-        /**
-         * Set a feature flag value. This is the only way to set constant feature flags.
-         * @param name feature name
-         * @param value true to enable, false to disable
-         * @return A reference to this Builder for chaining calls.
-         */
-        public Builder feature(@NonNull String name, boolean value) {
-            nSetBuilderFeature(mNativeBuilder, name, value);
-            return this;
-        }
-
        /**
         * Creates an instance of Engine
         *
@@ -404,7 +393,6 @@ public class Engine {
        /**
         * Set to `true` to forcibly disable parallel shader compilation in the backend.
         * Currently only honored by the GL backend.
-         * @Deprecated use "backend.disable_parallel_shader_compile" feature flag instead
         */
        public boolean disableParallelShaderCompile = false;

@@ -445,7 +433,6 @@ public class Engine {

        /**
         * Disable backend handles use-after-free checks.
-         * @Deprecated use "backend.disable_handle_use_after_free_check" feature flag instead
         */
        public boolean disableHandleUseAfterFreeCheck = false;

@@ -482,7 +469,6 @@ public class Engine {
         * Assert the native window associated to a SwapChain is valid when calling makeCurrent().
         * This is only supported for:
         *      - PlatformEGLAndroid
-         * @Deprecated use "backend.opengl.assert_native_window_is_valid" feature flag instead
         */
        public boolean assertNativeWindowIsValid = false;
    }
@@ -707,11 +693,11 @@ public class Engine {

    /**
     * Returns the maximum number of stereoscopic eyes supported by Filament. The actual number of
-     * eyes rendered is set at Engine creation time with the {@link Config#stereoscopicEyeCount}
-     * setting.
+     * eyes rendered is set at Engine creation time with the {@link
+     * Engine#Config#stereoscopicEyeCount} setting.
     *
     * @return the max number of stereoscopic eyes supported
-     * @see Config#stereoscopicEyeCount
+     * @see Engine#Config#stereoscopicEyeCount
     */
    public long getMaxStereoscopicEyes() {
        return nGetMaxStereoscopicEyes(getNativeObject());
@@ -908,8 +894,7 @@ public class Engine {

    /**
     * Returns whether the object is valid.
-     * @param ma Material
-     * @param mi MaterialInstance to check for validity
+     * @param object Object to check for validity
     * @return returns true if the specified object is valid.
     */
    public boolean isValidMaterialInstance(@NonNull Material ma, MaterialInstance mi) {
@@ -1331,39 +1316,6 @@ public class Engine {
     */
    public static native long getSteadyClockTimeNano();

-
-    /**
-     * Checks if a feature flag exists
-     * @param name name of the feature flag to check
-     * @return true if it exists false otherwise
-     */
-    public boolean hasFeatureFlag(@NonNull String name) {
-        return nHasFeatureFlag(mNativeObject, name);
-    }
-
-    /**
-     * Set the value of a non-constant feature flag.
-     * @param name name of the feature flag to set
-     * @param value value to set
-     * @return true if the value was set, false if the feature flag is constant or doesn't exist.
-     */
-    public boolean setFeatureFlag(@NonNull String name, boolean value) {
-        return nSetFeatureFlag(mNativeObject, name, value);
-    }
-
-    /**
-     * Retrieves the value of any feature flag.
-     * @param name name of the feature flag
-     * @return the value of the flag if it exists
-     * @exception IllegalArgumentException is thrown if the feature flag doesn't exist
-     */
-    public boolean getFeatureFlag(@NonNull String name) {
-        if (!hasFeatureFlag(name)) {
-            throw new IllegalArgumentException("The feature flag \"" + name + "\" doesn't exist");
-        }
-        return nGetFeatureFlag(mNativeObject, name);
-    }
-
    @UsedByReflection("TextureHelper.java")
    public long getNativeObject() {
        if (mNativeObject == 0) {
@@ -1453,9 +1405,6 @@ public class Engine {
    private static native int nGetSupportedFeatureLevel(long nativeEngine);
    private static native int nSetActiveFeatureLevel(long nativeEngine, int ordinal);
    private static native int nGetActiveFeatureLevel(long nativeEngine);
-    private static native boolean nHasFeatureFlag(long nativeEngine, String name);
-    private static native boolean nSetFeatureFlag(long nativeEngine, String name, boolean value);
-    private static native boolean nGetFeatureFlag(long nativeEngine, String name);

    private static native long nCreateBuilder();
    private static native void nDestroyBuilder(long nativeBuilder);
@@ -1471,6 +1420,5 @@ public class Engine {
    private static native void nSetBuilderFeatureLevel(long nativeBuilder, int ordinal);
    private static native void nSetBuilderSharedContext(long nativeBuilder, long sharedContext);
    private static native void nSetBuilderPaused(long nativeBuilder, boolean paused);
-    private static native void nSetBuilderFeature(long nativeBuilder, String name, boolean value);
    private static native long nBuilderBuild(long nativeBuilder);
 }
@@ -344,18 +344,9 @@ public class Material {
    }

    public static class Builder {
-        public enum ShadowSamplingQuality {
-            /** 2x2 PCF */
-            HARD,
-            /** 3x3 gaussian filter */
-            LOW,
-        }
-
        private Buffer mBuffer;
        private int mSize;
        private int mShBandCount = 0;
-        private ShadowSamplingQuality mShadowSamplingQuality = ShadowSamplingQuality.LOW;
-

        /**
         * Specifies the material data. The material data is a binary blob produced by
@@ -387,18 +378,6 @@ public class Material {
            return this;
        }

-        /**
-         * Set the quality of shadow sampling. This is only taken into account
-         * if this material is lit and in the surface domain.
-         * @param quality
-         * @return Reference to this Builder for chaining calls.
-         */
-        @NonNull
-        public Builder shadowSamplingQuality(ShadowSamplingQuality quality) {
-            mShadowSamplingQuality = quality;
-            return this;
-        }
-
        /**
         * Creates and returns the Material object.
         *
@@ -411,7 +390,7 @@ public class Material {
        @NonNull
        public Material build(@NonNull Engine engine) {
            long nativeMaterial = nBuilderBuild(engine.getNativeObject(),
-                mBuffer, mSize, mShBandCount, mShadowSamplingQuality.ordinal());
+                mBuffer, mSize, mShBandCount);
            if (nativeMaterial == 0) throw new IllegalStateException("Couldn't create Material");
            return new Material(nativeMaterial);
        }
@@ -1062,7 +1041,7 @@ public class Material {
        mNativeObject = 0;
    }

-    private static native long nBuilderBuild(long nativeEngine, @NonNull Buffer buffer, int size, int shBandCount, int shadowQuality);
+    private static native long nBuilderBuild(long nativeEngine, @NonNull Buffer buffer, int size, int shBandCount);
    private static native long nCreateInstance(long nativeMaterial);
    private static native long nCreateInstanceWithName(long nativeMaterial, @NonNull String name);
    private static native long nGetDefaultInstance(long nativeMaterial);
@@ -800,19 +800,6 @@ public class Texture {
            return this;
        }

-        /**
-         * Creates an external texture. The content must be set using setExternalImage().
-         * The sampler can be SAMPLER_EXTERNAL or SAMPLER_2D depending on the format. Generally
-         * YUV formats must use SAMPLER_EXTERNAL. This depends on the backend features and is not
-         * validated.
-         * @return This Builder, for chaining calls.
-         */
-        @NonNull
-        public Builder external() {
-            nBuilderExternal(mNativeBuilder);
-            return this;
-        }
-
        /**
         * Creates a new <code>Texture</code> instance.
         * @param engine The {@link Engine} to associate this <code>Texture</code> with.
@@ -1274,7 +1261,6 @@ public class Texture {
    private static native void nBuilderUsage(long nativeBuilder, int flags);
    private static native void nBuilderSwizzle(long nativeBuilder, int r, int g, int b, int a);
    private static native void nBuilderImportTexture(long nativeBuilder, long id);
-    private static native void nBuilderExternal(long nativeBuilder);
    private static native long nBuilderBuild(long nativeBuilder, long nativeEngine);

    private static native int nGetWidth(long nativeTexture, int level);
@@ -745,33 +745,6 @@ public class View {
        nSetFrontFaceWindingInverted(getNativeObject(), inverted);
    }

-    /**
-     * Returns true if transparent picking is enabled.
-     *
-     * @see #setTransparentPickingEnabled
-     */
-    public boolean isTransparentPickingEnabled() {
-        return nIsTransparentPickingEnabled(getNativeObject());
-    }
-
-    /**
-     * Enables or disables transparent picking. Disabled by default.
-     *
-     * When transparent picking is enabled, View::pick() will pick from both
-     * transparent and opaque renderables. When disabled, View::pick() will only
-     * pick from opaque renderables.
-     *
-     * <p>
-     * Transparent picking will create an extra pass for rendering depth
-     * from both transparent and opaque renderables. 
-     * </p>
-     *
-     * @param enabled true enables transparent picking, false disables it.
-     */
-    public void setTransparentPickingEnabled(boolean enabled) {
-        nSetTransparentPickingEnabled(getNativeObject(), enabled);
-    }
-
    /**
     * Sets options relative to dynamic lighting for this view.
     *
@@ -1308,8 +1281,6 @@ public class View {
    private static native boolean nIsPostProcessingEnabled(long nativeView);
    private static native void nSetFrontFaceWindingInverted(long nativeView, boolean inverted);
    private static native boolean nIsFrontFaceWindingInverted(long nativeView);
-    private static native void nSetTransparentPickingEnabled(long nativeView, boolean enabled);
-    private static native boolean nIsTransparentPickingEnabled(long nativeView);
    private static native void nSetAmbientOcclusion(long nativeView, int ordinal);
    private static native int nGetAmbientOcclusion(long nativeView);
    private static native void nSetAmbientOcclusionOptions(long nativeView, float radius, float bias, float power, float resolution, float intensity, float bilateralThreshold, int quality, int lowPassFilter, int upsampling, boolean enabled, boolean bentNormals, float minHorizonAngleRad);
@@ -1,5 +1,5 @@
 GROUP=com.google.android.filament
-VERSION_NAME=1.56.6
+VERSION_NAME=1.55.1

 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-8.8-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.6-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
@@ -6,10 +6,6 @@ plugins {

 project.ext.isSample = true

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

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

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

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

        // Tell the view which camera we want to use
        view.camera = camera
@@ -23,8 +23,6 @@ function print_help {
    echo "        This is sometimes needed instead of -c (which still misses some clean steps)."
    echo "    -d"
    echo "        Enable matdbg."
-    echo "    -t"
-    echo "        Enable fgviewer."
    echo "    -f"
    echo "        Always invoke CMake before incremental builds."
    echo "    -g"
@@ -127,27 +125,6 @@ function print_matdbg_help {
    echo ""
 }

-function print_fgviewer_help {
-    echo "fgviewer is enabled in the build, but some extra steps are needed."
-    echo ""
-    echo "FOR DESKTOP BUILDS:"
-    echo ""
-    echo "Please set the port environment variable before launching. e.g., on macOS do:"
-    echo "   export FILAMENT_FGVIEWER_PORT=8085"
-    echo ""
-    echo "FOR ANDROID BUILDS:"
-    echo ""
-    echo "1) For Android Studio builds, make sure to set:"
-    echo "       -Pcom.google.android.filament.fgviewer"
-    echo "   option in Preferences > Build > Compiler > Command line options."
-    echo ""
-    echo "2) The port number is hardcoded to 8085 so you will need to do:"
-    echo "       adb forward tcp:8085 tcp:8085"
-    echo ""
-    echo "3) Be sure to enable INTERNET permission in your app's manifest file."
-    echo ""
-}
-
 # Unless explicitly specified, NDK version will be selected as highest available version within same major release chain
 FILAMENT_NDK_VERSION=${FILAMENT_NDK_VERSION:-$(cat `dirname $0`/build/android/ndk.version | cut -f 1 -d ".")}

@@ -195,7 +172,6 @@ VULKAN_ANDROID_GRADLE_OPTION=""
 EGL_ON_LINUX_OPTION="-DFILAMENT_SUPPORTS_EGL_ON_LINUX=OFF"

 MATDBG_OPTION="-DFILAMENT_ENABLE_MATDBG=OFF"
-FGVIEWER_OPTION="-DFILAMENT_ENABLE_FGVIEWER=OFF"
 MATDBG_GRADLE_OPTION=""

 MATOPT_OPTION=""
@@ -264,7 +240,6 @@ function build_desktop_target {
            -DCMAKE_BUILD_TYPE="$1" \
            -DCMAKE_INSTALL_PREFIX="../${lc_target}/filament" \
            ${EGL_ON_LINUX_OPTION} \
-            ${FGVIEWER_OPTION} \
            ${MATDBG_OPTION} \
            ${MATOPT_OPTION} \
            ${ASAN_UBSAN_OPTION} \
@@ -401,7 +376,6 @@ function build_android_target {
            -DFILAMENT_NDK_VERSION="${FILAMENT_NDK_VERSION}" \
            -DCMAKE_INSTALL_PREFIX="../android-${lc_target}/filament" \
            -DCMAKE_TOOLCHAIN_FILE="../../build/toolchain-${arch}-linux-android.cmake" \
-            ${FGVIEWER_OPTION} \
            ${MATDBG_OPTION} \
            ${MATOPT_OPTION} \
            ${VULKAN_ANDROID_OPTION} \
@@ -639,7 +613,6 @@ function build_ios_target {
            -DPLATFORM_NAME="${platform}" \
            -DIOS=1 \
            -DCMAKE_TOOLCHAIN_FILE=../../third_party/clang/iOS.cmake \
-            ${FGVIEWER_OPTION} \
            ${MATDBG_OPTION} \
            ${MATOPT_OPTION} \
            ${STEREOSCOPIC_OPTION} \
@@ -829,7 +802,7 @@ function check_debug_release_build {

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

-while getopts ":hacCfgijmp:q:uvslwedtk:bx:S:X:" opt; do
+while getopts ":hacCfgijmp:q:uvslwedk:bx:S:X:" opt; do
    case ${opt} in
        h)
            print_help
@@ -850,12 +823,6 @@ while getopts ":hacCfgijmp:q:uvslwedtk:bx:S:X:" opt; do
            MATDBG_OPTION="-DFILAMENT_ENABLE_MATDBG=ON, -DFILAMENT_BUILD_FILAMAT=ON"
            MATDBG_GRADLE_OPTION="-Pcom.google.android.filament.matdbg"
            ;;
-        t)
-            # TODO: Uncomment below when fgviewer is ready
-            # PRINT_FGVIEWER_HELP=true
-            # FGVIEWER_OPTION="-DFILAMENT_ENABLE_FGVIEWER=ON"
-            #FGVIEWER_GRADLE_OPTION="-Pcom.google.android.filament.fgviewer"
-            ;;
        f)
            ISSUE_CMAKE_ALWAYS=true
            ;;
@@ -1060,7 +1027,3 @@ fi
 if [[ "${PRINT_MATDBG_HELP}" == "true" ]]; then
    print_matdbg_help
 fi
-
-if [[ "${PRINT_FGVIEWER_HELP}" == "true" ]]; then
-    print_fgviewer_help
-fi
@@ -1787,12 +1787,7 @@ non-shader data.
      declare a variable called <code>eyeDirection</code> you can access it in the fragment shader using
      <code>variable_eyeDirection</code>. In the vertex shader, the interpolant name is simply a member of
      the <code>MaterialVertexInputs</code> structure (<code>material.eyeDirection</code> in your example). Each
-      interpolant is of type <code>float4</code> (<code>vec4</code>) in the shaders. By default the precision of the
-      interpolant is <code>highp</code> in <em class="asterisk">both</em> the vertex and fragment shaders.
-      An alternate syntax can be used to specify both the name and precision of the interpolant.
-      In this case the specified precision is used as-is in both fragment and vertex stages, in
-      particular if <code>default</code> is specified the default precision is used is the fragment shader
-      (<code>mediump</code>) and in the vertex shader (<code>highp</code>).
+      interpolant is of type <code>float4</code> (<code>vec4</code>) in the shaders.

 </p></dd></dl><p></p><pre class="listing tilde"><code><span class="line">material {</span>
 <span class="line">    name : Skybox,</span>
@@ -1803,11 +1798,7 @@ non-shader data.
 <span class="line">        }</span>
 <span class="line">    ],</span>
 <span class="line">    variables : [</span>
-<span class="line">         eyeDirection,</span>
-<span class="line">         {</span>
-<span class="line">            name : eyeColor,</span>
-<span class="line">            precision : medium</span>
-<span class="line">         }</span>
+<span class="line">         eyeDirection</span>
 <span class="line">    ],</span>
 <span class="line">    vertexDomain : device,</span>
 <span class="line">    depthWrite : <span class="hljs-literal">false</span>,</span>
@@ -308,11 +308,6 @@ if (FILAMENT_ENABLE_MULTIVIEW)
    add_definitions(-DFILAMENT_ENABLE_MULTIVIEW)
 endif()

-# Whether to force the profiling mode.
-if (FILAMENT_FORCE_PROFILING_MODE)
-    add_definitions(-DFILAMENT_FORCE_PROFILING_MODE)
-endif()
-
 # ==================================================================================================
 # Definitions
 # ==================================================================================================
@@ -561,13 +556,6 @@ target_link_libraries(${TARGET} PUBLIC filaflat)
 target_link_libraries(${TARGET} PUBLIC filabridge)
 target_link_libraries(${TARGET} PUBLIC ibl-lite)

-if (FILAMENT_ENABLE_FGVIEWER)
-    target_link_libraries(${TARGET} PUBLIC fgviewer)
-    add_definitions(-DFILAMENT_ENABLE_FGVIEWER=1)
-else()
-    add_definitions(-DFILAMENT_ENABLE_FGVIEWER=0)
-endif()
-
 if (FILAMENT_ENABLE_MATDBG)
    target_link_libraries(${TARGET} PUBLIC matdbg)
    add_definitions(-DFILAMENT_ENABLE_MATDBG=1)
@@ -619,13 +607,6 @@ else()
            -Wover-aligned
            -Werror
    )
-    if (CMAKE_CXX_STANDARD EQUAL 20)
-        # The lambdas for passes in PostProcessManager.cpp capture this
-        # implicitly in a way that's deprecated in c++20, but can't easily be
-        # fixed in a way that's backwards compatible with c++17:
-        # https://www.nextptr.com/tutorial/ta1430524603/capture-this-in-lambda-expression-timeline-of-change
-        list(APPEND FILAMENT_WARNINGS -Wno-deprecated-this-capture)
-    endif()
 endif()

 target_compile_options(${TARGET} PRIVATE
@@ -179,18 +179,11 @@ if (FILAMENT_SUPPORTS_VULKAN)
            src/vulkan/caching/VulkanDescriptorSetManager.h
            src/vulkan/caching/VulkanPipelineLayoutCache.cpp
            src/vulkan/caching/VulkanPipelineLayoutCache.h
-            src/vulkan/memory/ResourceManager.cpp
-            src/vulkan/memory/ResourceManager.h
-            src/vulkan/memory/ResourcePointer.h
-            src/vulkan/memory/Resource.cpp
-            src/vulkan/memory/Resource.h
            src/vulkan/platform/VulkanPlatform.cpp
            src/vulkan/platform/VulkanPlatformSwapChainImpl.cpp
            src/vulkan/platform/VulkanPlatformSwapChainImpl.h
            src/vulkan/spirv/VulkanSpirvUtils.cpp
            src/vulkan/spirv/VulkanSpirvUtils.h
-            src/vulkan/VulkanAsyncHandles.cpp
-            src/vulkan/VulkanAsyncHandles.h
            src/vulkan/VulkanBlitter.cpp
            src/vulkan/VulkanBlitter.h
            src/vulkan/VulkanBuffer.cpp
@@ -221,17 +214,18 @@ if (FILAMENT_SUPPORTS_VULKAN)
            src/vulkan/VulkanSwapChain.h
            src/vulkan/VulkanReadPixels.cpp
            src/vulkan/VulkanReadPixels.h
+            src/vulkan/VulkanResourceAllocator.h
+            src/vulkan/VulkanResources.cpp
+            src/vulkan/VulkanResources.h
            src/vulkan/VulkanTexture.cpp
            src/vulkan/VulkanTexture.h
            src/vulkan/VulkanUtility.cpp
            src/vulkan/VulkanUtility.h
    )
-    if (LINUX OR WIN32)
-        list(APPEND SRCS src/vulkan/platform/VulkanPlatformLinuxWindows.cpp)
+    if (ANDROID OR LINUX OR WIN32)
+        list(APPEND SRCS src/vulkan/platform/VulkanPlatformAndroidLinuxWindows.cpp)
    elseif (APPLE OR IOS)
        list(APPEND SRCS src/vulkan/platform/VulkanPlatformApple.mm)
-    elseif (ANDROID)
-        list(APPEND SRCS src/vulkan/platform/VulkanPlatformAndroid.cpp)
    endif()
 endif()

@@ -390,9 +384,6 @@ else()
            -Wover-aligned
            -Werror
    )
-    if (CMAKE_CXX_STANDARD EQUAL 20)
-        list(APPEND FILAMENT_WARNINGS -Wno-deprecated-this-capture)
-    endif()
 endif()

 if (APPLE)
@@ -227,7 +227,6 @@ enum class DescriptorType : uint8_t {
    SHADER_STORAGE_BUFFER,
    SAMPLER,
    INPUT_ATTACHMENT,
-    SAMPLER_EXTERNAL
 };

 enum class DescriptorFlags : uint8_t {
@@ -319,20 +318,9 @@ struct Viewport {
    int32_t right() const noexcept { return left + int32_t(width); }
    //! get the top coordinate in window space of the viewport
    int32_t top() const noexcept { return bottom + int32_t(height); }
-
-    friend bool operator==(Viewport const& lhs, Viewport const& rhs) noexcept {
-        // clang can do this branchless with xor/or
-        return lhs.left == rhs.left && lhs.bottom == rhs.bottom &&
-               lhs.width == rhs.width && lhs.height == rhs.height;
-    }
-
-    friend bool operator!=(Viewport const& lhs, Viewport const& rhs) noexcept {
-        // clang is being dumb and uses branches
-        return bool(((lhs.left ^ rhs.left) | (lhs.bottom ^ rhs.bottom)) |
-                    ((lhs.width ^ rhs.width) | (lhs.height ^ rhs.height)));
-    }
 };

+
 /**
 * Specifies the mapping of the near and far clipping plane to window coordinates.
 */
@@ -88,7 +88,6 @@ public:
        VkFormat colorFormat = VK_FORMAT_UNDEFINED;
        VkFormat depthFormat = VK_FORMAT_UNDEFINED;
        VkExtent2D extent = {0, 0};
-        bool isProtected = false;
    };

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

-    /**
-     * Check if the surface is protected.
-     * @param handle             The handle returned by createSwapChain()
-     * @return                   Whether the swapchain is protected
-     */
-    virtual bool isProtected(SwapChainPtr handle);
-
    /**
     * Carry out a recreation of the swapchain.
     * @param handle             The handle returned by createSwapChain()
@@ -275,81 +267,8 @@ public:
     */
    VkQueue getGraphicsQueue() const noexcept;

-    /**
-    * @return The family index of the protected graphics queue selected for the
-    *          Vulkan backend.
-    */
-    uint32_t getProtectedGraphicsQueueFamilyIndex() const noexcept;
-
-    /**
-     * @return The index of the protected graphics queue (if there are multiple
-     *          graphics queues) selected for the Vulkan backend.
-     */
-    uint32_t getProtectedGraphicsQueueIndex() const noexcept;
-
-    /**
-     * @return The protected queue that was selected for the Vulkan backend.
-     */
-    VkQueue getProtectedGraphicsQueue() const noexcept;
-
-    struct ExternalImageMetadata {
-        /**
-         * The width of the external image
-         */
-        uint32_t width;
-
-        /**
-         * The height of the external image
-         */
-        uint32_t height;
-
-        /**
-         * The layer count of the external image
-         */
-        uint32_t layers;
-
-        /**
-         * The format of the external image
-         */
-        VkFormat format;
-
-        /**
-         * An external buffer can be protected. This tells you if it is.
-         */
-        bool isProtected;
-
-        /**
-         * The type of external format (opaque int) if used.
-         */
-        uint64_t externalFormat;
-
-        /**
-         * Image usage
-         */
-        VkImageUsageFlags usage;
-
-        /**
-         * Allocation size
-         */
-        VkDeviceSize allocationSize;
-
-        /**
-         * Heap information
-         */
-        uint32_t memoryTypeBits;
-    };
-    virtual ExternalImageMetadata getExternalImageMetadata(void* externalImage);
-
-    using ImageData = std::pair<VkImage, VkDeviceMemory>;
-    virtual ImageData createExternalImage(void* externalImage,
-            const ExternalImageMetadata& metadata);
-
 private:
    static ExtensionSet getSwapchainInstanceExtensions();
-    static ExternalImageMetadata getExternalImageMetadataImpl(void* externalImage,
-            VkDevice device);
-    static ImageData createExternalImageImpl(void* externalImage, VkDevice device,
-            const VkAllocationCallbacks* allocator, const ExternalImageMetadata& metadata);

    // Platform dependent helper methods
    using SurfaceBundle = std::tuple<VkSurfaceKHR, VkExtent2D>;
@@ -214,7 +214,6 @@ DECL_DRIVER_API_R_N(backend::TextureHandle, createTextureViewSwizzle,
        backend::TextureSwizzle, a)

 DECL_DRIVER_API_R_N(backend::TextureHandle, createTextureExternalImage,
-        backend::SamplerType, target,
        backend::TextureFormat, format,
        uint32_t, width,
        uint32_t, height,
@@ -400,6 +399,17 @@ 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,
+        uint32_t, plane)
+
 DECL_DRIVER_API_N(setExternalStream,
        backend::TextureHandle, th,
        backend::StreamHandle, sh)
@@ -24,7 +24,7 @@
    #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3)
        #include "backend/platforms/PlatformEGLAndroid.h"
    #endif
-#elif defined(FILAMENT_IOS)
+#elif defined(IOS)
    #if defined(FILAMENT_SUPPORTS_OPENGL) && !defined(FILAMENT_USE_EXTERNAL_GLES3)
        #include "backend/platforms/PlatformCocoaTouchGL.h"
    #endif
@@ -88,7 +88,7 @@ Platform* PlatformFactory::create(Backend* backend) noexcept {
        *backend = Backend::OPENGL;
 #elif defined(__ANDROID__)
        *backend = Backend::OPENGL;
-#elif defined(FILAMENT_IOS) || defined(__APPLE__)
+#elif defined(IOS) || defined(__APPLE__)
        *backend = Backend::METAL;
 #elif defined(FILAMENT_DRIVER_SUPPORTS_VULKAN)
        *backend = Backend::VULKAN;
@@ -119,7 +119,7 @@ Platform* PlatformFactory::create(Backend* backend) noexcept {
            return nullptr;
        #elif defined(__ANDROID__)
            return new PlatformEGLAndroid();
-        #elif defined(FILAMENT_IOS)
+        #elif defined(IOS)
            return new PlatformCocoaTouchGL();
        #elif defined(__APPLE__)
            return new PlatformCocoaGL();
@@ -1,28 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_SYSTRACEPROFILE_H
-#define TNT_FILAMENT_BACKEND_SYSTRACEPROFILE_H
-
-#include <utils/Systrace.h>
-
-#define PROFILE_SCOPE(marker)       SYSTRACE_NAME(marker)
-
-#define PROFILE_NAME_BEGINFRAME    "backend::beginFrame"
-#define PROFILE_NAME_ENDFRAME      "backend::endFrame"
-
-#endif // TNT_FILAMENT_BACKEND_SYSTRACEPROFILE_H
-
@@ -250,7 +250,7 @@ public:
    // In practice, MetalRingBuffer is used for argument buffers, which are kept in the constant
    // address space. Constant buffers have specific alignment requirements when specifying an
    // offset.
-#if defined(FILAMENT_IOS)
+#if defined(IOS)
 #if TARGET_OS_SIMULATOR
    // The iOS simulator has differing alignment requirements.
    static constexpr auto METAL_CONSTANT_BUFFER_OFFSET_ALIGNMENT = 256;
@@ -135,7 +135,6 @@ struct MetalContext {
    bool supportsTextureSwizzling = false;
    bool supportsAutoDepthResolve = false;
    bool supportsMemorylessRenderTargets = false;
-    bool supportsDepthClamp = false;
    uint8_t maxColorRenderTargets = 4;
    struct {
        uint8_t common;
@@ -155,7 +154,6 @@ struct MetalContext {

    RenderPassFlags currentRenderPassFlags;
    MetalRenderTarget* currentRenderTarget = nullptr;
-    bool validPipelineBound = false;

    // State trackers.
    PipelineStateTracker pipelineState;
@@ -163,7 +161,6 @@ struct MetalContext {
    CullModeStateTracker cullModeState;
    WindingStateTracker windingState;
    DepthClampStateTracker depthClampState;
-    ScissorRectStateTracker scissorRectState;
    Handle<HwRenderPrimitive> currentRenderPrimitive;

    // State caches.
@@ -151,11 +151,6 @@ MetalDriver::MetalDriver(
            mContext->highestSupportedGpuFamily.mac   >= 2;     // newer macOS GPUs
    }

-    mContext->supportsDepthClamp = false;
-    if (@available(macOS 10.11, iOS 11.0, *)) {
-        mContext->supportsDepthClamp = true;
-    }
-
    // In order to support resolve store action on depth attachment, the GPU needs to support it.
    // Note that support for depth resolve implies support for stencil resolve using .sample0 resolve filter.
    // (Other resolve filters are supported starting .apple5 and .mac2 families).
@@ -482,9 +477,7 @@ void MetalDriver::createTextureViewSwizzleR(Handle<HwTexture> th, Handle<HwTextu
    mContext->textures.insert(construct_handle<MetalTexture>(th, *mContext, src, r, g, b, a));
 }

-void MetalDriver::createTextureExternalImageR(Handle<HwTexture> th,
-        backend::SamplerType target,
-        backend::TextureFormat format,
+void MetalDriver::createTextureExternalImageR(Handle<HwTexture> th, backend::TextureFormat format,
        uint32_t width, uint32_t height, backend::TextureUsage usage, void* image) {
    mContext->textures.insert(construct_handle<MetalTexture>(
            th, *mContext, format, width, height, usage, (CVPixelBufferRef)image));
@@ -630,8 +623,6 @@ const char* toString(DescriptorType type) {
            return "SAMPLER";
        case DescriptorType::INPUT_ATTACHMENT:
            return "INPUT_ATTACHMENT";
-        case DescriptorType::SAMPLER_EXTERNAL:
-            return "SAMPLER_EXTERNAL";
    }
 }

@@ -804,20 +795,9 @@ void MetalDriver::destroyRenderPrimitive(Handle<HwRenderPrimitive> rph) {
 }

 void MetalDriver::destroyProgram(Handle<HwProgram> ph) {
-    if (UTILS_UNLIKELY(!ph)) {
-        return;
+    if (ph) {
+        destruct_handle<MetalProgram>(ph);
    }
-    // Remove any cached pipeline states that refer to these programs.
-    auto* metalProgram = handle_cast<MetalProgram>(ph);
-    const auto& functions = metalProgram->getFunctionsIfPresent();
-    if (UTILS_LIKELY(functions.isRaster())) { // only raster pipelines are cached
-        const auto& raster = functions.getRasterFunctions();
-        mContext->pipelineStateCache.removeIf([&](const MetalPipelineState& state) {
-            const auto& [fragment, vertex] = raster;
-            return state.fragmentFunction == fragment || state.vertexFunction == vertex;
-        });
-    }
-    destruct_handle<MetalProgram>(ph);
 }

 void MetalDriver::destroyTexture(Handle<HwTexture> th) {
@@ -839,24 +819,17 @@ void MetalDriver::destroyRenderTarget(Handle<HwRenderTarget> rth) {
 }

 void MetalDriver::destroySwapChain(Handle<HwSwapChain> sch) {
-    if (UTILS_UNLIKELY(!sch)) {
-        return;
-    }
-    auto* swapChain = handle_cast<MetalSwapChain>(sch);
-    if (mContext->currentDrawSwapChain == swapChain) {
-        mContext->currentDrawSwapChain = nullptr;
-    }
-    if (mContext->currentReadSwapChain == swapChain) {
-        mContext->currentReadSwapChain = nullptr;
-    }
-    // If the SwapChain is a pixel buffer, we need to wait for the current command buffer to
-    // complete before destroying it. This is because pixel buffer SwapChains hold a
-    // MetalExternalImage that could still being rendered into.
-    if (UTILS_UNLIKELY(swapChain->isPixelBuffer())) {
-        executeAfterCurrentCommandBufferCompletes(
-                [this, sch]() mutable { destruct_handle<MetalSwapChain>(sch); });
-    } else {
-        destruct_handle<MetalSwapChain>(sch);
+    if (sch) {
+        auto* swapChain = handle_cast<MetalSwapChain>(sch);
+        // If the SwapChain is a pixel buffer, we need to wait for the current command buffer to
+        // complete before destroying it. This is because pixel buffer SwapChains hold a
+        // MetalExternalImage that could still being rendered into.
+        if (UTILS_UNLIKELY(swapChain->isPixelBuffer())) {
+            executeAfterCurrentCommandBufferCompletes(
+                    [this, sch]() mutable { destruct_handle<MetalSwapChain>(sch); });
+        } else {
+            destruct_handle<MetalSwapChain>(sch);
+        }
    }
 }

@@ -879,20 +852,10 @@ void MetalDriver::destroyDescriptorSetLayout(Handle<HwDescriptorSetLayout> dslh)

 void MetalDriver::destroyDescriptorSet(Handle<HwDescriptorSet> dsh) {
    DEBUG_LOG("destroyDescriptorSet(dsh = %d)\n", dsh.getId());
-    if (!dsh) {
-        return;
+    if (dsh) {
+        executeAfterCurrentCommandBufferCompletes(
+                [this, dsh]() mutable { destruct_handle<MetalDescriptorSet>(dsh); });
    }
-
-    // Unbind this descriptor set.
-    auto* descriptorSet = handle_cast<MetalDescriptorSet>(dsh);
-    for (size_t i = 0; i < MAX_DESCRIPTOR_SET_COUNT; i++) {
-        if (UTILS_UNLIKELY(mContext->currentDescriptorSets[i] == descriptorSet)) {
-            mContext->currentDescriptorSets[i] = nullptr;
-        }
-    }
-
-    executeAfterCurrentCommandBufferCompletes(
-            [this, dsh]() mutable { destruct_handle<MetalDescriptorSet>(dsh); });
 }

 void MetalDriver::terminate() {
@@ -909,7 +872,7 @@ void MetalDriver::terminate() {
 }

 ShaderModel MetalDriver::getShaderModel() const noexcept {
-#if defined(FILAMENT_IOS)
+#if defined(IOS)
    return ShaderModel::MOBILE;
 #else
    return ShaderModel::DESKTOP;
@@ -983,7 +946,7 @@ bool MetalDriver::isTextureFormatMipmappable(TextureFormat format) {
        case MTLPixelFormatRGBA16Float:
            return true;

-#if !defined(FILAMENT_IOS)
+#if !defined(IOS)
        // Mipmappable only on desktop:
        case MTLPixelFormatR32Float:
        case MTLPixelFormatRG32Float:
@@ -991,7 +954,7 @@ bool MetalDriver::isTextureFormatMipmappable(TextureFormat format) {
            return true;
 #endif

-#if defined(FILAMENT_IOS)
+#if defined(IOS)
        // Mipmappable only on iOS:
        case MTLPixelFormatRGB9E5Float:
            return true;
@@ -1070,7 +1033,7 @@ bool MetalDriver::isProtectedTexturesSupported() {
 }

 bool MetalDriver::isDepthClampSupported() {
-    return mContext->supportsDepthClamp;
+    return true;
 }

 bool MetalDriver::isWorkaroundNeeded(Workaround workaround) {
@@ -1193,6 +1156,10 @@ void MetalDriver::setupExternalImage(void* image) {
    CVPixelBufferRetain(pixelBuffer);
 }

+void MetalDriver::setExternalImage(Handle<HwTexture> th, void* image) {}
+
+void MetalDriver::setExternalImagePlane(Handle<HwTexture> th, void* image, uint32_t plane) {}
+
 void MetalDriver::setExternalStream(Handle<HwTexture> th, Handle<HwStream> sh) {
 }

@@ -1260,8 +1227,6 @@ void MetalDriver::beginRenderPass(Handle<HwRenderTarget> rth,
    mContext->depthStencilState.invalidate();
    mContext->cullModeState.invalidate();
    mContext->windingState.invalidate();
-    mContext->scissorRectState.invalidate();
-    mContext->depthClampState.invalidate();
    mContext->currentPolygonOffset = {0.0f, 0.0f};

    mContext->finalizedDescriptorSets.clear();
@@ -1364,7 +1329,7 @@ void MetalDriver::startCapture(int) {
    if (@available(iOS 13, *)) {
        MTLCaptureDescriptor* descriptor = [MTLCaptureDescriptor new];
        descriptor.captureObject = mContext->device;
-#if defined(FILAMENT_IOS)
+#if defined(IOS)
        descriptor.destination = MTLCaptureDestinationDeveloperTools;
 #else
        descriptor.destination = MTLCaptureDestinationGPUTraceDocument;
@@ -1428,7 +1393,7 @@ void MetalDriver::readPixels(Handle<HwRenderTarget> src, uint32_t x, uint32_t y,
                                                               width:srcTextureSize.width
                                                              height:srcTextureSize.height
                                                           mipmapped:NO];
-#if defined(FILAMENT_IOS)
+#if defined(IOS)
    textureDescriptor.storageMode = MTLStorageModeShared;
 #else
    textureDescriptor.storageMode = MTLStorageModeManaged;
@@ -1447,7 +1412,7 @@ void MetalDriver::readPixels(Handle<HwRenderTarget> src, uint32_t x, uint32_t y,

    mContext->blitter->blit(getPendingCommandBuffer(mContext), args, "readPixels blit");

-#if !defined(FILAMENT_IOS)
+#if !defined(IOS)
    // Managed textures on macOS require explicit synchronization between GPU / CPU.
    id <MTLBlitCommandEncoder> blitEncoder = [getPendingCommandBuffer(mContext) blitCommandEncoder];
    [blitEncoder synchronizeResource:readPixelsTexture];
@@ -1655,7 +1620,6 @@ void MetalDriver::bindPipeline(PipelineState const& ps) {
    // during the draw call when the program is invalid. The shader compile error has already been
    // dumped to the console at this point, so it's fine to simply return early.
    if (FILAMENT_ENABLE_MATDBG && UTILS_UNLIKELY(!functions)) {
-        mContext->validPipelineBound = false;
        return;
    }

@@ -1734,12 +1698,10 @@ void MetalDriver::bindPipeline(PipelineState const& ps) {
    }

    // depth clip mode
-    if (mContext->supportsDepthClamp) {
-        MTLDepthClipMode depthClipMode = rs.depthClamp ? MTLDepthClipModeClamp : MTLDepthClipModeClip;
-        mContext->depthClampState.updateState(depthClipMode);
-        if (mContext->depthClampState.stateChanged()) {
-            [mContext->currentRenderPassEncoder setDepthClipMode:depthClipMode];
-        }
+    MTLDepthClipMode depthClipMode = rs.depthClamp ? MTLDepthClipModeClamp : MTLDepthClipModeClip;
+    mContext->depthClampState.updateState(depthClipMode);
+    if (mContext->depthClampState.stateChanged()) {
+        [mContext->currentRenderPassEncoder setDepthClipMode:depthClipMode];
    }

    // Set the depth-stencil state, if a state change is needed.
@@ -1788,8 +1750,6 @@ void MetalDriver::bindPipeline(PipelineState const& ps) {
                                                   clamp:0.0];
        mContext->currentPolygonOffset = ps.polygonOffset;
    }
-
-    mContext->validPipelineBound = true;
 }

 void MetalDriver::bindRenderPrimitive(Handle<HwRenderPrimitive> rph) {
@@ -1833,16 +1793,6 @@ void MetalDriver::bindDescriptorSet(
        backend::DescriptorSetHandle dsh,
        backend::descriptor_set_t set,
        backend::DescriptorSetOffsetArray&& offsets) {
-
-    if (UTILS_UNLIKELY(!dsh)) {
-        DEBUG_LOG("bindDescriptorSet(dsh = null, set = %d, offsets = [])\n", set);
-        mContext->currentDescriptorSets[set] = nullptr;
-        mContext->vertexDescriptorBindings.setBuffer(nil, 0, set);
-        mContext->fragmentDescriptorBindings.setBuffer(nil, 0, set);
-        mContext->dynamicOffsets.setOffsets(set, nullptr, 0);
-        return;
-    }
-
    auto descriptorSet = handle_cast<MetalDescriptorSet>(dsh);
    const size_t dynamicBindings = descriptorSet->layout->getDynamicOffsetCount();
    utils::FixedCapacityVector<size_t> offsetsVector(dynamicBindings, 0);
@@ -1887,10 +1837,6 @@ void MetalDriver::draw2(uint32_t indexOffset, uint32_t indexCount, uint32_t inst
            << "draw() without a valid command encoder.";
    DEBUG_LOG("draw2(...)\n");

-    if (FILAMENT_ENABLE_MATDBG && UTILS_UNLIKELY(!mContext->validPipelineBound)) {
-        return;
-    }
-
    // Bind the offset data.
    if (mContext->dynamicOffsets.isDirty()) {
        const auto [size, data] = mContext->dynamicOffsets.getOffsets();
@@ -2007,11 +1953,7 @@ void MetalDriver::scissor(Viewport scissorBox) {
            .height = static_cast<NSUInteger>(bottom - top)
    };

-    auto& srs = mContext->scissorRectState;
-    srs.updateState(scissorRect);
-    if (srs.stateChanged()) {
-        [mContext->currentRenderPassEncoder setScissorRect:scissorRect];
-    }
+    [mContext->currentRenderPassEncoder setScissorRect:scissorRect];
 }

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

 constexpr inline MTLVertexFormat getMetalFormat(ElementType type, bool normalized) noexcept {
@@ -196,7 +195,7 @@ inline MTLPixelFormat getMetalFormatLinear(MTLPixelFormat format) {
        case MTLPixelFormatRG8Unorm_sRGB: return MTLPixelFormatRG8Unorm;
        case MTLPixelFormatRGBA8Unorm_sRGB: return MTLPixelFormatRGBA8Unorm;
        case MTLPixelFormatBGRA8Unorm_sRGB: return MTLPixelFormatBGRA8Unorm;
-#if !defined(FILAMENT_IOS)
+#if !defined(IOS)
        case MTLPixelFormatBC1_RGBA_sRGB: return MTLPixelFormatBC1_RGBA;
        case MTLPixelFormatBC2_RGBA_sRGB: return MTLPixelFormatBC2_RGBA;
        case MTLPixelFormatBC3_RGBA_sRGB: return MTLPixelFormatBC3_RGBA;
@@ -268,7 +267,7 @@ constexpr inline bool isMetalFormatStencil(MTLPixelFormat format) {
        case MTLPixelFormatStencil8:
        case MTLPixelFormatDepth32Float_Stencil8:
        case MTLPixelFormatX32_Stencil8:
-#if !defined(FILAMENT_IOS)
+#if !defined(IOS)
        case MTLPixelFormatDepth24Unorm_Stencil8:
        case MTLPixelFormatX24_Stencil8:
 #endif
@@ -202,7 +202,6 @@ public:
    MetalProgram(MetalContext& context, Program&& program) noexcept;

    const MetalShaderCompiler::MetalFunctionBundle& getFunctions();
-    const MetalShaderCompiler::MetalFunctionBundle& getFunctionsIfPresent() const;

 private:
    void initialize();
@@ -438,7 +437,7 @@ struct MetalTimerQuery : public HwTimerQuery {

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

    std::shared_ptr<Status> status;
@@ -157,7 +157,7 @@ id<MTLTexture> MetalSwapChain::acquireDrawable() {
        textureDescriptor.height = headlessHeight;
        // Specify MTLTextureUsageShaderRead so the headless surface can be blitted from.
        textureDescriptor.usage = MTLTextureUsageRenderTarget | MTLTextureUsageShaderRead;
-#if defined(FILAMENT_IOS)
+#if defined(IOS)
        textureDescriptor.storageMode = MTLStorageModeShared;
 #else
        textureDescriptor.storageMode = MTLStorageModeManaged;
@@ -495,10 +495,6 @@ const MetalShaderCompiler::MetalFunctionBundle& MetalProgram::getFunctions() {
    return mFunctionBundle;
 }

-const MetalShaderCompiler::MetalFunctionBundle& MetalProgram::getFunctionsIfPresent() const {
-    return mFunctionBundle;
-}
-
 void MetalProgram::initialize() {
    if (!mToken) {
        return;
@@ -520,7 +516,7 @@ MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t le
    const BOOL mipmapped = levels > 1;
    const BOOL multisampled = samples > 1;

-#if defined(FILAMENT_IOS)
+#if defined(IOS)
    const BOOL textureArray = target == SamplerType::SAMPLER_2D_ARRAY;
    FILAMENT_CHECK_PRECONDITION(!textureArray || !multisampled)
            << "iOS does not support multisampled texture arrays.";
@@ -533,7 +529,7 @@ MetalTexture::MetalTexture(MetalContext& context, SamplerType target, uint8_t le
        switch (target) {
            case SamplerType::SAMPLER_2D:
                return MTLTextureType2DMultisample;
-#if !defined(FILAMENT_IOS)
+#if !defined(IOS)
            case SamplerType::SAMPLER_2D_ARRAY:
                return MTLTextureType2DMultisampleArray;
 #endif
@@ -856,7 +852,7 @@ void MetalTexture::loadWithBlit(uint32_t level, uint32_t slice, MTLRegion region
    descriptor.height = region.size.height;
    descriptor.depth = region.size.depth;

-#if defined(FILAMENT_IOS)
+#if defined(IOS)
    descriptor.storageMode = MTLStorageModeShared;
 #else
    descriptor.storageMode = MTLStorageModeManaged;
@@ -1294,8 +1290,7 @@ id<MTLArgumentEncoder> MetalDescriptorSetLayout::getArgumentEncoderSlow(id<MTLDe
                [arguments addObject:bufferArgument];
                break;
            }
-            case DescriptorType::SAMPLER:
-            case DescriptorType::SAMPLER_EXTERNAL: {
+            case DescriptorType::SAMPLER: {
                MTLArgumentDescriptor* textureArgument = [MTLArgumentDescriptor argumentDescriptor];
                textureArgument.index = binding.binding * 2;
                textureArgument.dataType = MTLDataTypeTexture;
@@ -1410,8 +1405,7 @@ id<MTLBuffer> MetalDescriptorSet::finalizeAndGetBuffer(MetalDriver* driver, Shad
                           atIndex:binding.binding * 2];
                break;
            }
-            case DescriptorType::SAMPLER:
-            case DescriptorType::SAMPLER_EXTERNAL: {
+            case DescriptorType::SAMPLER: {
                auto found = textures.find(binding.binding);
                if (found == textures.end()) {
                    [encoder setTexture:driver->mContext->emptyTexture atIndex:binding.binding * 2];
@@ -37,7 +37,7 @@ Driver* MetalPlatform::createDriver(void* /*sharedContext*/, const Platform::Dri
 id<MTLDevice> MetalPlatform::createDevice() noexcept {
    id<MTLDevice> result;

-#if !defined(FILAMENT_IOS)
+#if !defined(IOS)
    const bool forceIntegrated =
            NSProcessInfo.processInfo.environment[@"FILAMENT_FORCE_INTEGRATED_GPU"] != nil;
    if (forceIntegrated) {
@@ -83,10 +83,6 @@ public:
            return std::get<Compute>(mPrograms);
        }

-        bool isRaster() const { return std::holds_alternative<Raster>(mPrograms); }
-
-        bool isCompute() const { return std::holds_alternative<Compute>(mPrograms); }
-
        static MetalFunctionBundle none() {
            return MetalFunctionBundle(None{});
        }
@@ -226,11 +226,9 @@ MetalShaderCompiler::program_token_t MetalShaderCompiler::createProgram(
            CompilerPriorityQueue const priorityQueue = program.getPriorityQueue();
            mCompilerThreadPool.queue(priorityQueue, token,
                    [this, name, device = mDevice, program = std::move(program), token]() {
-                        @autoreleasepool {
-                            MetalFunctionBundle compiledProgram = compileProgram(program, device);
-                            token->set(compiledProgram);
-                            mCallbackManager.put(token->handle);
-                        }
+                        MetalFunctionBundle compiledProgram = compileProgram(program, device);
+                        token->set(compiledProgram);
+                        mCallbackManager.put(token->handle);
                    });

            break;
@@ -28,9 +28,7 @@

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

 namespace filament {
 namespace backend {
@@ -162,8 +160,6 @@ template<typename StateType,
         typename HashFn = utils::hash::MurmurHashFn<StateType>>
 class StateCache {

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

    StateCache() = default;
@@ -173,18 +169,6 @@ public:

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

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

@@ -212,7 +196,7 @@ private:
    StateCreator creator;
    id<MTLDevice> mDevice = nil;

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

 };

@@ -220,8 +204,9 @@ private:
 // Different kinds of state, like pipeline state, uniform buffer state, etc., are passed to the
 // current Metal command encoder and persist throughout the lifetime of the encoder (a frame).
 // StateTracker is used to prevent calling redundant state change methods.
-template <typename StateType, typename StateEqual = std::equal_to<StateType>>
+template<typename StateType>
 class StateTracker {
+
 public:

    // Call to force the state to dirty at the beginning of each frame, as all state must be
@@ -229,7 +214,7 @@ public:
    void invalidate() noexcept { mStateDirty = true; }

    void updateState(const StateType& newState) noexcept {
-        if (!StateEqual()(mCurrentState, newState)) {
+        if (mCurrentState != newState) {
            mCurrentState = newState;
            mStateDirty = true;
        }
@@ -250,6 +235,7 @@ private:

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

 // Pipeline state
@@ -357,16 +343,6 @@ using DepthStencilStateTracker = StateTracker<DepthStencilState>;
 using DepthStencilStateCache = StateCache<DepthStencilState, id<MTLDepthStencilState>,
        DepthStateCreator>;

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

 class MetalBufferObject;
@@ -150,7 +150,7 @@ id<MTLSamplerState> SamplerStateCreator::operator()(id<MTLDevice> device,
                MTLCompareFunctionNever : getCompareFunction(params.compareFunc);
    samplerDescriptor.supportArgumentBuffers = YES;

-#if defined(FILAMENT_IOS)
+#if defined(IOS)
    // Older Apple devices (and the simulator) don't support setting a comparison function in
    // MTLSamplerDescriptor.
    // In practice, this means shadows are not supported when running in the simulator.
@@ -32,7 +32,7 @@ Dispatcher NoopDriver::getDispatcher() const noexcept {
 }

 ShaderModel NoopDriver::getShaderModel() const noexcept {
-#if defined(__ANDROID__) || defined(FILAMENT_IOS) || defined(__EMSCRIPTEN__)
+#if defined(__ANDROID__) || defined(IOS) || defined(__EMSCRIPTEN__)
    return ShaderModel::MOBILE;
 #else
    return ShaderModel::DESKTOP;
@@ -265,6 +265,12 @@ TimerQueryResult NoopDriver::getTimerQueryValue(Handle<HwTimerQuery> tqh, uint64
    return TimerQueryResult::ERROR;
 }

+void NoopDriver::setExternalImage(Handle<HwTexture> th, void* image) {
+}
+
+void NoopDriver::setExternalImagePlane(Handle<HwTexture> th, void* image, uint32_t plane) {
+}
+
 void NoopDriver::setExternalStream(Handle<HwTexture> th, Handle<HwStream> sh) {
 }

@@ -69,9 +69,7 @@ public:
        assert_invariant(set < MAX_DESCRIPTOR_SET_COUNT);
        assert_invariant(binding < MAX_DESCRIPTOR_COUNT);
        assert_invariant(entry.binding < 128); // we reserve 1 bit for the type right now
-        mStorage[set][binding] = { (uint8_t)entry.binding,
-                                   entry.type == DescriptorType::SAMPLER ||
-                                   entry.type == DescriptorType::SAMPLER_EXTERNAL };
+        mStorage[set][binding] = { (uint8_t)entry.binding, entry.type == DescriptorType::SAMPLER };
        mActiveDescriptors[set].set(binding);
    }

@@ -96,7 +96,6 @@ GLDescriptorSet::GLDescriptorSet(OpenGLContext& gl, DescriptorSetLayoutHandle ds
                break;
            }
            case DescriptorType::SAMPLER:
-            case DescriptorType::SAMPLER_EXTERNAL:
                if (UTILS_UNLIKELY(gl.isES2())) {
                    desc.emplace<SamplerGLES2>();
                } else {
@@ -173,7 +172,6 @@ void GLDescriptorSet::update(OpenGLContext& gl,

            arg.target = t ? t->gl.target : 0;
            arg.id = t ? t->gl.id : 0;
-            arg.external = t ? t->gl.external :  false;
            if constexpr (std::is_same_v<T, Sampler> ||
                          std::is_same_v<T, SamplerWithAnisotropyWorkaround>) {
                if constexpr (std::is_same_v<T, SamplerWithAnisotropyWorkaround>) {
@@ -286,7 +284,7 @@ void GLDescriptorSet::bind(
            } 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, arg.external);
+                    gl.bindTexture(unit, arg.target, arg.id);
                    gl.bindSampler(unit, arg.sampler);
                    if (UTILS_UNLIKELY(arg.ref)) {
                        updateTextureView(gl, handleAllocator, unit, arg);
@@ -297,7 +295,7 @@ void GLDescriptorSet::bind(
            } 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, arg.external);
+                    gl.bindTexture(unit, arg.target, arg.id);
                    gl.bindSampler(unit, arg.sampler);
                    if (UTILS_UNLIKELY(arg.ref)) {
                        updateTextureView(gl, handleAllocator, unit, arg);
@@ -315,7 +313,7 @@ void GLDescriptorSet::bind(
                // 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, arg.external);
+                    gl.bindTexture(unit, arg.target, arg.id);
                    SamplerParams const params = arg.params;
                    glTexParameteri(arg.target, GL_TEXTURE_MIN_FILTER,
                            (GLint)GLUtils::getTextureFilter(params.filterMin));
@@ -111,9 +111,7 @@ private:

    // A sampler descriptor
    struct Sampler {
-        uint16_t target;                        // 2 (GLenum)
-        bool external = false;                  // 1
-        bool reserved = false;                  // 1
+        GLenum target = 0;                      // 4
        GLuint id = 0;                          // 4
        GLuint sampler = 0;                     // 4
        Handle<GLTextureRef> ref;               // 4
@@ -128,9 +126,7 @@ private:
    };

    struct SamplerWithAnisotropyWorkaround {
-        uint16_t target;                        // 2 (GLenum)
-        bool external = false;                  // 1
-        bool reserved = false;                  // 1
+        GLenum target = 0;                      // 4
        GLuint id = 0;                          // 4
        GLuint sampler = 0;                     // 4
        Handle<GLTextureRef> ref;               // 4
@@ -147,9 +143,7 @@ private:

    // A sampler descriptor for ES2
    struct SamplerGLES2 {
-        uint16_t target;                        // 2 (GLenum)
-        bool external = false;                  // 1
-        bool reserved = false;                  // 1
+        GLenum target = 0;                      // 4
        GLuint id = 0;                          // 4
        SamplerParams params{};                 // 4
        float anisotropy = 1.0f;                // 4
@@ -35,7 +35,7 @@ struct GLTextureRef {
    GLTextureRef() = default;
    // view reference counter
    uint16_t count = 1;
-    // Current per-view values of the texture (in GL we can only have a single View active at
+    // current per-view values of the texture (in GL we can only have a single View active at
    // a time, and this tracks that state). It's used to avoid unnecessarily change state.
    int8_t baseLevel = 127;
    int8_t maxLevel = -1;
@@ -50,7 +50,7 @@ struct GLTextureRef {
 struct GLTexture : public HwTexture {
    using HwTexture::HwTexture;
    struct GL {
-        GL() noexcept : imported(false), external(false), sidecarSamples(1), reserved1(0) {}
+        GL() noexcept : imported(false), sidecarSamples(1), reserved1(0) {}
        GLuint id = 0;          // texture or renderbuffer id
        GLenum target = 0;
        GLenum internalFormat = 0;
@@ -62,8 +62,7 @@ struct GLTexture : public HwTexture {
        int8_t maxLevel = -1;
        uint8_t reserved0 = 0;
        bool imported           : 1;
-        bool external           : 1;
-        uint8_t sidecarSamples  : 3;
+        uint8_t sidecarSamples  : 4;
        uint8_t reserved1       : 3;
        std::array<TextureSwizzle, 4> swizzle{
                TextureSwizzle::CHANNEL_0,
@@ -408,7 +408,7 @@ void OpenGLContext::initProcs(Procs* procs,
    procs->maxShaderCompilerThreadsKHR = +[](GLuint) {};

 #ifdef BACKEND_OPENGL_VERSION_GLES
-#   ifndef FILAMENT_IOS // FILAMENT_IOS is guaranteed to have ES3.x
+#   ifndef IOS // IOS is guaranteed to have ES3.x
 #       ifndef __EMSCRIPTEN__
    if (UTILS_UNLIKELY(major == 2)) {
        // Runtime OpenGL version is ES 2.x
@@ -438,7 +438,7 @@ void OpenGLContext::initProcs(Procs* procs,
        procs->maxShaderCompilerThreadsKHR = glMaxShaderCompilerThreadsKHR;
    }
 #       endif // __EMSCRIPTEN__
-#   endif // FILAMENT_IOS
+#   endif // IOS
 #else
    procs->maxShaderCompilerThreadsKHR = glMaxShaderCompilerThreadsARB;
 #endif
@@ -500,13 +500,11 @@ void OpenGLContext::initBugs(Bugs* bugs, Extensions const& exts,
            // qualcomm seems to have no problem with this (which is good for us)
            bugs->allow_read_only_ancillary_feedback_loop = true;

-#ifndef __EMSCRIPTEN__
            // Older Adreno devices that support ES3.0 only tend to be extremely buggy, so we
            // fall back to ES2.0.
            if (major == 3 && minor == 0) {
                bugs->force_feature_level0 = true;
            }
-#endif
        } else if (strstr(renderer, "Mali")) {
            // ARM GPU
            bugs->vao_doesnt_store_element_array_buffer_binding = true;
@@ -576,14 +574,14 @@ void OpenGLContext::initBugs(Bugs* bugs, Extensions const& exts,
    }

 #ifdef BACKEND_OPENGL_VERSION_GLES
-#   ifndef FILAMENT_IOS // FILAMENT_IOS is guaranteed to have ES3.x
+#   ifndef IOS // IOS is guaranteed to have ES3.x
    if (UTILS_UNLIKELY(major == 2)) {
        if (UTILS_UNLIKELY(!exts.OES_vertex_array_object)) {
            // we activate this workaround path, which does the reset of array buffer
            bugs->vao_doesnt_store_element_array_buffer_binding = true;
        }
    }
-#   endif // FILAMENT_IOS
+#   endif // IOS
 #else
    // feedback loops are allowed on GL desktop as long as writes are disabled
    bugs->allow_read_only_ancillary_feedback_loop = true;
@@ -616,25 +614,27 @@ FeatureLevel OpenGLContext::resolveFeatureLevel(GLint major, GLint minor,
                featureLevel = FeatureLevel::FEATURE_LEVEL_2;
                if (gets.max_texture_image_units >= MAX_FRAGMENT_SAMPLER_COUNT &&
                    gets.max_combined_texture_image_units >=
-                            (MAX_FRAGMENT_SAMPLER_COUNT + MAX_VERTEX_SAMPLER_COUNT)) {
+                    (MAX_FRAGMENT_SAMPLER_COUNT + MAX_VERTEX_SAMPLER_COUNT)) {
                    featureLevel = FeatureLevel::FEATURE_LEVEL_3;
                }
            }
        }
    }
-#   ifndef FILAMENT_IOS // FILAMENT_IOS is guaranteed to have ES3.x
+#   ifndef IOS // IOS is guaranteed to have ES3.x
    else if (UTILS_UNLIKELY(major == 2)) {
        // Runtime OpenGL version is ES 2.x
-        // note: mandatory extensions (all supported by Mali-400 and Adreno 304)
-        //      OES_depth_texture
-        //      OES_depth24
-        //      OES_packed_depth_stencil
-        //      OES_rgb8_rgba8
-        //      OES_standard_derivatives
-        //      OES_texture_npot
+#       if defined(BACKEND_OPENGL_LEVEL_GLES30)
+        // mandatory extensions (all supported by Mali-400 and Adreno 304)
+        assert_invariant(exts.OES_depth_texture);
+        assert_invariant(exts.OES_depth24);
+        assert_invariant(exts.OES_packed_depth_stencil);
+        assert_invariant(exts.OES_rgb8_rgba8);
+        assert_invariant(exts.OES_standard_derivatives);
+        assert_invariant(exts.OES_texture_npot);
+#       endif
        featureLevel = FeatureLevel::FEATURE_LEVEL_0;
    }
-#   endif // FILAMENT_IOS
+#   endif // IOS
 #else
    assert_invariant(gets.max_texture_image_units >= 16);
    assert_invariant(gets.max_combined_texture_image_units >= 32);
@@ -131,7 +131,7 @@ public:
    }

    inline bool isES2() const noexcept {
-#if defined(BACKEND_OPENGL_VERSION_GLES) && !defined(FILAMENT_IOS)
+#if defined(BACKEND_OPENGL_VERSION_GLES) && !defined(IOS)
 #   ifndef BACKEND_OPENGL_LEVEL_GLES30
            return true;
 #   else
@@ -153,7 +153,7 @@ public:

          void pixelStore(GLenum, GLint) noexcept;
    inline void activeTexture(GLuint unit) noexcept;
-    inline void bindTexture(GLuint unit, GLuint target, GLuint texId, bool external) noexcept;
+    inline void bindTexture(GLuint unit, GLuint target, GLuint texId) noexcept;

           void unbindTexture(GLenum target, GLuint id) noexcept;
           void unbindTextureUnit(GLuint unit) noexcept;
@@ -761,9 +761,7 @@ void OpenGLContext::bindBufferRange(GLenum target, GLuint index, GLuint buffer,
 #endif
 }

-void OpenGLContext::bindTexture(GLuint unit, GLuint target, GLuint texId, bool external) noexcept {
-    //  another texture is bound to the same unit with a different target,
-    //  unbind the texture from the current target
+void OpenGLContext::bindTexture(GLuint unit, GLuint target, GLuint texId) noexcept {
    update_state(state.textures.units[unit].target, target, [&]() {
        activeTexture(unit);
        glBindTexture(state.textures.units[unit].target, 0);
@@ -771,7 +769,7 @@ void OpenGLContext::bindTexture(GLuint unit, GLuint target, GLuint texId, bool e
    update_state(state.textures.units[unit].id, texId, [&]() {
        activeTexture(unit);
        glBindTexture(target, texId);
-    }, external);
+    }, target == GL_TEXTURE_EXTERNAL_OES);
 }

 void OpenGLContext::useProgram(GLuint program) noexcept {
@@ -23,7 +23,6 @@
 #include "OpenGLDriverFactory.h"
 #include "OpenGLProgram.h"
 #include "OpenGLTimerQuery.h"
-#include "SystraceProfile.h"
 #include "gl_headers.h"

 #include <backend/platforms/OpenGLPlatform.h>
@@ -92,47 +91,24 @@
 #define DEBUG_GROUP_MARKER_NONE       0x00    // no debug marker
 #define DEBUG_GROUP_MARKER_OPENGL     0x01    // markers in the gl command queue (req. driver support)
 #define DEBUG_GROUP_MARKER_BACKEND    0x02    // markers on the backend side (systrace)
-#define DEBUG_GROUP_MARKER_ALL        0xFF    // all markers
+#define DEBUG_GROUP_MARKER_ALL        0x03    // all markers

 #define DEBUG_MARKER_NONE             0x00    // no debug marker
 #define DEBUG_MARKER_OPENGL           0x01    // markers in the gl command queue (req. driver support)
 #define DEBUG_MARKER_BACKEND          0x02    // markers on the backend side (systrace)
-#define DEBUG_MARKER_PROFILE          0x04    // profiling on the backend side (systrace)
-#define DEBUG_MARKER_ALL              (0xFF & ~DEBUG_MARKER_PROFILE) // all markers
+#define DEBUG_MARKER_ALL              0x03    // all markers

 // set to the desired debug marker level (for user markers [default: All])
 #define DEBUG_GROUP_MARKER_LEVEL      DEBUG_GROUP_MARKER_ALL

 // set to the desired debug level (for internal debugging [Default: None])
-#define DEBUG_MARKER_LEVEL            DEBUG_MARKER_NONE
+#define DEBUG_MARKER_LEVEL      DEBUG_MARKER_NONE

-// Override the debug markers if we are forcing profiling mode
-#if defined(FILAMENT_FORCE_PROFILING_MODE)
-#   undef DEBUG_GROUP_MARKER_LEVEL
-#   undef DEBUG_MARKER_LEVEL
-
-#   define DEBUG_GROUP_MARKER_LEVEL   DEBUG_GROUP_MARKER_NONE
-#   define DEBUG_MARKER_LEVEL         DEBUG_MARKER_PROFILE
-#endif
-
-#if DEBUG_MARKER_LEVEL == DEBUG_MARKER_PROFILE
-#   define DEBUG_MARKER()
-#   define PROFILE_MARKER(marker) PROFILE_SCOPE(marker);
-#   if DEBUG_GROUP_MARKER_LEVEL != DEBUG_GROUP_MARKER_NONE
-#      error PROFILING is exclusive; group markers must be disabled.
-#   endif
-#   ifndef NDEBUG
-#      error PROFILING is meaningless in DEBUG mode.
-#   endif
-#elif DEBUG_MARKER_LEVEL > DEBUG_MARKER_NONE
-#   define DEBUG_MARKER() DebugMarker _debug_marker(*this, __func__);
-#   define PROFILE_MARKER(marker) DEBUG_MARKER()
-#   if DEBUG_MARKER_LEVEL & DEBUG_MARKER_PROFILE
-#      error PROFILING is exclusive; all other debug features must be disabled.
-#   endif
+#if DEBUG_MARKER_LEVEL > DEBUG_MARKER_NONE
+#   define DEBUG_MARKER() \
+        DebugMarker _debug_marker(*this, __func__);
 #else
 #   define DEBUG_MARKER()
-#   define PROFILE_MARKER(marker)
 #endif

 using namespace filament::math;
@@ -402,25 +378,28 @@ void OpenGLDriver::setPushConstant(backend::ShaderStage stage, uint8_t index,

 void OpenGLDriver::bindTexture(GLuint unit, GLTexture const* t) noexcept {
    assert_invariant(t != nullptr);
-    mContext.bindTexture(unit, t->gl.target, t->gl.id, t->gl.external);
+    mContext.bindTexture(unit, t->gl.target, t->gl.id);
 }

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

-            mBoundProgram = p;
-        }
+    // compile/link the program if needed and call glUseProgram
+    bool const success = p->use(this, mContext);
+    assert_invariant(success == p->isValid());
+  
+    if (success) {
+        // TODO: we could even improve this if the program could tell us which of the descriptors
+        //       bindings actually changed. In practice, it is likely that set 0 or 1 might not
+        //       change often.
+        decltype(mInvalidDescriptorSetBindings) changed;
+        changed.setValue((1 << MAX_DESCRIPTOR_SET_COUNT) - 1);
+        mInvalidDescriptorSetBindings |= changed;
+
+        mBoundProgram = p;
    }

    if (UTILS_UNLIKELY(mContext.isES2() && success)) {
@@ -1052,49 +1031,17 @@ void OpenGLDriver::createTextureViewSwizzleR(Handle<HwTexture> th, Handle<HwText
    CHECK_GL_ERROR(utils::slog.e)
 }

-void OpenGLDriver::createTextureExternalImageR(Handle<HwTexture> th, SamplerType target,
-    TextureFormat format, uint32_t width, uint32_t height, TextureUsage usage, void* image) {
-    DEBUG_MARKER()
-
-    usage |= TextureUsage::SAMPLEABLE;
-    usage &= ~TextureUsage::UPLOADABLE;
-
-    auto& gl = mContext;
-    GLenum internalFormat = getInternalFormat(format);
-    if (UTILS_UNLIKELY(gl.isES2())) {
-        // on ES2, format and internal format must match
-        // FIXME: handle compressed texture format
-        internalFormat = textureFormatToFormatAndType(format).first;
-    }
-    assert_invariant(internalFormat);
-
-    GLTexture* const t = construct<GLTexture>(th, target, 1, 1, width, height, 1, format, usage);
-    assert_invariant(t);
-
-    t->externalTexture = mPlatform.createExternalImageTexture();
-    if (t->externalTexture) {
-        t->gl.target = t->externalTexture->target;
-        t->gl.id = t->externalTexture->id;
-        // internalFormat actually depends on the external image, but it doesn't matter
-        // because it's not used anywhere for anything important.
-        t->gl.internalFormat = internalFormat;
-        t->gl.baseLevel = 0;
-        t->gl.maxLevel = 0;
-        t->gl.external = true; // forces bindTexture() call (they're never cached)
-    }
-
-    bindTexture(OpenGLContext::DUMMY_TEXTURE_BINDING, t);
-    if (mPlatform.setExternalImage(image, t->externalTexture)) {
-        // the target and id can be reset each time
-        t->gl.target = t->externalTexture->target;
-        t->gl.id = t->externalTexture->id;
-    }
+void OpenGLDriver::createTextureExternalImageR(Handle<HwTexture> th, backend::TextureFormat format,
+        uint32_t width, uint32_t height, backend::TextureUsage usage, void* image) {
+    createTextureR(th, SamplerType::SAMPLER_EXTERNAL, 1, format, 1, width, height, 1, usage);
+    setExternalImage(th, image);
 }

 void OpenGLDriver::createTextureExternalImagePlaneR(Handle<HwTexture> th,
        backend::TextureFormat format, uint32_t width, uint32_t height, backend::TextureUsage usage,
        void* image, uint32_t plane) {
-    // not relevant for the OpenGL backend
+    createTextureR(th, SamplerType::SAMPLER_EXTERNAL, 1, format, 1, width, height, 1, usage);
+    setExternalImagePlane(th, image, plane);
 }

 void OpenGLDriver::importTextureR(Handle<HwTexture> th, intptr_t id,
@@ -1114,7 +1061,6 @@ void OpenGLDriver::importTextureR(Handle<HwTexture> th, intptr_t id,
    switch (target) {
        case SamplerType::SAMPLER_EXTERNAL:
            t->gl.target = GL_TEXTURE_EXTERNAL_OES;
-            t->gl.external = true; // forces bindTexture() call (they're never cached)
            break;
        case SamplerType::SAMPLER_2D:
            t->gl.target = GL_TEXTURE_2D;
@@ -1381,13 +1327,13 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,
 #ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2

                // TODO: support multiview for iOS and WebGL
-#if !defined(__EMSCRIPTEN__) && !defined(FILAMENT_IOS)
+#if !defined(__EMSCRIPTEN__) && !defined(IOS)
                if (layerCount > 1) {
                    // if layerCount > 1, it means we use the multiview extension.
                    glFramebufferTextureMultiviewOVR(GL_FRAMEBUFFER, attachment,
                        t->gl.id, 0, binfo.layer, layerCount);
                } else
-#endif // !defined(__EMSCRIPTEN__) && !defined(FILAMENT_IOS)
+#endif // !defined(__EMSCRIPTEN__) && !defined(IOS)
                {
                    // GL_TEXTURE_2D_MULTISAMPLE_ARRAY is not supported in GLES
                    glFramebufferTextureLayer(GL_FRAMEBUFFER, attachment,
@@ -1715,7 +1661,7 @@ void OpenGLDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow,

    // See if we need the emulated rec709 output conversion
    if (UTILS_UNLIKELY(mContext.isES2())) {
-        sc->rec709 = ((flags & SWAP_CHAIN_CONFIG_SRGB_COLORSPACE) &&
+        sc->rec709 = (flags & SWAP_CHAIN_CONFIG_SRGB_COLORSPACE &&
                !mPlatform.isSRGBSwapChainSupported());
    }
 }
@@ -2807,6 +2753,25 @@ void OpenGLDriver::setupExternalImage(void* image) {
    mPlatform.retainExternalImage(image);
 }

+void OpenGLDriver::setExternalImage(Handle<HwTexture> th, void* image) {
+    DEBUG_MARKER()
+    GLTexture* t = handle_cast<GLTexture*>(th);
+    assert_invariant(t);
+    assert_invariant(t->target == SamplerType::SAMPLER_EXTERNAL);
+
+    bindTexture(OpenGLContext::DUMMY_TEXTURE_BINDING, t);
+    if (mPlatform.setExternalImage(image, t->externalTexture)) {
+        // the target and id can be reset each time
+        t->gl.target = t->externalTexture->target;
+        t->gl.id = t->externalTexture->id;
+        bindTexture(OpenGLContext::DUMMY_TEXTURE_BINDING, t);
+    }
+}
+
+void OpenGLDriver::setExternalImagePlane(Handle<HwTexture> th, void* image, uint32_t plane) {
+    DEBUG_MARKER()
+}
+
 void OpenGLDriver::setExternalStream(Handle<HwTexture> th, Handle<HwStream> sh) {
    auto& gl = mContext;
    if (gl.ext.OES_EGL_image_external_essl3) {
@@ -3483,7 +3448,7 @@ void OpenGLDriver::beginFrame(
        UTILS_UNUSED int64_t monotonic_clock_ns,
        UTILS_UNUSED int64_t refreshIntervalNs,
        UTILS_UNUSED uint32_t frameId) {
-    PROFILE_MARKER(PROFILE_NAME_BEGINFRAME)
+    DEBUG_MARKER()
    auto& gl = mContext;
    insertEventMarker("beginFrame");
    mPlatform.beginFrame(monotonic_clock_ns, refreshIntervalNs, frameId);
@@ -3518,7 +3483,7 @@ void OpenGLDriver::setPresentationTime(int64_t monotonic_clock_ns) {
 }

 void OpenGLDriver::endFrame(UTILS_UNUSED uint32_t frameId) {
-    PROFILE_MARKER(PROFILE_NAME_ENDFRAME)
+    DEBUG_MARKER()
 #if defined(__EMSCRIPTEN__)
    // WebGL builds are single-threaded so users might manipulate various GL state after we're
    // done with the frame. We do NOT officially support using Filament in this way, but we can
@@ -3526,7 +3491,7 @@ void OpenGLDriver::endFrame(UTILS_UNUSED uint32_t frameId) {
    auto& gl = mContext;
    gl.bindVertexArray(nullptr);
    for (int unit = OpenGLContext::DUMMY_TEXTURE_BINDING; unit >= 0; unit--) {
-        gl.bindTexture(unit, GL_TEXTURE_2D, 0, false);
+        gl.bindTexture(unit, GL_TEXTURE_2D, 0);
    }
    gl.disable(GL_CULL_FACE);
    gl.depthFunc(GL_LESS);
@@ -3910,14 +3875,6 @@ void OpenGLDriver::bindDescriptorSet(
        backend::DescriptorSetHandle dsh,
        backend::descriptor_set_t set,
        backend::DescriptorSetOffsetArray&& offsets) {
-
-    if (UTILS_UNLIKELY(!dsh)) {
-        mBoundDescriptorSets[set].dsh = dsh;
-        mInvalidDescriptorSetBindings.set(set, true);
-        mInvalidDescriptorSetBindingOffsets.set(set, true);
-        return;
-    }
-
    // handle_cast<> here also serves to validate the handle (it actually cannot return nullptr)
    GLDescriptorSet const* const ds = handle_cast<GLDescriptorSet*>(dsh);
    if (ds) {
@@ -174,8 +174,7 @@ void OpenGLProgram::initializeProgramState(OpenGLContext& context, GLuint progra
                    }
                    break;
                }
-                case DescriptorType::SAMPLER:
-                case DescriptorType::SAMPLER_EXTERNAL: {
+                case DescriptorType::SAMPLER: {
                    if (!entry.name.empty()) {
                        GLint const loc = glGetUniformLocation(program, entry.name.c_str());
                        if (loc >= 0) {
@@ -255,9 +254,7 @@ void OpenGLProgram::updateUniforms(
    for (size_t i = 0, c = records.uniforms.size(); i < c; i++) {
        Program::Uniform const& u = records.uniforms[i];
        GLint const loc = records.locations[i];
-        // mRec709Location is special, it is handled by setRec709ColorSpace() and the corresponding
-        // entry in `buffer` is typically not initialized, so we skip it.
-        if (loc < 0 || loc == mRec709Location) {
+        if (loc < 0) {
            continue;
        }
        // u.offset is in 'uint32_t' units
@@ -56,7 +56,7 @@
    #   define FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
    #endif

-#elif defined(FILAMENT_IOS)
+#elif defined(IOS)

    #define GLES_SILENCE_DEPRECATION

@@ -81,7 +81,7 @@
 #if defined(GL_VERSION_4_5)
 #elif defined(GL_ES_VERSION_3_1)
 #elif defined(GL_ES_VERSION_3_0)
-#   if !defined(FILAMENT_IOS) && !defined(__EMSCRIPTEN__)
+#   if !defined(IOS) && !defined(__EMSCRIPTEN__)
 #       error "GLES 3.0 headers only supported on iOS and WebGL2"
 #   endif
 #elif defined(GL_ES_VERSION_2_0)
@@ -98,7 +98,7 @@

 #if defined(GL_ES_VERSION_2_0)  // this basically means all versions of GLES

-#if defined(FILAMENT_IOS)
+#if defined(IOS)

 // iOS headers only provide prototypes, nothing to do.

@@ -271,7 +271,7 @@ void glGetBufferSubData(GLenum target, GLintptr offset, GLsizeiptr size, void *d
 #endif

 #ifdef GL_ES_VERSION_2_0
-#   ifndef FILAMENT_IOS
+#   ifndef IOS
 #      ifndef GL_OES_vertex_array_object
 #          error "Headers with GL_OES_vertex_array_object are mandatory unless on iOS"
 #      endif
@@ -715,16 +715,14 @@ void PlatformEGL::destroyExternalImage(ExternalTexture* texture) noexcept {

 bool PlatformEGL::setExternalImage(void* externalImage,
        UTILS_UNUSED_IN_RELEASE ExternalTexture* texture) noexcept {
-
-    // OES_EGL_image_external_essl3 must be present if the target is TEXTURE_EXTERNAL_OES
-    // GL_OES_EGL_image must be present if TEXTURE_2D is used
-
-#if defined(GL_OES_EGL_image) || defined(GL_OES_EGL_image_external_essl3)
+    if (UTILS_LIKELY(ext.gl.OES_EGL_image_external_essl3)) {
+        assert_invariant(texture->target == GL_TEXTURE_EXTERNAL_OES);
        // the texture is guaranteed to be bound here.
-        glEGLImageTargetTexture2DOES(texture->target,
+#ifdef GL_OES_EGL_image
+        glEGLImageTargetTexture2DOES(GL_TEXTURE_EXTERNAL_OES,
                static_cast<GLeglImageOES>(externalImage));
 #endif
-
+    }
    return true;
 }

@@ -64,14 +64,10 @@ public:
                break;
            }
        }
-        if (mLib) {
-            OSMesaGetProcAddress = (GetProcAddressFunc) dlsym(mLib, "OSMesaGetProcAddress");
-        } else {
-            OSMesaGetProcAddress = (GetProcAddressFunc) dlsym(RTLD_LOCAL, "OSMesaGetProcAddress");
-        }
+        FILAMENT_CHECK_PRECONDITION(mLib)
+                << "Unable to dlopen libOSMesa to create a software GL context";

-        FILAMENT_CHECK_PRECONDITION(OSMesaGetProcAddress)
-                << "Unable to against libOSMesa to create a software GL context";
+        OSMesaGetProcAddress = (GetProcAddressFunc) dlsym(mLib, "OSMesaGetProcAddress");

        OSMesaCreateContext = (CreateContextFunc) OSMesaGetProcAddress("OSMesaCreateContext");
        OSMesaDestroyContext =
@@ -80,9 +76,7 @@ public:
    }

    ~OSMesaAPI() {
-        if (mLib) {
-            dlclose(mLib);
-        }
+        dlclose(mLib);
    }
 private:
    void* mLib = nullptr;
@@ -19,8 +19,8 @@
 #include <Wingdi.h>

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

 namespace {

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

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

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

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

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

 	// We have to match pixel formats across the HDC and HGLRC (mContext)
@@ -270,10 +264,8 @@ bool PlatformWGL::makeCurrent(ContextType type, SwapChain* drawSwapChain,
    HDC hdc = wglSwapChain->hDc;
    if (hdc != NULL) {
        BOOL success = wglMakeCurrent(hdc, mContext);
-        if (!success) {
-            DWORD dwError = GetLastError();
-            ASSERT_POSTCONDITION_NON_FATAL(success, "wglMakeCurrent() failed. hdc = %p", hdc);
-            reportWindowsError(dwError);
+        if (!ASSERT_POSTCONDITION_NON_FATAL(success, "wglMakeCurrent() failed. hdc = %p", hdc)) {
+            reportLastWindowsError();
            wglMakeCurrent(0, NULL);
        }
    }
@@ -1,43 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "VulkanAsyncHandles.h"
-
-namespace filament::backend {
-
-VulkanTimerQuery::VulkanTimerQuery(std::tuple<uint32_t, uint32_t> indices)
-    : mStartingQueryIndex(std::get<0>(indices)),
-      mStoppingQueryIndex(std::get<1>(indices)) {}
-
-void VulkanTimerQuery::setFence(std::shared_ptr<VulkanCmdFence> fence) noexcept {
-    std::unique_lock<utils::Mutex> lock(mFenceMutex);
-    mFence = fence;
-}
-
-bool VulkanTimerQuery::isCompleted() noexcept {
-    std::unique_lock<utils::Mutex> lock(mFenceMutex);
-    // QueryValue is a synchronous call and might occur before beginTimerQuery has written anything
-    // into the command buffer, which is an error according to the validation layer that ships in
-    // the Android NDK.  Even when AVAILABILITY_BIT is set, validation seems to require that the
-    // timestamp has at least been written into a processed command buffer.
-
-    // This fence indicates that the corresponding buffer has been completed.
-    return mFence && mFence->getStatus() == VK_SUCCESS;
-}
-
-VulkanTimerQuery::~VulkanTimerQuery() = default;
-
-} // namespace filament::backend
@@ -1,81 +0,0 @@
-/*
- * Copyright (C) 2024 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_VULKANASYNCHANDLES_H
-#define TNT_FILAMENT_BACKEND_VULKANASYNCHANDLES_H
-
-#include <bluevk/BlueVK.h>
-
-#include "DriverBase.h"
-
-#include "vulkan/memory/Resource.h"
-
-#include <utils/Mutex.h>
-#include <utils/Condition.h>
-
-namespace filament::backend {
-
-// Wrapper to enable use of shared_ptr for implementing shared ownership of low-level Vulkan fences.
-struct VulkanCmdFence {
-    VulkanCmdFence(VkResult initialStatus) {
-        // Internally we use the VK_INCOMPLETE status to mean "not yet submitted". When this fence
-        // gets submitted, its status changes to VK_NOT_READY. Finally, when the GPU actually
-        // finishes executing the command buffer, the status changes to VK_SUCCESS.
-        status.store(initialStatus);
-    }
-
-    ~VulkanCmdFence() = default;
-
-    void setStatus(VkResult value) { status.store(value); }
-
-    VkResult getStatus() { return status.load(std::memory_order_acquire); }
-
-private:
-    std::atomic<VkResult> status;
-};
-
-struct VulkanFence : public HwFence, fvkmemory::ThreadSafeResource {
-    VulkanFence() {}
-    std::shared_ptr<VulkanCmdFence> fence;
-};
-
-struct VulkanTimerQuery : public HwTimerQuery, fvkmemory::ThreadSafeResource {
-    explicit VulkanTimerQuery(std::tuple<uint32_t, uint32_t> indices);
-    ~VulkanTimerQuery();
-
-    void setFence(std::shared_ptr<VulkanCmdFence> fence) noexcept;
-
-    bool isCompleted() noexcept;
-
-    uint32_t getStartingQueryIndex() const {
-        return mStartingQueryIndex;
-    }
-
-    uint32_t getStoppingQueryIndex() const {
-        return mStoppingQueryIndex;
-    }
-
-private:
-    uint32_t mStartingQueryIndex;
-    uint32_t mStoppingQueryIndex;
-
-    std::shared_ptr<VulkanCmdFence> mFence;
-    utils::Mutex mFenceMutex;
-};
-
-} // namespace filament::backend
-
-#endif // TNT_FILAMENT_BACKEND_VULKANHASYNCANDLES_H
@@ -126,7 +126,8 @@ struct BlitterUniforms {
 }// anonymous namespace

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

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

@@ -150,8 +151,7 @@ void VulkanBlitter::resolve(VulkanAttachment dst, VulkanAttachment src) {
    }
 #endif

-    VulkanCommandBuffer& commands = dst.texture->getIsProtected() ?
-            mCommands->getProtected() : mCommands->get();
+    VulkanCommandBuffer& commands = mCommands->get();
    commands.acquire(src.texture);
    commands.acquire(dst.texture);
    resolveFast(&commands, aspect, src, dst);
@@ -176,8 +176,7 @@ void VulkanBlitter::blit(VkFilter filter,
 #endif
    // src and dst should have the same aspect here
    VkImageAspectFlags const aspect = src.texture->getImageAspect();
-    VulkanCommandBuffer& commands = dst.texture->getIsProtected() ?
-            mCommands->getProtected() : mCommands->get();
+    VulkanCommandBuffer& commands = mCommands->get();
    commands.acquire(src.texture);
    commands.acquire(dst.texture);
    blitFast(&commands, aspect, filter, src, dst, srcRectPair, dstRectPair);
@@ -33,194 +33,275 @@ using namespace utils;

 namespace filament::backend {

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

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

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

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

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

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

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

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

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

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

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

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

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

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

-    mFenceStatus->setStatus(VK_NOT_READY);
-    UTILS_UNUSED_IN_RELEASE VkResult result =
-        vkQueueSubmit(mQueue, 1, &submitInfo, mFence);
+    int8_t const index = mCurrentCommandBufferIndex;
+    VulkanCommandBuffer const* currentbuf = mStorage[index].get();
+    VkSemaphore const renderingFinished = mSubmissionSignals[index];
+
+    vkEndCommandBuffer(currentbuf->buffer());
+
+    // If the injected semaphore is an "image available" semaphore that has not yet been signaled,
+    // it is sometimes fine to start executing commands anyway, as along as we stall the GPU at the
+    // VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT stage. However we need to assume the worst
+    // here and use VK_PIPELINE_STAGE_ALL_COMMANDS_BIT. This is a more aggressive stall, but it is
+    // the only safe option because the previously submitted command buffer might have set up some
+    // state that the new command buffer depends on.
+    VkPipelineStageFlags waitDestStageMasks[2] = {
+            VK_PIPELINE_STAGE_ALL_COMMANDS_BIT,
+            VK_PIPELINE_STAGE_ALL_COMMANDS_BIT,
+    };
+
+    VkSemaphore signals[2] = {
+            VK_NULL_HANDLE,
+            VK_NULL_HANDLE,
+    };
+    uint32_t waitSemaphoreCount = 0;
+    if (mSubmissionSignal) {
+        signals[waitSemaphoreCount++] = mSubmissionSignal;
+    }
+    if (mInjectedSignal) {
+        signals[waitSemaphoreCount++] = mInjectedSignal;
+    }
+    VkCommandBuffer const cmdbuffer = currentbuf->buffer();
+    VkSubmitInfo submitInfo{
+            .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
+            .waitSemaphoreCount = waitSemaphoreCount,
+            .pWaitSemaphores = waitSemaphoreCount > 0 ? signals : nullptr,
+            .pWaitDstStageMask = waitDestStageMasks,
+            .commandBufferCount = 1,
+            .pCommandBuffers = &cmdbuffer,
+            .signalSemaphoreCount = 1u,
+            .pSignalSemaphores = &renderingFinished,
+    };
+
+#if FVK_ENABLED(FVK_DEBUG_COMMAND_BUFFER)
+    FVK_LOGI << "Submitting cmdbuffer=" << cmdbuffer
+           << " wait=(" << signals[0] << ", " << signals[1] << ") "
+           << " signal=" << renderingFinished
+           << " fence=" << currentbuf->fence->fence
+           << utils::io::endl;
+#endif
+
+    auto& cmdfence = currentbuf->fence;
+    UTILS_UNUSED_IN_RELEASE VkResult result = VK_SUCCESS;
+    {
+        auto scope = cmdfence->setValue(VK_NOT_READY);
+        result = vkQueueSubmit(mQueue, 1, &submitInfo, cmdfence->getFence());
+    }

 #if FVK_ENABLED(FVK_DEBUG_COMMAND_BUFFER)
    if (result != VK_SUCCESS) {
@@ -228,298 +309,176 @@ VkSemaphore VulkanCommandBuffer::submit() {
    }
 #endif
    assert_invariant(result == VK_SUCCESS);
-    mWaitSemaphores.clear();
-    return mSubmission;
-}
-
-CommandBufferPool::CommandBufferPool(VulkanContext* context, VkDevice device, VkQueue queue,
-        uint8_t queueFamilyIndex, bool isProtected)
-    : mDevice(device),
-      mRecording(INVALID) {
-    VkCommandPoolCreateInfo createInfo = {
-        .sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO,
-        .flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT |
-                 VK_COMMAND_POOL_CREATE_TRANSIENT_BIT |
-                (isProtected ? VK_COMMAND_POOL_CREATE_PROTECTED_BIT : 0u),
-        .queueFamilyIndex = queueFamilyIndex,
-    };
-    vkCreateCommandPool(device, &createInfo, VKALLOC, &mPool);
-
-    for (size_t i = 0; i < CAPACITY; ++i) {
-        mBuffers.emplace_back(
-                std::make_unique<VulkanCommandBuffer>(context, device, queue, mPool, isProtected));
-    }
-}
-
-CommandBufferPool::~CommandBufferPool() {
-    wait();
-    gc();
-    vkDestroyCommandPool(mDevice, mPool, VKALLOC);
-}
-
-VulkanCommandBuffer& CommandBufferPool::getRecording() {
-    if (isRecording()) {
-        return *mBuffers[mRecording];
-    }
-
-    auto const findNext = [this]() {
-        for (int8_t i = 0; i < CAPACITY; ++i) {
-            if (!mSubmitted[i]) {
-                return i;
-            }
-        }
-        return INVALID;
-    };
-
-    while ((mRecording = findNext()) == INVALID) {
-        wait();
-        gc();
-    }
-
-    auto& recording = *mBuffers[mRecording];
-    recording.begin();
-
-#if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
-    if (mGroupMarkers) {
-        std::unique_ptr<VulkanGroupMarkers> markers = std::make_unique<VulkanGroupMarkers>();
-        while (!mGroupMarkers->empty()) {
-            auto [marker, timestamp] = mGroupMarkers->pop_bottom();
-            recording.pushMarker(marker.c_str());
-            markers->push(marker, timestamp);
-        }
-        std::swap(mGroupMarkers, markers);
-    }
-#endif
-
-    return recording;
-}
-
-void CommandBufferPool::gc() {
-    ActiveBuffers reclaimed;
-    mSubmitted.forEachSetBit([this,&reclaimed] (size_t index) {
-        auto& buffer = mBuffers[index];
-        if (buffer->getStatus() == VK_SUCCESS) {
-            reclaimed.set(index, true);
-            buffer->reset();
-        }
-    });
-    mSubmitted &= ~reclaimed;
-}
-
-void CommandBufferPool::update() {
-    mSubmitted.forEachSetBit([this] (size_t index) {
-        auto& buffer = mBuffers[index];
-        VkResult status = vkGetFenceStatus(mDevice, buffer->getVkFence());
-        if (status == VK_SUCCESS) {
-            buffer->setComplete();
-        }
-    });
-}
-
-VkSemaphore CommandBufferPool::flush() {
-    // We're not recording right now.
-    if (!isRecording()) {
-        return VK_NULL_HANDLE;
-    }
-    auto submitSemaphore = mBuffers[mRecording]->submit();
-    mSubmitted.set(mRecording, true);
-    mRecording = INVALID;
-    return submitSemaphore;
-}
-
-void CommandBufferPool::wait() {
-    uint8_t count = 0;
-    VkFence fences[CAPACITY];
-    mSubmitted.forEachSetBit([this, &count, &fences] (size_t index) {
-        fences[count++] = mBuffers[index]->getVkFence();
-    });
-    vkWaitForFences(mDevice, count, fences, VK_TRUE, UINT64_MAX);
-    update();
-}
-
-void CommandBufferPool::waitFor(VkSemaphore previousAction) {
-    if (!isRecording()) {
-        return;
-    }
-    auto& recording = mBuffers[mRecording];
-    recording->insertWait(previousAction);
-}
-
-#if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
-std::string CommandBufferPool::topMarker() const {
-    if (!mGroupMarkers || mGroupMarkers->empty()) {
-        return "";
-    }
-    return std::get<0>(mGroupMarkers->top());
-}
-
-void CommandBufferPool::pushMarker(char const* marker, VulkanGroupMarkers::Timestamp timestamp) {
-    if (!mGroupMarkers) {
-        mGroupMarkers = std::make_unique<VulkanGroupMarkers>();
-    }
-    mGroupMarkers->push(marker, timestamp);
-    getRecording().pushMarker(marker);
-}
-
-std::pair<std::string, VulkanGroupMarkers::Timestamp> CommandBufferPool::popMarker() {
-    assert_invariant(mGroupMarkers && !mGroupMarkers->empty());
-    auto ret = mGroupMarkers->pop();
-
-    // Note that if we're popping a marker while not recording, we would just pop the conceptual
-    // stack of marker (i.e. mGroupMarkers) and not carry out the pop on the command buffer.
-    if (isRecording()) {
-        getRecording().popMarker();
-    }
-    return ret;
-}
-
-void CommandBufferPool::insertEvent(char const* marker) {
-    getRecording().insertEvent(marker);
-}
-#endif // FVK_DEBUG_GROUP_MARKERS
-
-VulkanCommands::VulkanCommands(VkDevice device, VkQueue queue, uint32_t queueFamilyIndex,
-        VkQueue protectedQueue, uint32_t protectedQueueFamilyIndex, VulkanContext* context)
-    : mDevice(device),
-      mProtectedQueue(protectedQueue),
-      mProtectedQueueFamilyIndex(protectedQueueFamilyIndex),
-      mContext(context),
-      mPool(std::make_unique<CommandBufferPool>(context, device, queue, queueFamilyIndex, false)) {}
-
-void VulkanCommands::terminate() {
-    mPool.reset();
-    mProtectedPool.reset();
-}
-
-VulkanCommandBuffer& VulkanCommands::get() {
-    auto& ret = mPool->getRecording();
-    return ret;
-}
-
-VulkanCommandBuffer& VulkanCommands::getProtected() {
-    assert_invariant(mProtectedQueue != VK_NULL_HANDLE);
-
-    if (!mProtectedPool) {
-        mProtectedPool = std::make_unique<CommandBufferPool>(mContext, mDevice, mProtectedQueue,
-                mProtectedQueueFamilyIndex, true);
-    }
-    auto& ret = mProtectedPool->getRecording();
-    return ret;
-}
-
-bool VulkanCommands::flush() {
-    // It's possible to call flush and wait at "terminate", in which case, we'll just return.
-    if (!mPool && !mProtectedPool) {
-        return false;
-    }
-
-    VkSemaphore dependency = mInjectedDependency;
-    VkSemaphore lastSubmit = mLastSubmit;
-    bool hasFlushed = false;
-
-    // Note that we've ordered it so that the non-protected commands are followed by the protected
-    // commands.  This assumes that the protected commands will be that one doing the rendering into
-    // the protected memory (i.e. protected render target).
-    for (auto pool: {mPool.get(), mProtectedPool.get()}) {
-        if (!pool || !pool->isRecording()) {
-            continue;
-        }
-        if (dependency != VK_NULL_HANDLE) {
-            pool->waitFor(dependency);
-        }
-        if (lastSubmit != VK_NULL_HANDLE) {
-            pool->waitFor(lastSubmit);
-            lastSubmit = VK_NULL_HANDLE;
-        }
-        dependency = pool->flush();
-        hasFlushed = true;
-    }
-
-    if (hasFlushed) {
-        mInjectedDependency = VK_NULL_HANDLE;
-        mLastSubmit = dependency;
-    }

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

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

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

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

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

 #if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)

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

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

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

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

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

@@ -21,10 +21,8 @@

 #include "DriverBase.h"

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

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

 namespace filament::backend {

-using namespace fvkmemory;
-
 struct VulkanContext;

 #if FVK_ENABLED(FVK_DEBUG_GROUP_MARKERS)
@@ -51,122 +47,111 @@ public:
    void push(std::string const& marker, Timestamp start = {}) noexcept;
    std::pair<std::string, Timestamp> pop() noexcept;
    std::pair<std::string, Timestamp> pop_bottom() noexcept;
-    std::pair<std::string, Timestamp> const& top() const;
+    std::pair<std::string, Timestamp> top() const;
    bool empty() const noexcept;

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

 #endif // FVK_DEBUG_GROUP_MARKERS

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

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

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

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

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

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

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

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

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

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

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

 // Manages a set of command buffers and semaphores, exposing an API that is significantly simpler
@@ -180,6 +165,9 @@ private:
 //    - This creates a guarantee of in-order execution.
 //    - Semaphores are recycled to prevent create / destroy churn.
 //
+// - Notifies listeners when recording begins in a new VkCommandBuffer.
+//    - Used by PipelineCache so that it knows when to clear out its shadow state.
+//
 // - Allows 1 user to inject a "dependency" semaphore that stalls the next flush.
 //    - This is used for asynchronous acquisition of a swap chain image, since the GPU
 //      might require a valid swap chain image when it starts executing the command buffer.
@@ -195,17 +183,13 @@ private:
 class VulkanCommands {
 public:
    VulkanCommands(VkDevice device, VkQueue queue, uint32_t queueFamilyIndex,
-            VkQueue protectedQueue, uint32_t protectedQueueFamilyIndex, VulkanContext* context);
+            VulkanContext* context, VulkanResourceAllocator* allocator);

    void terminate();

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

-    // Creates a "current" protected capable command buffer if none exists, otherwise
-    // returns the current one.
-    VulkanCommandBuffer& getProtected();
-
    // Submits the current command buffer if it exists, then sets "current" to null.
    // If there are no outstanding commands then nothing happens and this returns false.
    bool flush();
@@ -213,17 +197,11 @@ public:
    // Returns the "rendering finished" semaphore for the most recent flush and removes
    // it from the existing dependency chain. This is especially useful for setting up
    // vkQueuePresentKHR.
-    VkSemaphore acquireFinishedSignal() {
-        VkSemaphore ret= mLastSubmit;
-        mLastSubmit = VK_NULL_HANDLE;
-        return ret;
-    }
+    VkSemaphore acquireFinishedSignal();

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

    // Destroys all command buffers that are no longer in use.
    void gc();
@@ -234,25 +212,42 @@ public:
    // Updates the atomic "status" variable in every extant fence.
    void updateFences();

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

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

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

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

 } // namespace filament::backend
@@ -1,7 +1,7 @@
 /*
 * Copyright (C) 2021 The Android Open Source Project
 *
- * Licensed under the Apache License, Version 2.0 (the "License");
+* Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
@@ -63,7 +63,7 @@
 #define FVK_DEBUG_SHADER_MODULE           0x00000800
 #define FVK_DEBUG_READ_PIXELS             0x00001000
 #define FVK_DEBUG_PIPELINE_CACHE          0x00002000
-#define FVK_DEBUG_STAGING_ALLOCATION      0x00004000
+#define FVK_DEBUG_ALLOCATION              0x00004000

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

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

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

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

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

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

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

 // end shorthands

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

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

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

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

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

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

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

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

 using namespace bluevk;

+using utils::FixedCapacityVector;
+
+
 namespace {

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

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

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

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

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

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

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

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

    bool isDepth() const;
    VkImage getImage() const;
@@ -72,11 +70,9 @@ public:
    std::tuple<uint32_t, uint32_t> getNextQuery();
    void clearQuery(uint32_t queryIndex);

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

 private:
    VkDevice mDevice;
@@ -86,9 +82,7 @@ private:
 };

 struct VulkanRenderPass {
-    // Between the begin and end command render pass we cache the command buffer
-    VulkanCommandBuffer* commandBuffer;
-    fvkmemory::resource_ptr<VulkanRenderTarget> renderTarget;
+    VulkanRenderTarget* renderTarget;
    VkRenderPass renderPass;
    RenderPassParams params;
    int currentSubpass;
@@ -99,9 +93,6 @@ struct VulkanRenderPass {
 struct VulkanContext {
 public:
    inline uint32_t selectMemoryType(uint32_t flags, VkFlags reqs) const {
-        if ((reqs & VK_MEMORY_PROPERTY_PROTECTED_BIT) != 0) {
-            assert_invariant(isProtectedMemorySupported() == true);
-        }
        for (uint32_t i = 0; i < VK_MAX_MEMORY_TYPES; i++) {
            if (flags & 1) {
                if ((mMemoryProperties.memoryTypes[i].propertyFlags & reqs) == reqs) {
@@ -122,19 +113,19 @@ public:
    }

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

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

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

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

    inline bool isDebugMarkersSupported() const noexcept {
@@ -150,30 +141,21 @@ public:
    }

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

    inline bool isLazilyAllocatedMemorySupported() const noexcept {
        return mLazilyAllocatedMemorySupported;
    }

-    inline bool isProtectedMemorySupported() const noexcept {
-        return mProtectedMemorySupported;
-    }
-
 private:
    VkPhysicalDeviceMemoryProperties mMemoryProperties = {};
-    VkPhysicalDeviceProperties2 mPhysicalDeviceProperties = {
-        .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_PROPERTIES_2
-    };
-    VkPhysicalDeviceFeatures2 mPhysicalDeviceFeatures = {
-        .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_FEATURES_2
-    };
+    VkPhysicalDeviceProperties mPhysicalDeviceProperties = {};
+    VkPhysicalDeviceFeatures mPhysicalDeviceFeatures = {};
    bool mDebugMarkersSupported = false;
    bool mDebugUtilsSupported = false;
    bool mMultiviewEnabled = false;
    bool mLazilyAllocatedMemorySupported = false;
-    bool mProtectedMemorySupported = false;

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

 #include "DriverBase.h"
 #include "private/backend/Driver.h"
@@ -78,9 +77,6 @@ public:
 #endif // FVK_ENABLED(FVK_DEBUG_DEBUG_UTILS)

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

    void debugCommandBegin(CommandStream* cmds, bool synchronous,
@@ -117,16 +113,21 @@ private:
    void collectGarbage();

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

-    resource_ptr<VulkanSwapChain> mCurrentSwapChain;
-    resource_ptr<VulkanRenderTarget> mDefaultRenderTarget;
+    VulkanSwapChain* mCurrentSwapChain = nullptr;
+    VulkanRenderTarget* mDefaultRenderTarget = nullptr;
    VulkanRenderPass mCurrentRenderPass = {};
    VmaAllocator mAllocator = VK_NULL_HANDLE;
    VkDebugReportCallbackEXT mDebugCallback = VK_NULL_HANDLE;

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

    VulkanCommands mCommands;
    VulkanPipelineLayoutCache mPipelineLayoutCache;
@@ -141,7 +142,7 @@ private:

    // This is necessary for us to write to push constants after binding a pipeline.
    struct {
-        resource_ptr<VulkanProgram> program;
+        VulkanProgram* program;
        VkPipelineLayout pipelineLayout;
        DescriptorSetMask descriptorSetMask;
    } mBoundPipeline = {};
@@ -69,8 +69,8 @@ VulkanFboCache::~VulkanFboCache() {
            << "Please explicitly call terminate() while the VkDevice is still alive.";
 }

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

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

-    for (FboMap::iterator iter = mFramebufferCache.begin(); iter != mFramebufferCache.end(); ++iter) {
+    for (auto iter = mFramebufferCache.begin(); iter != mFramebufferCache.end(); ++iter) {
        const FboVal fbo = iter->second;
        if (fbo.timestamp < evictTime && fbo.handle) {
            mRenderPassRefCount[iter->first.renderPass]--;
@@ -54,7 +54,7 @@ public:
        uint8_t usesLazilyAllocatedMemory; // 1 byte
        uint8_t subpassMask; // 1 byte
        uint8_t viewCount; // 1 byte
-        uint8_t padding[2];
+		uint8_t padding[2];
    };
    struct RenderPassVal {
        VkRenderPass handle;
@@ -98,10 +98,10 @@ public:
    ~VulkanFboCache();

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

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

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

 private:
    VkDevice mDevice;
-    using FboMap = tsl::robin_map<FboKey, FboVal, FboKeyHashFn, FboKeyEqualFn>;
-    FboMap mFramebufferCache;
-
+    tsl::robin_map<FboKey, FboVal, FboKeyHashFn, FboKeyEqualFn> mFramebufferCache;
    tsl::robin_map<RenderPassKey, RenderPassVal, RenderPassHash, RenderPassEq> mRenderPassCache;
    tsl::robin_map<VkRenderPass, uint32_t> mRenderPassRefCount;
    uint32_t mCurrentTime = 0;
@@ -22,8 +22,8 @@
 #include "VulkanDriver.h"

 #include "VulkanMemory.h"
+#include "VulkanResourceAllocator.h"
 #include "VulkanUtility.h"
-#include "vulkan/memory/ResourcePointer.h"
 #include "spirv/VulkanSpirvUtils.h"

 #include <backend/platforms/VulkanPlatform.h>
@@ -36,12 +36,15 @@ namespace filament::backend {

 namespace {

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

 void clampToFramebuffer(VkRect2D* rect, uint32_t fbWidth, uint32_t fbHeight) {
-    rect->offset.y = fbHeight - rect->offset.y - rect->extent.height;
    int32_t x = std::max(rect->offset.x, 0);
    int32_t y = std::max(rect->offset.y, 0);
    int32_t right = std::min(rect->offset.x + (int32_t) rect->extent.width, (int32_t) fbWidth);
@@ -87,8 +90,6 @@ BitmaskGroup fromBackendLayout(DescriptorSetLayout const& layout) {
                }
                break;
            }
-            // TODO: properly handle external sampler
-            case DescriptorType::SAMPLER_EXTERNAL:
            case DescriptorType::SAMPLER: {
                fromStageFlags(binding.stageFlags, binding.binding, mask.sampler);
                break;
@@ -105,41 +106,21 @@ BitmaskGroup fromBackendLayout(DescriptorSetLayout const& layout) {
    return mask;
 }

-fvkmemory::resource_ptr<VulkanTexture> initMsaaTexture(
-        fvkmemory::resource_ptr<VulkanTexture> texture, VkDevice device,
-        VkPhysicalDevice physicalDevice, VulkanContext const& context, VmaAllocator allocator,
-        VulkanCommands* commands, fvkmemory::ResourceManager* resManager, uint8_t levels,
-        uint8_t samples, VulkanStagePool& stagePool) {
-    assert_invariant(texture);
-    auto msTexture = texture->getSidecar();
-    if (UTILS_UNLIKELY(!msTexture)) {
-        // Clear all usage flags that are not related to attachments, so that we can
-        // use the transient usage flag.
-        const TextureUsage usage = texture->usage & TextureUsage::ALL_ATTACHMENTS;
-        assert_invariant(static_cast<uint16_t>(usage) != 0U);
-
-        msTexture = resource_ptr<VulkanTexture>::construct(resManager, device, physicalDevice,
-                context, allocator, resManager, commands, texture->target, levels, texture->format,
-                samples, texture->width, texture->height, texture->depth, usage, stagePool);
-        texture->setSidecar(msTexture);
-    }
-    return msTexture;
-}
-
 } // anonymous namespace

-void VulkanDescriptorSet::acquire(fvkmemory::resource_ptr<VulkanTexture> texture) {
-    mResources.push_back(texture);
-}
-
-void VulkanDescriptorSet::acquire(fvkmemory::resource_ptr<VulkanBufferObject> obj) {
-    mResources.push_back(obj);
-}
-
 VulkanDescriptorSetLayout::VulkanDescriptorSetLayout(DescriptorSetLayout const& layout)
-    : bitmask(fromBackendLayout(layout)),
+    : VulkanResource(VulkanResourceType::DESCRIPTOR_SET_LAYOUT),
+      bitmask(fromBackendLayout(layout)),
      count(Count::fromLayoutBitmask(bitmask)) {}

+void VulkanDescriptorSet::acquire(VulkanTexture* texture) {
+    mResources.acquire(texture);
+}
+
+void VulkanDescriptorSet::acquire(VulkanBufferObject* bufferObject) {
+    mResources.acquire(bufferObject);
+}
+
 PushConstantDescription::PushConstantDescription(backend::Program const& program) noexcept {
    mRangeCount = 0;
    for (auto stage : { ShaderStage::VERTEX, ShaderStage::FRAGMENT, ShaderStage::COMPUTE }) {
@@ -163,9 +144,9 @@ PushConstantDescription::PushConstantDescription(backend::Program const& program
    }
 }

-void PushConstantDescription::write(VkCommandBuffer cmdbuf, VkPipelineLayout layout,
+void PushConstantDescription::write(VulkanCommands* commands, VkPipelineLayout layout,
        backend::ShaderStage stage, uint8_t index, backend::PushConstantVariant const& value) {
-
+    VulkanCommandBuffer* cmdbuf = &(commands->get());
    uint32_t binaryValue = 0;
    UTILS_UNUSED_IN_RELEASE auto const& types = mTypes[(uint8_t) stage];
    if (std::holds_alternative<bool>(value)) {
@@ -181,12 +162,13 @@ void PushConstantDescription::write(VkCommandBuffer cmdbuf, VkPipelineLayout lay
        int const ival = std::get<int>(value);
        binaryValue = *reinterpret_cast<uint32_t const*>(&ival);
    }
-    vkCmdPushConstants(cmdbuf, layout, getVkStage(stage), index * ENTRY_SIZE, ENTRY_SIZE,
+    vkCmdPushConstants(cmdbuf->buffer(), layout, getVkStage(stage), index * ENTRY_SIZE, ENTRY_SIZE,
            &binaryValue);
 }

 VulkanProgram::VulkanProgram(VkDevice device, Program const& builder) noexcept
    : HwProgram(builder.getName()),
+      VulkanResource(VulkanResourceType::PROGRAM),
      mInfo(new(std::nothrow) PipelineInfo(builder)),
      mDevice(device) {

@@ -252,239 +234,158 @@ VulkanProgram::~VulkanProgram() {
 }

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

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

 VulkanRenderTarget::VulkanRenderTarget(VkDevice device, VkPhysicalDevice physicalDevice,
-        VulkanContext const& context, fvkmemory::ResourceManager* resourceManager,
-        VmaAllocator allocator, VulkanCommands* commands, uint32_t width, uint32_t height,
-        uint8_t samples, VulkanAttachment color[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT],
+        VulkanContext const& context, VmaAllocator allocator, VulkanCommands* commands,
+        VulkanResourceAllocator* handleAllocator,
+        uint32_t width, uint32_t height, uint8_t samples,
+        VulkanAttachment color[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT],
        VulkanAttachment depthStencil[2], VulkanStagePool& stagePool, uint8_t layerCount)
    : HwRenderTarget(width, height),
+      VulkanResource(VulkanResourceType::RENDER_TARGET),
      mOffscreen(true),
-      mProtected(false),
-      mInfo(std::make_unique<Auxiliary>()) {
-    auto& depth = depthStencil[0];
+      mSamples(samples),
+      mLayerCount(layerCount) {
+    for (int index = 0; index < MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT; index++) {
+        mColor[index] = color[index];
+    }
+    mDepth = depthStencil[0];
+    VulkanTexture* depthTexture = (VulkanTexture*) mDepth.texture;
+
+    if (samples == 1) {
+        return;
+    }

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

-    auto& rpkey = mInfo->rpkey;
-    rpkey.samples = samples;
-    rpkey.depthFormat = depth.getFormat();
-    rpkey.viewCount = layerCount;
-
-    auto& fbkey = mInfo->fbkey;
-    fbkey.width = width;
-    fbkey.height = height;
-    fbkey.samples = samples;
-
-    std::vector<VulkanAttachment>& attachments = mInfo->attachments;
-    std::vector<VulkanAttachment> msaa;
-
+    // Create sidecar MSAA textures for color attachments if they don't already exist.
    for (int index = 0; index < MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT; index++) {
-        VulkanAttachment& attachment = color[index];
-        auto texture = attachment.texture;
-        if (!texture) {
-            rpkey.colorFormat[index] = VK_FORMAT_UNDEFINED;
-            continue;
-        }
+        VulkanAttachment const& spec = color[index];
+        VulkanTexture* texture = (VulkanTexture*) spec.texture;
+        if (texture && texture->samples == 1) {
+            auto msTexture = texture->getSidecar();
+            if (UTILS_UNLIKELY(!msTexture)) {
+                // Clear all usage flags that are not related to attachments, so that we can
+                // use the transient usage flag.
+                const TextureUsage usage = texture->usage & TextureUsage::ALL_ATTACHMENTS;
+                assert_invariant(static_cast<uint16_t>(usage) != 0U);

-        mProtected |= texture->getIsProtected();
-
-        attachments.push_back(attachment);
-        mInfo->colors.set(index);
-
-        rpkey.colorFormat[index] = attachment.getFormat();
-        fbkey.color[index] = attachment.getImageView();
-        fbkey.resolve[index] = VK_NULL_HANDLE;
-
-        if (samples > 1) {
-            VulkanAttachment msaaAttachment = {};
-            if (texture->samples == 1) {
-                auto msaaTexture = initMsaaTexture(texture, device, physicalDevice, context,
-                        allocator, commands, resourceManager, texture->levels, samples, stagePool);
-                if (msaaTexture && msaaTexture->isTransientAttachment()) {
-                    rpkey.usesLazilyAllocatedMemory |= (1 << index);
-                }
-                if (attachment.texture->samples == 1) {
-                    rpkey.needsResolveMask |= (1 << index);
-                }
-                msaaAttachment = {
-                    .texture = msaaTexture,
-                    .layerCount = layerCount,
-                };
-
-                fbkey.resolve[index] = attachment.getImageView();
-            } else {
-                msaaAttachment = {
-                    .texture = texture,
-                    .layerCount = layerCount,
-                };
+                // TODO: This should be allocated with the ResourceAllocator.
+                msTexture = new VulkanTexture(device, physicalDevice, context, allocator, commands,
+                        handleAllocator,
+                        texture->target, ((VulkanTexture const*) texture)->levels, texture->format,
+                        samples, texture->width, texture->height, texture->depth, usage,
+                        stagePool, true /* heap allocated */);
+                texture->setSidecar(msTexture);
            }
-            fbkey.color[index] = msaaAttachment.getImageView();
-            msaa.push_back(msaaAttachment);
+            mMsaaAttachments[index] = {.texture = msTexture};
+        }
+        if (texture && texture->samples > 1) {
+            mMsaaAttachments[index] = mColor[index];
        }
    }

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

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

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

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

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

-void VulkanRenderTarget::emitBarriersBeginRenderPass(VulkanCommandBuffer& commands) {
-    auto& attachments = mInfo->attachments;
-    auto samples = mInfo->fbkey.samples;
-    auto barrier = [&commands](VulkanAttachment& attachment, VulkanLayout const layout) {
-        auto tex = attachment.texture;
-        auto const& range = attachment.getSubresourceRange();
-        if (tex->getLayout(range.baseMipLevel, range.baseArrayLayer) != layout &&
-                !tex->transitionLayout(&commands, range, layout)) {
-            // If the layout transition did not emit a barrier, we do it manually here.
-            tex->samplerToAttachmentBarrier(&commands, range);
-        }
-    };
-
-    for (size_t i = 0, count = mInfo->colors.count(); i < count; ++i) {
-        auto& attachment = attachments[i];
-        auto tex = attachment.texture;
-        if (samples == 1 || tex->samples == 1) {
-            barrier(attachment, VulkanLayout::COLOR_ATTACHMENT);
-        }
-    }
-    if (mInfo->msaaIndex != Auxiliary::UNDEFINED_INDEX) {
-        for (size_t i = mInfo->msaaIndex, count = mInfo->msaaIndex + mInfo->colors.count();
-                i < count; ++i) {
-            barrier(attachments[i], VulkanLayout::COLOR_ATTACHMENT);
-        }
-    }
-    if (mInfo->depthIndex != Auxiliary::UNDEFINED_INDEX) {
-        barrier(attachments[mInfo->depthIndex], VulkanLayout::DEPTH_ATTACHMENT);
-    }
-    if (mInfo->msaaDepthIndex != Auxiliary::UNDEFINED_INDEX) {
-        barrier(attachments[mInfo->msaaDepthIndex], VulkanLayout::DEPTH_ATTACHMENT);
-    }
-}
-
-void VulkanRenderTarget::emitBarriersEndRenderPass(VulkanCommandBuffer& commands) {
-    if (isSwapChain()) {
-        return;
-    }
-
-    for (auto& attachment: mInfo->attachments) {
-        auto const& range = attachment.getSubresourceRange();
-        bool const isDepth = attachment.isDepth();
-        auto texture = attachment.texture;
-        if (isDepth) {
-            texture->setLayout(range, VulkanFboCache::FINAL_DEPTH_ATTACHMENT_LAYOUT);
-            if (!texture->transitionLayout(&commands, range, VulkanLayout::DEPTH_SAMPLER)) {
-                texture->attachmentToSamplerBarrier(&commands, range);
-            }
-        } else {
-            texture->setLayout(range, VulkanFboCache::FINAL_COLOR_ATTACHMENT_LAYOUT);
-            if (!texture->transitionLayout(&commands, range, VulkanLayout::READ_WRITE)) {
-                texture->attachmentToSamplerBarrier(&commands, range);
-            }
-        }
-    }
-}
-
 VulkanVertexBufferInfo::VulkanVertexBufferInfo(
        uint8_t bufferCount, uint8_t attributeCount, AttributeArray const& attributes)
    : HwVertexBufferInfo(bufferCount, attributeCount),
+      VulkanResource(VulkanResourceType::VERTEX_BUFFER_INFO),
      mInfo(attributes.size()) {
+
    auto attribDesc = mInfo.mSoa.data<PipelineInfo::ATTRIBUTE_DESCRIPTION>();
    auto bufferDesc = mInfo.mSoa.data<PipelineInfo::BUFFER_DESCRIPTION>();
    auto offsets = mInfo.mSoa.data<PipelineInfo::OFFSETS>();
@@ -522,15 +423,19 @@ VulkanVertexBufferInfo::VulkanVertexBufferInfo(
 }

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

-void VulkanVertexBuffer::setBuffer(fvkmemory::resource_ptr<VulkanBufferObject> bufferObject,
-        uint32_t index) {
+void VulkanVertexBuffer::setBuffer(VulkanResourceAllocator const& allocator,
+        VulkanBufferObject* bufferObject, uint32_t index) {
+    VulkanVertexBufferInfo const* const vbi =
+            const_cast<VulkanResourceAllocator&>(allocator).handle_cast<VulkanVertexBufferInfo*>(vbih);
    size_t const count = vbi->getAttributeCount();
    VkBuffer* const vkbuffers = getVkBuffers();
    int8_t const* const attribToBuffer = vbi->getAttributeToBuffer();
@@ -539,20 +444,48 @@ void VulkanVertexBuffer::setBuffer(fvkmemory::resource_ptr<VulkanBufferObject> b
            vkbuffers[attribIndex] = bufferObject->buffer.getGpuBuffer();
        }
    }
-    mResources.push_back(bufferObject);
+    mResources.acquire(bufferObject);
 }

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

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

 } // namespace filament::backend
@@ -20,14 +20,13 @@
 // This needs to be at the top
 #include "DriverBase.h"

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

+#include <private/backend/SamplerGroup.h>
 #include <backend/Program.h>

 #include <utils/bitset.h>
@@ -35,8 +34,6 @@
 #include <utils/Mutex.h>
 #include <utils/StructureOfArrays.h>

-#include <array>
-
 namespace filament::backend {

 namespace {
@@ -57,7 +54,7 @@ inline uint8_t collapsedCount(Bitmask const& mask) {
 class VulkanTimestamps;
 struct VulkanBufferObject;

-struct VulkanDescriptorSetLayout : public HwDescriptorSetLayout, fvkmemory::Resource {
+struct VulkanDescriptorSetLayout : public VulkanResource, HwDescriptorSetLayout {
    static constexpr uint8_t UNIQUE_DESCRIPTOR_SET_COUNT = 4;
    static constexpr uint8_t MAX_BINDINGS = 25;

@@ -131,19 +128,17 @@ private:
    VkDescriptorSetLayout mVkLayout = VK_NULL_HANDLE;
 };

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

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

    ~VulkanDescriptorSet() {
@@ -152,24 +147,14 @@ public:
        }
    }

-    void setOffsets(backend::DescriptorSetOffsetArray&& offsets) noexcept {
-        mOffsets = std::move(offsets);
-    }
+    void acquire(VulkanTexture* texture);

-    backend::DescriptorSetOffsetArray const* getOffsets() {
-        return &mOffsets;
-    }
-
-    void acquire(fvkmemory::resource_ptr<VulkanTexture> texture);
-    void acquire(fvkmemory::resource_ptr<VulkanBufferObject> buffer);
+    void acquire(VulkanBufferObject* texture);

    VkDescriptorSet const vkSet;
-    UniformBufferBitmask const dynamicUboMask;
-    uint8_t const uniqueDynamicUboCount;

 private:
-    backend::DescriptorSetOffsetArray mOffsets;
-    std::vector<fvkmemory::resource_ptr<fvkmemory::Resource>> mResources;
+    VulkanAcquireOnlyResourceManager mResources;
    OnRecycle mOnRecycleFn;
 };

@@ -177,11 +162,14 @@ using PushConstantNameArray = utils::FixedCapacityVector<char const*>;
 using PushConstantNameByStage = std::array<PushConstantNameArray, Program::SHADER_TYPE_COUNT>;

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

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

 private:
@@ -192,10 +180,12 @@ private:
    uint32_t mRangeCount;
 };

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

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

    inline VkShaderModule getVertexShader() const {
@@ -204,6 +194,10 @@ struct VulkanProgram : public HwProgram, fvkmemory::Resource {

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

+    // Get a list of the sampler binding indices so that we don't have to loop through all possible
+    // samplers.
+    inline BindingList const& getBindings() const { return mInfo->bindings; }
+
    inline uint32_t getPushConstantRangeCount() const {
        return mInfo->pushConstantDescription.getVkRangeCount();
    }
@@ -212,9 +206,9 @@ struct VulkanProgram : public HwProgram, fvkmemory::Resource {
        return mInfo->pushConstantDescription.getVkRanges();
    }

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

 #if FVK_ENABLED_DEBUG_SAMPLER_NAME
@@ -231,10 +225,22 @@ private:
    struct PipelineInfo {
        explicit PipelineInfo(backend::Program const& program) noexcept
            : pushConstantDescription(program)
+#if FVK_ENABLED_DEBUG_SAMPLER_NAME
+            , bindingToName(MAX_SAMPLER_COUNT, "")
+#endif
            {}

+        BindingList bindings;
+
        VkShaderModule shaders[MAX_SHADER_MODULES] = { VK_NULL_HANDLE };
+
        PushConstantDescription pushConstantDescription;
+
+#if FVK_ENABLED_DEBUG_SAMPLER_NAME
+        // We store the sampler name mapped from binding index (only for debug purposes).
+        utils::FixedCapacityVector<std::string> bindingToName;
+#endif
+
    };

    PipelineInfo* mInfo;
@@ -249,88 +255,47 @@ private:
 //
 // We use private inheritance to shield clients from the width / height fields in HwRenderTarget,
 // which are not representative when this is the default render target.
-struct VulkanRenderTarget : private HwRenderTarget, fvkmemory::Resource {
+struct VulkanRenderTarget : private HwRenderTarget, VulkanResource {
    // Creates an offscreen render target.
    VulkanRenderTarget(VkDevice device, VkPhysicalDevice physicalDevice,
-            VulkanContext const& context, fvkmemory::ResourceManager* resourceManager,
-            VmaAllocator allocator, VulkanCommands* commands, uint32_t width, uint32_t height,
+            VulkanContext const& context, VmaAllocator allocator,
+            VulkanCommands* commands,
+            VulkanResourceAllocator* handleAllocator,
+            uint32_t width, uint32_t height,
            uint8_t samples, VulkanAttachment color[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT],
            VulkanAttachment depthStencil[2], VulkanStagePool& stagePool, uint8_t layerCount);

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

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

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

 struct VulkanBufferObject;

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

@@ -377,24 +342,33 @@ private:
    PipelineInfo mInfo;
 };

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

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

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

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

@@ -402,7 +376,7 @@ struct VulkanIndexBuffer : public HwIndexBuffer, fvkmemory::Resource {
    const VkIndexType indexType;
 };

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

@@ -410,15 +384,66 @@ struct VulkanBufferObject : public HwBufferObject, fvkmemory::Resource {
    const BufferObjectBinding bindingType;
 };

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

+struct VulkanRenderPrimitive : public HwRenderPrimitive, VulkanResource {
+    VulkanRenderPrimitive(VulkanResourceAllocator* resourceAllocator,
+            PrimitiveType pt, Handle<HwVertexBuffer> vbh, Handle<HwIndexBuffer> ibh);
+
+    ~VulkanRenderPrimitive() {
+        mResources.clear();
+    }
+
+    VulkanVertexBuffer* vertexBuffer = nullptr;
+    VulkanIndexBuffer* indexBuffer = nullptr;
+
+private:
+    // Keep references to the vertex buffer and the index buffer.
+    FixedSizeVulkanResourceManager<2> mResources;
+};
+
+struct VulkanFence : public HwFence, VulkanResource {
+    VulkanFence()
+        : VulkanResource(VulkanResourceType::FENCE) {}
+
+    explicit VulkanFence(std::shared_ptr<VulkanCmdFence> fence)
+        : VulkanResource(VulkanResourceType::FENCE),
+          fence(fence) {}
+
+    std::shared_ptr<VulkanCmdFence> fence;
+};
+
+struct VulkanTimerQuery : public HwTimerQuery, VulkanThreadSafeResource {
+    explicit VulkanTimerQuery(std::tuple<uint32_t, uint32_t> indices);
+    ~VulkanTimerQuery();
+
+    void setFence(std::shared_ptr<VulkanCmdFence> fence) noexcept;
+
+    bool isCompleted() noexcept;
+
+    uint32_t getStartingQueryIndex() const {
+        return mStartingQueryIndex;
+    }
+
+    uint32_t getStoppingQueryIndex() const {
+        return mStoppingQueryIndex;
+    }
+
+private:
+    uint32_t mStartingQueryIndex;
+    uint32_t mStoppingQueryIndex;
+
+    std::shared_ptr<VulkanCmdFence> mFence;
+    utils::Mutex mFenceMutex;
+};
+
+
 inline constexpr VkBufferUsageFlagBits getBufferObjectUsage(
        BufferObjectBinding bindingType) noexcept {
    switch(bindingType) {
@@ -31,7 +31,6 @@
 #pragma clang diagnostic ignored "-Wnullability-completeness"
 #pragma clang diagnostic ignored "-Wextra-semi"
 #pragma clang diagnostic ignored "-Wc++98-compat-extra-semi"
-#pragma clang diagnostic ignored "-Wthread-safety-analysis"

 static const PFN_vkGetInstanceProcAddr& vkGetInstanceProcAddr = bluevk::vkGetInstanceProcAddr;
 static const PFN_vkGetDeviceProcAddr& vkGetDeviceProcAddr = bluevk::vkGetDeviceProcAddr;
@@ -66,12 +66,17 @@ void VulkanPipelineCache::bindPipeline(VulkanCommandBuffer* commands) {
    VkCommandBuffer const cmdbuffer = commands->buffer();

    PipelineCacheEntry* cacheEntry = getOrCreatePipeline();
+    // Check if the required pipeline is already bound.
+    if (cacheEntry->handle == commands->pipeline()) {
+        return;
+    }

    // If an error occurred, allow higher levels to handle it gracefully.
    assert_invariant(cacheEntry != nullptr && "Failed to create/find pipeline");

    mBoundPipeline = mPipelineRequirements;
    vkCmdBindPipeline(cmdbuffer, VK_PIPELINE_BIND_POINT_GRAPHICS, cacheEntry->handle);
+    commands->setPipeline(cacheEntry->handle);
 }

 VulkanPipelineCache::PipelineCacheEntry* VulkanPipelineCache::createPipeline() noexcept {
@@ -241,7 +246,7 @@ VulkanPipelineCache::PipelineCacheEntry* VulkanPipelineCache::createPipeline() n
    return &mPipelines.emplace(mPipelineRequirements, cacheEntry).first.value();
 }

-void VulkanPipelineCache::bindProgram(fvkmemory::resource_ptr<VulkanProgram> program) noexcept {
+void VulkanPipelineCache::bindProgram(VulkanProgram* program) noexcept {
    mPipelineRequirements.shaders[0] = program->getVertexShader();
    mPipelineRequirements.shaders[1] = program->getFragmentShader();

@@ -19,6 +19,7 @@

 #include "VulkanCommands.h"
 #include "VulkanMemory.h"
+#include "VulkanResources.h"
 #include "VulkanUtility.h"

 #include <backend/DriverEnums.h>
@@ -43,6 +44,7 @@ namespace filament::backend {
 struct VulkanProgram;
 struct VulkanBufferObject;
 struct VulkanTexture;
+class VulkanResourceAllocator;

 // VulkanPipelineCache manages a cache of descriptor sets and pipelines.
 //
@@ -120,7 +122,7 @@ public:
    void bindPipeline(VulkanCommandBuffer* commands);

    // Each of the following methods are fast and do not make Vulkan calls.
-    void bindProgram(fvkmemory::resource_ptr<VulkanProgram> program) noexcept;
+    void bindProgram(VulkanProgram* program) noexcept;
    void bindRasterState(const RasterState& rasterState) noexcept;
    void bindRenderPass(VkRenderPass renderPass, int subpassIndex) noexcept;
    void bindPrimitiveTopology(VkPrimitiveTopology topology) noexcept;
@@ -117,10 +117,9 @@ void VulkanReadPixels::terminate() noexcept {
 VulkanReadPixels::VulkanReadPixels(VkDevice device)
    : mDevice(device) {}

-void VulkanReadPixels::run(fvkmemory::resource_ptr<VulkanRenderTarget> srcTarget, uint32_t const x,
-        uint32_t const y, uint32_t const width, uint32_t const height,
-        uint32_t const graphicsQueueFamilyIndex, PixelBufferDescriptor&& pbd,
-        SelecteMemoryFunction const& selectMemoryFunc,
+void VulkanReadPixels::run(VulkanRenderTarget* srcTarget, uint32_t const x, uint32_t const y,
+        uint32_t const width, uint32_t const height, uint32_t const graphicsQueueFamilyIndex,
+        PixelBufferDescriptor&& pbd, SelecteMemoryFunction const& selectMemoryFunc,
        OnReadCompleteFunction const& readCompleteFunc) {
    assert_invariant(mDevice != VK_NULL_HANDLE);

@@ -144,7 +143,7 @@ void VulkanReadPixels::run(fvkmemory::resource_ptr<VulkanRenderTarget> srcTarget

    VkCommandPool& cmdpool = mCommandPool;

-    fvkmemory::resource_ptr<VulkanTexture> srcTexture = srcTarget->getColor0().texture;
+    VulkanTexture* srcTexture = srcTarget->getColor(0).texture;
    assert_invariant(srcTexture);
    VkFormat const srcFormat = srcTexture->getVkFormat();
    bool const swizzle
@@ -231,7 +230,7 @@ void VulkanReadPixels::run(fvkmemory::resource_ptr<VulkanRenderTarget> srcTarget
        },
    });

-    VulkanAttachment const srcAttachment = srcTarget->getColor0();
+    VulkanAttachment const srcAttachment = srcTarget->getColor(0);
    VkImageSubresourceRange const srcRange = srcAttachment.getSubresourceRange();
    srcTexture->transitionLayout(cmdbuffer, srcRange, VulkanLayout::TRANSFER_SRC);

@@ -17,7 +17,6 @@
 #ifndef TNT_FILAMENT_BACKEND_VULKANREADPIXELS_H
 #define TNT_FILAMENT_BACKEND_VULKANREADPIXELS_H

-#include "vulkan/memory/ResourcePointer.h"
 #include "private/backend/Driver.h"

 #include <bluevk/BlueVK.h>
@@ -73,9 +72,9 @@ public:

    void terminate() noexcept;

-    void run(fvkmemory::resource_ptr<VulkanRenderTarget> srcTarget, uint32_t x, uint32_t y,
-            uint32_t width, uint32_t height, uint32_t graphicsQueueFamilyIndex,
-            PixelBufferDescriptor&& pbd, SelecteMemoryFunction const& selectMemoryFunc,
+    void run(VulkanRenderTarget* srcTarget, uint32_t x, uint32_t y, uint32_t width, uint32_t height,
+            uint32_t graphicsQueueFamilyIndex, PixelBufferDescriptor&& pbd,
+            SelecteMemoryFunction const& selectMemoryFunc,
            OnReadCompleteFunction const& readCompleteFunc);

    // This method will block until all of the in-flight requests are complete.
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2023 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_VULKANRESOURCEALLOCATOR_H
+#define TNT_FILAMENT_BACKEND_VULKANRESOURCEALLOCATOR_H
+
+#include "VulkanConstants.h"
+#include "VulkanHandles.h"
+
+#include <private/backend/HandleAllocator.h>
+
+#include <utils/FixedCapacityVector.h>
+#include <utils/Log.h>
+
+#include <type_traits>
+#include <unordered_set>
+
+namespace filament::backend {
+
+#define RESOURCE_TYPE_COUNT (static_cast<int>(VulkanResourceType::END_TYPE))
+#define DEBUG_RESOURCE_LEAKS FVK_ENABLED(FVK_DEBUG_RESOURCE_LEAK)
+
+#if DEBUG_RESOURCE_LEAKS
+    #define TRACK_INCREMENT()                                           \
+    if (!IS_HEAP_ALLOC_TYPE(obj->getType())) {                          \
+        mDebugOnlyResourceCount[static_cast<size_t>(obj->getType())]++; \
+    }
+    #define TRACK_DECREMENT()                                           \
+    if (!IS_HEAP_ALLOC_TYPE(obj->getType())) {                          \
+        mDebugOnlyResourceCount[static_cast<size_t>(obj->getType())]--; \
+    }
+#else
+    // No-op
+    #define TRACK_INCREMENT()
+    #define TRACK_DECREMENT()
+#endif
+
+class VulkanResourceAllocator {
+public:
+    using AllocatorImpl = HandleAllocatorVK;
+    VulkanResourceAllocator(size_t arenaSize, bool disableUseAfterFreeCheck)
+        : mHandleAllocatorImpl("Handles", arenaSize, disableUseAfterFreeCheck)
+#if DEBUG_RESOURCE_LEAKS
+        , mDebugOnlyResourceCount(RESOURCE_TYPE_COUNT) {
+        std::memset(mDebugOnlyResourceCount.data(), 0, sizeof(size_t) * RESOURCE_TYPE_COUNT);
+    }
+#else
+    {}
+#endif
+
+    template<typename D, typename... ARGS>
+    inline Handle<D> initHandle(ARGS&&... args) noexcept {
+        auto handle = mHandleAllocatorImpl.allocateAndConstruct<D>(std::forward<ARGS>(args)...);
+        auto obj = handle_cast<D*>(handle);
+        obj->initResource(handle.getId());
+        TRACK_INCREMENT();
+        return handle;
+    }
+
+    template<typename D>
+    inline Handle<D> allocHandle() noexcept {
+        return mHandleAllocatorImpl.allocate<D>();
+    }
+
+    template<typename D, typename B, typename... ARGS>
+    inline typename std::enable_if<std::is_base_of<B, D>::value, D>::type* construct(
+            Handle<B> const& handle, ARGS&&... args) noexcept {
+        auto obj = mHandleAllocatorImpl.construct<D, B>(handle, std::forward<ARGS>(args)...);
+        obj->initResource(handle.getId());
+        TRACK_INCREMENT();
+        return obj;
+    }
+
+    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>& handle) noexcept {
+        return mHandleAllocatorImpl.handle_cast<Dp, B>(handle);
+    }
+
+    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) noexcept {
+        return mHandleAllocatorImpl.handle_cast<Dp, B>(handle);
+    }
+
+    template<typename D, typename B>
+    inline void destruct(Handle<B> handle) noexcept {
+        auto obj = handle_cast<D*>(handle);
+        TRACK_DECREMENT();
+        mHandleAllocatorImpl.deallocate(handle, obj);
+    }
+
+    inline void associateHandle(HandleBase::HandleId id, utils::CString&& tag) noexcept {
+        mHandleAllocatorImpl.associateTagToHandle(id, std::move(tag));
+    }
+
+private:
+    AllocatorImpl mHandleAllocatorImpl;
+
+#if DEBUG_RESOURCE_LEAKS
+public:
+    void print() {
+        FVK_LOGD << "Resource Allocator state (debug only)" << utils::io::endl;
+        for (size_t i = 0; i < RESOURCE_TYPE_COUNT; i++) {
+            FVK_LOGD << "[" << i << "]=" << mDebugOnlyResourceCount[i] << utils::io::endl;
+        }
+        FVK_LOGD << "+++++++++++++++++++++++++++++++++++++" << utils::io::endl;
+    }
+private:
+    utils::FixedCapacityVector<size_t> mDebugOnlyResourceCount;
+#endif
+
+};
+
+#undef TRACK_INCREMENT
+#undef TRACK_DECREMENT
+#undef DEBUG_RESOURCE_LEAKS
+
+} // namespace filament::backend
+
+#endif // TNT_FILAMENT_BACKEND_VULKANRESOURCEALLOCATOR_H
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2023 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 "VulkanResources.h"
+#include "VulkanHandles.h"
+#include "VulkanResourceAllocator.h"
+#include "VulkanPipelineCache.h"
+
+namespace filament::backend {
+
+void deallocateResource(VulkanResourceAllocator* allocator, VulkanResourceType type,
+        HandleBase::HandleId id) {
+
+    if (IS_HEAP_ALLOC_TYPE(type)) {
+        return;
+    }
+
+    switch (type) {
+        case VulkanResourceType::BUFFER_OBJECT:
+            allocator->destruct<VulkanBufferObject>(Handle<HwBufferObject>(id));
+            break;
+        case VulkanResourceType::INDEX_BUFFER:
+            allocator->destruct<VulkanIndexBuffer>(Handle<HwIndexBuffer>(id));
+            break;
+        case VulkanResourceType::PROGRAM:
+            allocator->destruct<VulkanProgram>(Handle<HwProgram>(id));
+            break;
+        case VulkanResourceType::RENDER_TARGET:
+            allocator->destruct<VulkanRenderTarget>(Handle<HwRenderTarget>(id));
+            break;
+        case VulkanResourceType::SAMPLER_GROUP:
+            allocator->destruct<VulkanSamplerGroup>(Handle<HwSamplerGroup>(id));
+            break;
+        case VulkanResourceType::SWAP_CHAIN:
+            allocator->destruct<VulkanSwapChain>(Handle<HwSwapChain>(id));
+            break;
+        case VulkanResourceType::TEXTURE:
+            allocator->destruct<VulkanTexture>(Handle<HwTexture>(id));
+            break;
+        case VulkanResourceType::TIMER_QUERY:
+            allocator->destruct<VulkanTimerQuery>(Handle<HwTimerQuery>(id));
+            break;
+        case VulkanResourceType::VERTEX_BUFFER_INFO:
+            allocator->destruct<VulkanVertexBufferInfo>(Handle<HwVertexBufferInfo>(id));
+            break;
+        case VulkanResourceType::VERTEX_BUFFER:
+            allocator->destruct<VulkanVertexBuffer>(Handle<HwVertexBuffer>(id));
+            break;
+        case VulkanResourceType::RENDER_PRIMITIVE:
+            allocator->destruct<VulkanRenderPrimitive>(Handle<VulkanRenderPrimitive>(id));
+            break;
+        case VulkanResourceType::DESCRIPTOR_SET_LAYOUT:
+            allocator->destruct<VulkanDescriptorSetLayout>(Handle<VulkanDescriptorSetLayout>(id));
+            break;
+        case VulkanResourceType::DESCRIPTOR_SET:
+            allocator->destruct<VulkanDescriptorSet>(Handle<VulkanDescriptorSet>(id));
+            break;
+
+        // If the resource is heap allocated, then the resource manager just skip refcounted
+        // destruction.
+        case VulkanResourceType::FENCE:
+        case VulkanResourceType::HEAP_ALLOCATED:
+        case VulkanResourceType::END_TYPE:
+            break;
+    }
+}
+
+} // namespace filament::backend
@@ -0,0 +1,313 @@
+/*
+ * Copyright (C) 2023 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_VULKANRESOURCES_H
+#define TNT_FILAMENT_BACKEND_VULKANRESOURCES_H
+
+#include "VulkanUtility.h"
+
+#include <backend/Handle.h>
+
+#include <tsl/robin_set.h>
+#include <utils/Mutex.h>
+#include <utils/Panic.h>
+
+#include <mutex>
+#include <unordered_set>
+
+namespace filament::backend {
+
+class VulkanResourceAllocator;
+struct VulkanThreadSafeResource;
+
+// Subclasses of VulkanResource must provide this enum in their construction.
+enum class VulkanResourceType : uint8_t {
+    BUFFER_OBJECT = 0,
+    INDEX_BUFFER = 1,
+    PROGRAM = 2,
+    RENDER_TARGET = 3,
+    SAMPLER_GROUP = 4,
+    SWAP_CHAIN = 5,
+    RENDER_PRIMITIVE = 6,
+    TEXTURE = 7,
+    TIMER_QUERY = 8,
+    VERTEX_BUFFER = 9,
+    VERTEX_BUFFER_INFO = 10,
+    DESCRIPTOR_SET_LAYOUT = 11,
+    DESCRIPTOR_SET = 12,
+
+    // Below are resources that are managed manually (i.e. not ref counted).
+    FENCE = 13,
+    HEAP_ALLOCATED = 14,
+
+    END_TYPE = 15,  // A placeholder
+};
+
+#define IS_HEAP_ALLOC_TYPE(f)                                                                      \
+    (f == VulkanResourceType::FENCE || f == VulkanResourceType::HEAP_ALLOCATED)
+
+
+// This is a ref-counting base class that tracks how many references of this resource exist. This
+// class is paired with VulkanResourceManagerImpl which is responsible for incrementing or
+// decrementing the count. Once mRefCount == 0, VulkanResourceManagerImpl will also call the
+// appropriate destructor. VulkanCommandBuffer, VulkanDriver, and composite structure like
+// VulkanRenderPrimitive are owners of VulkanResourceManagerImpl instances.
+struct VulkanResourceBase {
+protected:
+    explicit VulkanResourceBase(VulkanResourceType type)
+        : mRefCount(IS_HEAP_ALLOC_TYPE(type) ? 1 : 0),
+          mType(uint32_t(type)),
+          mHandleId(0) {
+    }
+
+private:
+    inline VulkanResourceType getType() const noexcept {
+        return VulkanResourceType(mType);
+    }
+
+    inline HandleBase::HandleId getId() const noexcept {
+        return mHandleId;
+    }
+
+    inline void initResource(HandleBase::HandleId id) noexcept {
+        mHandleId = id;
+    }
+
+    inline void ref() noexcept {
+        if (IS_HEAP_ALLOC_TYPE(getType())) {
+            return;
+        }
+        assert_invariant(mRefCount < ((1<<24) - 1));
+        ++mRefCount;
+    }
+
+    inline void deref() noexcept {
+        if (IS_HEAP_ALLOC_TYPE(getType())) {
+            return;
+        }
+        assert_invariant(mRefCount > 0);
+        --mRefCount;
+    }
+
+    inline size_t refcount() const noexcept {
+        return mRefCount;
+    }
+
+    uint32_t mRefCount : 24; // 16M is enough for the refcount
+    uint32_t mType : 8; // must be uint32_t or MSVC doesn't pack it. no codegen impact w/ clang.
+    HandleBase::HandleId mHandleId;
+
+    friend struct VulkanThreadSafeResource;
+    friend class VulkanResourceAllocator;
+
+    template<typename RT, typename ST>
+    friend class VulkanResourceManagerImpl;
+};
+
+static_assert(sizeof(VulkanResourceBase) == 8, "VulkanResourceBase should be 8 bytes");
+
+struct VulkanThreadSafeResource {
+protected:
+    explicit VulkanThreadSafeResource(VulkanResourceType type)
+        : mImpl(type) {}
+
+private:
+    inline VulkanResourceType getType() {
+        return mImpl.getType();
+    }
+
+    inline HandleBase::HandleId getId() {
+        return mImpl.getId();
+    }
+
+    inline void initResource(HandleBase::HandleId id) noexcept {
+        std::unique_lock<utils::Mutex> lock(mMutex);
+        mImpl.initResource(id);
+    }
+
+    inline void ref() noexcept {
+        std::unique_lock<utils::Mutex> lock(mMutex);
+        mImpl.ref();
+    }
+
+    inline void deref() noexcept {
+        std::unique_lock<utils::Mutex> lock(mMutex);
+        mImpl.deref();
+    }
+
+    inline size_t refcount() noexcept {
+        std::unique_lock<utils::Mutex> lock(mMutex);
+        return mImpl.refcount();
+    }
+
+    utils::Mutex mMutex;
+    VulkanResourceBase mImpl;
+
+    friend class VulkanResourceAllocator;
+    template<typename RT, typename ST>
+    friend class VulkanResourceManagerImpl;
+};
+
+using VulkanResource = VulkanResourceBase;
+
+namespace {
+
+// When the size of the resource set is known to be small, (for example for VulkanRenderPrimitive),
+// we just use a std::array to back the set.
+template<std::size_t SIZE>
+using FixedCapacityResourceSet = CappedArray<VulkanResource*, SIZE>;
+
+// robin_set/map are useful for sets that are acquire only and the set will be iterated when the set
+// is cleared.
+using FastIterationResourceSet = tsl::robin_set<VulkanResource*>;
+
+// unoredered_set is used in the general case where insert/erase can occur at will. This is useful
+// for the basic object ownership count - i.e. VulkanDriver.
+using ResourceSet = std::unordered_set<VulkanResource*>;
+
+using ThreadSafeResourceSet = std::unordered_set<VulkanThreadSafeResource*>;
+
+} // anonymous namespace
+
+class VulkanResourceAllocator;
+
+#define LOCK_IF_NEEDED()                                                                           \
+    if constexpr (std::is_base_of_v<VulkanThreadSafeResource, ResourceType>) {                     \
+        mMutex->lock();                                                                            \
+    }
+
+#define UNLOCK_IF_NEEDED()                                                                         \
+    if constexpr (std::is_base_of_v<VulkanThreadSafeResource, ResourceType>) {                     \
+        mMutex->unlock();                                                                          \
+    }
+
+void deallocateResource(VulkanResourceAllocator* allocator, VulkanResourceType type,
+        HandleBase::HandleId id);
+
+template<typename ResourceType, typename SetType>
+class VulkanResourceManagerImpl {
+public:
+    explicit VulkanResourceManagerImpl(VulkanResourceAllocator* allocator)
+        : mAllocator(allocator) {
+        if constexpr (std::is_base_of_v<VulkanThreadSafeResource, ResourceType>) {
+            mMutex = std::make_unique<utils::Mutex>();
+        }
+    }
+
+    VulkanResourceManagerImpl(const VulkanResourceManagerImpl& other) = delete;
+    void operator=(const VulkanResourceManagerImpl& other) = delete;
+    VulkanResourceManagerImpl(const VulkanResourceManagerImpl&& other) = delete;
+    void operator=(const VulkanResourceManagerImpl&& other) = delete;
+
+    ~VulkanResourceManagerImpl() {
+        clear();
+    }
+
+    inline void acquire(ResourceType* resource) {
+        if (IS_HEAP_ALLOC_TYPE(resource->getType())) {
+            return;
+        }
+
+        LOCK_IF_NEEDED();
+        if (mResources.find(resource) != mResources.end()) {
+            UNLOCK_IF_NEEDED();
+            return;
+        }
+        mResources.insert(resource);
+        UNLOCK_IF_NEEDED();
+        resource->ref();
+    }
+
+    // Transfers ownership from one resource set to another
+    template <typename tSetType>
+    inline void acquireAll(VulkanResourceManagerImpl<ResourceType, tSetType>* srcResources) {
+        copyAll(srcResources);
+        srcResources->clear();
+    }
+
+    // Transfers ownership from one resource set to another
+    template <typename tSetType>
+    inline void copyAll(VulkanResourceManagerImpl<ResourceType, tSetType>* srcResources) {
+        LOCK_IF_NEEDED();
+        for (auto iter = srcResources->mResources.begin(); iter != srcResources->mResources.end();
+                iter++) {
+            acquire(*iter);
+        }
+        UNLOCK_IF_NEEDED();
+    }
+
+    inline void release(ResourceType* resource) {
+        if (IS_HEAP_ALLOC_TYPE(resource->getType())) {
+            return;
+        }
+
+        LOCK_IF_NEEDED();
+        auto resItr = mResources.find(resource);
+        if (resItr == mResources.end()) {
+            UNLOCK_IF_NEEDED();
+            return;
+        }
+        mResources.erase(resItr);
+        UNLOCK_IF_NEEDED();
+        derefImpl(resource);
+    }
+
+    inline void clear() {
+        LOCK_IF_NEEDED();
+        for (auto iter = mResources.begin(); iter != mResources.end(); iter++) {
+            derefImpl(*iter);
+        }
+        mResources.clear();
+        UNLOCK_IF_NEEDED();
+    }
+
+    inline size_t size() {
+        return mResources.size();
+    }
+
+private:
+    inline void derefImpl(ResourceType* resource) {
+        resource->deref();
+        if (resource->refcount() != 0) {
+            return;
+        }
+        deallocateResource(mAllocator, resource->getType(), resource->getId());
+    }
+
+    VulkanResourceAllocator* mAllocator;
+    SetType mResources;
+    std::unique_ptr<utils::Mutex> mMutex;
+
+    template <typename, typename> friend class VulkanResourceManagerImpl;
+};
+
+using VulkanAcquireOnlyResourceManager
+        = VulkanResourceManagerImpl<VulkanResource, FastIterationResourceSet>;
+using VulkanResourceManager = VulkanResourceManagerImpl<VulkanResource, ResourceSet>;
+
+template<std::size_t SIZE>
+using FixedSizeVulkanResourceManager =
+        VulkanResourceManagerImpl<VulkanResource, FixedCapacityResourceSet<SIZE>>;
+
+using VulkanThreadSafeResourceManager
+        = VulkanResourceManagerImpl<VulkanThreadSafeResource, ThreadSafeResourceSet>;
+
+#undef LOCK_IF_NEEDED
+#undef UNLOCK_IF_NEEDED
+
+} // namespace filament::backend
+
+#endif // TNT_FILAMENT_BACKEND_VULKANRESOURCES_H
@@ -16,7 +16,6 @@

 #include "VulkanStagePool.h"

-#include "VulkanCommands.h"
 #include "VulkanConstants.h"
 #include "VulkanImageUtility.h"
 #include "VulkanMemory.h"
@@ -38,7 +37,6 @@ VulkanStage const* VulkanStagePool::acquireStage(uint32_t numBytes) {
    if (iter != mFreeStages.end()) {
        auto stage = iter->second;
        mFreeStages.erase(iter);
-        stage->lastAccessed = mCurrentFrame;
        mUsedStages.insert(stage);
        return stage;
    }
@@ -61,7 +59,7 @@ VulkanStage const* VulkanStagePool::acquireStage(uint32_t numBytes) {
    UTILS_UNUSED_IN_RELEASE VkResult result = vmaCreateBuffer(mAllocator, &bufferInfo,
            &allocInfo, &stage->buffer, &stage->memory, nullptr);

-#if FVK_ENABLED(FVK_DEBUG_STAGING_ALLOCATION)
+#if FVK_ENABLED(FVK_DEBUG_ALLOCATION)
    if (result != VK_SUCCESS) {
        FVK_LOGE << "Allocation error: " << result << utils::io::endl;
    }
@@ -76,7 +74,6 @@ VulkanStageImage const* VulkanStagePool::acquireImage(PixelDataFormat format, Pi
    for (auto image : mFreeImages) {
        if (image->format == vkformat && image->width == width && image->height == height) {
            mFreeImages.erase(image);
-            image->lastAccessed = mCurrentFrame;
            mUsedImages.insert(image);
            return image;
        }
@@ -17,7 +17,8 @@
 #ifndef TNT_FILAMENT_BACKEND_VULKANSTAGEPOOL_H
 #define TNT_FILAMENT_BACKEND_VULKANSTAGEPOOL_H

-#include "backend/DriverEnums.h"
+#include "VulkanCommands.h"
+#include "VulkanContext.h"
 #include "VulkanMemory.h"

 #include <map>
@@ -25,8 +26,6 @@

 namespace filament::backend {

-class VulkanCommands;
-
 // Immutable POD representing a shared CPU-GPU staging area.
 struct VulkanStage {
    VmaAllocation memory;
@@ -15,8 +15,6 @@
 */

 #include "VulkanSwapChain.h"
-
-#include "VulkanCommands.h"
 #include "VulkanTexture.h"

 #include <utils/FixedCapacityVector.h>
@@ -28,18 +26,19 @@ using namespace utils;
 namespace filament::backend {

 VulkanSwapChain::VulkanSwapChain(VulkanPlatform* platform, VulkanContext const& context,
-        fvkmemory::ResourceManager* resourceManager, VmaAllocator allocator,
-        VulkanCommands* commands, VulkanStagePool& stagePool, void* nativeWindow, uint64_t flags,
-        VkExtent2D extent)
-    : mPlatform(platform),
-      mResourceManager(resourceManager),
+        VmaAllocator allocator, VulkanCommands* commands, VulkanResourceAllocator* handleAllocator,
+        VulkanStagePool& stagePool,
+        void* nativeWindow, uint64_t flags, VkExtent2D extent)
+    : VulkanResource(VulkanResourceType::SWAP_CHAIN),
+      mPlatform(platform),
      mCommands(commands),
      mAllocator(allocator),
+      mHandleAllocator(handleAllocator),
      mStagePool(stagePool),
      mHeadless(extent.width != 0 && extent.height != 0 && !nativeWindow),
      mFlushAndWaitOnResize(platform->getCustomization().flushAndWaitOnWindowResize),
      mTransitionSwapChainImageLayoutForPresent(
-              platform->getCustomization().transitionSwapChainImageLayoutForPresent),
+            platform->getCustomization().transitionSwapChainImageLayoutForPresent),
      mAcquired(false),
      mIsFirstRenderPass(true) {
    swapChain = mPlatform->createSwapChain(nativeWindow, flags, extent);
@@ -54,9 +53,6 @@ VulkanSwapChain::~VulkanSwapChain() {
    mCommands->flush();
    mCommands->wait();

-    mColors = {};
-    mDepth = {};
-
    mPlatform->destroy(swapChain);
 }

@@ -67,24 +63,14 @@ void VulkanSwapChain::update() {
    mColors.reserve(bundle.colors.size());
    VkDevice const device = mPlatform->getDevice();

-    TextureUsage depthUsage = TextureUsage::DEPTH_ATTACHMENT;
-    TextureUsage colorUsage = TextureUsage::COLOR_ATTACHMENT;
-    if (bundle.isProtected) {
-        depthUsage |= TextureUsage::PROTECTED;
-        colorUsage |= TextureUsage::PROTECTED;
-    }
    for (auto const color: bundle.colors) {
-        auto colorTexture = fvkmemory::resource_ptr<VulkanTexture>::construct(mResourceManager,
-                device, mAllocator, mResourceManager, mCommands, color, VK_NULL_HANDLE,
-                bundle.colorFormat, 1, bundle.extent.width, bundle.extent.height, colorUsage,
-                mStagePool);
-        mColors.push_back(colorTexture);
+        mColors.push_back(std::make_unique<VulkanTexture>(device, mAllocator, mCommands, mHandleAllocator,
+                color, bundle.colorFormat, 1, bundle.extent.width, bundle.extent.height,
+                TextureUsage::COLOR_ATTACHMENT, mStagePool, true /* heap allocated */));
    }
-
-    mDepth = fvkmemory::resource_ptr<VulkanTexture>::construct(mResourceManager, device,
-        mAllocator, mResourceManager, mCommands, bundle.depth, VK_NULL_HANDLE,
-        bundle.depthFormat, 1, bundle.extent.width, bundle.extent.height, depthUsage,
-        mStagePool);
+    mDepth = std::make_unique<VulkanTexture>(device, mAllocator, mCommands, mHandleAllocator,
+            bundle.depth, bundle.depthFormat, 1, bundle.extent.width, bundle.extent.height,
+            TextureUsage::DEPTH_ATTACHMENT, mStagePool, true /* heap allocated */);

    mExtent = bundle.extent;
 }
@@ -103,7 +89,7 @@ void VulkanSwapChain::present() {
    }

    mCommands->flush();
-
+    
    // call the image ready wait function
    if (mExplicitImageReadyWait != nullptr) {
        mExplicitImageReadyWait(swapChain);
@@ -143,7 +129,7 @@ void VulkanSwapChain::acquire(bool& resized) {
    VkResult const result = mPlatform->acquire(swapChain, &imageSyncData);
    mCurrentSwapIndex = imageSyncData.imageIndex;
    mExplicitImageReadyWait = imageSyncData.explicitImageReadyWait;
-    FILAMENT_CHECK_POSTCONDITION(result == VK_SUCCESS || result == VK_SUBOPTIMAL_KHR)
+    FILAMENT_CHECK_POSTCONDITION(result == VK_SUCCESS || result == VK_SUBOPTIMAL_KHR) 
        << "Cannot acquire in swapchain.";
    if (imageSyncData.imageReadySemaphore != VK_NULL_HANDLE) {
        mCommands->injectDependency(imageSyncData.imageReadySemaphore);
@@ -19,9 +19,9 @@

 #include "DriverBase.h"

+#include "VulkanCommands.h"
 #include "VulkanContext.h"
-#include "VulkanTexture.h"
-#include "vulkan/memory/Resource.h"
+#include "VulkanResources.h"

 #include <backend/platforms/VulkanPlatform.h>

@@ -36,14 +36,14 @@ namespace filament::backend {

 struct VulkanHeadlessSwapChain;
 struct VulkanSurfaceSwapChain;
-class VulkanCommands;
+class VulkanResourceAllocator;

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

    ~VulkanSwapChain();

@@ -51,15 +51,15 @@ struct VulkanSwapChain : public HwSwapChain, fvkmemory::Resource {

    void acquire(bool& reized);

-    fvkmemory::resource_ptr<VulkanTexture> getCurrentColor() const noexcept {
+    inline VulkanTexture* getCurrentColor() const noexcept {
        uint32_t const imageIndex = mCurrentSwapIndex;
        FILAMENT_CHECK_PRECONDITION(
            imageIndex != VulkanPlatform::ImageSyncData::INVALID_IMAGE_INDEX);
-        return mColors[imageIndex];
+        return mColors[imageIndex].get();
    }

-    inline fvkmemory::resource_ptr<VulkanTexture> getDepth() const noexcept {
-        return mDepth;
+    inline VulkanTexture* getDepth() const noexcept {
+        return mDepth.get();
    }

    inline bool isFirstRenderPass() const noexcept {
@@ -74,18 +74,15 @@ struct VulkanSwapChain : public HwSwapChain, fvkmemory::Resource {
        return mExtent;
    }

-    inline bool isProtected() noexcept {
-        return mPlatform->isProtected(swapChain);
-    }
 private:
 	static constexpr int IMAGE_READY_SEMAPHORE_COUNT = FVK_MAX_COMMAND_BUFFERS;

    void update();

    VulkanPlatform* mPlatform;
-    fvkmemory::ResourceManager* mResourceManager;
    VulkanCommands* mCommands;
    VmaAllocator mAllocator;
+    VulkanResourceAllocator* const mHandleAllocator;
    VulkanStagePool& mStagePool;
    bool const mHeadless;
    bool const mFlushAndWaitOnResize;
@@ -93,8 +90,8 @@ private:

    // We create VulkanTextures based on VkImages. VulkanTexture has facilities for doing layout
    // transitions, which are useful here.
-    utils::FixedCapacityVector<fvkmemory::resource_ptr<VulkanTexture>> mColors;
-    fvkmemory::resource_ptr<VulkanTexture> mDepth;
+    utils::FixedCapacityVector<std::unique_ptr<VulkanTexture>> mColors;
+    std::unique_ptr<VulkanTexture> mDepth;
    VkExtent2D mExtent;
    uint32_t mCurrentSwapIndex;
    std::function<void(Platform::SwapChain* handle)> mExplicitImageReadyWait = nullptr;
@@ -14,11 +14,10 @@
 * limitations under the License.
 */

-#include "VulkanCommands.h"
 #include "VulkanMemory.h"
+#include "VulkanResourceAllocator.h"
 #include "VulkanTexture.h"
 #include "VulkanUtility.h"
-#include "vulkan/memory/ResourcePointer.h"

 #include <DataReshaper.h>
 #include <backend/DriverEnums.h>
@@ -148,56 +147,72 @@ inline VulkanLayout getDefaultLayoutImpl(VkImageUsageFlags vkusage) {

 VulkanTextureState::VulkanTextureState(VkDevice device, VmaAllocator allocator,
        VulkanCommands* commands, VulkanStagePool& stagePool, VkFormat format,
-        VkImageViewType viewType, uint8_t levels, uint8_t layerCount, VulkanLayout defaultLayout,
-        bool isProtected)
-    : mVkFormat(format),
+        VkImageViewType viewType, uint8_t levels, uint8_t layerCount, VulkanLayout defaultLayout)
+    : VulkanResource(VulkanResourceType::HEAP_ALLOCATED),
+      mVkFormat(format),
      mViewType(viewType),
      mFullViewRange{filament::backend::getImageAspect(format), 0, levels, 0, layerCount},
      mDefaultLayout(defaultLayout),
-      mIsProtected(isProtected),
      mStagePool(stagePool),
      mDevice(device),
      mAllocator(allocator),
      mCommands(commands),
      mIsTransientAttachment(false) {}

+VulkanTextureState* VulkanTexture::getSharedState() {
+    VulkanTextureState* state = mAllocator->handle_cast<VulkanTextureState*>(mState);
+    return state;
+}
+
+VulkanTextureState const* VulkanTexture::getSharedState() const {
+    VulkanTextureState const* state = mAllocator->handle_cast<VulkanTextureState const*>(mState);
+    return state;
+}
+
 // Constructor for internally passed VkImage
-VulkanTexture::VulkanTexture(VkDevice device, VmaAllocator allocator,
-        fvkmemory::ResourceManager* resourceManager, VulkanCommands* commands, VkImage image,
-        VkDeviceMemory memory, VkFormat format, uint8_t samples, uint32_t width,
-        uint32_t height, TextureUsage tusage, VulkanStagePool& stagePool)
-    : HwTexture(SamplerType::SAMPLER_2D, 1, samples, width, height, 1, TextureFormat::UNUSED,
-              tusage),
-      mState(fvkmemory::resource_ptr<VulkanTextureState>::construct(resourceManager, device,
-              allocator, commands, stagePool, format, imgutil::getViewType(SamplerType::SAMPLER_2D),
-              1, 1, getDefaultLayoutImpl(tusage), any(usage & TextureUsage::PROTECTED))) {
-    mState->mTextureImage = image;
-    mState->mTextureImageMemory = memory;
-    mPrimaryViewRange = mState->mFullViewRange;
+VulkanTexture::VulkanTexture(
+        VkDevice device, VmaAllocator allocator, VulkanCommands* commands,
+        VulkanResourceAllocator* handleAllocator,
+        VkImage image, VkFormat format, uint8_t samples, uint32_t width, uint32_t height,
+        TextureUsage tusage, VulkanStagePool& stagePool, bool heapAllocated)
+        : HwTexture(SamplerType::SAMPLER_2D, 1, samples, width, height, 1, TextureFormat::UNUSED,
+                tusage),
+          VulkanResource(
+                  heapAllocated ? VulkanResourceType::HEAP_ALLOCATED : VulkanResourceType::TEXTURE),
+          mAllocator(handleAllocator),
+          mState(handleAllocator->initHandle<VulkanTextureState>(
+                  device, allocator, commands, stagePool,
+                  format, imgutil::getViewType(SamplerType::SAMPLER_2D), 1, 1,
+                  getDefaultLayoutImpl(tusage))) {
+    auto* const state = getSharedState();
+    state->mTextureImage = image;
+    mPrimaryViewRange = state->mFullViewRange;
 }

 // Constructor for user facing texture
 VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
-        VulkanContext const& context, VmaAllocator allocator,
-        fvkmemory::ResourceManager* resourceManager, VulkanCommands* commands, SamplerType target,
-        uint8_t levels, TextureFormat tformat, uint8_t samples, uint32_t w, uint32_t h,
-        uint32_t depth, TextureUsage tusage, VulkanStagePool& stagePool)
+        VulkanContext const& context, VmaAllocator allocator, VulkanCommands* commands,
+        VulkanResourceAllocator* handleAllocator, SamplerType target, uint8_t levels,
+        TextureFormat tformat, uint8_t samples, uint32_t w, uint32_t h, uint32_t depth,
+        TextureUsage tusage, VulkanStagePool& stagePool, bool heapAllocated)
    : HwTexture(target, levels, samples, w, h, depth, tformat, tusage),
-      mState(fvkmemory::resource_ptr<VulkanTextureState>::construct(resourceManager, device,
-              allocator, commands, stagePool, backend::getVkFormat(tformat),
-              imgutil::getViewType(target), levels, getLayerCount(target, depth),
-              VulkanLayout::UNDEFINED, any(usage & TextureUsage::PROTECTED))) {
+      VulkanResource(
+              heapAllocated ? VulkanResourceType::HEAP_ALLOCATED : VulkanResourceType::TEXTURE),
+      mAllocator(handleAllocator),
+      mState(handleAllocator->initHandle<VulkanTextureState>(device, allocator, commands, stagePool,
+              backend::getVkFormat(tformat), imgutil::getViewType(target), levels,
+              getLayerCount(target, depth), VulkanLayout::UNDEFINED)) {
+    auto* const state = getSharedState();
+
    // Create an appropriately-sized device-only VkImage, but do not fill it yet.
-    VkImageCreateInfo imageInfo{
-        .sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
-        .imageType = target == SamplerType::SAMPLER_3D ? VK_IMAGE_TYPE_3D : VK_IMAGE_TYPE_2D,
-        .format = mState->mVkFormat,
-        .extent = {w, h, depth},
-        .mipLevels = levels,
-        .arrayLayers = 1,
-        .tiling = VK_IMAGE_TILING_OPTIMAL,
-        .usage = 0,
-    };
+    VkImageCreateInfo imageInfo{.sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
+            .imageType = target == SamplerType::SAMPLER_3D ? VK_IMAGE_TYPE_3D : VK_IMAGE_TYPE_2D,
+            .format = state->mVkFormat,
+            .extent = {w, h, depth},
+            .mipLevels = levels,
+            .arrayLayers = 1,
+            .tiling = VK_IMAGE_TILING_OPTIMAL,
+            .usage = 0};
    if (target == SamplerType::SAMPLER_CUBEMAP) {
        imageInfo.arrayLayers = 6;
        imageInfo.flags = VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT;
@@ -217,9 +232,6 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
        imageInfo.arrayLayers = depth * 6;
        imageInfo.extent.depth = 1;
    }
-    if (any(usage & TextureUsage::PROTECTED)) {
-        imageInfo.flags |= VK_IMAGE_CREATE_PROTECTED_BIT;
-    }

    if (any(usage & TextureUsage::BLIT_SRC)) {
        imageInfo.usage |= VK_IMAGE_USAGE_TRANSFER_SRC_BIT;
@@ -236,7 +248,7 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
        none(tusage & ~TextureUsage::ALL_ATTACHMENTS) &&
        // Usage contains at least one attachment flag.
        any(tusage & TextureUsage::ALL_ATTACHMENTS);
-    mState->mIsTransientAttachment = useTransientAttachment;
+    state->mIsTransientAttachment = useTransientAttachment;

    const VkImageUsageFlags transientFlag =
       useTransientAttachment ? VK_IMAGE_USAGE_TRANSIENT_ATTACHMENT_BIT : 0U;
@@ -281,7 +293,7 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
    // any kind of attachment (color or depth).
    const auto& limits = context.getPhysicalDeviceLimits();
    if (imageInfo.usage & VK_IMAGE_USAGE_SAMPLED_BIT) {
-        samples = reduceSampleCount(samples, isVkDepthFormat(mState->mVkFormat)
+        samples = reduceSampleCount(samples, isVkDepthFormat(state->mVkFormat)
                                                     ? limits.sampledImageDepthSampleCounts
                                                     : limits.sampledImageColorSampleCounts);
    }
@@ -295,12 +307,12 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
    this->samples = samples;
    imageInfo.samples = (VkSampleCountFlagBits) samples;

-    VkResult error = vkCreateImage(mState->mDevice, &imageInfo, VKALLOC, &mState->mTextureImage);
+    VkResult error = vkCreateImage(state->mDevice, &imageInfo, VKALLOC, &state->mTextureImage);
    if (error || FVK_ENABLED(FVK_DEBUG_TEXTURE)) {
        FVK_LOGD << "vkCreateImage: "
-            << "image = " << mState->mTextureImage << ", "
+            << "image = " << state->mTextureImage << ", "
            << "result = " << error << ", "
-            << "handle = " << utils::io::hex << mState->mTextureImage << utils::io::dec << ", "
+            << "handle = " << utils::io::hex << state->mTextureImage << utils::io::dec << ", "
            << "extent = " << w << "x" << h << "x"<< depth << ", "
            << "mipLevels = " << int(levels) << ", "
            << "TextureUsage = " << static_cast<int>(usage) << ", "
@@ -309,18 +321,17 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
            << "type = " << imageInfo.imageType << ", "
            << "flags = " << imageInfo.flags << ", "
            << "target = " << static_cast<int>(target) <<", "
-            << "format = " << mState->mVkFormat << utils::io::endl;
+            << "format = " << state->mVkFormat << utils::io::endl;
    }
    FILAMENT_CHECK_POSTCONDITION(!error) << "Unable to create image.";

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

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

@@ -332,29 +343,37 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
        .allocationSize = memReqs.size,
        .memoryTypeIndex = memoryTypeIndex,
    };
-    error = vkAllocateMemory(mState->mDevice, &allocInfo, nullptr, &mState->mTextureImageMemory);
+    error = vkAllocateMemory(state->mDevice, &allocInfo, nullptr, &state->mTextureImageMemory);
    FILAMENT_CHECK_POSTCONDITION(!error) << "Unable to allocate image memory.";
-    error = vkBindImageMemory(mState->mDevice, mState->mTextureImage, mState->mTextureImageMemory,
-            0);
+    error = vkBindImageMemory(state->mDevice, state->mTextureImage, state->mTextureImageMemory, 0);
    FILAMENT_CHECK_POSTCONDITION(!error) << "Unable to bind image.";

    // Spec out the "primary" VkImageView that shaders use to sample from the image.
-    mPrimaryViewRange = mState->mFullViewRange;
+    mPrimaryViewRange = state->mFullViewRange;

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

-    mState->mDefaultLayout = getDefaultLayoutImpl(imageInfo.usage);
+    VulkanCommandBuffer& commandsBuf = state->mCommands->get();
+    commandsBuf.acquire(this);
+
+    auto const defaultLayout = state->mDefaultLayout = getDefaultLayoutImpl(imageInfo.usage);
+    transitionLayout(&commandsBuf, mPrimaryViewRange, defaultLayout);
 }

 // Constructor for creating a texture view
 VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
        VulkanContext const& context, VmaAllocator allocator, VulkanCommands* commands,
-        fvkmemory::resource_ptr<VulkanTexture> src, uint8_t baseLevel,
+        VulkanResourceAllocator* handleAllocator, VulkanTexture const* src, uint8_t baseLevel,
        uint8_t levelCount)
    : HwTexture(src->target, src->levels, src->samples, src->width, src->height, src->depth,
-            src->format, src->usage) {
+              src->format, src->usage),
+      VulkanResource(VulkanResourceType::TEXTURE),
+      mAllocator(handleAllocator) {
    mState = src->mState;
+    auto* state = getSharedState();
+
+    state->refs++;
    mPrimaryViewRange = src->mPrimaryViewRange;
    mPrimaryViewRange.baseMipLevel = src->mPrimaryViewRange.baseMipLevel + baseLevel;
    mPrimaryViewRange.levelCount = levelCount;
@@ -363,21 +382,31 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
 // Constructor for creating a texture view with swizzle
 VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
        VulkanContext const& context, VmaAllocator allocator, VulkanCommands* commands,
-        fvkmemory::resource_ptr<VulkanTexture> src, VkComponentMapping swizzle)
+        VulkanResourceAllocator* handleAllocator, VulkanTexture const* src,
+        VkComponentMapping swizzle)
    : HwTexture(src->target, src->levels, src->samples, src->width, src->height, src->depth,
-              src->format, src->usage) {
+              src->format, src->usage),
+      VulkanResource(VulkanResourceType::TEXTURE),
+      mAllocator(handleAllocator) {
    mState = src->mState;
+    auto* state = getSharedState();
+    state->refs++;
    mPrimaryViewRange = src->mPrimaryViewRange;
    mSwizzle = composeSwizzle(src->mSwizzle, swizzle);
 }

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

@@ -386,7 +415,7 @@ void VulkanTexture::updateImage(const PixelBufferDescriptor& data, uint32_t widt
    assert_invariant(width <= this->width && height <= this->height);
    assert_invariant(depth <= this->depth * ((target == SamplerType::SAMPLER_CUBEMAP ||
                        target == SamplerType::SAMPLER_CUBEMAP_ARRAY) ? 6 : 1));
-    assert_invariant(!mState->mIsProtected);
+    auto* const state = getSharedState();
    const PixelBufferDescriptor* hostData = &data;
    PixelBufferDescriptor reshapedData;

@@ -399,7 +428,7 @@ void VulkanTexture::updateImage(const PixelBufferDescriptor& data, uint32_t widt

    // If format conversion is both required and supported, use vkCmdBlitImage.
    const VkFormat hostFormat = backend::getVkFormat(hostData->format, hostData->type);
-    const VkFormat deviceFormat = getVkFormatLinear(mState->mVkFormat);
+    const VkFormat deviceFormat = getVkFormatLinear(state->mVkFormat);
    if (hostFormat != deviceFormat && hostFormat != VK_FORMAT_UNDEFINED) {
        assert_invariant(xoffset == 0 && yoffset == 0 && zoffset == 0 &&
                "Offsets not yet supported when format conversion is required.");
@@ -411,16 +440,16 @@ void VulkanTexture::updateImage(const PixelBufferDescriptor& data, uint32_t widt

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

-    VulkanCommandBuffer& commands = mState->mCommands->get();
+    VulkanCommandBuffer& commands = state->mCommands->get();
    VkCommandBuffer const cmdbuf = commands.buffer();
-    commands.acquire(fvkmemory::resource_ptr<VulkanTexture>::cast(this));
+    commands.acquire(this);

    VkBufferImageCopy copyRegion = {
        .bufferOffset = {},
@@ -466,24 +495,25 @@ void VulkanTexture::updateImage(const PixelBufferDescriptor& data, uint32_t widt

    transitionLayout(&commands, transitionRange, newLayout);

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

    transitionLayout(&commands, transitionRange, nextLayout);
 }

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

-    VulkanCommandBuffer& commands = mState->mCommands->get();
+    VulkanCommandBuffer& commands = state->mCommands->get();
    VkCommandBuffer const cmdbuf = commands.buffer();
-    commands.acquire(fvkmemory::resource_ptr<VulkanTexture>::cast(this));
+    commands.acquire(this);

    // TODO: support blit-based format conversion for 3D images and cubemaps.
    const int layer = 0;
@@ -506,13 +536,14 @@ void VulkanTexture::updateImageWithBlit(const PixelBufferDescriptor& hostData, u
    transitionLayout(&commands, range, newLayout);

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

    transitionLayout(&commands, range, oldLayout);
 }

 VulkanLayout VulkanTexture::getDefaultLayout() const {
-    return mState->mDefaultLayout;
+    auto* const state = getSharedState();
+    return state->mDefaultLayout;
 }

 VkImageView VulkanTexture::getAttachmentView(VkImageSubresourceRange range) {
@@ -531,43 +562,42 @@ VkImageView VulkanTexture::getViewForType(VkImageSubresourceRange const& range,

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

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

 bool VulkanTexture::transitionLayout(VulkanCommandBuffer* commands,
        VkImageSubresourceRange const& range, VulkanLayout newLayout) {
-    if (transitionLayout(commands->buffer(), range, newLayout)) {
-        commands->acquire(fvkmemory::resource_ptr<VulkanTexture>::cast(this));
-        return true;
-    }
-    return false;
+    return transitionLayout(commands->buffer(), range, newLayout);
 }

 bool VulkanTexture::transitionLayout(VkCommandBuffer cmdbuf, VkImageSubresourceRange const& range,
        VulkanLayout newLayout) {
+    auto* const state = getSharedState();
    VulkanLayout const oldLayout = getLayout(range.baseArrayLayer, range.baseMipLevel);

    uint32_t const firstLayer = range.baseArrayLayer;
@@ -598,7 +628,7 @@ bool VulkanTexture::transitionLayout(VkCommandBuffer cmdbuf, VkImageSubresourceR
                    continue;
                }
                hasTransitions = hasTransitions || imgutil::transitionLayout(cmdbuf, {
-                    .image = mState->mTextureImage,
+                    .image = state->mTextureImage,
                    .oldLayout = layout,
                    .newLayout = newLayout,
                    .subresources = {
@@ -613,7 +643,7 @@ bool VulkanTexture::transitionLayout(VkCommandBuffer cmdbuf, VkImageSubresourceR
        }
    } else if (newLayout != oldLayout) {
        hasTransitions = imgutil::transitionLayout(cmdbuf, {
-            .image = mState->mTextureImage,
+            .image = state->mTextureImage,
            .oldLayout = oldLayout,
            .newLayout = newLayout,
            .subresources = range,
@@ -646,6 +676,7 @@ bool VulkanTexture::transitionLayout(VkCommandBuffer cmdbuf, VkImageSubresourceR
 void VulkanTexture::samplerToAttachmentBarrier(VulkanCommandBuffer* commands,
        VkImageSubresourceRange const& range) {
    VkCommandBuffer const cmdbuf = commands->buffer();
+    auto* const state = getSharedState();
    VkImageLayout const layout =
            imgutil::getVkLayout(getLayout(range.baseArrayLayer, range.baseMipLevel));
    VkImageMemoryBarrier barrier = {
@@ -657,7 +688,7 @@ void VulkanTexture::samplerToAttachmentBarrier(VulkanCommandBuffer* commands,
            .newLayout = layout,
            .srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
            .dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
-            .image = mState->mTextureImage,
+            .image = state->mTextureImage,
            .subresourceRange = range,
    };
    vkCmdPipelineBarrier(cmdbuf, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT,
@@ -669,6 +700,7 @@ void VulkanTexture::samplerToAttachmentBarrier(VulkanCommandBuffer* commands,
 void VulkanTexture::attachmentToSamplerBarrier(VulkanCommandBuffer* commands,
        VkImageSubresourceRange const& range) {
    VkCommandBuffer const cmdbuf = commands->buffer();
+    auto* const state = getSharedState();
    VkImageLayout const layout
            = imgutil::getVkLayout(getLayout(range.baseArrayLayer, range.baseMipLevel));
    VkImageMemoryBarrier barrier = {
@@ -679,7 +711,7 @@ void VulkanTexture::attachmentToSamplerBarrier(VulkanCommandBuffer* commands,
            .newLayout = layout,
            .srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
            .dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
-            .image = mState->mTextureImage,
+            .image = state->mTextureImage,
            .subresourceRange = range,
    };
    vkCmdPipelineBarrier(cmdbuf, VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
@@ -687,6 +719,7 @@ void VulkanTexture::attachmentToSamplerBarrier(VulkanCommandBuffer* commands,
 }

 void VulkanTexture::setLayout(VkImageSubresourceRange const& range, VulkanLayout newLayout) {
+    auto* const state = getSharedState();
    uint32_t const firstLayer = range.baseArrayLayer;
    uint32_t const lastLayer = firstLayer + range.layerCount;
    uint32_t const firstLevel = range.baseMipLevel;
@@ -699,32 +732,34 @@ void VulkanTexture::setLayout(VkImageSubresourceRange const& range, VulkanLayout
        for (uint32_t layer = firstLayer; layer < lastLayer; ++layer) {
            uint32_t const first = (layer << 16) | firstLevel;
            uint32_t const last = (layer << 16) | lastLevel;
-            mState->mSubresourceLayouts.clear(first, last);
+            state->mSubresourceLayouts.clear(first, last);
        }
    } else {
        for (uint32_t layer = firstLayer; layer < lastLayer; ++layer) {
            uint32_t const first = (layer << 16) | firstLevel;
            uint32_t const last = (layer << 16) | lastLevel;
-            mState->mSubresourceLayouts.add(first, last, newLayout);
+            state->mSubresourceLayouts.add(first, last, newLayout);
        }
    }
 }

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

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

    for (uint32_t layer = firstLayer; layer < lastLayer; ++layer) {
        for (uint32_t level = firstLevel; level < lastLevel; ++level) {
@@ -733,16 +768,16 @@ void VulkanTexture::print() const {
                layer < (mPrimaryViewRange.baseArrayLayer + mPrimaryViewRange.layerCount) &&
                level >= mPrimaryViewRange.baseMipLevel &&
                level < (mPrimaryViewRange.baseMipLevel + mPrimaryViewRange.levelCount);
-            FVK_LOGD << "[" << mState->mTextureImage << "]: (" << layer << "," << level
+            FVK_LOGD << "[" << state->mTextureImage << "]: (" << layer << "," << level
                          << ")=" << getLayout(layer, level)
                          << " primary=" << primary
                          << utils::io::endl;
        }
    }

-    for (auto view: mState->mCachedImageViews) {
+    for (auto view: state->mCachedImageViews) {
        auto& range = view.first.range;
-        FVK_LOGD << "[" << mState->mTextureImage << ", imageView=" << view.second << "]=>"
+        FVK_LOGD << "[" << state->mTextureImage << ", imageView=" << view.second << "]=>"
                      << " (" << range.baseArrayLayer << "," << range.baseMipLevel << ")"
                      << " count=(" << range.layerCount << "," << range.levelCount << ")"
                      << " aspect=" << range.aspectMask << " viewType=" << view.first.type
@@ -20,9 +20,8 @@
 #include "DriverBase.h"

 #include "VulkanBuffer.h"
+#include "VulkanResources.h"
 #include "VulkanImageUtility.h"
-#include "vulkan/memory/Resource.h"
-#include "vulkan/memory/ResourcePointer.h"

 #include <utils/Hash.h>
 #include <utils/RangeMap.h>
@@ -31,12 +30,12 @@

 namespace filament::backend {

-struct VulkanTextureState : public fvkmemory::Resource {
+class VulkanResourceAllocator;
+
+struct VulkanTextureState : public VulkanResource {
    VulkanTextureState(VkDevice device, VmaAllocator allocator, VulkanCommands* commands,
            VulkanStagePool& stagePool, VkFormat format, VkImageViewType viewType, uint8_t levels,
-            uint8_t layerCount, VulkanLayout defaultLayout, bool isProtected);
-
-    ~VulkanTextureState();
+            uint8_t layerCount, VulkanLayout defaultLayout);

    struct ImageViewKey {
        VkImageSubresourceRange range;  // 4 * 5 bytes
@@ -59,8 +58,10 @@ struct VulkanTextureState : public fvkmemory::Resource {

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

+    uint32_t refs = 1;
+
    // The texture with the sidecar owns the sidecar.
-    fvkmemory::resource_ptr<VulkanTexture> mSidecarMSAA;
+    std::unique_ptr<VulkanTexture> mSidecarMSAA;
    VkDeviceMemory mTextureImageMemory = VK_NULL_HANDLE;

    VkFormat const mVkFormat;
@@ -69,8 +70,6 @@ struct VulkanTextureState : public fvkmemory::Resource {
    VkImage mTextureImage = VK_NULL_HANDLE;
    VulkanLayout mDefaultLayout;

-    bool mIsProtected = false;
-
    // Track the image layout of each subresource using a sparse range map.
    utils::RangeMap<uint32_t, VulkanLayout> mSubresourceLayouts;

@@ -82,32 +81,37 @@ struct VulkanTextureState : public fvkmemory::Resource {
    bool mIsTransientAttachment;
 };

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

    // Specialized constructor for internally created textures (e.g. from a swap chain)
    // The texture will never destroy the given VkImage, but it does manages its subresources.
-    VulkanTexture(VkDevice device, VmaAllocator allocator,
-            fvkmemory::ResourceManager* resourceManager, VulkanCommands* commands, VkImage image,
-            VkDeviceMemory memory, VkFormat format, uint8_t samples, uint32_t width, uint32_t height,
-            TextureUsage tusage, VulkanStagePool& stagePool);
+    VulkanTexture(VkDevice device, VmaAllocator allocator, VulkanCommands* commands,
+            VulkanResourceAllocator* handleAllocator,
+            VkImage image,
+            VkFormat format, uint8_t samples, uint32_t width, uint32_t height, TextureUsage tusage,
+            VulkanStagePool& stagePool, bool heapAllocated = false);

    // Constructor for creating a texture view for wrt specific mip range
    VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice, VulkanContext const& context,
            VmaAllocator allocator, VulkanCommands* commands,
-            fvkmemory::resource_ptr<VulkanTexture> src, uint8_t baseLevel, uint8_t levelCount);
+            VulkanResourceAllocator* handleAllocator,
+            VulkanTexture const* src, uint8_t baseLevel, uint8_t levelCount);

    // Constructor for creating a texture view for swizzle.
    VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice, VulkanContext const& context,
            VmaAllocator allocator, VulkanCommands* commands,
-            fvkmemory::resource_ptr<VulkanTexture> src, VkComponentMapping swizzle);
+            VulkanResourceAllocator* handleAllocator,
+            VulkanTexture const* src, VkComponentMapping swizzle);

-    ~VulkanTexture() = default;
+    ~VulkanTexture();

    // Uploads data into a subregion of a 2D or 3D texture.
    void updateImage(const PixelBufferDescriptor& data, uint32_t width, uint32_t height,
@@ -115,14 +119,16 @@ struct VulkanTexture : public HwTexture, fvkmemory::Resource {

    // Returns the primary image view, which is used for shader sampling.
    VkImageView getPrimaryImageView() {
-        return getImageView(mPrimaryViewRange, mState->mViewType, mSwizzle);
+        VulkanTextureState* state = getSharedState();
+        return getImageView(mPrimaryViewRange, state->mViewType, mSwizzle);
    }

    VkImageViewType getViewType() const {
-        return mState->mViewType;
+        VulkanTextureState const* state = getSharedState();
+        return state->mViewType;
    }

-    VkImageSubresourceRange const& getPrimaryViewRange() const { return mPrimaryViewRange; }
+    VkImageSubresourceRange getPrimaryViewRange() const { return mPrimaryViewRange; }

    VulkanLayout getPrimaryImageLayout() const {
        return getLayout(mPrimaryViewRange.baseArrayLayer, mPrimaryViewRange.baseMipLevel);
@@ -148,28 +154,29 @@ struct VulkanTexture : public HwTexture, fvkmemory::Resource {
    VkImageView getViewForType(VkImageSubresourceRange const& range, VkImageViewType type);

    VkFormat getVkFormat() const {
-        return mState->mVkFormat;
+        VulkanTextureState const* state = getSharedState();
+        return state->mVkFormat;
    }
    VkImage getVkImage() const {
-        return mState->mTextureImage;
+        VulkanTextureState const* state = getSharedState();
+        return state->mTextureImage;
    }

    VulkanLayout getLayout(uint32_t layer, uint32_t level) const;

-    void setSidecar(fvkmemory::resource_ptr<VulkanTexture> sidecar) {
-        mState->mSidecarMSAA = sidecar;
+    void setSidecar(VulkanTexture* sidecar) {
+        VulkanTextureState* state = getSharedState();
+        state->mSidecarMSAA.reset(sidecar);
    }

-    fvkmemory::resource_ptr<VulkanTexture> getSidecar() const {
-        return mState->mSidecarMSAA;
+    VulkanTexture* getSidecar() const {
+        VulkanTextureState const* state = getSharedState();
+        return state->mSidecarMSAA.get();
    }

    bool isTransientAttachment() const {
-        return mState->mIsTransientAttachment;
-    }
-
-    bool getIsProtected() const {
-        return mState->mIsProtected;
+        VulkanTextureState const* state = getSharedState();
+        return state->mIsTransientAttachment;
    }

    bool transitionLayout(VulkanCommandBuffer* commands, VkImageSubresourceRange const& range,
@@ -197,6 +204,9 @@ struct VulkanTexture : public HwTexture, fvkmemory::Resource {
 #endif

 private:
+    VulkanTextureState* getSharedState();
+    VulkanTextureState const* getSharedState() const;
+
    // Gets or creates a cached VkImageView for a range of miplevels, array layers, viewType, and
    // swizzle (or not).
    VkImageView getImageView(VkImageSubresourceRange range, VkImageViewType viewType,
@@ -205,7 +215,9 @@ private:
    void updateImageWithBlit(const PixelBufferDescriptor& hostData, uint32_t width, uint32_t height,
            uint32_t depth, uint32_t miplevel);

-    fvkmemory::resource_ptr<VulkanTextureState> mState;
+    VulkanResourceAllocator* const mAllocator;
+
+    Handle<VulkanTextureState> mState;

    // Track the range of subresources that define the "primary" image view, which is the special
    // image view that gets bound to an actual texture sampler.
@@ -16,11 +16,11 @@

 #include "VulkanDescriptorSetManager.h"

-#include <vulkan/VulkanCommands.h>
 #include <vulkan/VulkanHandles.h>
 #include <vulkan/VulkanUtility.h>
 #include <vulkan/VulkanConstants.h>
 #include <vulkan/VulkanImageUtility.h>
+#include <vulkan/VulkanResources.h>
 #include <utils/FixedCapacityVector.h>
 #include <utils/Panic.h>

@@ -274,7 +274,7 @@ public:
    DescriptorInfinitePool(VkDevice device)
        : mDevice(device) {}

-    VkDescriptorSet obtainSet(fvkmemory::resource_ptr<VulkanDescriptorSetLayout> layout) {
+    VkDescriptorSet obtainSet(VulkanDescriptorSetLayout* layout) {
        auto const vklayout = layout->getVkLayout();
        DescriptorPool* sameTypePool = nullptr;
        for (auto& pool: mPools) {
@@ -325,12 +325,13 @@ public:
    DescriptorSetLayoutManager(VkDevice device)
        : mDevice(device) {}

-    VkDescriptorSetLayout getVkLayout(VulkanDescriptorSetLayout::Bitmask const& bitmasks) {
+    VkDescriptorSetLayout getVkLayout(VulkanDescriptorSetLayout* layout) {
+        auto const& bitmasks = layout->bitmask;
        if (auto itr = mVkLayouts.find(bitmasks); itr != mVkLayouts.end()) {
            return itr->second;
        }
-        auto vklayout = createLayout(mDevice, bitmasks);
-        mVkLayouts[bitmasks] = vklayout;
+        auto vklayout = createLayout(mDevice, layout->bitmask);
+        mVkLayouts[layout->bitmask] = vklayout;
        return vklayout;
    }

@@ -346,11 +347,74 @@ private:
            mVkLayouts;
 };

+class VulkanDescriptorSetManager::DescriptorSetHistory {
+private:
+    using TextureBundle = std::pair<VulkanTexture*, VkImageSubresourceRange>;
+
+public:
+    DescriptorSetHistory()
+        : dynamicUboCount(0),
+          mResources(nullptr) {}
+
+    DescriptorSetHistory(UniformBufferBitmask const& dynamicUbo, uint8_t uniqueDynamicUboCount,
+            VulkanResourceAllocator* allocator, VulkanDescriptorSet* set)
+        : dynamicUboMask(dynamicUbo),
+          dynamicUboCount(uniqueDynamicUboCount),
+          mResources(allocator),
+          mSet(set),
+          mBound(false) {
+        assert_invariant(set);
+        // initial state is unbound.
+        unbind();
+    }
+
+    ~DescriptorSetHistory() {
+        if (mSet) {
+            mResources.clear();
+        }
+    }
+
+    void setOffsets(backend::DescriptorSetOffsetArray&& offsets) noexcept {
+        mOffsets = std::move(offsets);
+        mBound = false;
+    }
+
+    void write(uint8_t binding) noexcept { mBound = false; }
+
+    // Ownership will be transfered to the commandbuffer.
+    void bind(VulkanCommandBuffer* commands, VkPipelineLayout pipelineLayout,
+            uint8_t index) noexcept {
+        VkCommandBuffer const cmdbuffer = commands->buffer();
+        vkCmdBindDescriptorSets(cmdbuffer, VK_PIPELINE_BIND_POINT_GRAPHICS, pipelineLayout, index,
+                1, &mSet->vkSet, dynamicUboCount, mOffsets.data());
+
+        commands->acquire(mSet);
+        mResources.clear();
+        mBound = true;
+    }
+
+    void unbind() noexcept {
+        mResources.acquire(mSet);
+        mBound = false;
+    }
+
+    bool bound() const noexcept { return mBound; }
+
+    UniformBufferBitmask const dynamicUboMask;
+    uint8_t const dynamicUboCount;
+
+private:
+    FixedSizeVulkanResourceManager<1> mResources;
+    VulkanDescriptorSet* mSet = nullptr;
+
+    backend::DescriptorSetOffsetArray mOffsets;
+    bool mBound = false;
+};

 VulkanDescriptorSetManager::VulkanDescriptorSetManager(VkDevice device,
-        fvkmemory::ResourceManager* resourceManager)
+        VulkanResourceAllocator* resourceAllocator)
    : mDevice(device),
-      mResourceManager(resourceManager),
+      mResourceAllocator(resourceAllocator),
      mLayoutManager(std::make_unique<DescriptorSetLayoutManager>(device)),
      mDescriptorPool(std::make_unique<DescriptorInfinitePool>(device)) {}

@@ -359,72 +423,64 @@ VulkanDescriptorSetManager::~VulkanDescriptorSetManager() = default;
 void VulkanDescriptorSetManager::terminate() noexcept{
    mLayoutManager.reset();
    mDescriptorPool.reset();
-    clearHistory();
+    mHistory.clear();
 }

 // bind() is not really binding the set but just stashing until we have all the info
 // (pipelinelayout).
-void VulkanDescriptorSetManager::bind(uint8_t setIndex,
-        fvkmemory::resource_ptr<VulkanDescriptorSet> set,
+void VulkanDescriptorSetManager::bind(uint8_t setIndex, VulkanDescriptorSet* set,
        backend::DescriptorSetOffsetArray&& offsets) {
-    set->setOffsets(std::move(offsets));
-    mStashedSets[setIndex] = set;
-}
+    auto history = mHistory[set].get();
+    history->setOffsets(std::move(offsets));

-void VulkanDescriptorSetManager::unbind(uint8_t setIndex) {
-    mStashedSets[setIndex] = {};
+    auto lastHistory = mStashedSets[setIndex];
+    if (lastHistory) {
+        lastHistory->unbind();
+    }
+    mStashedSets[setIndex] = history;
 }

 void VulkanDescriptorSetManager::commit(VulkanCommandBuffer* commands,
        VkPipelineLayout pipelineLayout, DescriptorSetMask const& setMask) {
+    DescriptorSetHistoryArray& updateSets = mStashedSets;
+
    // setMask indicates the set of descriptor sets the driver wants to bind, curMask is the
    // actual set of sets that *needs* to be bound.
    DescriptorSetMask curMask = setMask;

-    auto& updateSets = mStashedSets;
-    auto& lastBoundSets = mLastBoundInfo.boundSets;
-
    setMask.forEachSetBit([&](size_t index) {
-        if (!updateSets[index] || updateSets[index] == lastBoundSets[index]) {
+        if (!updateSets[index] || updateSets[index]->bound()) {
            curMask.unset(index);
        }
    });

-    if (curMask.none() &&
-            (mLastBoundInfo.pipelineLayout == pipelineLayout && mLastBoundInfo.setMask == setMask &&
-                    mLastBoundInfo.boundSets == updateSets)) {
-        return;
-    }
-
-    curMask.forEachSetBit([&updateSets, commands, pipelineLayout](size_t index) {
-        // This code actually binds the descriptor sets.
-        auto set = updateSets[index];
-        VkCommandBuffer const cmdbuffer = commands->buffer();
-        vkCmdBindDescriptorSets(cmdbuffer, VK_PIPELINE_BIND_POINT_GRAPHICS, pipelineLayout, index,
-                1, &set->vkSet, set->uniqueDynamicUboCount, set->getOffsets()->data());
-        commands->acquire(set);
-    });
-
-    mStashedSets = {};
-
-    mLastBoundInfo = {
+    BoundInfo nextInfo = {
        pipelineLayout,
        setMask,
        updateSets,
    };
+    if (curMask.none() && mLastBoundInfo == nextInfo) {
+        return;
+    }
+
+    curMask.forEachSetBit([&updateSets, commands, pipelineLayout](size_t index) {
+        updateSets[index]->bind(commands, pipelineLayout, index);
+    });
+    mLastBoundInfo = nextInfo;
 }

-void VulkanDescriptorSetManager::updateBuffer(fvkmemory::resource_ptr<VulkanDescriptorSet> set,
-        uint8_t binding, fvkmemory::resource_ptr<VulkanBufferObject> bufferObject,
-        VkDeviceSize offset, VkDeviceSize size) noexcept {
+void VulkanDescriptorSetManager::updateBuffer(VulkanDescriptorSet* set, uint8_t binding,
+        VulkanBufferObject* bufferObject, VkDeviceSize offset, VkDeviceSize size) noexcept {
    VkDescriptorBufferInfo const info = {
        .buffer = bufferObject->buffer.getGpuBuffer(),
        .offset = offset,
        .range = size,
    };
-    VkDescriptorType type = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;

-    if (set->dynamicUboMask.test(binding)) {
+    VkDescriptorType type = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
+    auto& history = mHistory[set];
+
+    if (history->dynamicUboMask.test(binding)) {
        type = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER_DYNAMIC;
    }
    VkWriteDescriptorSet const descriptorWrite = {
@@ -438,11 +494,11 @@ void VulkanDescriptorSetManager::updateBuffer(fvkmemory::resource_ptr<VulkanDesc
    };
    vkUpdateDescriptorSets(mDevice, 1, &descriptorWrite, 0, nullptr);
    set->acquire(bufferObject);
+    history->write(binding);
 }

-void VulkanDescriptorSetManager::updateSampler(fvkmemory::resource_ptr<VulkanDescriptorSet> set,
-        uint8_t binding, fvkmemory::resource_ptr<VulkanTexture> texture,
-        VkSampler sampler) noexcept {
+void VulkanDescriptorSetManager::updateSampler(VulkanDescriptorSet* set, uint8_t binding,
+        VulkanTexture* texture, VkSampler sampler) noexcept {
    VkDescriptorImageInfo info{
        .sampler = sampler,
    };
@@ -470,37 +526,47 @@ void VulkanDescriptorSetManager::updateSampler(fvkmemory::resource_ptr<VulkanDes
    };
    vkUpdateDescriptorSets(mDevice, 1, &descriptorWrite, 0, nullptr);
    set->acquire(texture);
+    mHistory[set]->write(binding);
 }

-void VulkanDescriptorSetManager::updateInputAttachment(
-        fvkmemory::resource_ptr<VulkanDescriptorSet> set,
-        VulkanAttachment const& attachment) noexcept {
+void VulkanDescriptorSetManager::updateInputAttachment(VulkanDescriptorSet* set,
+        VulkanAttachment attachment) noexcept {
    // TOOD: fill-in this region
 }

-fvkmemory::resource_ptr<VulkanDescriptorSet> VulkanDescriptorSetManager::createSet(
-        Handle<HwDescriptorSet> handle, fvkmemory::resource_ptr<VulkanDescriptorSetLayout> layout) {
+void VulkanDescriptorSetManager::createSet(Handle<HwDescriptorSet> handle,
+        VulkanDescriptorSetLayout* layout) {
    auto const vkSet = mDescriptorPool->obtainSet(layout);
    auto const& count = layout->count;
    auto const vklayout = layout->getVkLayout();
-    return fvkmemory::resource_ptr<VulkanDescriptorSet>::make(mResourceManager, handle, vkSet,
-            layout->bitmask.dynamicUbo, layout->count.dynamicUbo,
-            [vkSet, count, vklayout, this](VulkanDescriptorSet*) {
-                // Note that mDescriptorPool could be gone due to terminate (when the backend shuts
-                // down).
-                if (mDescriptorPool) {
-                    mDescriptorPool->recycle(count, vklayout, vkSet);
-                }
+    VulkanDescriptorSet* set = mResourceAllocator->construct<VulkanDescriptorSet>(handle,
+            mResourceAllocator, vkSet, [vkSet, count, vklayout, this](VulkanDescriptorSet* set) {
+                eraseSetFromHistory(set);
+                mDescriptorPool->recycle(count, vklayout, vkSet);
            });
+    mHistory[set] = std::make_unique<DescriptorSetHistory>(layout->bitmask.dynamicUbo,
+            layout->count.dynamicUbo, mResourceAllocator, set);
 }

-void VulkanDescriptorSetManager::initVkLayout(
-        fvkmemory::resource_ptr<VulkanDescriptorSetLayout> layout) {
-    layout->setVkLayout(mLayoutManager->getVkLayout(layout->bitmask));
+void VulkanDescriptorSetManager::destroySet(Handle<HwDescriptorSet> handle) {
+    VulkanDescriptorSet* set = mResourceAllocator->handle_cast<VulkanDescriptorSet*>(handle);
+    eraseSetFromHistory(set);
 }

-void VulkanDescriptorSetManager::clearHistory() {
-    mStashedSets = {};
+void VulkanDescriptorSetManager::initVkLayout(VulkanDescriptorSetLayout* layout) {
+    layout->setVkLayout(mLayoutManager->getVkLayout(layout));
 }

+void VulkanDescriptorSetManager::eraseSetFromHistory(VulkanDescriptorSet* set) {
+    DescriptorSetHistory* history = mHistory[set].get();
+    mHistory.erase(set);
+
+    for (uint8_t i = 0; i < mStashedSets.size(); ++i) {
+        if (mStashedSets[i] == history) {
+            mStashedSets[i] = nullptr;
+        }
+    }
+}
+
+
 } // namespace filament::backend
@@ -17,10 +17,9 @@
 #ifndef TNT_FILAMENT_BACKEND_CACHING_VULKANDESCRIPTORSETMANAGER_H
 #define TNT_FILAMENT_BACKEND_CACHING_VULKANDESCRIPTORSETMANAGER_H

-#include "vulkan/VulkanHandles.h"
-#include "vulkan/VulkanTexture.h"
-#include "vulkan/VulkanUtility.h"
-#include "vulkan/memory/ResourcePointer.h"
+#include <vulkan/VulkanResourceAllocator.h>
+#include <vulkan/VulkanTexture.h>
+#include <vulkan/VulkanUtility.h>

 #include <backend/DriverEnums.h>
 #include <backend/Program.h>
@@ -47,55 +46,71 @@ public:

    using DescriptorSetLayoutArray = VulkanDescriptorSetLayout::DescriptorSetLayoutArray;

-    VulkanDescriptorSetManager(VkDevice device, fvkmemory::ResourceManager* resourceManager);
+    VulkanDescriptorSetManager(VkDevice device, VulkanResourceAllocator* resourceAllocator);
    ~VulkanDescriptorSetManager();

    void terminate() noexcept;

-    void updateBuffer(fvkmemory::resource_ptr<VulkanDescriptorSet> set, uint8_t binding,
-            fvkmemory::resource_ptr<VulkanBufferObject> bufferObject, VkDeviceSize offset,
-            VkDeviceSize size) noexcept;
+    void updateBuffer(VulkanDescriptorSet* set, uint8_t binding,
+            VulkanBufferObject* bufferObject, VkDeviceSize offset, VkDeviceSize size) noexcept;

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

-    void updateInputAttachment(fvkmemory::resource_ptr<VulkanDescriptorSet> set,
-            VulkanAttachment const& attachment) noexcept;
+    void updateInputAttachment(VulkanDescriptorSet* set, VulkanAttachment attachment) noexcept;

-    void bind(uint8_t setIndex, fvkmemory::resource_ptr<VulkanDescriptorSet> set,
-            backend::DescriptorSetOffsetArray&& offsets);
-
-    void unbind(uint8_t setIndex);
+    void bind(uint8_t setIndex, VulkanDescriptorSet* set, backend::DescriptorSetOffsetArray&& offsets);

    void commit(VulkanCommandBuffer* commands, VkPipelineLayout pipelineLayout,
            DescriptorSetMask const& setMask);

-    fvkmemory::resource_ptr<VulkanDescriptorSet> createSet(Handle<HwDescriptorSet> handle,
-            fvkmemory::resource_ptr<VulkanDescriptorSetLayout> layout);
+    void setPlaceHolders(VkSampler sampler, VulkanTexture* texture,
+            VulkanBufferObject* bufferObject) noexcept;

-    void initVkLayout(fvkmemory::resource_ptr<VulkanDescriptorSetLayout> layout);
+    void createSet(Handle<HwDescriptorSet> handle, VulkanDescriptorSetLayout* layout);

-    void clearHistory();
+    void destroySet(Handle<HwDescriptorSet> handle);
+
+    void initVkLayout(VulkanDescriptorSetLayout* layout);

 private:
+    class DescriptorSetHistory;
    class DescriptorSetLayoutManager;
    class DescriptorInfinitePool;

-    using DescriptorSetArray =
-            std::array<fvkmemory::resource_ptr<VulkanDescriptorSet>, UNIQUE_DESCRIPTOR_SET_COUNT>;
+    void eraseSetFromHistory(VulkanDescriptorSet* set);
+
+    using DescriptorSetHistoryArray =
+            std::array<DescriptorSetHistory*, UNIQUE_DESCRIPTOR_SET_COUNT>;
+
+    struct BoundInfo {
+        VkPipelineLayout pipelineLayout = VK_NULL_HANDLE;
+        DescriptorSetMask setMask;
+        DescriptorSetHistoryArray boundSets;
+
+        bool operator==(BoundInfo const& info) const {
+            if (pipelineLayout != info.pipelineLayout || setMask != info.setMask) {
+                return false;
+            }
+            bool equal = true;
+            setMask.forEachSetBit([&](size_t i) {
+                if (boundSets[i] != info.boundSets[i]) {
+                    equal = false;
+                }
+            });
+            return equal;
+        }
+    };

    VkDevice mDevice;
-    fvkmemory::ResourceManager* mResourceManager;
+    VulkanResourceAllocator* mResourceAllocator;
    std::unique_ptr<DescriptorSetLayoutManager> mLayoutManager;
    std::unique_ptr<DescriptorInfinitePool> mDescriptorPool;
    std::pair<VulkanAttachment, VkDescriptorImageInfo> mInputAttachment;
-    DescriptorSetArray mStashedSets = {};
+    std::unordered_map<VulkanDescriptorSet*, std::unique_ptr<DescriptorSetHistory>> mHistory;
+    DescriptorSetHistoryArray mStashedSets = {};

-    struct {
-        VkPipelineLayout pipelineLayout = VK_NULL_HANDLE;
-        DescriptorSetMask setMask;
-        DescriptorSetArray boundSets = {};
-    } mLastBoundInfo;
+    BoundInfo mLastBoundInfo;
 };

 }// namespace filament::backend
--- a/Show More
+++ b/Show More