Disable gltfio mipmapping

2025-06-10 14:00:53 -07:00
146 changed files with 1497 additions and 1075 deletions
@@ -17,17 +17,15 @@ runs:
        echo "Date: ${TSTAMP}" >> /tmp/commit_msg.txt
        echo "" >> /tmp/commit_msg.txt
        echo "${{ github.event.head_commit.message }}" >> /tmp/commit_msg.txt
-    - name: Find commit message (PR)
+    - name: Checkout code
      shell: bash
      id: checkout_code
      if: github.event_name == 'pull_request'
      run: |
-        echo "+++++ head commit message +++++"
-        echo "$(git log -1 --no-merges)"
-        echo "+++++++++++++++++++++++++++++++"
        echo "hash=$(git rev-parse HEAD)" >> "$GITHUB_OUTPUT"
-        git checkout ${{ github.event.pull_request.head.sha }}
-        echo "$(git log -1 --no-merges)" >> /tmp/commit_msg.txt
+        git checkout ${{ github.event.pull_request.head.ref }}
+        COMMIT_MESSAGE=$(git log -1)
+        echo "$(git log -1)" >> /tmp/commit_msg.txt
    - shell: bash
      id: action_output
      run: |
@@ -38,8 +36,8 @@ runs:
        echo "----- got commit message ---"
        cat /tmp/commit_msg.txt
        echo "----------------------------"
-    - name: Cleanup Find commit message (PR)
+    - name: Uncheckout code
      shell: bash
      if: github.event_name == 'pull_request'
      run: |
-        git checkout ${{ steps.checkout_code.outputs.hash }}
+        git checkout ${{ steps.checkout_code.outputs.hash }}
@@ -122,6 +122,9 @@ jobs:
          fetch-depth: 0
      - id: get_commit_msg
        uses: ./.github/actions/get-commit-msg
+      - uses: actions/checkout@v4.1.6
+        with:
+          fetch-depth: 0
      - uses: ./.github/actions/mac-prereq
      - name: Cache Mesa and deps
        uses: actions/cache@v4
@@ -49,8 +49,6 @@ option(FILAMENT_SUPPORTS_OSMESA "Enable OSMesa (headless GL context) for Filamen

 option(FILAMENT_ENABLE_FGVIEWER "Enable the frame graph viewer" OFF)

-option(FILAMENT_USE_ABSEIL_LOGGING "Use Abseil to log, may increase binary size" OFF)
-
 # This is to disable GTAO for the short-term while we investigate a way to better manage size increases.
 # On the regular filament build (where size is of less concern), we enable GTAO by default.
 option(FILAMENT_DISABLE_GTAO "Disable GTAO" OFF)
@@ -593,10 +591,6 @@ if (CMAKE_BUILD_TYPE STREQUAL "Debug" AND NOT FILAMENT_BACKEND_DEBUG_FLAG STREQU
    unset(FILAMENT_BACKEND_DEBUG_FLAG)
 endif()

-if (FILAMENT_USE_ABSEIL_LOGGING)
-    add_definitions(-DFILAMENT_USE_ABSEIL_LOGGING)
-endif()
-
 # ==================================================================================================
 # Material compilation flags
 # ==================================================================================================
@@ -6,4 +6,8 @@ We are chaning the way Vulkan buffers are handled. We need to switch over to a m
 **If you are cherry-picking a commit into an rc/ branch**: add the release note under the
 appropriate header in [RELEASE_NOTES.md](./RELEASE_NOTES.md).

-## Release notes for next branch cut
+## Release notes for next branch cut
+
+- samples: samples now have a CLI to select backend api
+- materials: sampler now export their type in the material binary [⚠️ **New Material Version**]
+- materials: new mutable specialization constants feature. See the [materials documentation](https://google.github.io/filament/Materials.html) for details. [⚠️ **New Material Version**]
@@ -31,7 +31,7 @@ repositories {
 }

 dependencies {
-    implementation 'com.google.android.filament:filament-android:1.61.2'
+    implementation 'com.google.android.filament:filament-android:1.61.0'
 }
 ```

@@ -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', '~> 1.61.2'
+pod 'Filament', '~> 1.61.0'
 ```

 ## Documentation
@@ -7,10 +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).

-## v1.61.2
-
- samples: samples now have a CLI to select backend api
-
 ## v1.61.1


@@ -59,10 +59,6 @@ add_library(smol-v STATIC IMPORTED)
 set_target_properties(smol-v PROPERTIES IMPORTED_LOCATION
        ${FILAMENT_DIR}/lib/${ANDROID_ABI}/libsmol-v.a)

-add_library(abseil STATIC IMPORTED)
-set_target_properties(abseil PROPERTIES IMPORTED_LOCATION
-        ${FILAMENT_DIR}/lib/${ANDROID_ABI}/libabseil.a)
-
 if (FILAMENT_ENABLE_FGVIEWER)
    add_library(fgviewer STATIC IMPORTED)
    set_target_properties(fgviewer PROPERTIES IMPORTED_LOCATION
@@ -132,7 +128,6 @@ target_link_libraries(filament-jni
    PRIVATE jnigraphics
    PRIVATE utils
    PRIVATE perfetto
-    PRIVATE abseil

    # libgeometry is PUBLIC because gltfio uses it.
    PUBLIC geometry
@@ -60,6 +60,14 @@ static void setParameter(JNIEnv* env, jlong nativeMaterialInstance, jstring name
    env->ReleaseStringUTFChars(name_, name);
 }

+template<typename T>
+static void setConstant(JNIEnv* env, jlong nativeMaterialInstance, jstring name_, T v) {
+    MaterialInstance* instance = (MaterialInstance*) nativeMaterialInstance;
+    const char *name = env->GetStringUTFChars(name_, 0);
+    instance->setConstant(name, v);
+    env->ReleaseStringUTFChars(name_, name);
+}
+
 extern "C"
 JNIEXPORT void JNICALL
 Java_com_google_android_filament_MaterialInstance_nSetParameterBool(JNIEnv *env, jclass,
@@ -264,6 +272,13 @@ Java_com_google_android_filament_MaterialInstance_nSetParameterTexture(
    env->ReleaseStringUTFChars(name_, name);
 }

+extern "C"
+JNIEXPORT void JNICALL
+Java_com_google_android_filament_MaterialInstance_nSetConstantBool(JNIEnv *env, jclass,
+        jlong nativeMaterialInstance, jstring name_, jboolean x) {
+    setConstant(env, nativeMaterialInstance, name_, bool(x));
+}
+
 extern "C"
 JNIEXPORT void JNICALL
 Java_com_google_android_filament_MaterialInstance_nSetScissor(
@@ -402,6 +402,16 @@ public class MaterialInstance {
        nSetParameterFloat4(getNativeObject(), name, color[0], color[1], color[2], color[3]);
    }

+    /**
+     * Sets the value of a bool constant.
+     *
+     * @param name the name of the material constant
+     * @param x    the value of the material constant
+     */
+    public void setConstant(@NonNull String name, boolean x) {
+        nSetConstantBool(getNativeObject(), name, x);
+    }
+
    /**
     * Set-up a custom scissor rectangle; by default it is disabled.
     *
@@ -921,6 +931,9 @@ public class MaterialInstance {
            @NonNull String name, int element, @NonNull @Size(min = 1) float[] v,
            @IntRange(from = 0) int offset, @IntRange(from = 1) int count);

+    private static native void nSetConstantBool(long nativeMaterialInstance,
+            @NonNull String name, boolean x);
+
    private static native void nSetParameterTexture(long nativeMaterialInstance,
            @NonNull String name, long nativeTexture, long sampler);

@@ -1,5 +1,5 @@
 GROUP=com.google.android.filament
-VERSION_NAME=1.61.2
+VERSION_NAME=1.61.0

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

@@ -211,7 +211,7 @@ when using textures.
 This property can dramatically change the appearance of a surface. Non-metallic surfaces have
 chromatic diffuse reflection and achromatic specular reflection (reflected light does not change
 color). Metallic surfaces do not have any diffuse reflection and chromatic specular reflection
-(reflected light takes on the color of the surfaced as defined by `baseColor`). 
+(reflected light takes on the color of the surfaced as defined by `baseColor`).

 The effect of `metallic` is shown in figure [metallicProperty] (click on the image to see a
 larger version).
@@ -247,7 +247,7 @@ The effect of `roughness` on metallic surfaces is shown in figure [roughnessCond
 When refraction through an object is enabled (using a `refractonType` of `thin` or `solid`), the
 `roughness` property will also affect the refractions, as shown in figure
 [roughnessRefractionProperty] (click on the image to see a larger version).
-                             
+
 ![Figure [roughnessRefractionProperty]: Refractive sphere with `roughness` varying from 0.0
 (left) to 1.0 (right)](images/materials/refraction_roughness.png)

@@ -306,7 +306,7 @@ The sheen color controls the color appearance and strength of an optional sheen
 base layer described by the properties above. The sheen layer always sits below the clear coat layer
 if such a layer is present.

-The sheen layer can be used to represent cloth and fabric materials. Please refer to 
+The sheen layer can be used to represent cloth and fabric materials. Please refer to
 section [Cloth model] for more information about cloth and fabric materials.

 The effect of `sheenColor` is shown in figure [materialSheenColor]
@@ -519,14 +519,14 @@ light to bend further away from the initial path.

 Table [commonMatIOR] describes acceptable refractive indices for various types of materials.

-Material                   |        IOR       
+Material                   |        IOR
 --------------------------:|:-----------------
 Air                        | 1.0
-Water                      | 1.33             
-Common liquids             | 1.33 to 1.5      
-Common gemstones           | 1.58 to 2.33     
-Plastics, glass            | 1.5 to 1.58      
-Other dielectric materials | 1.33 to 1.58     
+Water                      | 1.33
+Common liquids             | 1.33 to 1.5
+Common gemstones           | 1.58 to 2.33
+Plastics, glass            | 1.5 to 1.58
+Other dielectric materials | 1.33 to 1.58
 [Table [commonMatIOR]: Index of refraction of common materials]

 The appearance of a refractive material will greatly depend on the `refractionType` and
@@ -1091,30 +1091,37 @@ Value
    `bool` or `number`, depending on the `type` of the constant. The type must be one of the types
    described in table [materialConstantsTypes].

-         Type          |            Description                   |      Default
-:----------------------|:-----------------------------------------|:------------------
-int                    | A signed, 32 bit GLSL int                |         0
-float                  | A single-precision GLSL float            |         0.0
-bool                   | A GLSL bool                              |         false
+    Constants may also be specified as mutable by setting the `mutable` property to `true`. Only
+    `bool` spec constants may be specified as mutable.
+
+| Type  | Description                   | Default | May be mutable? |
+|:------|:------------------------------|:--------|-----------------|
+| int   | A signed, 32 bit GLSL int     |         | no              |
+| float | A single-precision GLSL float | 0.0     | no              |
+| bool  | A GLSL bool                   | false   | yes             |
 [Table [materialConstantsTypes]: Material constants types]

 Description
 :   Lists the constant parameters accepted by your material. These constants can be set, or
    "specialized", at runtime when loading a material package. Multiple materials can be loaded from
-    the same material package with differing constant parameter specializations. Once a material is
-    loaded from a material package, its constant parameters cannot be changed. Compared to regular
-    parameters, constant parameters allow the compiler to generate more efficient code. Access
-    constant parameters from the shader by prefixing the name with `materialConstant_`. For example,
-    a constant parameter named `myConstant` is accessed in the shader as
-    `materialConstant_myConstant`. If a constant parameter is not set at runtime, the default is
-    used.
+    the same material package with differing constant parameter specializations. If a constant
+    parameter is specialized as mutable, it may be changed at any time on a per-instance basis via
+    `MaterialInstance::setConstant(name, value)`. Otherwise, once a material is loaded from a
+    material package, its constant parameters cannot be changed.
+
+    Compared to regular parameters, constant parameters allow the compiler to generate more
+    efficient code. Access constant parameters from the shader by prefixing the name with
+    `materialConstant_`. For example, a constant parameter named `myConstant` is accessed in the
+    shader as `materialConstant_myConstant`. If a constant parameter is not set at runtime, the
+    default is used.

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ JSON
 material {
    constants : [
        {
           name : overrideAlpha,
-           type : bool
+           type : bool,
+           mutable : true,
        },
        {
           name : customAlpha,
@@ -2553,7 +2560,7 @@ standard skybox material. It produces a list of 2 parameters, named `showSun` an
 respectively a boolean and a cubemap texture.

 ```text
-$ matc --reflect parameters filament/src/materials/skybox.mat 
+$ matc --reflect parameters filament/src/materials/skybox.mat
 {
  "parameters": [
    {
@@ -2569,7 +2576,7 @@ $ matc --reflect parameters filament/src/materials/skybox.mat
    }
  ]
 }
-``` 
+```

 ### --variant-filter

@@ -601,10 +601,6 @@ target_link_libraries(${TARGET} PUBLIC filaflat)
 target_link_libraries(${TARGET} PUBLIC filabridge)
 target_link_libraries(${TARGET} PUBLIC ibl-lite)

-if (FILAMENT_USE_ABSEIL_LOGGING)
-    target_link_libraries(${TARGET} PUBLIC absl::log)
-endif()
-
 if (FILAMENT_ENABLE_FGVIEWER)
    target_link_libraries(${TARGET} PUBLIC fgviewer)
    add_definitions(-DFILAMENT_ENABLE_FGVIEWER=1)
@@ -92,7 +92,7 @@ Copy your platform's Makefile below into a `Makefile` inside the same directory.
 ### Linux

 ```make
-FILAMENT_LIBS=-lfilament -lbackend -lbluegl -lbluevk -lfilabridge -lfilaflat -lutils -lgeometry -lsmol-v -lvkshaders -libl -labseil
+FILAMENT_LIBS=-lfilament -lbackend -lbluegl -lbluevk -lfilabridge -lfilaflat -lutils -lgeometry -lsmol-v -lvkshaders -libl
 CC=clang++

 main: main.o
@@ -110,13 +110,12 @@ clean:
 ### macOS

 ```make
-FILAMENT_LIBS=-lfilament -lbackend -lbluegl -lbluevk -lfilabridge -lfilaflat -lutils -lgeometry -lsmol-v -lvkshaders -libl -labseil
+FILAMENT_LIBS=-lfilament -lbackend -lbluegl -lbluevk -lfilabridge -lfilaflat -lutils -lgeometry -lsmol-v -lvkshaders -libl
 FRAMEWORKS=-framework Cocoa -framework Metal -framework CoreVideo
 CC=clang++
-ARCH ?= $(shell uname -m)

 main: main.o
-	$(CC) -Llib/$(ARCH)/ main.o $(FILAMENT_LIBS) $(FRAMEWORKS) -o main
+	$(CC) -Llib/x86_64/ main.o $(FILAMENT_LIBS) $(FRAMEWORKS) -o main

 main.o: main.cpp
 	$(CC) -Iinclude/ -std=c++17 -c main.cpp
@@ -140,7 +139,7 @@ used to change the run-time library version.

 ```make
 FILAMENT_LIBS=filament.lib backend.lib bluegl.lib bluevk.lib filabridge.lib filaflat.lib \
-              utils.lib geometry.lib smol-v.lib ibl.lib vkshaders.lib abseil.lib
+              utils.lib geometry.lib smol-v.lib ibl.lib vkshaders.lib
 CC=cl.exe

 main.exe: main.obj
@@ -403,10 +403,6 @@ endif()
 target_link_libraries(${TARGET} PUBLIC math)
 target_link_libraries(${TARGET} PUBLIC utils)

-if (FILAMENT_USE_ABSEIL_LOGGING)
-    target_link_libraries(${TARGET} PRIVATE absl::log)
-endif()
-
 # Android, iOS, and WebGL do not use bluegl.
 if(FILAMENT_SUPPORTS_OPENGL AND NOT IOS AND NOT ANDROID AND NOT WEBGL)
    target_link_libraries(${TARGET} PRIVATE bluegl)
@@ -149,13 +149,6 @@ public:
         *      - PlatformEGLAndroid
         */
        bool assertNativeWindowIsValid = false;
-
-        /**
-         * The action to take if a Drawable cannot be acquired. If true, the
-         * frame is aborted instead of panic. This is only supported for:
-         *      - PlatformMetal
-         */
-        bool metalDisablePanicOnDrawableFailure = false;
    };

    Platform() noexcept;
@@ -20,6 +20,7 @@
 #include <utils/CString.h>
 #include <utils/FixedCapacityVector.h>
 #include <utils/Invocable.h>
+#include <utils/bitset.h>

 #include <backend/DriverEnums.h>

@@ -66,6 +67,7 @@ public:
    using DescriptorBindingsInfo = utils::FixedCapacityVector<Descriptor>;
    using DescriptorSetInfo = std::array<DescriptorBindingsInfo, MAX_DESCRIPTOR_SET_COUNT>;
    using SpecializationConstantsInfo = utils::FixedCapacityVector<SpecializationConstant>;
+    using MutableSpecConstantsInfo = utils::bitset8;
    using ShaderBlob = utils::FixedCapacityVector<uint8_t>;
    using ShaderSource = std::array<ShaderBlob, SHADER_TYPE_COUNT>;

@@ -102,7 +104,8 @@ public:
    Program& descriptorBindings(backend::descriptor_set_t set,
            DescriptorBindingsInfo descriptorBindings) noexcept;

-    Program& specializationConstants(SpecializationConstantsInfo specConstants) noexcept;
+    Program& specializationConstants(SpecializationConstantsInfo specConstants,
+            uint32_t firstMutableId, MutableSpecConstantsInfo mutableSpecConstants) noexcept;

    struct PushConstant {
        utils::CString name;
@@ -128,7 +128,7 @@ protected:
    bool setExternalImage(ExternalImageHandleRef externalImage, ExternalTexture* texture) noexcept override;

    /**
-     * Logs glGetError() to LOG(ERROR)
+     * Logs glGetError() to slog.e
     * @param name a string giving some context on the error. Typically __func__.
     */
    static void logEglError(const char* name) noexcept;
@@ -39,7 +39,7 @@
 #define FILAMENT_DEBUG_COMMANDS_NONE         0x0
 // Command debugging enabled. No logging by default.
 #define FILAMENT_DEBUG_COMMANDS_ENABLE       0x1
-// Command debugging enabled. Every command logged to DLOG(INFO)
+// Command debugging enabled. Every command logged to slog.d
 #define FILAMENT_DEBUG_COMMANDS_LOG          0x2
 // Command debugging enabled. Every command logged to systrace
 #define FILAMENT_DEBUG_COMMANDS_SYSTRACE     0x4
@@ -16,7 +16,7 @@

 #include "private/backend/CircularBuffer.h"

-#include <utils/Logger.h>
+#include <utils/Log.h>
 #include <utils/Panic.h>
 #include <utils/architecture.h>
 #include <utils/ashmem.h>
@@ -127,7 +127,7 @@ void* CircularBuffer::alloc(size_t size) {
                "couldn't allocate " << (size * 2 / 1024) <<
                " KiB of virtual address space for the command buffer";

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

        // guard page at the end
        void* guard = (void*)(uintptr_t(data) + size * 2);
@@ -20,12 +20,12 @@

 #include <private/utils/Tracing.h>

-#include <utils/Logger.h>
-#include <utils/Mutex.h>
-#include <utils/Panic.h>
 #include <utils/compiler.h>
-#include <utils/debug.h>
+#include <utils/Log.h>
+#include <utils/Mutex.h>
 #include <utils/ostream.h>
+#include <utils/Panic.h>
+#include <utils/debug.h>

 #include <algorithm>
 #include <mutex>
@@ -121,10 +121,11 @@ void CommandBufferQueue::flush() {

 #ifndef NDEBUG
        size_t const totalUsed = circularBuffer.size() - mFreeSpace;
-        DLOG(INFO) << "CommandStream used too much space (will block): "
-                   << "needed space " << requiredSize << " out of " << mFreeSpace
-                   << ", totalUsed=" << totalUsed << ", current=" << used
-                   << ", queue size=" << mCommandBuffersToExecute.size() << " buffers";
+        slog.d << "CommandStream used too much space (will block): "
+                << "needed space " << requiredSize << " out of " << mFreeSpace
+                << ", totalUsed=" << totalUsed << ", current=" << used
+                << ", queue size=" << mCommandBuffersToExecute.size() << " buffers"
+                << io::endl;

        mHighWatermark = std::max(mHighWatermark, totalUsed);
 #endif
@@ -22,13 +22,10 @@
 #include <utils/CallStack.h>
 #endif

-#include <private/utils/Tracing.h>
-
-#include <utils/Logger.h>
-#include <utils/Profiler.h>
 #include <utils/compiler.h>
+#include <utils/Log.h>
 #include <utils/ostream.h>
-#include <utils/sstream.h>
+#include <utils/Profiler.h>

 #include <cstddef>
 #include <functional>
@@ -132,10 +129,9 @@ void CommandType<void (Driver::*)(ARGS...)>::Command<METHOD>::log(std::index_seq
 #if DEBUG_COMMAND_STREAM
    static_assert(UTILS_HAS_RTTI, "DEBUG_COMMAND_STREAM can only be used with RTTI");
    std::string command = utils::CallStack::demangleTypeName(typeid(Command).name()).c_str();
-    DLOG(INFO) << extractMethodName(command) << " : size=" << sizeof(Command);
-    utils::io::sstream parameterPack;
-    printParameterPack(parameterPack, std::get<I>(mArgs)...);
-    DLOG(INFO) << "\t" << parameterPack.c_str();
+    slog.d << extractMethodName(command) << " : size=" << sizeof(Command) << "\n\t";
+    printParameterPack(slog.d, std::get<I>(mArgs)...);
+    slog.d << io::endl;
 #endif
 }

@@ -25,9 +25,9 @@

 #include <private/utils/Tracing.h>

-#include <utils/Logger.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
+#include <utils/Log.h>
 #include <utils/ostream.h>

 #include <math/half.h>
@@ -149,7 +149,7 @@ void DriverBase::scheduleRelease(AcquiredImage const& image) noexcept {
 void DriverBase::debugCommandBegin(CommandStream* cmds, bool synchronous, const char* methodName) noexcept {
    if constexpr (bool(FILAMENT_DEBUG_COMMANDS > FILAMENT_DEBUG_COMMANDS_NONE)) {
        if constexpr (bool(FILAMENT_DEBUG_COMMANDS & FILAMENT_DEBUG_COMMANDS_LOG)) {
-            DLOG(INFO) << methodName;
+            utils::slog.d << methodName << utils::io::endl;
        }
        if constexpr (bool(FILAMENT_DEBUG_COMMANDS & FILAMENT_DEBUG_COMMANDS_SYSTRACE)) {
            FILAMENT_TRACING_CONTEXT(FILAMENT_TRACING_CATEGORY_FILAMENT);
@@ -20,7 +20,7 @@

 #include <utils/Allocator.h>
 #include <utils/CString.h>
-#include <utils/Logger.h>
+#include <utils/Log.h>
 #include <utils/Panic.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
@@ -57,8 +57,8 @@ HandleAllocator<P0, P1, P2>::Allocator::Allocator(AreaPolicy::HeapArea const& ar
    size_t const maxHeapSize = std::min(area.size(), HANDLE_INDEX_MASK * getAlignment());

    if (UTILS_UNLIKELY(maxHeapSize != area.size())) {
-        LOG(WARNING) << "HandleAllocator heap size reduced to " << maxHeapSize << " from "
-                     << area.size();
+        slog.w << "HandleAllocator heap size reduced to "
+               << maxHeapSize << " from " << area.size() << io::endl;
    }

    // make sure we start with a clean arena. This is needed to ensure that all blocks start
@@ -80,8 +80,18 @@ Program& Program::attributes(AttributesInfo attributes) noexcept {
    return *this;
 }

-Program& Program::specializationConstants(SpecializationConstantsInfo specConstants) noexcept {
+Program& Program::specializationConstants(SpecializationConstantsInfo specConstants,
+        uint32_t firstMutableId, MutableSpecConstantsInfo mutableSpecConstants) noexcept {
+    // String the two lists together.
    mSpecializationConstants = std::move(specConstants);
+    uint32_t firstMutableIndex = specConstants.size();
+    mSpecializationConstants.reserve(specConstants.size() + mutableSpecConstants.size());
+    for (uint32_t i = 0; i < mutableSpecConstants.size(); i++) {
+        mSpecializationConstants[i + firstMutableIndex] = SpecializationConstant {
+                .id = i + firstMutableId,
+                .value = mutableSpecConstants[i],
+        };
+    }
    return *this;
 }

@@ -19,8 +19,8 @@
 #include "MetalContext.h"
 #include "MetalUtils.h"

-#include <utils/Logger.h>
 #include <utils/Panic.h>
+#include <utils/Log.h>

 namespace filament::backend {

@@ -323,7 +323,7 @@ id<MTLFunction> MetalBlitter::compileFragmentFunction(BlitFunctionKey key) const
    if (!library || !function) {
        if (error) {
            auto description = [error.localizedDescription cStringUsingEncoding:NSUTF8StringEncoding];
-            LOG(ERROR) << description;
+            utils::slog.e << description << utils::io::endl;
        }
    }
    FILAMENT_CHECK_POSTCONDITION(library && function)
@@ -349,7 +349,7 @@ id<MTLFunction> MetalBlitter::getBlitVertexFunction() {
    if (!library || !function) {
        if (error) {
            auto description = [error.localizedDescription cStringUsingEncoding:NSUTF8StringEncoding];
-            LOG(ERROR) << description;
+            utils::slog.e << description << utils::io::endl;
        }
    }
    FILAMENT_CHECK_POSTCONDITION(library && function)
@@ -18,8 +18,8 @@

 #include "MetalContext.h"

-#include <utils/Logger.h>
 #include <utils/Panic.h>
+#include <utils/Log.h>
 #include <utils/trap.h>

 #include <thread>
@@ -77,7 +77,8 @@ void MetalBufferPool::releaseBuffer(MetalBufferPoolEntry const *stage) noexcept

    auto iter = mUsedStages.find(stage);
    if (iter == mUsedStages.end()) {
-        LOG(ERROR) << "Unknown Metal buffer: " << stage->capacity << " bytes";
+        utils::slog.e << "Unknown Metal buffer: " << stage->capacity << " bytes"
+                << utils::io::endl;
        return;
    }
    stage->lastAccessed = mCurrentFrame;
@@ -18,9 +18,8 @@

 #include "MetalHandles.h"

-#include <utils/FixedCapacityVector.h>
-#include <utils/Logger.h>
 #include <utils/debug.h>
+#include <utils/FixedCapacityVector.h>

 #include <utility>

@@ -113,8 +112,8 @@ id<MTLCommandBuffer> getPendingCommandBuffer(MetalContext* context) {
        auto errorCode = (MTLCommandBufferError)buffer.error.code;
        if (@available(macOS 11.0, *)) {
            if (errorCode == MTLCommandBufferErrorMemoryless) {
-                LOG(WARNING) << "Metal: memoryless geometry limit reached. Continuing with private "
-                                "storage mode.";
+                utils::slog.w << "Metal: memoryless geometry limit reached. "
+                        "Continuing with private storage mode." << utils::io::endl;
                context->memorylessLimitsReached = true;
            }
        }
@@ -38,10 +38,10 @@
 #include <Metal/Metal.h>
 #include <QuartzCore/QuartzCore.h>

-#include <utils/Invocable.h>
-#include <utils/Logger.h>
+#include <utils/Log.h>
 #include <utils/Panic.h>
 #include <utils/sstream.h>
+#include <utils/Invocable.h>

 #include <algorithm>

@@ -78,18 +78,20 @@ Driver* MetalDriverFactory::create(PlatformMetal* const platform, const Platform
    //    MetalVertexBufferInfo        : 552       moderate
    // -- less than or equal to 552 bytes

-    DLOG(INFO) << "MetalSwapChain: " << sizeof(MetalSwapChain);
-    DLOG(INFO) << "MetalBufferObject: " << sizeof(MetalBufferObject);
-    DLOG(INFO) << "MetalVertexBuffer: " << sizeof(MetalVertexBuffer);
-    DLOG(INFO) << "MetalVertexBufferInfo: " << sizeof(MetalVertexBufferInfo);
-    DLOG(INFO) << "MetalIndexBuffer: " << sizeof(MetalIndexBuffer);
-    DLOG(INFO) << "MetalRenderPrimitive: " << sizeof(MetalRenderPrimitive);
-    DLOG(INFO) << "MetalTexture: " << sizeof(MetalTexture);
-    DLOG(INFO) << "MetalTimerQuery: " << sizeof(MetalTimerQuery);
-    DLOG(INFO) << "HwStream: " << sizeof(HwStream);
-    DLOG(INFO) << "MetalRenderTarget: " << sizeof(MetalRenderTarget);
-    DLOG(INFO) << "MetalFence: " << sizeof(MetalFence);
-    DLOG(INFO) << "MetalProgram: " << sizeof(MetalProgram);
+    utils::slog.d
+           << "\nMetalSwapChain: " << sizeof(MetalSwapChain)
+           << "\nMetalBufferObject: " << sizeof(MetalBufferObject)
+           << "\nMetalVertexBuffer: " << sizeof(MetalVertexBuffer)
+           << "\nMetalVertexBufferInfo: " << sizeof(MetalVertexBufferInfo)
+           << "\nMetalIndexBuffer: " << sizeof(MetalIndexBuffer)
+           << "\nMetalRenderPrimitive: " << sizeof(MetalRenderPrimitive)
+           << "\nMetalTexture: " << sizeof(MetalTexture)
+           << "\nMetalTimerQuery: " << sizeof(MetalTimerQuery)
+           << "\nHwStream: " << sizeof(HwStream)
+           << "\nMetalRenderTarget: " << sizeof(MetalRenderTarget)
+           << "\nMetalFence: " << sizeof(MetalFence)
+           << "\nMetalProgram: " << sizeof(MetalProgram)
+           << utils::io::endl;
 #endif
    return MetalDriver::create(platform, driverConfig);
 }
@@ -133,18 +135,19 @@ MetalDriver::MetalDriver(

    initializeSupportedGpuFamilies(mContext);

-    LOG(INFO) << "Supported GPU families: ";
+    utils::slog.v << "Supported GPU families: " << utils::io::endl;
    if (mContext->highestSupportedGpuFamily.common > 0) {
-        LOG(INFO) << "  MTLGPUFamilyCommon" << (int) mContext->highestSupportedGpuFamily.common;
+        utils::slog.v << "  MTLGPUFamilyCommon" << (int) mContext->highestSupportedGpuFamily.common << utils::io::endl;
    }
    if (mContext->highestSupportedGpuFamily.apple > 0) {
-        LOG(INFO) << "  MTLGPUFamilyApple" << (int) mContext->highestSupportedGpuFamily.apple;
+        utils::slog.v << "  MTLGPUFamilyApple" << (int) mContext->highestSupportedGpuFamily.apple << utils::io::endl;
    }
    if (mContext->highestSupportedGpuFamily.mac > 0) {
-        LOG(INFO) << "  MTLGPUFamilyMac" << (int) mContext->highestSupportedGpuFamily.mac;
+        utils::slog.v << "  MTLGPUFamilyMac" << (int) mContext->highestSupportedGpuFamily.mac << utils::io::endl;
    }
-    LOG(INFO) << "Features:";
-    LOG(INFO) << "  readWriteTextureSupport: " << (bool) mContext->device.readWriteTextureSupport;
+    utils::slog.v << "Features:" << utils::io::endl;
+    utils::slog.v << "  readWriteTextureSupport: " <<
+            (bool) mContext->device.readWriteTextureSupport << utils::io::endl;

    // In order to support texture swizzling, the GPU needs to support it and the system be running
    // iOS 13+.
@@ -585,7 +588,7 @@ void MetalDriver::createProgramR(Handle<HwProgram> rph, Program&& program) {
 #if FILAMENT_METAL_DEBUG_LOG
    auto handleId = rph.getId();
    DEBUG_LOG("createProgramR(rph = %d, program = ", handleId);
-    DLOG(INFO) << program;
+    utils::slog.d << program << utils::io::endl;
 #endif
    construct_handle<MetalProgram>(rph, *mContext, std::move(program));
 }
@@ -2074,7 +2077,7 @@ void MetalDriver::dispatchCompute(Handle<HwProgram> program, math::uint3 workGro
                                                            error:&error];
    if (error) {
        auto description = [error.localizedDescription cStringUsingEncoding:NSUTF8StringEncoding];
-        LOG(ERROR) << description;
+        utils::slog.e << description << utils::io::endl;
    }
    assert_invariant(!error);

@@ -20,14 +20,14 @@
 #include "MetalEnums.h"
 #include "MetalUtils.h"

-#include <utils/Logger.h>
 #include <utils/Panic.h>
+#include <utils/Log.h>
 #include <utils/trap.h>

 #define NSERROR_CHECK(message)                                                                     \
    if (error) {                                                                                   \
        auto description = [error.localizedDescription cStringUsingEncoding:NSUTF8StringEncoding]; \
-        LOG(ERROR) << description;                                                                 \
+        utils::slog.e << description << utils::io::endl;                                           \
    }                                                                                              \
    FILAMENT_CHECK_POSTCONDITION(error == nil) << message;

@@ -27,11 +27,10 @@

 #include "private/backend/BackendUtils.h"

-#include <utils/Logger.h>
-#include <utils/Panic.h>
 #include <utils/compiler.h>
-#include <utils/debug.h>
+#include <utils/Panic.h>
 #include <utils/trap.h>
+#include <utils/debug.h>

 #include <math/scalar.h>

@@ -116,14 +115,14 @@ MetalSwapChain::MetalSwapChain(
      type(SwapChainType::CAMETALLAYER) {

    if (!(flags & SwapChain::CONFIG_TRANSPARENT) && !nativeWindow.opaque) {
-        LOG(WARNING) << "Warning: Filament SwapChain has no CONFIG_TRANSPARENT flag, but the "
-                        "CAMetaLayer("
-                     << (__bridge void*) nativeWindow << ") has .opaque set to NO.";
+        utils::slog.w << "Warning: Filament SwapChain has no CONFIG_TRANSPARENT flag, "
+                         "but the CAMetaLayer(" << (__bridge void*) nativeWindow << ")"
+                         " has .opaque set to NO." << utils::io::endl;
    }
    if ((flags & SwapChain::CONFIG_TRANSPARENT) && nativeWindow.opaque) {
-        LOG(WARNING) << "Warning: Filament SwapChain has the CONFIG_TRANSPARENT flag, but the "
-                        "CAMetaLayer("
-                     << (__bridge void*) nativeWindow << ") has .opaque set to YES.";
+        utils::slog.w << "Warning: Filament SwapChain has the CONFIG_TRANSPARENT flag, "
+                         "but the CAMetaLayer(" << (__bridge void*) nativeWindow << ")"
+                         " has .opaque set to YES." << utils::io::endl;
    }

    // Needed so we can use the SwapChain as a blit source.
@@ -21,7 +21,6 @@
 #include <backend/Program.h>

 #include <utils/JobSystem.h>
-#include <utils/Logger.h>
 #include <utils/Mutex.h>

 #include <chrono>
@@ -148,7 +147,7 @@ bool MetalShaderCompiler::isParallelShaderCompileSupported() const noexcept {
            if (error) {
                auto description =
                        [error.localizedDescription cStringUsingEncoding:NSUTF8StringEncoding];
-                LOG(WARNING) << description;
+                utils::slog.w << description << utils::io::endl;
                errorMessage = error.localizedDescription;
            }
            PANIC_LOG("Failed to compile Metal program.");
@@ -179,7 +178,7 @@ bool MetalShaderCompiler::isParallelShaderCompileSupported() const noexcept {
            if (error) {
                auto description =
                        [error.localizedDescription cStringUsingEncoding:NSUTF8StringEncoding];
-                LOG(WARNING) << description;
+                utils::slog.w << description << utils::io::endl;
                errorMessage = error.localizedDescription;
            }
            PANIC_LOG("Failed to load main0 in Metal program.");
@@ -18,7 +18,7 @@

 #include "MetalEnums.h"

-#include <utils/Logger.h>
+#include <utils/Log.h>

 namespace filament {
 namespace backend {
@@ -95,7 +95,7 @@ id<MTLRenderPipelineState> PipelineStateCreator::operator()(id<MTLDevice> device
            [NSString stringWithFormat:@"Could not create Metal pipeline state: %@",
                error ? error.localizedDescription : @"unknown error"];
        auto description = [errorMessage cStringUsingEncoding:NSUTF8StringEncoding];
-        LOG(ERROR) << description;
+        utils::slog.e << description << utils::io::endl;
        [[NSException exceptionWithName:@"MetalRenderPipelineFailure"
                                 reason:errorMessage
                               userInfo:nil] raise];
@@ -155,7 +155,7 @@ id<MTLSamplerState> SamplerStateCreator::operator()(id<MTLDevice> device,
    // MTLSamplerDescriptor.
    // In practice, this means shadows are not supported when running in the simulator.
    if (![device supportsFeatureSet:MTLFeatureSet_iOS_GPUFamily3_v1]) {
-        LOG(WARNING) << "Warning: sample comparison not supported by this GPU";
+        utils::slog.w << "Warning: sample comparison not supported by this GPU" << utils::io::endl;
        samplerDescriptor.compareFunction = MTLCompareFunctionNever;
    }
 #endif
@@ -19,7 +19,7 @@

 #include "MetalDriverFactory.h"

-#include <utils/Logger.h>
+#include <utils/Log.h>

 #import <Foundation/Foundation.h>

@@ -53,9 +53,6 @@ PlatformMetal::~PlatformMetal() noexcept {
 }

 Driver* PlatformMetal::createDriver(void* /*sharedContext*/, const Platform::DriverConfig& driverConfig) noexcept {
-    pImpl->mDrawableFailureBehavior = driverConfig.metalDisablePanicOnDrawableFailure
-            ? DrawableFailureBehavior::ABORT_FRAME
-            : DrawableFailureBehavior::PANIC;
    return MetalDriverFactory::create(this, driverConfig);
 }

@@ -132,8 +129,9 @@ void PlatformMetalImpl::createDeviceImpl(MetalDevice& outDevice) {
        result = MTLCreateSystemDefaultDevice();
    }

-    LOG(INFO) << "Selected physical device '"
-              << [result.name cStringUsingEncoding:NSUTF8StringEncoding] << "'";
+    utils::slog.i << "Selected physical device '"
+                  << [result.name cStringUsingEncoding:NSUTF8StringEncoding] << "'"
+                  << utils::io::endl;

    outDevice.device = result;
    mDevice = result;
@@ -360,7 +360,7 @@ void GLDescriptorSet::bind(
            }
        }, entry.desc);
    });
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void GLDescriptorSet::validate(HandleAllocatorGL& allocator,
@@ -18,7 +18,6 @@

 #include "private/backend/Driver.h"

-#include <utils/Logger.h>
 #include <utils/compiler.h>
 #include <utils/ostream.h>
 #include <utils/trap.h>
@@ -26,7 +25,6 @@
 #include <string_view>

 #include <stddef.h>
-#include <cstdio>

 namespace filament::backend {

@@ -57,21 +55,19 @@ std::string_view getGLErrorString(GLenum error) noexcept {
 }

 UTILS_NOINLINE
-GLenum checkGLError(const char* function, size_t line) noexcept {
+GLenum checkGLError(io::ostream& out, const char* function, size_t line) noexcept {
    GLenum const error = glGetError();
    if (UTILS_VERY_UNLIKELY(error != GL_NO_ERROR)) {
        auto const string = getGLErrorString(error);
-        char hexError[16];
-        snprintf(hexError, sizeof(hexError), "%#x", error);
-        LOG(ERROR) << "OpenGL error " << hexError << " (" << string << ") in \"" << function
-                   << "\" at line " << line;
+        out << "OpenGL error " << io::hex << error << " (" << string << ") in \""
+            << function << "\" at line " << io::dec << line << io::endl;
    }
    return error;
 }

 UTILS_NOINLINE
-void assertGLError(const char* function, size_t line) noexcept {
-    GLenum const err = checkGLError(function, line);
+void assertGLError(io::ostream& out, const char* function, size_t line) noexcept {
+    GLenum const err = checkGLError(out, function, line);
    if (UTILS_VERY_UNLIKELY(err != GL_NO_ERROR)) {
        debug_trap();
    }
@@ -101,21 +97,19 @@ std::string_view getFramebufferStatusString(GLenum status) noexcept {
 }

 UTILS_NOINLINE
-GLenum checkFramebufferStatus(GLenum target, const char* function, size_t line) noexcept {
+GLenum checkFramebufferStatus(io::ostream& out, GLenum target, const char* function, size_t line) noexcept {
    GLenum const status = glCheckFramebufferStatus(target);
    if (UTILS_VERY_UNLIKELY(status != GL_FRAMEBUFFER_COMPLETE)) {
        auto const string = getFramebufferStatusString(status);
-        char hexStatus[16];
-        snprintf(hexStatus, sizeof(hexStatus), "%#x", status);
-        LOG(ERROR) << "OpenGL framebuffer error " << hexStatus << " (" << string << ") in \""
-                   << function << "\" at line " << line;
+        out << "OpenGL framebuffer error " << io::hex << status << " (" << string << ") in \""
+            << function << "\" at line " << io::dec << line << io::endl;
    }
    return status;
 }

 UTILS_NOINLINE
-void assertFramebufferStatus(GLenum target, const char* function, size_t line) noexcept {
-    GLenum const status = checkFramebufferStatus(target, function, line);
+void assertFramebufferStatus(io::ostream& out, GLenum target, const char* function, size_t line) noexcept {
+    GLenum const status = checkFramebufferStatus(out, target, function, line);
    if (UTILS_VERY_UNLIKELY(status != GL_FRAMEBUFFER_COMPLETE)) {
        debug_trap();
    }
@@ -33,21 +33,21 @@
 namespace filament::backend::GLUtils {

 std::string_view getGLErrorString(GLenum error) noexcept;
-GLenum checkGLError(const char* function, size_t line) noexcept;
-void assertGLError(const char* function, size_t line) noexcept;
+GLenum checkGLError(utils::io::ostream& out, const char* function, size_t line) noexcept;
+void assertGLError(utils::io::ostream& out, const char* function, size_t line) noexcept;

 std::string_view getFramebufferStatusString(GLenum err) noexcept;
-GLenum checkFramebufferStatus(GLenum target, const char* function, size_t line) noexcept;
-void assertFramebufferStatus(GLenum target, const char* function, size_t line) noexcept;
+GLenum checkFramebufferStatus(utils::io::ostream& out, GLenum target, const char* function, size_t line) noexcept;
+void assertFramebufferStatus(utils::io::ostream& out, GLenum target, const char* function, size_t line) noexcept;

 #ifdef NDEBUG
-#   define CHECK_GL_ERROR()
-#   define CHECK_GL_ERROR_NON_FATAL()
-#   define CHECK_GL_FRAMEBUFFER_STATUS(target)
+#   define CHECK_GL_ERROR(out)
+#   define CHECK_GL_ERROR_NON_FATAL(out)
+#   define CHECK_GL_FRAMEBUFFER_STATUS(out, target)
 #else
-#   define CHECK_GL_ERROR() { GLUtils::assertGLError(__func__, __LINE__); }
-#   define CHECK_GL_ERROR_NON_FATAL() { GLUtils::checkGLError(__func__, __LINE__); }
-#   define CHECK_GL_FRAMEBUFFER_STATUS(target) { GLUtils::checkFramebufferStatus( target, __func__, __LINE__); }
+#   define CHECK_GL_ERROR(out) { GLUtils::assertGLError(out, __func__, __LINE__); }
+#   define CHECK_GL_ERROR_NON_FATAL(out) { GLUtils::checkGLError(out, __func__, __LINE__); }
+#   define CHECK_GL_FRAMEBUFFER_STATUS(out, target) { GLUtils::checkFramebufferStatus(out, target, __func__, __LINE__); }
 #endif

 constexpr GLuint getComponentCount(ElementType const type) noexcept {
@@ -22,9 +22,9 @@
 #include <backend/platforms/OpenGLPlatform.h>
 #include <backend/DriverEnums.h>

-#include <utils/Logger.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
+#include <utils/Log.h>
 #include <utils/ostream.h>

 #include <functional>
@@ -77,8 +77,8 @@ OpenGLContext::OpenGLContext(OpenGLPlatform& platform,
    state.version  = (char const*)glGetString(GL_VERSION);
    state.shader   = (char const*)glGetString(GL_SHADING_LANGUAGE_VERSION);

-    LOG(INFO) << "[" << state.vendor << "], [" << state.renderer << "], "
-                 "[" << state.version << "], [" << state.shader << "]";
+    slog.v << "[" << state.vendor << "], [" << state.renderer << "], "
+              "[" << state.version << "], [" << state.shader << "]" << io::endl;

    /*
     * Figure out GL / GLES version, extensions and capabilities we need to
@@ -164,33 +164,51 @@ OpenGLContext::OpenGLContext(OpenGLPlatform& platform,
    }
 #endif

-    LOG(INFO) << "Feature level: " << +mFeatureLevel;
-    LOG(INFO) << "Active workarounds: ";
+    slog.v << "Feature level: " << +mFeatureLevel << '\n';
+    slog.v << "Active workarounds: " << '\n';
    UTILS_NOUNROLL
    for (auto [enabled, name, _] : mBugDatabase) {
        if (enabled) {
-            LOG(INFO) << name;
+            slog.v << name << '\n';
        }
    }
+    flush(slog.v);

 #ifndef NDEBUG
    // this is useful for development
-    LOG(INFO) << "GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT = " << gets.max_anisotropy;
-    LOG(INFO) << "GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS = " << gets.max_combined_texture_image_units;
-    LOG(INFO) << "GL_MAX_TEXTURE_SIZE = " << gets.max_texture_size;
-    LOG(INFO) << "GL_MAX_CUBE_MAP_TEXTURE_SIZE = " << gets.max_cubemap_texture_size;
-    LOG(INFO) << "GL_MAX_3D_TEXTURE_SIZE = " << gets.max_3d_texture_size;
-    LOG(INFO) << "GL_MAX_ARRAY_TEXTURE_LAYERS = " << gets.max_array_texture_layers;
-    LOG(INFO) << "GL_MAX_DRAW_BUFFERS = " << gets.max_draw_buffers;
-    LOG(INFO) << "GL_MAX_RENDERBUFFER_SIZE = " << gets.max_renderbuffer_size;
-    LOG(INFO) << "GL_MAX_SAMPLES = " << gets.max_samples;
-    LOG(INFO) << "GL_MAX_TEXTURE_IMAGE_UNITS = " << gets.max_texture_image_units;
-    LOG(INFO) << "GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS = "
-              << gets.max_transform_feedback_separate_attribs;
-    LOG(INFO) << "GL_MAX_UNIFORM_BLOCK_SIZE = " << gets.max_uniform_block_size;
-    LOG(INFO) << "GL_MAX_UNIFORM_BUFFER_BINDINGS = " << gets.max_uniform_buffer_bindings;
-    LOG(INFO) << "GL_NUM_PROGRAM_BINARY_FORMATS = " << gets.num_program_binary_formats;
-    LOG(INFO) << "GL_UNIFORM_BUFFER_OFFSET_ALIGNMENT = " << gets.uniform_buffer_offset_alignment;
+    slog.v
+            << "GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT = "
+                    << gets.max_anisotropy << '\n'
+            << "GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS = "
+                    << gets.max_combined_texture_image_units << '\n'
+            << "GL_MAX_TEXTURE_SIZE = "
+                    << gets.max_texture_size << '\n'
+            << "GL_MAX_CUBE_MAP_TEXTURE_SIZE = "
+                    << gets.max_cubemap_texture_size << '\n'
+            << "GL_MAX_3D_TEXTURE_SIZE = "
+                    << gets.max_3d_texture_size << '\n'
+            << "GL_MAX_ARRAY_TEXTURE_LAYERS = "
+                    << gets.max_array_texture_layers << '\n'
+            << "GL_MAX_DRAW_BUFFERS = "
+                    << gets.max_draw_buffers << '\n'
+            << "GL_MAX_RENDERBUFFER_SIZE = "
+                    << gets.max_renderbuffer_size << '\n'
+            << "GL_MAX_SAMPLES = "
+                    << gets.max_samples << '\n'
+            << "GL_MAX_TEXTURE_IMAGE_UNITS = "
+                    << gets.max_texture_image_units << '\n'
+            << "GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS = "
+                    << gets.max_transform_feedback_separate_attribs << '\n'
+            << "GL_MAX_UNIFORM_BLOCK_SIZE = "
+                    << gets.max_uniform_block_size << '\n'
+            << "GL_MAX_UNIFORM_BUFFER_BINDINGS = "
+                    << gets.max_uniform_buffer_bindings << '\n'
+            << "GL_NUM_PROGRAM_BINARY_FORMATS = "
+                    << gets.num_program_binary_formats << '\n'
+            << "GL_UNIFORM_BUFFER_OFFSET_ALIGNMENT = "
+                    << gets.uniform_buffer_offset_alignment << '\n'
+            ;
+    flush(slog.v);
 #endif

 #ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
@@ -224,14 +242,15 @@ OpenGLContext::OpenGLContext(OpenGLPlatform& platform,
    if (ext.KHR_debug) {
        auto cb = +[](GLenum, GLenum type, GLuint, GLenum severity, GLsizei length,
                const GLchar* message, const void *) {
-            auto logSeverity = utils::LogSeverity::kInfo;
+            io::ostream* stream = &slog.i;
            switch (severity) {
-                case GL_DEBUG_SEVERITY_HIGH:    logSeverity = utils::LogSeverity::kError;   break;
-                case GL_DEBUG_SEVERITY_MEDIUM:  logSeverity = utils::LogSeverity::kWarning; break;
-                case GL_DEBUG_SEVERITY_LOW:     logSeverity = utils::LogSeverity::kInfo;    break;
+                case GL_DEBUG_SEVERITY_HIGH:    stream = &slog.e;   break;
+                case GL_DEBUG_SEVERITY_MEDIUM:  stream = &slog.w;   break;
+                case GL_DEBUG_SEVERITY_LOW:     stream = &slog.d;   break;
                case GL_DEBUG_SEVERITY_NOTIFICATION:
                default: break;
            }
+            io::ostream& out = *stream;
            const char* level = ": ";
            switch (type) {
                case GL_DEBUG_TYPE_ERROR:               level = "ERROR: ";               break;
@@ -243,7 +262,7 @@ OpenGLContext::OpenGLContext(OpenGLPlatform& platform,
                case GL_DEBUG_TYPE_MARKER:              level = "MARKER: ";              break;
                default: break;
            }
-            LOG(LEVEL(logSeverity)) << "KHR_debug " << level << std::string_view{ message, size_t(length) };
+            out << "KHR_debug " << level << std::string_view{ message, size_t(length) } << io::endl;
        };
        glEnable(GL_DEBUG_OUTPUT);
        glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS);
@@ -688,8 +707,9 @@ void OpenGLContext::initExtensionsGLES(Extensions* ext, GLint major, GLint minor
    GLUtils::unordered_string_set const exts = GLUtils::split(extensions);
    if constexpr (DEBUG_PRINT_EXTENSIONS) {
        for (auto extension: exts) {
-            DLOG(INFO) << "\"" << std::string_view(extension) << "\"";
+            slog.d << "\"" << std::string_view(extension) << "\"\n";
        }
+        flush(slog.d);
    }

    // figure out and initialize the extensions we need
@@ -763,8 +783,9 @@ void OpenGLContext::initExtensionsGL(Extensions* ext, GLint major, GLint minor)
    }
    if constexpr (DEBUG_PRINT_EXTENSIONS) {
        for (auto extension: exts) {
-            DLOG(INFO) << "\"" << std::string_view(extension) << "\"";
+            slog.d << "\"" << std::string_view(extension) << "\"\n";
        }
+        flush(slog.d);
    }

    using namespace std::literals;
@@ -1024,7 +1045,7 @@ GLuint OpenGLContext::getSamplerSlow(SamplerParams params) const noexcept {
                std::min(gets.max_anisotropy, anisotropy));
    }
 #endif
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
    mSamplerMap[params] = s;
    return s;
 }
@@ -48,13 +48,12 @@

 #include <type_traits>
 #include <utils/BitmaskEnum.h>
-#include <utils/CString.h>
 #include <utils/FixedCapacityVector.h>
+#include <utils/CString.h>
 #include <utils/Invocable.h>
-#include <utils/Logger.h>
+#include <utils/Log.h>
 #include <utils/Panic.h>
 #include <utils/Slice.h>
-#include <utils/Systrace.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
 #include <utils/ostream.h>
@@ -185,18 +184,20 @@ OpenGLDriver* OpenGLDriver::create(OpenGLPlatform* platform,
    //    GLVertexBufferInfo        : 132       moderate
    // -- less than or equal to 136 bytes

-    DLOG(INFO) << "GLSwapChain: " << sizeof(GLSwapChain);
-    DLOG(INFO) << "GLBufferObject: " << sizeof(GLBufferObject);
-    DLOG(INFO) << "GLVertexBuffer: " << sizeof(GLVertexBuffer);
-    DLOG(INFO) << "GLVertexBufferInfo: " << sizeof(GLVertexBufferInfo);
-    DLOG(INFO) << "GLIndexBuffer: " << sizeof(GLIndexBuffer);
-    DLOG(INFO) << "GLRenderPrimitive: " << sizeof(GLRenderPrimitive);
-    DLOG(INFO) << "GLTexture: " << sizeof(GLTexture);
-    DLOG(INFO) << "GLTimerQuery: " << sizeof(GLTimerQuery);
-    DLOG(INFO) << "GLStream: " << sizeof(GLStream);
-    DLOG(INFO) << "GLRenderTarget: " << sizeof(GLRenderTarget);
-    DLOG(INFO) << "GLFence: " << sizeof(GLFence);
-    DLOG(INFO) << "OpenGLProgram: " << sizeof(OpenGLProgram);
+    slog.d
+           << "\nGLSwapChain: " << sizeof(GLSwapChain)
+           << "\nGLBufferObject: " << sizeof(GLBufferObject)
+           << "\nGLVertexBuffer: " << sizeof(GLVertexBuffer)
+           << "\nGLVertexBufferInfo: " << sizeof(GLVertexBufferInfo)
+           << "\nGLIndexBuffer: " << sizeof(GLIndexBuffer)
+           << "\nGLRenderPrimitive: " << sizeof(GLRenderPrimitive)
+           << "\nGLTexture: " << sizeof(GLTexture)
+           << "\nGLTimerQuery: " << sizeof(GLTimerQuery)
+           << "\nGLStream: " << sizeof(GLStream)
+           << "\nGLRenderTarget: " << sizeof(GLRenderTarget)
+           << "\nGLFence: " << sizeof(GLFence)
+           << "\nOpenGLProgram: " << sizeof(OpenGLProgram)
+           << io::endl;
 #endif

    // here we check we're on a supported version of GL before initializing the driver
@@ -288,7 +289,7 @@ OpenGLDriver::OpenGLDriver(OpenGLPlatform* platform, const Platform::DriverConfi
    mStreamsWithPendingAcquiredImage.reserve(8);

 #ifndef NDEBUG
-    LOG(INFO) << "OS version: " << mPlatform.getOSVersion();
+    slog.i << "OS version: " << mPlatform.getOSVersion() << io::endl;
 #endif

    // Timer queries are core in GL 3.3, otherwise we need EXT_disjoint_timer_query
@@ -667,7 +668,7 @@ void OpenGLDriver::createIndexBufferR(
    gl.bindVertexArray(nullptr);
    gl.bindBuffer(GL_ELEMENT_ARRAY_BUFFER, ib->gl.buffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, size, nullptr, getBufferUsage(usage));
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::createBufferObjectR(Handle<HwBufferObject> boh,
@@ -692,7 +693,7 @@ void OpenGLDriver::createBufferObjectR(Handle<HwBufferObject> boh,
        glBufferData(bo->gl.binding, byteCount, nullptr, getBufferUsage(usage));
    }

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::createRenderPrimitiveR(Handle<HwRenderPrimitive> rph,
@@ -729,7 +730,7 @@ void OpenGLDriver::createRenderPrimitiveR(Handle<HwRenderPrimitive> rph,
    // this records the index buffer into the currently bound VAO
    gl.bindBuffer(GL_ELEMENT_ARRAY_BUFFER, ib->gl.buffer);

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::createProgramR(Handle<HwProgram> ph, Program&& program) {
@@ -759,7 +760,7 @@ void OpenGLDriver::createProgramR(Handle<HwProgram> ph, Program&& program) {
    }

    construct<OpenGLProgram>(ph, *this, std::move(program));
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 UTILS_NOINLINE
@@ -952,7 +953,7 @@ void OpenGLDriver::createTextureR(Handle<HwTexture> th, SamplerType target, uint
        renderBufferStorage(t->gl.id, internalFormat, w, h, samples);
    }

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::createTextureViewR(Handle<HwTexture> th,
@@ -998,7 +999,7 @@ void OpenGLDriver::createTextureViewR(Handle<HwTexture> th,
    assert_invariant(ref);
    ref->count++;

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::createTextureViewSwizzleR(Handle<HwTexture> th, Handle<HwTexture> srch,
@@ -1061,7 +1062,7 @@ void OpenGLDriver::createTextureViewSwizzleR(Handle<HwTexture> th, Handle<HwText
    assert_invariant(ref);
    ref->count++;

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::createTextureExternalImage2R(Handle<HwTexture> th, SamplerType target,
@@ -1224,7 +1225,7 @@ void OpenGLDriver::importTextureR(Handle<HwTexture> th, intptr_t id,
 #endif
    }

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::updateVertexArrayObject(GLRenderPrimitive* rp, GLVertexBuffer const* vb) {
@@ -1484,7 +1485,7 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,
                // we shouldn't be here
                break;
        }
-        CHECK_GL_ERROR()
+        CHECK_GL_ERROR(utils::slog.e)
    } else
 #ifndef __EMSCRIPTEN__
 #ifdef GL_EXT_multisampled_render_to_texture
@@ -1505,7 +1506,7 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,
            glFramebufferRenderbuffer(GL_FRAMEBUFFER, attachment,
                    GL_RENDERBUFFER, t->gl.id);
        }
-        CHECK_GL_ERROR()
+        CHECK_GL_ERROR(utils::slog.e)
    } else
 #endif // GL_EXT_multisampled_render_to_texture
 #endif // __EMSCRIPTEN__
@@ -1587,13 +1588,13 @@ void OpenGLDriver::framebufferTexture(TargetBufferInfo const& binfo,
                break;
        }

-        CHECK_GL_ERROR()
+        CHECK_GL_ERROR(utils::slog.e)
    }

    rt->gl.resolve |= resolveFlags;

-    CHECK_GL_ERROR()
-    CHECK_GL_FRAMEBUFFER_STATUS(GL_FRAMEBUFFER)
+    CHECK_GL_ERROR(utils::slog.e)
+    CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_FRAMEBUFFER)
 }

 void OpenGLDriver::renderBufferStorage(GLuint rbo, GLenum internalformat, uint32_t width, // NOLINT(readability-convert-member-functions-to-static)
@@ -1622,7 +1623,7 @@ void OpenGLDriver::renderBufferStorage(GLuint rbo, GLenum internalformat, uint32
    // unbind the renderbuffer, to avoid any later confusion
    glBindRenderbuffer(GL_RENDERBUFFER, 0);

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::createDefaultRenderTargetR(
@@ -1719,7 +1720,7 @@ void OpenGLDriver::createRenderTargetR(Handle<HwRenderTarget> rth,
        if (UTILS_LIKELY(!getContext().isES2())) {
            glDrawBuffers((GLsizei)maxDrawBuffers, bufs);
        }
-        CHECK_GL_ERROR()
+        CHECK_GL_ERROR(utils::slog.e)
    }
 #endif

@@ -1759,7 +1760,7 @@ void OpenGLDriver::createRenderTargetR(Handle<HwRenderTarget> rth,
    assert_invariant(any(targets & TargetBufferFlags::ALL));
    assert_invariant(tmin == tmax);

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::createFenceR(Handle<HwFence> fh, int) {
@@ -2110,7 +2111,7 @@ void OpenGLDriver::setAcquiredImage(Handle<HwStream> sh, void* hwbuffer, const m

    if (UTILS_UNLIKELY(glstream->user_thread.pending.image)) {
        scheduleRelease(glstream->user_thread.pending);
-        LOG(WARNING) << "Acquired image is set more than once per frame.";
+        slog.w << "Acquired image is set more than once per frame." << io::endl;
    }

    glstream->user_thread.pending = mPlatform.transformAcquiredImage({
@@ -2559,7 +2560,7 @@ void OpenGLDriver::makeCurrent(Handle<HwSwapChain> schDraw, Handle<HwSwapChain>

                // OpenGL context has changed, resynchronize the state with the cache
                mContext.synchronizeStateAndCache(index);
-                DLOG(INFO) << "*** OpenGL context change : " << (index ? "protected" : "default");
+                slog.d << "*** OpenGL context change : " << (index ? "protected" : "default") << io::endl;
            });

    mCurrentDrawSwapChain = scDraw;
@@ -2600,7 +2601,7 @@ void OpenGLDriver::setVertexBufferObject(Handle<HwVertexBuffer> vbh,
        vb->bufferObjectsVersion = (version + 1) % kMaxVersion;
    }

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::updateIndexBuffer(
@@ -2617,7 +2618,7 @@ void OpenGLDriver::updateIndexBuffer(

    scheduleDestroy(std::move(p));

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::registerBufferObjectStreams(Handle<HwBufferObject> boh, BufferObjectStreamDescriptor&& streams) {
@@ -2697,7 +2698,7 @@ void OpenGLDriver::updateBufferObject(

    scheduleDestroy(std::move(bd));

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::updateBufferObjectUnsynchronized(
@@ -2744,7 +2745,7 @@ retry:
            scheduleDestroy(std::move(bd));
        }
    }
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 #endif
 }

@@ -2794,7 +2795,7 @@ void OpenGLDriver::generateMipmaps(Handle<HwTexture> th) {

    glGenerateMipmap(t->gl.target);

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::setTextureData(GLTexture const* t, uint32_t level,
@@ -2903,7 +2904,7 @@ void OpenGLDriver::setTextureData(GLTexture const* t, uint32_t level,

    scheduleDestroy(std::move(p));

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::setCompressedTextureData(GLTexture const* t, uint32_t level,
@@ -2989,7 +2990,7 @@ void OpenGLDriver::setCompressedTextureData(GLTexture const* t, uint32_t level,

    scheduleDestroy(std::move(p));

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::setupExternalImage2(Platform::ExternalImageHandleRef image) {
@@ -3152,7 +3153,7 @@ void OpenGLDriver::beginRenderPass(Handle<HwRenderTarget> rth,
    TargetBufferFlags discardFlags = params.flags.discardStart & rt->targets;

    GLuint const fbo = gl.bindFramebuffer(GL_FRAMEBUFFER, rt->gl.fbo);
-    CHECK_GL_FRAMEBUFFER_STATUS(GL_FRAMEBUFFER)
+    CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_FRAMEBUFFER)

    // each render-pass starts with a disabled scissor
    gl.disable(GL_SCISSOR_TEST);
@@ -3164,7 +3165,7 @@ void OpenGLDriver::beginRenderPass(Handle<HwRenderTarget> rth,
        if (attachmentCount) {
            gl.procs.invalidateFramebuffer(GL_FRAMEBUFFER, attachmentCount, attachments.data());
        }
-        CHECK_GL_ERROR()
+        CHECK_GL_ERROR(utils::slog.e)
    } else {
        // It's important to clear the framebuffer before drawing, as it resets
        // the fb to a known state (resets fb compression and possibly other things).
@@ -3251,7 +3252,7 @@ void OpenGLDriver::endRenderPass(int) {
            if (attachmentCount) {
                gl.procs.invalidateFramebuffer(GL_FRAMEBUFFER, attachmentCount, attachments.data());
            }
-           CHECK_GL_ERROR()
+           CHECK_GL_ERROR(utils::slog.e)
        }
    }

@@ -3297,13 +3298,13 @@ void OpenGLDriver::resolvePass(ResolveAction action, GLRenderTarget const* rt,
        gl.bindFramebuffer(GL_READ_FRAMEBUFFER, read);
        gl.bindFramebuffer(GL_DRAW_FRAMEBUFFER, draw);

-        CHECK_GL_FRAMEBUFFER_STATUS(GL_READ_FRAMEBUFFER)
-        CHECK_GL_FRAMEBUFFER_STATUS(GL_DRAW_FRAMEBUFFER)
+        CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_READ_FRAMEBUFFER)
+        CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_DRAW_FRAMEBUFFER)

        gl.disable(GL_SCISSOR_TEST);
        glBlitFramebuffer(0, 0, (GLint)rt->width, (GLint)rt->height,
                0, 0, (GLint)rt->width, (GLint)rt->height, mask, GL_NEAREST);
-        CHECK_GL_ERROR()
+        CHECK_GL_ERROR(utils::slog.e)
    }
 #endif
 }
@@ -3482,7 +3483,7 @@ void OpenGLDriver::readPixels(Handle<HwRenderTarget> src,
        if (buffer) {
            gl.bindFramebuffer(GL_FRAMEBUFFER, s->gl.fbo_read ? s->gl.fbo_read : s->gl.fbo);
            glReadPixels(GLint(x), GLint(y), GLint(width), GLint(height), glFormat, glType, buffer);
-            CHECK_GL_ERROR()
+            CHECK_GL_ERROR(utils::slog.e)

            // now we need to flip the buffer vertically to match our API
            size_t const stride = p.stride ? p.stride : width;
@@ -3514,7 +3515,7 @@ void OpenGLDriver::readPixels(Handle<HwRenderTarget> src,
    glBufferData(GL_PIXEL_PACK_BUFFER, pboSize, nullptr, GL_STATIC_DRAW);
    glReadPixels(GLint(x), GLint(y), GLint(width), GLint(height), glFormat, glType, nullptr);
    gl.bindBuffer(GL_PIXEL_PACK_BUFFER, 0);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    // we're forced to make a copy on the heap because otherwise it deletes std::function<> copy
    // constructor.
@@ -3554,7 +3555,7 @@ void OpenGLDriver::readPixels(Handle<HwRenderTarget> src,
        glDeleteBuffers(1, &pbo);
        scheduleDestroy(std::move(p));
        delete pUserBuffer;
-        CHECK_GL_ERROR()
+        CHECK_GL_ERROR(utils::slog.e)
    });
 #endif
 }
@@ -3579,7 +3580,7 @@ void OpenGLDriver::readBufferSubData(BufferObjectHandle boh,
        glCopyBufferSubData(bo->gl.binding, GL_PIXEL_PACK_BUFFER, offset, 0, size);
        gl.bindBuffer(bo->gl.binding, 0);
        gl.bindBuffer(GL_PIXEL_PACK_BUFFER, 0);
-        CHECK_GL_ERROR()
+        CHECK_GL_ERROR(utils::slog.e)

        // then, we schedule a mapBuffer of the PBO later, once the fence has signaled
        auto* pUserBuffer = new BufferDescriptor(std::move(p));
@@ -3596,7 +3597,7 @@ void OpenGLDriver::readBufferSubData(BufferObjectHandle boh,
            glDeleteBuffers(1, &pbo);
            scheduleDestroy(std::move(p));
            delete pUserBuffer;
-            CHECK_GL_ERROR()
+            CHECK_GL_ERROR(utils::slog.e)
        });
    } else {
        gl.bindBuffer(bo->gl.binding, bo->gl.id);
@@ -3609,7 +3610,7 @@ void OpenGLDriver::readBufferSubData(BufferObjectHandle boh,
        }
        gl.bindBuffer(bo->gl.binding, 0);
        scheduleDestroy(std::move(p));
-        CHECK_GL_ERROR()
+        CHECK_GL_ERROR(utils::slog.e)
    }
 #endif
 }
@@ -3639,7 +3640,7 @@ void OpenGLDriver::whenFrameComplete(const std::function<void()>& fn) noexcept {
 void OpenGLDriver::whenGpuCommandsComplete(const std::function<void()>& fn) noexcept {
    GLsync sync = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
    mGpuCommandCompleteOps.emplace_back(sync, fn);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::executeGpuCommandsCompleteOps() noexcept {
@@ -3857,7 +3858,7 @@ void OpenGLDriver::clearWithRasterPipe(TargetBufferFlags clearFlags,
        }
    }

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void OpenGLDriver::resolve(
@@ -3968,7 +3969,7 @@ void OpenGLDriver::blit(
        case SamplerType::SAMPLER_EXTERNAL:
            break;
    }
-    CHECK_GL_FRAMEBUFFER_STATUS(GL_DRAW_FRAMEBUFFER)
+    CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_DRAW_FRAMEBUFFER)

    gl.bindFramebuffer(GL_READ_FRAMEBUFFER, fbo[1]);
    switch (s->target) {
@@ -3994,14 +3995,14 @@ void OpenGLDriver::blit(
        case SamplerType::SAMPLER_EXTERNAL:
            break;
    }
-    CHECK_GL_FRAMEBUFFER_STATUS(GL_READ_FRAMEBUFFER)
+    CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_READ_FRAMEBUFFER)

    gl.disable(GL_SCISSOR_TEST);
    glBlitFramebuffer(
            srcOrigin.x, srcOrigin.y, srcOrigin.x + size.x, srcOrigin.y + size.y,
            dstOrigin.x, dstOrigin.y, dstOrigin.x + size.x, dstOrigin.y + size.y,
            mask, GL_NEAREST);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    gl.unbindFramebuffer(GL_DRAW_FRAMEBUFFER);
    gl.unbindFramebuffer(GL_READ_FRAMEBUFFER);
@@ -4064,15 +4065,15 @@ void OpenGLDriver::blitDEPRECATED(TargetBufferFlags buffers,
    gl.bindFramebuffer(GL_READ_FRAMEBUFFER, s->gl.fbo);
    gl.bindFramebuffer(GL_DRAW_FRAMEBUFFER, d->gl.fbo);

-    CHECK_GL_FRAMEBUFFER_STATUS(GL_READ_FRAMEBUFFER)
-    CHECK_GL_FRAMEBUFFER_STATUS(GL_DRAW_FRAMEBUFFER)
+    CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_READ_FRAMEBUFFER)
+    CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_DRAW_FRAMEBUFFER)

    gl.disable(GL_SCISSOR_TEST);
    glBlitFramebuffer(
            srcRect.left, srcRect.bottom, srcRect.right(), srcRect.top(),
            dstRect.left, dstRect.bottom, dstRect.right(), dstRect.top(),
            GL_COLOR_BUFFER_BIT, glFilterMode);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 #endif
 }

@@ -4199,9 +4200,9 @@ void OpenGLDriver::draw2(uint32_t indexOffset, uint32_t indexCount, uint32_t ins
 #endif

 #if FILAMENT_ENABLE_MATDBG
-    CHECK_GL_ERROR_NON_FATAL()
+    CHECK_GL_ERROR_NON_FATAL(utils::slog.e)
 #else
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 #endif
 }

@@ -4231,9 +4232,9 @@ void OpenGLDriver::draw2GLES2(uint32_t indexOffset, uint32_t indexCount, uint32_
            reinterpret_cast<const void*>(indexOffset << rp->gl.indicesShift));

 #if FILAMENT_ENABLE_MATDBG
-    CHECK_GL_ERROR_NON_FATAL()
+    CHECK_GL_ERROR_NON_FATAL(utils::slog.e)
 #else
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 #endif
 }

@@ -4283,9 +4284,9 @@ void OpenGLDriver::dispatchCompute(Handle<HwProgram> program, uint3 workGroupCou
 #endif // BACKEND_OPENGL_LEVEL_GLES31

 #if FILAMENT_ENABLE_MATDBG
-    CHECK_GL_ERROR_NON_FATAL()
+    CHECK_GL_ERROR_NON_FATAL(utils::slog.e)
 #else
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 #endif
 }

@@ -214,7 +214,7 @@ void OpenGLProgram::initializeProgramState(OpenGLContext& context, GLuint progra
                case DescriptorType::INPUT_ATTACHMENT:
                    break;
            }
-            CHECK_GL_ERROR()
+            CHECK_GL_ERROR(utils::slog.e)
        }
    }

@@ -114,14 +114,14 @@ void TimerQueryNativeFactory::createTimerQuery(GLTimerQuery* tq) {

    tq->state = std::make_shared<GLTimerQuery::State>();
    mContext.procs.genQueries(1u, &tq->state->gl.query);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void TimerQueryNativeFactory::destroyTimerQuery(GLTimerQuery* tq) {
    assert_invariant(tq->state);

    mContext.procs.deleteQueries(1u, &tq->state->gl.query);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    tq->state.reset();
 }
@@ -131,14 +131,14 @@ void TimerQueryNativeFactory::beginTimeElapsedQuery(GLTimerQuery* tq) {

    tq->state->elapsed.store(int64_t(TimerQueryResult::NOT_READY), std::memory_order_relaxed);
    mContext.procs.beginQuery(GL_TIME_ELAPSED, tq->state->gl.query);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 void TimerQueryNativeFactory::endTimeElapsedQuery(OpenGLDriver& driver, GLTimerQuery* tq) {
    assert_invariant(tq->state);

    mContext.procs.endQuery(GL_TIME_ELAPSED);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    std::weak_ptr<GLTimerQuery::State> const weak = tq->state;

@@ -153,7 +153,7 @@ void TimerQueryNativeFactory::endTimeElapsedQuery(OpenGLDriver& driver, GLTimerQ

        GLuint available = 0;
        context.procs.getQueryObjectuiv(state->gl.query, GL_QUERY_RESULT_AVAILABLE, &available);
-        CHECK_GL_ERROR()
+        CHECK_GL_ERROR(utils::slog.e)
        if (!available) {
            // we need to try this one again later
            return false;
@@ -31,14 +31,14 @@

 #include <private/utils/Tracing.h>

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

 #include <algorithm>
 #include <array>
@@ -65,9 +65,9 @@ static std::string to_string(bool const b) { return b ? "true" : "false"; }
 static std::string to_string(int const i) { return std::to_string(i); }
 static std::string to_string(float const f) { return "float(" + std::to_string(f) + ")"; }

-static void logCompilationError(ShaderStage shaderType, const char* name, GLuint shaderId,
-        CString const& sourceCode) noexcept;
-static void logProgramLinkError(char const* name, GLuint program) noexcept;
+static void logCompilationError(io::ostream& out, ShaderStage shaderType, const char* name,
+        GLuint shaderId, CString const& sourceCode) noexcept;
+static void logProgramLinkError(io::ostream& out, char const* name, GLuint program) noexcept;

 static void process_GOOGLE_cpp_style_line_directive(OpenGLContext const& context, char* source,
        size_t len) noexcept;
@@ -122,18 +122,12 @@ struct ShaderCompilerService::OpenGLProgramToken : ProgramToken {
    }

    std::optional<CallbackManager::Handle> handle{};
-
-    // Only valid when the blob functions are provided by users. The validity of this variable
-    // doesn't guarantee that the program was created from the cache blob.
    BlobCacheKey key;

    // Used for the `THREAD_POOL` mode.
    mutable Mutex lock;
    mutable Condition cond;
    bool signaled = false;
-
-    // Indicate this program was created from the cache blob.
-    bool retrievedFromBlobCache = false;
 };

 ShaderCompilerService::OpenGLProgramToken::~OpenGLProgramToken() {
@@ -265,7 +259,6 @@ ShaderCompilerService::program_token_t ShaderCompilerService::createProgram(
    // Try retrieving the cached program blob if available.
    token->gl.program = mBlobCache.retrieve(&token->key, mDriver.mPlatform, program);
    if (token->gl.program) {
-        token->retrievedFromBlobCache = true;
        return token;
    }

@@ -344,15 +337,12 @@ GLuint ShaderCompilerService::getProgram(program_token_t& token) {

    assert_invariant(token);// This function should be called when the token is still alive.

-    // Finalize any pending shader compilation tasks only when the token was created without cache.
-    if (!token->retrievedFromBlobCache) {
-        if (token->compiler.mMode == Mode::THREAD_POOL) {
-            auto const job = token->compiler.mCompilerThreadPool.dequeue(token);
-            if (!job) {
-                // It's likely that the job was already completed. But it may be still being
-                // executed at this moment. Just try waiting for it to avoid a race.
-                token->wait();
-            }
+    if (token->compiler.mMode == Mode::THREAD_POOL) {
+        auto const job = token->compiler.mCompilerThreadPool.dequeue(token);
+        if (!job) {
+            // It's likely that the job was already completed. But it may be still being
+            // executed at this moment. Just try waiting for it to avoid a race.
+            token->wait();
        }
    }

@@ -443,9 +433,8 @@ void ShaderCompilerService::ensureTokenIsReady(program_token_t const& token) {
            // just log warnings here instead of repeatedly checking compile status. If this turns
            // out to be a real issue later, we would need to consider doing the canonical way.
            if (!isCompileCompleted(token)) {
-                LOG(WARNING)
-                        << "Shader compilation for OpenGL program " << token->name.c_str_safe()
-                        << " is not completed yet. The following program link may not succeed.";
+                slog.w << "Shader compilation for OpenGL program " << token->name.c_str_safe()
+                       << " is not completed yet. The following program link may not succeed.";
            }

            linkProgram(mDriver.getContext(), token);
@@ -655,7 +644,8 @@ void ShaderCompilerService::executeTickOps() noexcept {
        }
        // Something went wrong. Log the error message.
        const ShaderStage type = static_cast<ShaderStage>(i);
-        logCompilationError(type, token->name.c_str_safe(), shader, token->shaderSourceCode[i]);
+        logCompilationError(slog.e, type, token->name.c_str_safe(), shader,
+                token->shaderSourceCode[i]);
    }
 }

@@ -707,7 +697,7 @@ void ShaderCompilerService::executeTickOps() noexcept {
    glGetProgramiv(token->gl.program, GL_LINK_STATUS, &status);
    if (UTILS_UNLIKELY(status != GL_TRUE)) {
        // Something went wrong. Log the error message.
-        logProgramLinkError(token->name.c_str_safe(), token->gl.program);
+        logProgramLinkError(slog.e, token->name.c_str_safe(), token->gl.program);
        linked = false;
    }
    // No need to keep the shaders around regardless of the result of the program linking.
@@ -757,7 +747,7 @@ void ShaderCompilerService::executeTickOps() noexcept {
 // ------------------------------------------------------------------------------------------------

 UTILS_NOINLINE
-/* static */ void logCompilationError(ShaderStage shaderType, const char* name,
+/* static */ void logCompilationError(io::ostream& out, ShaderStage shaderType, const char* name,
        GLuint const shaderId, UTILS_UNUSED_IN_RELEASE CString const& sourceCode) noexcept {

    { // scope for the temporary string storage
@@ -779,9 +769,8 @@ UTILS_NOINLINE
        CString infoLog(length);
        glGetShaderInfoLog(shaderId, length, nullptr, infoLog.data());

-        LOG(ERROR) << "Compilation error in " << to_string(shaderType) << " shader \"" << name
-                   << "\":";
-        LOG(ERROR) << "\"" << infoLog.c_str() << "\"";
+        out << "Compilation error in " << to_string(shaderType) << " shader \"" << name << "\":\n"
+            << "\"" << infoLog.c_str() << "\"" << io::endl;
    }

 #ifndef NDEBUG
@@ -796,25 +785,26 @@ UTILS_NOINLINE
        } else {
            line = shader.substr(start, end - start);
        }
-        LOG(ERROR) << lc++ << ":   " << line.c_str();
+        out << lc++ << ":   " << line.c_str() << '\n';
        if (end == std::string::npos) {
            break;
        }
        start = end + 1;
    }
-    LOG(ERROR) << "";
+    out << io::endl;
 #endif
 }

 UTILS_NOINLINE
-/* static */ void logProgramLinkError(char const* name, GLuint program) noexcept {
+/* static */ void logProgramLinkError(io::ostream& out, char const* name, GLuint program) noexcept {
    GLint length = 0;
    glGetProgramiv(program, GL_INFO_LOG_LENGTH, &length);

    CString infoLog(length);
    glGetProgramInfoLog(program, length, nullptr, infoLog.data());

-    LOG(ERROR) << "Link error in \"" << name << "\":\n" << "\"" << infoLog.c_str() << "\"";
+    out << "Link error in \"" << name << "\":\n"
+        << "\"" << infoLog.c_str() << "\"" << io::endl;
 }

 // If usages of the Google-style line directive are present, remove them, as some
@@ -96,7 +96,7 @@ CocoaExternalImage::SharedGl::~SharedGl() noexcept {
 CocoaExternalImage::CocoaExternalImage(const CVOpenGLTextureCacheRef textureCache,
        const SharedGl &sharedGl) noexcept : mSharedGl(sharedGl), mTextureCache(textureCache) {
    glGenFramebuffers(1, &mFBO);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 CocoaExternalImage::~CocoaExternalImage() noexcept {
@@ -125,7 +125,7 @@ bool CocoaExternalImage::set(CVPixelBufferRef image) noexcept {
    mTexture = createTextureFromImage(image);
    mRgbaTexture = encodeCopyRectangleToTexture2D(CVOpenGLTextureGetName(mTexture),
            CVPixelBufferGetWidth(image), CVPixelBufferGetHeight(image));
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    return true;
 }
@@ -182,33 +182,33 @@ GLuint CocoaExternalImage::encodeCopyRectangleToTexture2D(GLuint rectangle,
    // Create a texture to hold the result of the blit image.
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA8, width, height);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    // source textures
    glBindSampler(0, mSharedGl.sampler);
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_RECTANGLE, rectangle);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    // destination texture
    glBindFramebuffer(GL_FRAMEBUFFER, mFBO);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

-    CHECK_GL_FRAMEBUFFER_STATUS(GL_FRAMEBUFFER)
-    CHECK_GL_ERROR()
+    CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_FRAMEBUFFER)
+    CHECK_GL_ERROR(utils::slog.e)

    // draw
    glViewport(0, 0, width, height);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
    glUseProgram(mSharedGl.program);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
    glDisableVertexAttribArray(0);
    glDrawArrays(GL_TRIANGLES, 0, 3);
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    mState.restore();
-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    return texture;
 }
@@ -119,7 +119,7 @@ CocoaTouchExternalImage::CocoaTouchExternalImage(const CVOpenGLESTextureCacheRef

    glGenFramebuffers(1, &mFBO);

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)
 }

 CocoaTouchExternalImage::~CocoaTouchExternalImage() noexcept {
@@ -247,7 +247,7 @@ GLuint CocoaTouchExternalImage::encodeColorConversionPass(GLuint yPlaneTexture,
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA8, width, height);

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    // source textures
    glBindSampler(0, mSharedGl.sampler);
@@ -261,8 +261,8 @@ GLuint CocoaTouchExternalImage::encodeColorConversionPass(GLuint yPlaneTexture,
    glBindFramebuffer(GL_FRAMEBUFFER, mFBO);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);

-    CHECK_GL_ERROR()
-    CHECK_GL_FRAMEBUFFER_STATUS(GL_FRAMEBUFFER)
+    CHECK_GL_ERROR(utils::slog.e)
+    CHECK_GL_FRAMEBUFFER_STATUS(utils::slog.e, GL_FRAMEBUFFER)

    // geometry
    glBindVertexArray(0);
@@ -275,7 +275,7 @@ GLuint CocoaTouchExternalImage::encodeColorConversionPass(GLuint yPlaneTexture,
    glUseProgram(mSharedGl.program);
    glDrawArrays(GL_TRIANGLES, 0, 3);

-    CHECK_GL_ERROR()
+    CHECK_GL_ERROR(utils::slog.e)

    mState.restore();

@@ -20,9 +20,9 @@

 #include <backend/Platform.h>

-#include <utils/Logger.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
+#include <utils/Log.h>
 #include <utils/ostream.h>

 #if __has_include(<android/surface_texture.h>)
@@ -59,7 +59,7 @@ void ExternalStreamManagerAndroid::destroy(ExternalStreamManagerAndroid* pExtern
 ExternalStreamManagerAndroid::ExternalStreamManagerAndroid() noexcept
        : mVm(VirtualMachineEnv::get()) {
    if (__builtin_available(android 28, *)) {
-        DLOG(INFO) << "Using ASurfaceTexture";
+        slog.d << "Using ASurfaceTexture" << io::endl;
    }
 }

@@ -32,9 +32,9 @@
 #endif
 #include <utils/compiler.h>

-#include <utils/Invocable.h>
-#include <utils/Logger.h>
 #include <utils/debug.h>
+#include <utils/Invocable.h>
+#include <utils/Log.h>
 #include <utils/ostream.h>

 #include <algorithm>
@@ -74,7 +74,7 @@ void PlatformEGL::logEglError(const char* name) noexcept {
 }

 void PlatformEGL::logEglError(const char* name, EGLint error) noexcept {
-    LOG(ERROR) << name << " failed with " << getEglErrorName(error);
+    slog.e << name << " failed with " << getEglErrorName(error) << io::endl;
 }

 const char* PlatformEGL::getEglErrorName(EGLint error) noexcept {
@@ -101,7 +101,7 @@ void PlatformEGL::clearGlError() noexcept {
    // clear GL error that may have been set by previous calls
    GLenum const error = glGetError();
    if (error != GL_NO_ERROR) {
-        LOG(WARNING) << "Ignoring pending GL error " << io::hex << error;
+        slog.w << "Ignoring pending GL error " << io::hex << error << io::endl;
    }
 }

@@ -142,7 +142,7 @@ Driver* PlatformEGL::createDriver(void* sharedContext, const DriverConfig& drive
    }

    if (UTILS_UNLIKELY(!initialized)) {
-        LOG(ERROR) << "eglInitialize failed";
+        slog.e << "eglInitialize failed" << io::endl;
        return nullptr;
    }

@@ -29,12 +29,13 @@
 #include <android/native_window.h>
 #include <android/hardware_buffer.h>

-#include <utils/Logger.h>
-#include <utils/Panic.h>
 #include <utils/android/PerformanceHintManager.h>
-#include <utils/compiler.h>
+
 #include <utils/compiler.h>
 #include <utils/ostream.h>
+#include <utils/Panic.h>
+#include <utils/Log.h>
+#include <utils/compiler.h>
 #include <utils/ostream.h>

 #include <EGL/egl.h>
@@ -326,7 +327,7 @@ bool PlatformEGLAndroid::setImage(ExternalImageEGLAndroid const* eglExternalImag
            EGL_NATIVE_BUFFER_ANDROID, clientBuffer, imageAttrs);
    if (eglImage == EGL_NO_IMAGE_KHR) {
        // Handle error
-        LOG(ERROR) << "Failed to create EGL image";
+        slog.e << "Failed to create EGL image" << io::endl;
        glDeleteTextures(1, &texture->id);
        return false;
    }
@@ -339,7 +340,7 @@ bool PlatformEGLAndroid::setImage(ExternalImageEGLAndroid const* eglExternalImag
    glBindTexture(texture->target, texture->id);
    GLenum error = glGetError();
    if (UTILS_UNLIKELY(error != GL_NO_ERROR)) {
-        LOG(ERROR) << "Error after glBindTexture: " << error;
+        slog.e << "Error after glBindTexture: " << error << io::endl;
        glDeleteTextures(1, &texture->id);
        eglDestroyImageKHR(eglGetCurrentDisplay(), eglImage);
        glActiveTexture(prevActiveTexture);
@@ -349,7 +350,7 @@ bool PlatformEGLAndroid::setImage(ExternalImageEGLAndroid const* eglExternalImag
    glEGLImageTargetTexture2DOES(texture->target, static_cast<GLeglImageOES>(eglImage));
    error = glGetError();
    if (UTILS_UNLIKELY(error != GL_NO_ERROR)) {
-        LOG(ERROR) << "Error after glEGLImageTargetTexture2DOES: " << error;
+        slog.e << "Error after glEGLImageTargetTexture2DOES: " << error << io::endl;
        glDeleteTextures(1, &texture->id);
        eglDestroyImageKHR(eglGetCurrentDisplay(), eglImage);
        glActiveTexture(prevActiveTexture);
@@ -407,7 +408,7 @@ AcquiredImage PlatformEGLAndroid::transformAcquiredImage(AcquiredImage source) n

    EGLClientBuffer clientBuffer = eglGetNativeClientBufferANDROID(pHardwareBuffer);
    if (!clientBuffer) {
-        LOG(ERROR) << "Unable to get EGLClientBuffer from AHardwareBuffer.";
+        slog.e << "Unable to get EGLClientBuffer from AHardwareBuffer." << io::endl;
        return {};
    }

@@ -426,7 +427,7 @@ AcquiredImage PlatformEGLAndroid::transformAcquiredImage(AcquiredImage source) n
    EGLImageKHR eglImage = eglCreateImageKHR(mEGLDisplay,
            EGL_NO_CONTEXT, EGL_NATIVE_BUFFER_ANDROID, clientBuffer, attributes.data());
    if (eglImage == EGL_NO_IMAGE_KHR) {
-        LOG(ERROR) << "eglCreateImageKHR returned no image.";
+        slog.e << "eglCreateImageKHR returned no image." << io::endl;
        return {};
    }

@@ -441,7 +442,7 @@ AcquiredImage PlatformEGLAndroid::transformAcquiredImage(AcquiredImage source) n
    auto patchedCallback = [](void* image, void* userdata) {
        Closure* closure = (Closure*)userdata;
        if (eglDestroyImageKHR(closure->display, (EGLImageKHR) image) == EGL_FALSE) {
-            LOG(ERROR) << "eglDestroyImageKHR failed.";
+            slog.e << "eglDestroyImageKHR failed." << io::endl;
        }
        closure->acquiredImage.callback(closure->acquiredImage.image, closure->acquiredImage.userData);
        delete closure;
@@ -21,9 +21,9 @@
 #include <EGL/egl.h>
 #include <EGL/eglext.h>

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

 using namespace utils;

@@ -42,12 +42,12 @@ backend::Driver* PlatformEGLHeadless::createDriver(void* sharedContext,
        const Platform::DriverConfig& driverConfig) noexcept {
    EGLBoolean bindAPI = eglBindAPI(EGL_OPENGL_API);
    if (UTILS_UNLIKELY(!bindAPI)) {
-        LOG(ERROR) << "eglBindAPI EGL_OPENGL_API failed";
+        slog.e << "eglBindAPI EGL_OPENGL_API failed" << io::endl;
        return nullptr;
    }
    int bindBlueGL = bluegl::bind();
    if (UTILS_UNLIKELY(bindBlueGL != 0)) {
-        LOG(ERROR) << "bluegl bind failed";
+        slog.e << "bluegl bind failed" << io::endl;
        return nullptr;
    }

@@ -16,7 +16,7 @@

 #include <backend/platforms/PlatformGLX.h>

-#include <utils/Logger.h>
+#include <utils/Log.h>
 #include <utils/Panic.h>

 #include <X11/Xlib.h>
@@ -84,7 +84,7 @@ static PFNGLXGETPROCADDRESSPROC getProcAddress;
 static bool loadLibraries() {
    g_glx.library = dlopen(LIBRARY_GLX, RTLD_LOCAL | RTLD_NOW);
    if (!g_glx.library) {
-        LOG(ERROR) << "Could not find library " << LIBRARY_GLX;
+        utils::slog.e << "Could not find library " << LIBRARY_GLX << utils::io::endl;
        return false;
    }

@@ -115,7 +115,7 @@ static bool loadLibraries() {

    g_x11.library = dlopen(LIBRARY_X11, RTLD_LOCAL | RTLD_NOW);
    if (!g_x11.library) {
-        LOG(ERROR) << "Could not find library " << LIBRARY_X11;
+        utils::slog.e << "Could not find library " << LIBRARY_X11 << utils::io::endl;
        return false;
    }

@@ -134,7 +134,7 @@ Driver* PlatformGLX::createDriver(void* sharedGLContext,
    // Get the display device
    mGLXDisplay = g_x11.openDisplay(NULL);
    if (mGLXDisplay == nullptr) {
-        LOG(ERROR) << "Failed to open X display. (exiting).";
+        utils::slog.e << "Failed to open X display. (exiting)." << utils::io::endl;
        exit(1);
    }

@@ -145,7 +145,8 @@ Driver* PlatformGLX::createDriver(void* sharedGLContext,

        r = g_glx.queryContext(mGLXDisplay, sharedCtx, GLX_FBCONFIG_ID, &usedFbId);
        if (r != 0) {
-            LOG(ERROR) << "Failed to get GLX_FBCONFIG_ID from shared GL context.";
+            utils::slog.e << "Failed to get GLX_FBCONFIG_ID from shared GL context."
+                          << utils::io::endl;
            return nullptr;
        }

@@ -153,7 +154,7 @@ Driver* PlatformGLX::createDriver(void* sharedGLContext,
        GLXFBConfig* fbConfigs = g_glx.getFbConfigs(mGLXDisplay, 0, &numConfigs);

        if (fbConfigs == nullptr) {
-            LOG(ERROR) << "Failed to get the available GLXFBConfigs.";
+            utils::slog.e << "Failed to get the available GLXFBConfigs." << utils::io::endl;
            return nullptr;
        }

@@ -163,7 +164,8 @@ Driver* PlatformGLX::createDriver(void* sharedGLContext,
        for (int i = 0; i < numConfigs; ++i) {
            r = g_glx.getFbConfigAttrib(mGLXDisplay, fbConfigs[i], GLX_FBCONFIG_ID, &fbId);
            if (r != 0) {
-                LOG(ERROR) << "Failed to get GLX_FBCONFIG_ID for entry " << i << ".";
+                utils::slog.e << "Failed to get GLX_FBCONFIG_ID for entry " << i << "."
+                              << utils::io::endl;
                continue;
            }

@@ -174,7 +176,8 @@ Driver* PlatformGLX::createDriver(void* sharedGLContext,
        }

        if (fbIndex < 0) {
-            LOG(ERROR) << "Failed to find an `GLXFBConfig` with the requested ID.";
+            utils::slog.e << "Failed to find an `GLXFBConfig` with the requested ID."
+                          << utils::io::endl;
            return nullptr;
        }

@@ -199,7 +202,8 @@ Driver* PlatformGLX::createDriver(void* sharedGLContext,
            getProcAddress((GLubyte*)"glXCreateContextAttribsARB");

    if (glXCreateContextAttribs == nullptr) {
-        LOG(INFO) << "Unable to retrieve function pointer for `glXCreateContextAttribs()`.";
+        utils::slog.i << "Unable to retrieve function pointer for `glXCreateContextAttribs()`."
+                      << utils::io::endl;
        return nullptr;
    }

@@ -32,7 +32,7 @@
 #include "GL/glext.h"
 #include "GL/wglext.h"

-#include <utils/Logger.h>
+#include <utils/Log.h>
 #include <utils/Panic.h>

 namespace {
@@ -55,7 +55,8 @@ void reportWindowsError(DWORD dwError) {
        0, nullptr
 	);

-    LOG(ERROR) << "Windows error code: " << dwError << ". " << lpMessageBuffer;
+    utils::slog.e << "Windows error code: " << dwError << ". " << lpMessageBuffer
+            << utils::io::endl;

    LocalFree(lpMessageBuffer);
 }
@@ -105,7 +106,7 @@ Driver* PlatformWGL::createDriver(void* sharedGLContext,
    HDC whdc = mWhdc = GetDC(mHWnd);
    if (whdc == NULL) {
        dwError = GetLastError();
-        LOG(ERROR) << "CreateWindowA() failed";
+        utils::slog.e << "CreateWindowA() failed" << utils::io::endl;
        goto error;
    }

@@ -116,7 +117,8 @@ Driver* PlatformWGL::createDriver(void* sharedGLContext,
    tempContext = wglCreateContext(whdc);
    if (!wglMakeCurrent(whdc, tempContext)) {
        dwError = GetLastError();
-        LOG(ERROR) << "wglMakeCurrent() failed, whdc=" << whdc << ", tempContext=" << tempContext;
+        utils::slog.e << "wglMakeCurrent() failed, whdc=" << whdc << ", tempContext=" <<
+                tempContext << utils::io::endl;
        goto error;
    }

@@ -140,7 +142,7 @@ Driver* PlatformWGL::createDriver(void* sharedGLContext,
    }

    if (!mContext) {
-        LOG(ERROR) << "wglCreateContextAttribs() failed, whdc=" << whdc;
+        utils::slog.e << "wglCreateContextAttribs() failed, whdc=" << whdc << utils::io::endl;
        goto error;
    }

@@ -150,7 +152,8 @@ Driver* PlatformWGL::createDriver(void* sharedGLContext,

    if (!wglMakeCurrent(whdc, mContext)) {
        dwError = GetLastError();
-        LOG(ERROR) << "wglMakeCurrent() failed, whdc=" << whdc << ", mContext=" << mContext;
+        utils::slog.e << "wglMakeCurrent() failed, whdc=" << whdc << ", mContext=" <<
+                mContext << utils::io::endl;
        goto error;
    }

@@ -40,7 +40,7 @@ inline void blitFast(VulkanCommandBuffer* commands, VkImageAspectFlags aspect, V
        FVK_LOGD << "Fast blit from=" << src.texture->getVkImage() << ",level=" << (int) src.level
                      << " layout=" << src.getLayout()
                      << " to=" << dst.texture->getVkImage() << ",level=" << (int) dst.level
-                      << " layout=" << dst.getLayout();
+                      << " layout=" << dst.getLayout() << utils::io::endl;
    }

    VkImageSubresourceRange const srcRange = src.getSubresourceRange();
@@ -80,7 +80,7 @@ inline void resolveFast(VulkanCommandBuffer* commands, VkImageAspectFlags aspect
        FVK_LOGD << "Fast blit from=" << src.texture->getVkImage() << ",level=" << (int) src.level
                      << " layout=" << src.getLayout()
                      << " to=" << dst.texture->getVkImage() << ",level=" << (int) dst.level
-                      << " layout=" << dst.getLayout();
+                      << " layout=" << dst.getLayout() << utils::io::endl;
    }

    VkImageSubresourceRange const srcRange = src.getSubresourceRange();
@@ -215,7 +215,7 @@ VkSemaphore VulkanCommandBuffer::submit() {
    }
    FVK_LOGI << ") "
             << " signal=" << mSubmission
-             << " fence=" << mFence;
+             << " fence=" << mFence << utils::io::endl;
 #endif

    mFenceStatus->setStatus(VK_NOT_READY);
@@ -224,7 +224,7 @@ VkSemaphore VulkanCommandBuffer::submit() {

 #if FVK_ENABLED(FVK_DEBUG_COMMAND_BUFFER)
    if (result != VK_SUCCESS) {
-        FVK_LOGD << "Failed command buffer submission result: " << result;
+        FVK_LOGD << "Failed command buffer submission result: " << result << utils::io::endl;
    }
 #endif
    assert_invariant(result == VK_SUCCESS);
@@ -490,7 +490,7 @@ void VulkanCommands::pushGroupMarker(char const* str, VulkanGroupMarkers::Timest
        mProtectedPool->pushMarker(str, timestamp);
    }
 #if FVK_ENABLED(FVK_DEBUG_PRINT_GROUP_MARKERS)
-    FVK_LOGD << "----> " << str;
+    FVK_LOGD << "----> " << str << utils::io::endl;
 #endif
 }

@@ -502,7 +502,8 @@ void VulkanCommands::popGroupMarker() {
    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";
+    FVK_LOGD << "<---- " << marker << " elapsed: " << (diff.count() * 1000) << " ms"
+             << utils::io::endl;
 #else
    mPool->popMarker();
 #endif // FVK_DEBUG_PRINT_GROUP_MARKERS
@@ -17,7 +17,7 @@
 #ifndef TNT_FILAMENT_BACKEND_VULKANCONSTANTS_H
 #define TNT_FILAMENT_BACKEND_VULKANCONSTANTS_H

-#include <utils/Logger.h>
+#include <utils/Log.h>

 #include <stdint.h>

@@ -73,8 +73,8 @@
 #define FVK_DEBUG_RESOURCE_LEAK           0x00010000

 // Set this to enable logging "only" to one output stream. This is useful in the case where we want
-// to debug with print statements and want ordered logging (e.g LOG(INFO) and LOG(ERROR) will not
-// appear in order of calls).
+// to debug with print statements and want ordered logging (e.g slog.i and slog.e will not appear in
+// order of calls).
 #define FVK_DEBUG_FORCE_LOG_TO_I          0x00020000

 // Enable a minimal set of traces to assess the performance of the backend.
@@ -174,15 +174,15 @@ static_assert(FVK_ENABLED(FVK_DEBUG_VALIDATION));
 #endif

 #if FVK_ENABLED(FVK_DEBUG_FORCE_LOG_TO_I)
-    #define FVK_LOGI LOG(INFO)
+    #define FVK_LOGI (utils::slog.i)
    #define FVK_LOGD FVK_LOGI
    #define FVK_LOGE FVK_LOGI
    #define FVK_LOGW FVK_LOGI
 #else
-    #define FVK_LOGE LOG(ERROR)
-    #define FVK_LOGW LOG(WARNING)
-    #define FVK_LOGD DLOG(INFO)
-    #define FVK_LOGI LOG(INFO)
+    #define FVK_LOGE (utils::slog.e)
+    #define FVK_LOGW (utils::slog.w)
+    #define FVK_LOGD (utils::slog.d)
+    #define FVK_LOGI (utils::slog.i)
 #endif

 // All vkCreate* functions take an optional allocator. For now we select the default allocator by
@@ -104,15 +104,15 @@ VKAPI_ATTR VkBool32 VKAPI_CALL debugReportCallback(VkDebugReportFlagsEXT flags,
        VkDebugReportObjectTypeEXT objectType, uint64_t object, size_t location,
        int32_t messageCode, const char* pLayerPrefix, const char* pMessage, void* pUserData) {
    if (flags & VK_DEBUG_REPORT_ERROR_BIT_EXT) {
-        FVK_LOGE << "VULKAN ERROR: (" << pLayerPrefix << ") " << pMessage;
+        FVK_LOGE << "VULKAN ERROR: (" << pLayerPrefix << ") " << pMessage << utils::io::endl;
    } else {
        // TODO: emit best practices warnings about aggressive pipeline barriers.
        if (strstr(pMessage, "ALL_GRAPHICS_BIT") || strstr(pMessage, "ALL_COMMANDS_BIT")) {
            return VK_FALSE;
        }
-        FVK_LOGW << "VULKAN WARNING: (" << pLayerPrefix << ") " << pMessage;
+        FVK_LOGW << "VULKAN WARNING: (" << pLayerPrefix << ") " << pMessage << utils::io::endl;
    }
-    FVK_LOGE;
+    FVK_LOGE << utils::io::endl;
    return VK_FALSE;
 }
 #endif // FVK_ENABLED(FVK_DEBUG_VALIDATION)
@@ -122,16 +122,18 @@ VKAPI_ATTR VkBool32 VKAPI_CALL debugUtilsCallback(VkDebugUtilsMessageSeverityFla
        VkDebugUtilsMessageTypeFlagsEXT types, const VkDebugUtilsMessengerCallbackDataEXT* cbdata,
        void* pUserData) {
    if (severity & VK_DEBUG_UTILS_MESSAGE_SEVERITY_ERROR_BIT_EXT) {
-        FVK_LOGE << "VULKAN ERROR: (" << cbdata->pMessageIdName << ") " << cbdata->pMessage;
+        FVK_LOGE << "VULKAN ERROR: (" << cbdata->pMessageIdName << ") " << cbdata->pMessage
+                 << utils::io::endl;
    } else {
        // TODO: emit best practices warnings about aggressive pipeline barriers.
        if (strstr(cbdata->pMessage, "ALL_GRAPHICS_BIT")
                || strstr(cbdata->pMessage, "ALL_COMMANDS_BIT")) {
            return VK_FALSE;
        }
-        FVK_LOGW << "VULKAN WARNING: (" << cbdata->pMessageIdName << ") " << cbdata->pMessage;
+        FVK_LOGW << "VULKAN WARNING: (" << cbdata->pMessageIdName << ") " << cbdata->pMessage
+                 << utils::io::endl;
    }
-    FVK_LOGE << "";
+    FVK_LOGE << utils::io::endl;
    return VK_FALSE;
 }
 #endif // FVK_ENABLED(FVK_DEBUG_DEBUG_UTILS)
@@ -274,18 +276,20 @@ Driver* VulkanDriver::create(VulkanPlatform* platform, VulkanContext const& cont
    //    VulkanRenderTarget            : 312       few
    // -- less than or equal to 312 bytes

-    FVK_LOGD << "VulkanSwapChain: " << sizeof(VulkanSwapChain);
-    FVK_LOGD << "VulkanBufferObject: " << sizeof(VulkanBufferObject);
-    FVK_LOGD << "VulkanVertexBuffer: " << sizeof(VulkanVertexBuffer);
-    FVK_LOGD << "VulkanVertexBufferInfo: " << sizeof(VulkanVertexBufferInfo);
-    FVK_LOGD << "VulkanIndexBuffer: " << sizeof(VulkanIndexBuffer);
-    FVK_LOGD << "VulkanRenderPrimitive: " << sizeof(VulkanRenderPrimitive);
-    FVK_LOGD << "VulkanTexture: " << sizeof(VulkanTexture);
-    FVK_LOGD << "VulkanTimerQuery: " << sizeof(VulkanTimerQuery);
-    FVK_LOGD << "HwStream: " << sizeof(HwStream);
-    FVK_LOGD << "VulkanRenderTarget: " << sizeof(VulkanRenderTarget);
-    FVK_LOGD << "VulkanFence: " << sizeof(VulkanFence);
-    FVK_LOGD << "VulkanProgram: " << sizeof(VulkanProgram);
+    FVK_LOGD
+           << "\nVulkanSwapChain: " << sizeof(VulkanSwapChain)
+           << "\nVulkanBufferObject: " << sizeof(VulkanBufferObject)
+           << "\nVulkanVertexBuffer: " << sizeof(VulkanVertexBuffer)
+           << "\nVulkanVertexBufferInfo: " << sizeof(VulkanVertexBufferInfo)
+           << "\nVulkanIndexBuffer: " << sizeof(VulkanIndexBuffer)
+           << "\nVulkanRenderPrimitive: " << sizeof(VulkanRenderPrimitive)
+           << "\nVulkanTexture: " << sizeof(VulkanTexture)
+           << "\nVulkanTimerQuery: " << sizeof(VulkanTimerQuery)
+           << "\nHwStream: " << sizeof(HwStream)
+           << "\nVulkanRenderTarget: " << sizeof(VulkanRenderTarget)
+           << "\nVulkanFence: " << sizeof(VulkanFence)
+           << "\nVulkanProgram: " << sizeof(VulkanProgram)
+           << utils::io::endl;
 #endif

    assert_invariant(platform);
@@ -795,12 +799,14 @@ void VulkanDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow,
    mResourceManager.gc();

    if ((flags & backend::SWAP_CHAIN_CONFIG_SRGB_COLORSPACE) != 0 && !isSRGBSwapChainSupported()) {
-        FVK_LOGW << "sRGB swapchain requested, but Platform does not support it";
+        FVK_LOGW << "sRGB swapchain requested, but Platform does not support it"
+                 << utils::io::endl;
        flags = flags | ~(backend::SWAP_CHAIN_CONFIG_SRGB_COLORSPACE);
    }
    if (flags & backend::SWAP_CHAIN_CONFIG_PROTECTED_CONTENT) {
        if (!isProtectedContentSupported()) {
-            FVK_LOGW << "protected swapchain requested, but Platform does not support it";
+            FVK_LOGW << "protected swapchain requested, but Platform does not support it"
+                << utils::io::endl;
        }
    }
    auto swapChain = resource_ptr<VulkanSwapChain>::make(&mResourceManager, sch, mPlatform,
@@ -811,7 +817,8 @@ void VulkanDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow,
 void VulkanDriver::createSwapChainHeadlessR(Handle<HwSwapChain> sch, uint32_t width,
        uint32_t height, uint64_t flags) {
    if ((flags & backend::SWAP_CHAIN_CONFIG_SRGB_COLORSPACE) != 0 && !isSRGBSwapChainSupported()) {
-        FVK_LOGW << "sRGB swapchain requested, but Platform does not support it";
+        FVK_LOGW << "sRGB swapchain requested, but Platform does not support it"
+                      << utils::io::endl;
        flags = flags | ~(backend::SWAP_CHAIN_CONFIG_SRGB_COLORSPACE);
    }
    assert_invariant(width > 0 && height > 0 && "Vulkan requires non-zero swap chain dimensions.");
@@ -1299,7 +1306,7 @@ TimerQueryResult VulkanDriver::getTimerQueryValue(Handle<HwTimerQuery> tqh, uint
    uint64_t const end = results.endTime;
    if (begin >= end) {
        // TODO: queries might have ran on different command buffers.
-        FVK_LOGW << "Timestamps are not monotonically increasing. ";
+        FVK_LOGW << "Timestamps are not monotonically increasing. " << utils::io::endl;
        *elapsedTime = 0;
        return TimerQueryResult::ERROR;
    }
@@ -2037,7 +2044,7 @@ void VulkanDriver::debugCommandBegin(CommandStream* cmds, bool synchronous, cons
        assert_invariant(inRenderPass);
        inRenderPass = false;
    } else if (inRenderPass && OUTSIDE_COMMANDS.find(command) != OUTSIDE_COMMANDS.end()) {
-        FVK_LOGE << command.data() << " issued inside a render pass.";
+        FVK_LOGE << command.data() << " issued inside a render pass." << utils::io::endl;
    }
 #endif
 }
@@ -100,7 +100,8 @@ VkFramebuffer VulkanFboCache::getFramebuffer(FboKey const& config) noexcept {
        << "for render pass " << config.renderPass << ", "
        << "samples = " << int(config.samples) << ", "
        << "depth = " << (config.depth ? 1 : 0) << ", "
-        << "attachmentCount = " << attachmentCount;
+        << "attachmentCount = " << attachmentCount
+        << utils::io::endl;
    #endif

    VkFramebufferCreateInfo info {
@@ -340,7 +341,8 @@ VkRenderPass VulkanFboCache::getRenderPass(RenderPassKey const& config) noexcept
             << "needsResolveMask = " << int(config.needsResolveMask) << ", "
             << "usesLazilyAllocatedMemory = " << int(config.usesLazilyAllocatedMemory) << ", "
             << "viewCount = " << int(config.viewCount) << ", "
-             << "colorAttachmentCount[0] = " << subpasses[0].colorAttachmentCount;
+             << "colorAttachmentCount[0] = " << subpasses[0].colorAttachmentCount
+             << utils::io::endl;
 #endif

    return renderPass;
@@ -287,7 +287,7 @@ VulkanProgram::VulkanProgram(VkDevice device, Program const& builder) noexcept

 #if FVK_ENABLED(FVK_DEBUG_SHADER_MODULE)
    FVK_LOGD << "Created VulkanProgram " << builder << ", shaders = (" << modules[0]
-             << ", " << modules[1] << ")";
+             << ", " << modules[1] << ")" << utils::io::endl;
 #endif
 }

@@ -218,7 +218,8 @@ VulkanPipelineCache::PipelineCacheEntry* VulkanPipelineCache::createPipeline() n

    #if FVK_ENABLED(FVK_DEBUG_SHADER_MODULE)
        FVK_LOGD << "vkCreateGraphicsPipelines with shaders = ("
-                 << shaderStages[0].module << ", " << shaderStages[1].module << ")";
+                 << shaderStages[0].module << ", " << shaderStages[1].module << ")"
+                 << utils::io::endl;
    #endif
    PipelineCacheEntry cacheEntry = {
        .lastUsed = mCurrentTime,
@@ -227,7 +228,7 @@ VulkanPipelineCache::PipelineCacheEntry* VulkanPipelineCache::createPipeline() n
            VKALLOC, &cacheEntry.handle);
    assert_invariant(error == VK_SUCCESS);
    if (error != VK_SUCCESS) {
-        FVK_LOGE << "vkCreateGraphicsPipelines error " << error;
+        FVK_LOGE << "vkCreateGraphicsPipelines error " << error << utils::io::endl;
        return nullptr;
    }
    return &mPipelines.emplace(mPipelineRequirements, cacheEntry).first.value();
@@ -241,7 +242,7 @@ void VulkanPipelineCache::bindProgram(fvkmemory::resource_ptr<VulkanProgram> pro
 #if FVK_ENABLED(FVK_DEBUG_SHADER_MODULE)
    if (mPipelineRequirements.shaders[0] == VK_NULL_HANDLE ||
            mPipelineRequirements.shaders[1] == VK_NULL_HANDLE) {
-        FVK_LOGE << "Binding missing shader: " << program->name.c_str();
+        FVK_LOGE << "Binding missing shader: " << program->name.c_str() << utils::io::endl;
    }
 #endif
 }
@@ -42,7 +42,7 @@ fvkmemory::resource_ptr<VulkanTimerQuery> VulkanQueryManager::getNextQuery(
        fvkmemory::ResourceManager* resourceManager) {
    auto unused = ~mUsed;
    if (unused.empty()) {
-        FVK_LOGE << "More than " << mUsed.size() << " timers are not supported.";
+        FVK_LOGE << "More than " << mUsed.size() << " timers are not supported." << utils::io::endl;
        return {};
    }

@@ -171,7 +171,7 @@ void VulkanReadPixels::run(fvkmemory::resource_ptr<VulkanRenderTarget> srcTarget
 #if FVK_ENABLED(FVK_DEBUG_READ_PIXELS)
    FVK_LOGD << "readPixels created image=" << stagingImage
             << " to copy from image=" << srcTexture->getVkImage()
-             << " src-layout=" << srcTexture->getLayout(0, 0);
+             << " src-layout=" << srcTexture->getLayout(0, 0) << utils::io::endl;
 #endif

    VkMemoryRequirements memReqs;
@@ -188,7 +188,8 @@ void VulkanReadPixels::run(fvkmemory::resource_ptr<VulkanRenderTarget> srcTarget
        memoryTypeIndex = selectMemoryFunc(memReqs.memoryTypeBits,
                VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);
        FVK_LOGW
-                << "readPixels is slow because VK_MEMORY_PROPERTY_HOST_CACHED_BIT is not available";
+                << "readPixels is slow because VK_MEMORY_PROPERTY_HOST_CACHED_BIT is not available"
+                << utils::io::endl;
    }

    FILAMENT_CHECK_POSTCONDITION(memoryTypeIndex < VK_MAX_MEMORY_TYPES)
@@ -304,7 +305,7 @@ void VulkanReadPixels::run(fvkmemory::resource_ptr<VulkanRenderTarget> srcTarget
                                 fence = readCompleteFence]() mutable {
        VkResult status = vkWaitForFences(device, 1, &fence, VK_TRUE, UINT64_MAX);
        if (status != VK_SUCCESS) {
-            FVK_LOGE << "Failed to wait for readPixels fence";
+            FVK_LOGE << "Failed to wait for readPixels fence" << utils::io::endl;
            return;
        }

@@ -322,7 +323,7 @@ void VulkanReadPixels::run(fvkmemory::resource_ptr<VulkanRenderTarget> srcTarget
                    fvkutils::getComponentCount(srcFormat), srcPixels,
                    static_cast<int>(subResourceLayout.rowPitch), static_cast<int>(width),
                    static_cast<int>(height), swizzle)) {
-            FVK_LOGE << "Unsupported PixelDataFormat or PixelDataType";
+            FVK_LOGE << "Unsupported PixelDataFormat or PixelDataType" << utils::io::endl;
        }

        vkUnmapMemory(device, stagingMemory);
@@ -108,9 +108,9 @@ VulkanStage* VulkanStagePool::allocateNewStage(uint32_t capacity) {

 #if FVK_ENABLED(FVK_DEBUG_STAGING_ALLOCATION)
    if (result != VK_SUCCESS) {
-        FVK_LOGE << "Allocation error: " << result;
+        FVK_LOGE << "Allocation error: " << result << utils::io::endl;
    } else {
-        FVK_LOGD << "Allocated stage with hndl " << buffer;
+        FVK_LOGD << "Allocated stage with hndl " << buffer << utils::io::endl;
    }
 #endif

@@ -188,8 +188,8 @@ VkImageUsageFlags getUsage(VulkanContext const& context, uint8_t samples,
            VkFormatProperties props;
            vkGetPhysicalDeviceFormatProperties(physicalDevice, vkFormat, &props);
            if (!(props.optimalTilingFeatures & VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT)) {
-                FVK_LOGW << "Texture usage is SAMPLEABLE but format " << vkFormat
-                         << " is not sampleable with optimal tiling.";
+                FVK_LOGW << "Texture usage is SAMPLEABLE but format " << vkFormat << " is not "
+                        "sampleable with optimal tiling." << utils::io::endl;
            }
        }
 #endif
@@ -361,7 +361,7 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
            imageInfo.flags = VK_IMAGE_CREATE_2D_ARRAY_COMPATIBLE_BIT;
        } else {
            FVK_LOGW << "Note: creating 2D views on 3D image is not available on this platform. "
-                     << "i.e. we cannot render to slices of a 3D image";
+                     << "i.e. we cannot render to slices of a 3D image" << utils::io::endl;
        }
    } else if (target == SamplerType::SAMPLER_CUBEMAP) {
        imageInfo.arrayLayers = 6;
@@ -420,7 +420,7 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
            << "type = " << imageInfo.imageType << ", "
            << "flags = " << imageInfo.flags << ", "
            << "target = " << static_cast<int>(target) <<", "
-            << "format = " << vkFormat;
+            << "format = " << vkFormat << utils::io::endl;
    }
    FILAMENT_CHECK_POSTCONDITION(result == VK_SUCCESS) << "Unable to create image."
                                                       << " error=" << static_cast<int32_t>(result);
@@ -731,14 +731,14 @@ bool VulkanTexture::transitionLayout(VkCommandBuffer cmdbuf, VkImageSubresourceR
                 << range.levelCount << ")" << " from=" << oldLayout << " to=" << newLayout
                 << " format=" << mState->mVkFormat << " depth="
                 << fvkutils::isVkDepthFormat(mState->mVkFormat)
-                 << " slice-by-slice=" << transitionSliceBySlice;
+                 << " slice-by-slice=" << transitionSliceBySlice << utils::io::endl;
 #endif
    } else {
 #if FVK_ENABLED(FVK_DEBUG_LAYOUT_TRANSITION)
        FVK_LOGD << "transition texture=" << mState->mTextureImage << " (" << range.baseArrayLayer
                 << "," << range.baseMipLevel << ")" << " count=(" << range.layerCount << ","
                 << range.levelCount << ")" << " to=" << newLayout
-                 << " is skipped because of no change in layout";
+                 << " is skipped because of no change in layout" << utils::io::endl;
 #endif
    }

@@ -849,7 +849,8 @@ void VulkanTexture::print() const {
                level < (mPrimaryViewRange.baseMipLevel + mPrimaryViewRange.levelCount);
            FVK_LOGD << "[" << mState->mTextureImage << "]: (" << layer << "," << level
                          << ")=" << getLayout(layer, level)
-                          << " primary=" << primary;
+                          << " primary=" << primary
+                          << utils::io::endl;
        }
    }

@@ -858,7 +859,8 @@ void VulkanTexture::print() const {
        FVK_LOGD << "[" << mState->mTextureImage << ", imageView=" << view.second << "]=>"
                      << " (" << range.baseArrayLayer << "," << range.baseMipLevel << ")"
                      << " count=(" << range.layerCount << "," << range.levelCount << ")"
-                      << " aspect=" << range.aspectMask << " viewType=" << view.first.type;
+                      << " aspect=" << range.aspectMask << " viewType=" << view.first.type
+                      << utils::io::endl;
    }
 }
 #endif
@@ -17,7 +17,6 @@
 #include "vulkan/memory/ResourceManager.h"
 #include "vulkan/VulkanHandles.h"

-#include <utils/Logger.h>
 #include <utils/Panic.h>

 namespace filament::backend::fvkmemory {
@@ -128,11 +127,11 @@ void ResourceManager::traceConstruction(ResourceType type, HandleId id) {

 void ResourceManager::print() const noexcept {
 #if FVK_ENABLED(FVK_DEBUG_RESOURCE_LEAK)
-    LOG(ERROR) << "-------------------";
+    utils::slog.e << "-------------------" << utils::io::endl;
    for (size_t i = 0; i < (size_t) ResourceType::UNDEFINED_TYPE; ++i) {
-        LOG(ERROR) << "    " << getTypeStr((ResourceType) i) << "=" << COUNTER[i];
+        utils::slog.e <<"    " << getTypeStr((ResourceType) i) << "=" << COUNTER[i] << utils::io::endl;
    }
-    LOG(ERROR) << "+++++++++++++++++++";
+    utils::slog.e << "+++++++++++++++++++" << utils::io::endl;
 #endif
 }

@@ -25,9 +25,8 @@
 #include "vulkan/utils/Helper.h"

 #include <bluevk/BlueVK.h>
-#include <utils/Logger.h>
-#include <utils/Panic.h>
 #include <utils/PrivateImplementation-impl.h>
+#include <utils/Panic.h>

 #define SWAPCHAIN_RET_FUNC(func, handle, ...)                                                      \
    if (mImpl->mSurfaceSwapChains.find(handle) != mImpl->mSurfaceSwapChains.end()) {               \
@@ -115,7 +114,7 @@ void printDeviceInfo(VkInstance instance, VkPhysicalDevice device) {
        chainStruct(&physicalDeviceProperties2, &driverProperties);
        vkGetPhysicalDeviceProperties2(device, &physicalDeviceProperties2);
        FVK_LOGI << "Vulkan device driver: " << driverProperties.driverName << " "
-                 << driverProperties.driverInfo;
+                      << driverProperties.driverInfo << utils::io::endl;
    }

    VkPhysicalDeviceProperties deviceProperties;
@@ -152,7 +151,7 @@ void printDeviceInfo(VkInstance instance, VkPhysicalDevice device) {
                  << "(vendor " << utils::io::hex << vendorID << ", "
                  << "device " << deviceID << ", "
                  << "driver " << driverVersion << ", " << utils::io::dec << "api " << major << "."
-                  << minor << ")";
+                  << minor << ")" << utils::io::endl;
 }

 #if FVK_ENABLED(FVK_DEBUG_VALIDATION)
@@ -175,7 +174,7 @@ void printDepthFormats(VkPhysicalDevice device) {
            FVK_LOGI << format << " ";
        }
    }
-    FVK_LOGI << "";
+    FVK_LOGI << utils::io::endl;
 }
 #endif

@@ -295,10 +294,10 @@ VkInstance createInstance(ExtensionSet const& requiredExts) {
    } else {
 #if defined(__ANDROID__)
        FVK_LOGD << "Validation layers are not available; did you set jniLibs in your "
-                 << "gradle file?";
+                 << "gradle file?" << utils::io::endl;
 #else
        FVK_LOGD << "Validation layer not available; did you install the Vulkan SDK?\n"
-                 << "Please ensure that VK_LAYER_PATH is set correctly.";
+                 << "Please ensure that VK_LAYER_PATH is set correctly." << utils::io::endl;
 #endif // __ANDROID__

    }
@@ -923,7 +922,7 @@ Driver* VulkanPlatform::createDriver(void* sharedContext,
    // Keep a copy of context for swapchains.
    mImpl->mContext = context;

-    return VulkanDriver::create(this, mImpl->mContext, driverConfig);
+    return VulkanDriver::create(this, context, driverConfig);
 }

 // This needs to be explictly written for
@@ -985,7 +984,8 @@ SwapChainPtr VulkanPlatform::createSwapChain(void* nativeWindow, uint64_t flags,

    if (flags & backend::SWAP_CHAIN_CONFIG_PROTECTED_CONTENT) {
        if (!mImpl->mContext.mProtectedMemorySupported) {
-            LOG(WARNING) << "protected swapchain requested, but VulkanPlatform does not support it";
+            utils::slog.w << "protected swapchain requested, but VulkanPlatform does not support it"
+                << utils::io::endl;
        }
    }

@@ -163,7 +163,8 @@ VkResult VulkanPlatformSurfaceSwapChain::create() {
    // the number of images, though there may be limits related to the total amount of memory used
    // by presentable images."
    if (maxImageCount != 0 && desiredImageCount > maxImageCount) {
-        FVK_LOGE << "Swap chain does not support " << desiredImageCount << " images.";
+        FVK_LOGE << "Swap chain does not support " << desiredImageCount << " images."
+                      << utils::io::endl;
        desiredImageCount = caps.minImageCount;
    }

@@ -265,7 +266,8 @@ VkResult VulkanPlatformSurfaceSwapChain::create() {
           << "swapchain-size=" << mSwapChainBundle.colors.size() << ", "
           << "identity-transform=" << (caps.currentTransform == 1) << ", "
           << "depth=" << mSwapChainBundle.depthFormat << ", "
-           << "protected=" << mSwapChainBundle.isProtected;
+           << "protected=" << mSwapChainBundle.isProtected
+           << io::endl;

    VkSemaphoreCreateInfo const semaphoreCreateInfo = {
            .sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO,
@@ -291,7 +293,7 @@ VkResult VulkanPlatformSurfaceSwapChain::acquire(VulkanPlatform::ImageSyncData*
    // Users should be notified of a suboptimal surface, but it should not cause a cascade of
    // log messages or a loop of re-creations.
    if (result == VK_SUBOPTIMAL_KHR && !mSuboptimal) {
-        FVK_LOGW << "Vulkan Driver: Suboptimal swap chain.";
+        FVK_LOGW << "Vulkan Driver: Suboptimal swap chain." << io::endl;
        mSuboptimal = true;
    }
    return result;
@@ -313,7 +315,7 @@ VkResult VulkanPlatformSurfaceSwapChain::present(uint32_t index, VkSemaphore fin
    // On Android Q and above, a suboptimal surface is always reported after screen rotation:
    // https://android-developers.googleblog.com/2020/02/handling-device-orientation-efficiently.html
    if (result == VK_SUBOPTIMAL_KHR && !mSuboptimal) {
-        FVK_LOGW << "Vulkan Driver: Suboptimal swap chain.";
+        FVK_LOGW << "Vulkan Driver: Suboptimal swap chain." << utils::io::endl;
        mSuboptimal = true;
    }
    return result;
@@ -17,7 +17,7 @@
 #ifndef TNT_FILAMENT_BACKEND_WEBGPUCONSTANTS_H
 #define TNT_FILAMENT_BACKEND_WEBGPUCONSTANTS_H

-#include <utils/Logger.h>
+#include <utils/Log.h>

 #include <cstdint>

@@ -32,8 +32,8 @@ constexpr size_t WEBGPU_BUFFER_SIZE_MODULUS = 4;
 #define FWGPU_PRINT_SYSTEM         0x00000002

 // Set this to enable logging "only" to one output stream. This is useful in the case where we want
-// to debug with print statements and want ordered logging (e.g LOG(INFO) and LOG(ERROR) will not
-// appear in order of calls).
+// to debug with print statements and want ordered logging (e.g slog.i and slog.e will not appear in
+// order of calls).
 #define FWGPU_DEBUG_FORCE_LOG_TO_I 0x00000004

 // Useful default combinations
@@ -54,15 +54,15 @@ constexpr size_t WEBGPU_BUFFER_SIZE_MODULUS = 4;
 #define FWGPU_ENABLED(flags) (((FWGPU_DEBUG_FLAGS) & (flags)) == (flags))

 #if FWGPU_ENABLED(FWGPU_DEBUG_FORCE_LOG_TO_I)
-    #define FWGPU_LOGI LOG(INFO)
+    #define FWGPU_LOGI (utils::slog.i)
    #define FWGPU_LOGD FWGPU_LOGI
    #define FWGPU_LOGE FWGPU_LOGI
    #define FWGPU_LOGW FWGPU_LOGI
 #else
-    #define FWGPU_LOGE LOG(ERROR)
-    #define FWGPU_LOGW LOG(WARNING)
-    #define FWGPU_LOGD DLOG(INFO)
-    #define FWGPU_LOGI LOG(INFO)
+    #define FWGPU_LOGE (utils::slog.e)
+    #define FWGPU_LOGW (utils::slog.w)
+    #define FWGPU_LOGD (utils::slog.d)
+    #define FWGPU_LOGI (utils::slog.i)
 #endif

 constexpr uint64_t REQUEST_ADAPTER_TIMEOUT_NANOSECONDS =
@@ -336,15 +336,15 @@ void WebGPUDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow,

    FWGPU_LOGW << "WebGPU support is highly experimental, in development, and tested for only a "
                  "small set of simple samples (e.g. hellotriangle and texturedquad), thus issues "
-                  "are likely to be encountered at this stage.";
+                  "are likely to be encountered at this stage."
+               << utils::io::endl;
 #if !FWGPU_ENABLED(FWGPU_PRINT_SYSTEM) && !defined(NDEBUG)
-    char printSystemHex[16];
-    snprintf(printSystemHex, sizeof(printSystemHex), "%#x", FWGPU_PRINT_SYSTEM);
-    FWGPU_LOGI << "If the FILAMENT_BACKEND_DEBUG_FLAG variable were set with the " << printSystemHex
+    FWGPU_LOGI << "If the FILAMENT_BACKEND_DEBUG_FLAG variable were set with the " << utils::io::hex
+               << FWGPU_PRINT_SYSTEM << utils::io::dec
               << " bit flag on during build time the application would print system details "
                  "about the selected graphics device, surface, etc. To see this try "
                  "rebuilding Filament with that flag, e.g. ./build.sh -x "
-               << FWGPU_PRINT_SYSTEM << " ...";
+               << FWGPU_PRINT_SYSTEM << " ..." << utils::io::endl;
 #endif
 }

@@ -807,7 +807,6 @@ void WebGPUDriver::beginRenderPass(Handle<HwRenderTarget> renderTargetHandle,

    wgpu::TextureView defaultColorView = nullptr;
    wgpu::TextureView defaultDepthStencilView = nullptr;
-    wgpu::TextureFormat defaultDepthStencilFormat = wgpu::TextureFormat::Undefined;

    std::array<wgpu::TextureView, MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT> customColorViews{};
    uint32_t customColorViewCount = 0;
@@ -821,7 +820,6 @@ void WebGPUDriver::beginRenderPass(Handle<HwRenderTarget> renderTargetHandle,
        assert_invariant(mSwapChain && mTextureView);
        defaultColorView = mTextureView;
        defaultDepthStencilView = mSwapChain->getDepthTextureView();
-        defaultDepthStencilFormat = mSwapChain->getDepthFormat();
    } else {
        // Resolve views for custom render target
        const auto& colorInfos = renderTarget->getColorAttachmentInfos();
@@ -879,7 +877,6 @@ void WebGPUDriver::beginRenderPass(Handle<HwRenderTarget> renderTargetHandle,
            params,
            defaultColorView,
            defaultDepthStencilView,
-            defaultDepthStencilFormat,
            customColorViews.data(),
            customColorViewCount,
            customDepthView,
@@ -29,7 +29,6 @@
 #include <utils/ostream.h>

 #include <webgpu/webgpu_cpp.h>
-#include <dawn/webgpu_cpp_print.h>

 #include <array>
 #include <cstdint>
@@ -188,7 +187,7 @@ namespace {
                        switch (status) {
                            case wgpu::CompilationInfoRequestStatus::CallbackCancelled:
                                FWGPU_LOGW << "Shader compilation info callback cancelled for "
-                                           << descriptor.label << "?";
+                                           << descriptor.label << "?" << utils::io::endl;
                                return;
                            case wgpu::CompilationInfoRequestStatus::Success:
                                break;
@@ -204,7 +203,8 @@ namespace {
                                                   << " line#:" << message.lineNum
                                                   << " linePos:" << message.linePos
                                                   << " offset:" << message.offset
-                                                   << " length:" << message.length;
+                                                   << " length:" << message.length
+                                                   << utils::io::endl;
                                        break;
                                    case wgpu::CompilationMessageType::Warning:
                                        FWGPU_LOGW
@@ -212,7 +212,7 @@ namespace {
                                                << message.message << " line#:" << message.lineNum
                                                << " linePos:" << message.linePos
                                                << " offset:" << message.offset
-                                                << " length:" << message.length;
+                                                << " length:" << message.length << utils::io::endl;
                                        break;
                                    case wgpu::CompilationMessageType::Error:
                                        errorCount++;
@@ -231,7 +231,8 @@ namespace {
                                    << errorStream.str();
                        }
 #if FWGPU_ENABLED(FWGPU_DEBUG_VALIDATION)
-                        FWGPU_LOGD << descriptor.label << " compiled successfully";
+                        FWGPU_LOGD << descriptor.label << " compiled successfully"
+                                   << utils::io::endl;
 #endif
                    }),
            SHADER_COMPILATION_TIMEOUT_NANOSECONDS);
@@ -73,7 +73,6 @@ wgpu::StoreOp WebGPURenderTarget::getStoreOperation(RenderPassParams const& para
 void WebGPURenderTarget::setUpRenderPassAttachments(wgpu::RenderPassDescriptor& outDescriptor,
        RenderPassParams const& params, wgpu::TextureView const& defaultColorTextureView,
        wgpu::TextureView const& defaultDepthStencilTextureView,
-        wgpu::TextureFormat const& defaultDepthStencilFormat,
        wgpu::TextureView const* customColorTextureViews, uint32_t customColorTextureViewCount,
        wgpu::TextureView const& customDepthTextureView,
        wgpu::TextureView const& customStencilTextureView,
@@ -94,39 +93,30 @@ void WebGPURenderTarget::setUpRenderPassAttachments(wgpu::RenderPassDescriptor&
        if (defaultDepthStencilTextureView) {
            mDepthStencilAttachmentDescriptor = {
                .view = defaultDepthStencilTextureView,
-                .depthLoadOp =
-                        WebGPURenderTarget::getLoadOperation(params, TargetBufferFlags::DEPTH),
+                .depthLoadOp = WebGPURenderTarget::getLoadOperation(params, TargetBufferFlags::DEPTH),
                .depthStoreOp =
                        WebGPURenderTarget::getStoreOperation(params, TargetBufferFlags::DEPTH),
                .depthClearValue = static_cast<float>(params.clearDepth),
                .depthReadOnly =
                        (params.readOnlyDepthStencil & RenderPassParams::READONLY_DEPTH) > 0,
-                .stencilLoadOp = wgpu::LoadOp::Undefined,
-                .stencilStoreOp = wgpu::StoreOp::Undefined,
+                .stencilLoadOp =
+                        WebGPURenderTarget::getLoadOperation(params, TargetBufferFlags::STENCIL),
+                .stencilStoreOp =
+                        WebGPURenderTarget::getStoreOperation(params, TargetBufferFlags::STENCIL),
                .stencilClearValue = params.clearStencil,
                .stencilReadOnly =
                        (params.readOnlyDepthStencil & RenderPassParams::READONLY_STENCIL) > 0,
            };
-
-            if (defaultDepthStencilFormat == wgpu::TextureFormat::Depth24PlusStencil8 ||
-                    defaultDepthStencilFormat == wgpu::TextureFormat::Depth32FloatStencil8 ||
-                    defaultDepthStencilFormat == wgpu::TextureFormat::Stencil8) {
-                mDepthStencilAttachmentDescriptor.stencilLoadOp =
-                        WebGPURenderTarget::getLoadOperation(params, TargetBufferFlags::STENCIL);
-                mDepthStencilAttachmentDescriptor.stencilStoreOp =
-                        WebGPURenderTarget::getStoreOperation(params, TargetBufferFlags::STENCIL);
-            }
            mHasDepthStencilAttachment = true;
        }
-    } else { // Custom Render Target
+    } else {// Custom Render Target
        for (uint32_t i = 0; i < customColorTextureViewCount; ++i) {
            if (customColorTextureViews[i]) {
                mColorAttachmentDescriptors.push_back({ .view = customColorTextureViews[i],
                    // .resolveTarget = nullptr; // TODO: MSAA resolve for custom RT
-                    .loadOp =
-                            WebGPURenderTarget::getLoadOperation(params, getTargetBufferFlagsAt(i)),
-                    .storeOp = WebGPURenderTarget::getStoreOperation(params,
-                            getTargetBufferFlagsAt(i)),
+                    .loadOp = WebGPURenderTarget::getLoadOperation(params, getTargetBufferFlagsAt(i)),
+                    .storeOp =
+                            WebGPURenderTarget::getStoreOperation(params, getTargetBufferFlagsAt(i)),
                    .clearValue = { .r = params.clearColor.r,
                        .g = params.clearColor.g,
                        .b = params.clearColor.b,
@@ -46,7 +46,6 @@ public:
            // For default render target:
            wgpu::TextureView const& defaultColorTextureView,
            wgpu::TextureView const& defaultDepthStencilTextureView,
-            wgpu::TextureFormat const& defaultDepthStencilFormat,
            // For custom render targets:
            wgpu::TextureView const* customColorTextureViews, // Array of views
            uint32_t customColorTextureViewCount,
@@ -54,50 +54,52 @@ utils::io::ostream& operator<<(utils::io::ostream& out,
 }

 void printSurfaceCapabilitiesDetails(wgpu::SurfaceCapabilities const& capabilities) {
-    FWGPU_LOGI << "WebGPU surface capabilities:";
-    FWGPU_LOGI << "  surface usages: " << capabilities.usages;
-    FWGPU_LOGI << "  surface formats (" << capabilities.formatCount << "):";
+    FWGPU_LOGI << "WebGPU surface capabilities:" << utils::io::endl;
+    FWGPU_LOGI << "  surface usages: " << capabilities.usages << utils::io::endl;
+    FWGPU_LOGI << "  surface formats (" << capabilities.formatCount << "):" << utils::io::endl;
    if (capabilities.formatCount > 0 && capabilities.formats != nullptr) {
        std::for_each(capabilities.formats, capabilities.formats + capabilities.formatCount,
                [](wgpu::TextureFormat const format) {
-                    FWGPU_LOGI << "    " << format;
+                    FWGPU_LOGI << "    " << format << utils::io::endl;
                });
    }
-    FWGPU_LOGI << "  surface present modes (" << capabilities.presentModeCount << "):";
+    FWGPU_LOGI << "  surface present modes (" << capabilities.presentModeCount
+               << "):" << utils::io::endl;
    if (capabilities.presentModeCount > 0 && capabilities.presentModes != nullptr) {
        std::for_each(capabilities.presentModes,
                capabilities.presentModes + capabilities.presentModeCount,
                [](wgpu::PresentMode const presentMode) {
-                    FWGPU_LOGI << "    " << presentMode;
+                    FWGPU_LOGI << "    " << presentMode << utils::io::endl;
                });
    }
-    FWGPU_LOGI << "  surface alpha modes (" << capabilities.alphaModeCount << "):";
+    FWGPU_LOGI << "  surface alpha modes (" << capabilities.alphaModeCount
+               << "):" << utils::io::endl;
    if (capabilities.alphaModeCount > 0 && capabilities.alphaModes != nullptr) {
        std::for_each(capabilities.alphaModes,
                capabilities.alphaModes + capabilities.alphaModeCount,
                [](wgpu::CompositeAlphaMode const alphaMode) {
-                    FWGPU_LOGI << "    " << alphaMode;
+                    FWGPU_LOGI << "    " << alphaMode << utils::io::endl;
                });
    }
 }

 void printSurfaceConfiguration(wgpu::SurfaceConfiguration const& config,
        wgpu::TextureFormat depthFormat) {
-    FWGPU_LOGI << "WebGPU surface configuration:";
-    FWGPU_LOGI << "  surface format: " << config.format;
-    FWGPU_LOGI << "  surface usage: " << config.usage;
-    FWGPU_LOGI << "  surface view formats (" << config.viewFormatCount << "):";
+    FWGPU_LOGI << "WebGPU surface configuration:" << utils::io::endl;
+    FWGPU_LOGI << "  surface format: " << config.format << utils::io::endl;
+    FWGPU_LOGI << "  surface usage: " << config.usage << utils::io::endl;
+    FWGPU_LOGI << "  surface view formats (" << config.viewFormatCount << "):" << utils::io::endl;
    if (config.viewFormatCount > 0 && config.viewFormats != nullptr) {
        std::for_each(config.viewFormats, config.viewFormats + config.viewFormatCount,
                [](wgpu::TextureFormat const viewFormat) {
-                    FWGPU_LOGI << "    " << viewFormat;
+                    FWGPU_LOGI << "    " << viewFormat << utils::io::endl;
                });
    }
-    FWGPU_LOGI << "  surface alpha mode: " << config.alphaMode;
-    FWGPU_LOGI << "  surface width: " << config.width;
-    FWGPU_LOGI << "  surface height: " << config.height;
-    FWGPU_LOGI << "  surface present mode: " << config.presentMode;
-    FWGPU_LOGI << "WebGPU selected depth format: " << depthFormat;
+    FWGPU_LOGI << "  surface alpha mode: " << config.alphaMode << utils::io::endl;
+    FWGPU_LOGI << "  surface width: " << config.width << utils::io::endl;
+    FWGPU_LOGI << "  surface height: " << config.height << utils::io::endl;
+    FWGPU_LOGI << "  surface present mode: " << config.presentMode << utils::io::endl;
+    FWGPU_LOGI << "WebGPU selected depth format: " << depthFormat << utils::io::endl;
 }
 #endif// FWGPU_ENABLED(FWGPU_PRINT_SYSTEM)

@@ -187,7 +189,8 @@ void printSurfaceConfiguration(wgpu::SurfaceConfiguration const& config,
        // We prefer premultiplied to unpremuliplied until that assumption should be adjusted.
        FWGPU_LOGW << "Auto, Inherit, & Opaque composite alpha modes not supported. Filament has "
                      "historically used these. Premultiplied alpha composite mode for "
-                      "transparency is being selected as a fallback, but may not work as expected.";
+                      "transparency is being selected as a fallback, but may not work as expected."
+                   << utils::io::endl;
        return wgpu::CompositeAlphaMode::Premultiplied;
    } else {
        FILAMENT_CHECK_POSTCONDITION(unpremultipliedAvailable)
@@ -197,7 +200,8 @@ void printSurfaceConfiguration(wgpu::SurfaceConfiguration const& config,
        FWGPU_LOGW << "Auto, Inherit, & Opaque composite alpha modes not supported. Filament has "
                      "historically used these. Unpremultiplied alpha composite mode for "
                      "transparency is being selected as a fallback "
-                      "(premulitipled is not available either), but may not work as expected.";
+                      "(premulitipled is not available either), but may not work as expected."
+                   << utils::io::endl;
        return wgpu::CompositeAlphaMode::Unpremultiplied;
    }
 }
@@ -270,7 +274,7 @@ WebGPUSwapChain::WebGPUSwapChain(wgpu::Surface&& surface, wgpu::Extent2D const&
      mDepthTextureView(createDepthTextureView(mDepthTexture, mDepthFormat, mNeedStencil)) {
    wgpu::SurfaceCapabilities capabilities = {};
    if (!mSurface.GetCapabilities(adapter, &capabilities)) {
-        FWGPU_LOGW << "Failed to get WebGPU surface capabilities";
+        FWGPU_LOGW << "Failed to get WebGPU surface capabilities" << utils::io::endl;
    } else {
 #if FWGPU_ENABLED(FWGPU_PRINT_SYSTEM)
        printSurfaceCapabilitiesDetails(capabilities);
@@ -293,7 +297,8 @@ void WebGPUSwapChain::setExtent(wgpu::Extent2D const& currentSurfaceSize) {
    if (mConfig.width != currentSurfaceSize.width || mConfig.height != currentSurfaceSize.height) {
        mConfig.width = currentSurfaceSize.width;
        mConfig.height = currentSurfaceSize.height;
-        FWGPU_LOGD << "Resizing to width " << mConfig.width << " height " << mConfig.height;
+        FWGPU_LOGD << "Resizing to width " << mConfig.width << " height " << mConfig.height
+                   << utils::io::endl;
 #if FWGPU_ENABLED(FWGPU_PRINT_SYSTEM)
        printSurfaceConfiguration(mConfig, mDepthFormat);
 #endif
@@ -249,17 +249,18 @@ void assertLimitsAreExpressedInRequirementsStruct() {
 void printInstanceDetails(wgpu::Instance const& instance) {
    wgpu::SupportedWGSLLanguageFeatures supportedWGSLLanguageFeatures{};
    if (!instance.GetWGSLLanguageFeatures(&supportedWGSLLanguageFeatures)) {
-        FWGPU_LOGW << "Failed to get WebGPU instance supported WGSL language features";
+        FWGPU_LOGW << "Failed to get WebGPU instance supported WGSL language features"
+                   << utils::io::endl;
    } else {
        FWGPU_LOGI << "WebGPU instance supported WGSL language features ("
-                   << supportedWGSLLanguageFeatures.featureCount << "):";
+                   << supportedWGSLLanguageFeatures.featureCount << "):" << utils::io::endl;
        if (supportedWGSLLanguageFeatures.featureCount > 0 &&
                supportedWGSLLanguageFeatures.features != nullptr) {
            std::for_each(supportedWGSLLanguageFeatures.features,
                    supportedWGSLLanguageFeatures.features +
                            supportedWGSLLanguageFeatures.featureCount,
                    [](wgpu::WGSLLanguageFeatureName const featureName) {
-                        FWGPU_LOGI << "  " << featureName;
+                        FWGPU_LOGI << "  " << featureName << utils::io::endl;
                    });
        }
    }
@@ -271,7 +272,7 @@ void printInstanceDetails(wgpu::Instance const& instance) {
    wgpu::DawnTogglesDescriptor dawnTogglesDescriptor{};
 #if defined(FILAMENT_WEBGPU_IMMEDIATE_ERROR_HANDLING)
 #if FWGPU_ENABLED(FWGPU_PRINT_SYSTEM)
-    FWGPU_LOGI << "setting on toggle enable_immediate_error_handling";
+    FWGPU_LOGI << "setting on toggle enable_immediate_error_handling" << utils::io::endl;
 #endif
    /**
     * Have the un-captured error callback invoked immediately when an error occurs, rather than
@@ -315,7 +316,7 @@ void printLimit(std::string_view name, const std::variant<uint32_t, uint64_t> va
    if (undefined) {
        FWGPU_LOGI << "UNDEFINED";
    }
-    FWGPU_LOGI << "";
+    FWGPU_LOGI << utils::io::endl;
 }
 #endif// FWGPU_ENABLED(FWGPU_PRINT_SYSTEM)

@@ -402,23 +403,23 @@ STREAM_TYPE& operator<<(STREAM_TYPE& out, AdapterDetails const& details) noexcep

 #if FWGPU_ENABLED(FWGPU_PRINT_SYSTEM)
 void printAdapterDetails(AdapterDetails const& details) {
-    FWGPU_LOGI << "Selected WebGPU adapter info: " << details;
+    FWGPU_LOGI << "Selected WebGPU adapter info: " << details << utils::io::endl;
    wgpu::SupportedFeatures supportedFeatures{};
    details.adapter.GetFeatures(&supportedFeatures);
    FWGPU_LOGI << "WebGPU adapter supported features (" << supportedFeatures.featureCount
-               << "):";
+               << "):" << utils::io::endl;
    if (supportedFeatures.featureCount > 0 && supportedFeatures.features != nullptr) {
        std::for_each(supportedFeatures.features,
                supportedFeatures.features + supportedFeatures.featureCount,
                [](wgpu::FeatureName const featureName) {
-                    FWGPU_LOGI << "  " << featureName;
+                    FWGPU_LOGI << "  " << featureName << utils::io::endl;
                });
    }
    wgpu::Limits supportedLimits{};
    if (!details.adapter.GetLimits(&supportedLimits)) {
-        FWGPU_LOGW << "Failed to get WebGPU adapter supported limits";
+        FWGPU_LOGW << "Failed to get WebGPU adapter supported limits" << utils::io::endl;
    } else {
-        FWGPU_LOGI << "WebGPU adapter supported limits:";
+        FWGPU_LOGI << "WebGPU adapter supported limits:" << utils::io::endl;
        printLimits(supportedLimits);
    }
 }
@@ -445,14 +446,14 @@ struct AdapterDetailsHash final {
                })) {
 #if FWGPU_ENABLED(FWGPU_PRINT_SYSTEM)
        FWGPU_LOGI << "WebGPU adapter " << details
-                   << " does not have the minimum required features.";
-        FWGPU_LOGI << "Missing required feature(s): ";
+                   << " does not have the minimum required features." << utils::io::endl;
+        FWGPU_LOGI << "  Missing required feature(s): ";
        for (wgpu::FeatureName const& requiredFeature: REQUIRED_FEATURES) {
            if (!details.adapter.HasFeature(requiredFeature)) {
-                FWGPU_LOGI << requiredFeature;
+                FWGPU_LOGI << requiredFeature << " ";
            }
        }
-        FWGPU_LOGI << "";
+        FWGPU_LOGI << utils::io::endl;
 #endif
        return false;
    }
@@ -461,7 +462,7 @@ struct AdapterDetailsHash final {
            << "Failed to get limits for WebGPU adapter: " << details;
    if (!satisfiesLimits(supportedLimits)) {
 #if FWGPU_ENABLED(FWGPU_PRINT_SYSTEM)
-        FWGPU_LOGI << " (for WebGPU adapter " << details << ")";
+        FWGPU_LOGI << " (for WebGPU adapter " << details << ")" << utils::io::endl;
 #endif
        return false;
    }
@@ -517,9 +518,9 @@ struct AdapterDetailsHash final {
    }
    FILAMENT_CHECK_POSTCONDITION(!compatibleAdapters.empty()) << "No WebGPU adapters found!";
 #if FWGPU_ENABLED(FWGPU_PRINT_SYSTEM)
-    FWGPU_LOGI << compatibleAdapters.size() << " WebGPU adapter(s) found:";
+    FWGPU_LOGI << compatibleAdapters.size() << " WebGPU adapter(s) found:" << utils::io::endl;
    for (auto& details: compatibleAdapters) {
-        FWGPU_LOGI << "  WebGPU adapter: " << details;
+        FWGPU_LOGI << "  WebGPU adapter: " << details << utils::io::endl;
    }
 #endif
    return compatibleAdapters;
@@ -581,19 +582,19 @@ void printDeviceDetails(wgpu::Device const& device) {
    wgpu::SupportedFeatures supportedFeatures{};
    device.GetFeatures(&supportedFeatures);
    FWGPU_LOGI << "WebGPU device supported features (" << supportedFeatures.featureCount
-               << "):";
+               << "):" << utils::io::endl;
    if (supportedFeatures.featureCount > 0 && supportedFeatures.features != nullptr) {
        std::for_each(supportedFeatures.features,
                supportedFeatures.features + supportedFeatures.featureCount,
                [](wgpu::FeatureName const featureName) {
-                    FWGPU_LOGI << "  " << featureName;
+                    FWGPU_LOGI << "  " << featureName << utils::io::endl;
                });
    }
    wgpu::Limits supportedLimits{};
    if (!device.GetLimits(&supportedLimits)) {
-        FWGPU_LOGW << "Failed to get WebGPU supported device limits";
+        FWGPU_LOGW << "Failed to get WebGPU supported device limits" << utils::io::endl;
    } else {
-        FWGPU_LOGI << "WebGPU device supported limits:";
+        FWGPU_LOGI << "WebGPU device supported limits:" << utils::io::endl;
        printLimits(supportedLimits);
    }
 }
@@ -634,7 +635,8 @@ wgpu::Device WebGPUPlatform::requestDevice(wgpu::Adapter const& adapter) {
                    wgpu::StringView message) {
                if (reason == wgpu::DeviceLostReason::Destroyed) {
 #if FWGPU_ENABLED(FWGPU_DEBUG_VALIDATION)
-                    FWGPU_LOGD << "WebGPU device lost due to being destroyed (expected)";
+                    FWGPU_LOGD << "WebGPU device lost due to being destroyed (expected)"
+                               << utils::io::endl;
 #endif
                    return;
                }
@@ -646,7 +648,7 @@ wgpu::Device WebGPUPlatform::requestDevice(wgpu::Adapter const& adapter) {
    deviceDescriptor.SetUncapturedErrorCallback(
            [](wgpu::Device const&, wgpu::ErrorType errorType, wgpu::StringView message) {
                FWGPU_LOGE << "WebGPU device error: " << errorTypeToString(errorType) << " "
-                           << message.data;
+                           << message.data << utils::io::endl;
            });
    wgpu::Device device = nullptr;
    wgpu::WaitStatus status = mInstance.WaitAny(
@@ -699,7 +701,8 @@ Driver* WebGPUPlatform::createDriver(void* sharedContext,
        const Platform::DriverConfig& driverConfig) noexcept {
    if (sharedContext) {
        FWGPU_LOGW << "sharedContext is ignored/unused in the WebGPU backend. A non-null "
-                      "sharedContext was provided, but it will be ignored.";
+                      "sharedContext was provided, but it will be ignored."
+                   << utils::io::endl;
    }
    return WebGPUDriver::create(*this, driverConfig);
 }
@@ -84,8 +84,6 @@ std::string ScreenshotParams::expectedFilePath() const {
 }

 const std::string ScreenshotParams::filePrefix() const {
-    // TODO(b/422804941): If there are platform specific goldens, when on those platforms append a
-    //  unique platform identifying string to this.
    return mFileName;
 }

@@ -42,7 +42,6 @@ namespace test {
 */
 class ScreenshotParams {
 public:
-    // TODO(b/422804941): Add a set of environments where this test should use a different golden.
    ScreenshotParams(int width, int height, std::string fileName, uint32_t expectedPixelHash,
            bool isSrgb = false);

@@ -41,8 +41,6 @@ Shader::Shader(DriverApi& api, Cleanup& cleanup, ShaderConfig config) : mCleanup
        descriptors[kDescriptorSetIndex][i] = {
                config.uniforms[i].name, kLayouts[i], config.uniforms[i].samplerInfo };
    }
-    // TODO(b/422803382): When the shader language isn't GLSL dont' use the ShaderGenerator to
-    //  compile the shader.
    ShaderGenerator shaderGen(
            std::move(config.vertexShader), std::move(config.fragmentShader), BackendTest::sBackend,
            BackendTest::sIsMobilePlatform, std::move(descriptors));
@@ -31,9 +31,7 @@ struct UniformConfig {

 // All describing a shader that should be created.
 struct ShaderConfig {
-    filament::backend::ShaderLanguage vertexLanguage;
    std::string vertexShader;
-    filament::backend::ShaderLanguage fragmentLanguage;
    std::string fragmentShader;
    std::vector<UniformConfig> uniforms;
 };
@@ -215,20 +215,18 @@ Shader SharedShaders::makeShader(filament::backend::DriverApi& api, Cleanup& cle
    std::optional<ShaderText> fragment;
    std::optional<std::string> uniform;
    if (getShaderLanguage(BackendTest::sBackend) != ShaderLanguage::GLSL) {
-        // TODO(b/422803382): If any shaders need backend/shader language specific shaders rather
-        //  than transpiled versions of the GLSL shader, check here and create a shader with that
-        //  config instead
+        // TODO: If any shaders need backend/shader language specific shaders rather than transpiled
+        // versions of the GLSL shader, check environment.
    }
    vertex = GetGlslVertexShader(request.mVertexType);
    fragment = GetGlslFragmentShader(request.mFragmentType);
    uniform = GetGlslUniform(request.mUniformType);
    if (vertex.has_value() && fragment.has_value() && uniform.has_value()) {
-        return Shader(api, cleanup,
-                ShaderConfig{ .vertexLanguage = filament::backend::ShaderLanguage::ESSL3,
-                    .vertexShader = vertex->withUniform(*uniform),
-                    .fragmentLanguage = filament::backend::ShaderLanguage::ESSL3,
-                    .fragmentShader = fragment->withUniform(*uniform),
-                    .uniforms = GetUniformConfig(request.mUniformType) });
+        return Shader(
+                api, cleanup, ShaderConfig{
+                        vertex->withUniform(*uniform), fragment->withUniform(*uniform),
+                        GetUniformConfig(request.mUniformType)}
+        );
    }
    abort();
 }
@@ -25,7 +25,7 @@
 #include <backend/Handle.h>

 #include <utils/Hash.h>
-#include <utils/Logger.h>
+#include <utils/Log.h>

 #include <fstream>
 #include <string>
@@ -137,7 +137,8 @@ TEST_F(BackendTest, FeedbackLoops) {
        // Create a RenderTarget for each miplevel.
        Handle<HwRenderTarget> renderTargets[kNumLevels];
        for (uint8_t level = 0; level < kNumLevels; level++) {
-            LOG(INFO) << "Level " << int(level) << ": " << (kTexWidth >> level) << "x" << (kTexHeight >> level);
+            slog.i << "Level " << int(level) << ": " <<
+                    (kTexWidth >> level) << "x" << (kTexHeight >> level) << io::endl;
            renderTargets[level] = cleanup.add(api.createRenderTarget( TargetBufferFlags::COLOR,
                    kTexWidth >> level, kTexHeight >> level, 1, 0, { texture, level, 0 }, {}, {}));
        }
@@ -317,15 +317,6 @@ public:
         */
        size_t metalUploadBufferSizeBytes = 512 * 1024;

-        /**
-         * The action to take if a Drawable cannot be acquired.
-         *
-         * Each frame rendered requires a CAMetalDrawable texture, which is
-         * presented on-screen at the completion of each frame. These are
-         * limited and provided round-robin style by the system.
-         */
-        bool metalDisablePanicOnDrawableFailure = false;
-
        /**
         * Set to `true` to forcibly disable parallel shader compilation in the backend.
         * Currently only honored by the GL and Metal backends.
@@ -86,6 +86,9 @@ public:
            std::is_same_v<math::mat3f, T>
    >;

+    template<typename T>
+    using is_supported_constant_parameter_t = std::enable_if_t<std::is_same_v<bool, T>>;
+
    /**
     * Creates a new MaterialInstance using another MaterialInstance as a template for initialization.
     * The new MaterialInstance is an instance of the same Material of the template instance and
@@ -237,13 +240,13 @@ public:

    /**
     * Gets the value of a parameter by name.
-     * 
+     *
     * Note: Only supports non-texture parameters such as numeric and math types.
-     * 
+     *
     * @param name          Name of the parameter as defined by Material. Cannot be nullptr.
     * @param nameLength    Length in `char` of the name parameter.
     * @throws utils::PreConditionPanic if name doesn't exist or no-op if exceptions are disabled.
-     * 
+     *
     * @see Material::hasParameter
     */
    template<typename T>
@@ -261,6 +264,53 @@ public:
        return getParameter<T>(name, strlen(name));
    }

+    /**
+     * Set a mutable constant parameter by name.
+     *
+     * @param name          Name of the parameter as defined by Material. Cannot be nullptr.
+     * @param nameLength    Length in `char` of the name parameter.
+     * @param value         Value of the parameter to set.
+     * @throws utils::PreConditionPanic if name doesn't exist or no-op if exceptions are disabled.
+     */
+    template<typename T, typename = is_supported_constant_parameter_t<T>>
+    void setConstant(const char* UTILS_NONNULL name, size_t nameLength, T const& value);
+
+    /** inline helper to provide the name as a null-terminated string literal */
+    template<typename T, typename = is_supported_constant_parameter_t<T>>
+    void setConstant(StringLiteral const name, T const& value) {
+        setConstant<T>(name.data, name.size, value);
+    }
+
+    /** inline helper to provide the name as a null-terminated C string */
+    template<typename T, typename = is_supported_constant_parameter_t<T>>
+    void setConstant(const char* UTILS_NONNULL name, T const& value) {
+        setConstant<T>(name, strlen(name), value);
+    }
+
+    /**
+     * Gets the value of a mutable constant parameter by name.
+     *
+     * @param name          Name of the parameter as defined by Material. Cannot be nullptr.
+     * @param nameLength    Length in `char` of the name parameter.
+     * @throws utils::PreConditionPanic if name doesn't exist or no-op if exceptions are disabled.
+     *
+     * @see Material::hasConstant
+     */
+    template<typename T, typename = is_supported_constant_parameter_t<T>>
+    T getConstant(const char* UTILS_NONNULL name, size_t nameLength) const;
+
+    /** inline helper to provide the name as a null-terminated C string */
+    template<typename T, typename = is_supported_constant_parameter_t<T>>
+    T getConstant(StringLiteral const name) const {
+        return getConstant<T>(name.data, name.size);
+    }
+
+    /** inline helper to provide the name as a null-terminated C string */
+    template<typename T, typename = is_supported_constant_parameter_t<T>>
+    T getConstant(const char* UTILS_NONNULL name) const {
+        return getConstant<T>(name, strlen(name));
+    }
+
    /**
     * Set-up a custom scissor rectangle; by default it is disabled.
     *
@@ -22,10 +22,10 @@

 #include <private/utils/Tracing.h>

-#include <utils/FixedCapacityVector.h>
-#include <utils/Logger.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
+#include <utils/FixedCapacityVector.h>
+#include <utils/Log.h>
 #include <utils/ostream.h>

 #include <algorithm>
@@ -112,11 +112,13 @@ void FrameInfoManager::beginFrame(DriverApi& driver, Config const& config, uint3
        using namespace utils;
        auto h = getFrameInfoHistory(1);
        if (!h.empty()) {
-            DLOG(INFO) << frameId << ": " << h[0].frameId << " (" << frameId - h[0].frameId << ")"
-                       << ", Dm=" << h[0].endFrame - h[0].beginFrame
-                       << ", L =" << h[0].backendBeginFrame - h[0].beginFrame
-                       << ", Db=" << h[0].backendEndFrame - h[0].backendBeginFrame
-                       << ", T =" << h[0].frameTime;
+            slog.d << frameId << ": "
+                   << h[0].frameId << " (" << frameId - h[0].frameId << ")"
+                   << ", Dm=" << h[0].endFrame - h[0].beginFrame
+                   << ", L =" << h[0].backendBeginFrame - h[0].beginFrame
+                   << ", Db=" << h[0].backendEndFrame - h[0].backendBeginFrame
+                   << ", T =" << h[0].frameTime
+                   << io::endl;
        }
    }
 }
@@ -34,7 +34,7 @@

 #include <utils/BinaryTreeArray.h>
 #include <utils/JobSystem.h>
-#include <utils/Logger.h>
+#include <utils/Log.h>
 #include <utils/Slice.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
@@ -366,12 +366,14 @@ bool Froxelizer::update() noexcept {

        uniformsNeedUpdating = true;

-        DLOG(INFO) << "Froxel: " << viewport.width << "x" << viewport.height << " / "
-                   << froxelDimension.x << "x" << froxelDimension.y << io::endl
-                   << "Froxel: " << froxelCountX << "x" << froxelCountY << "x" << froxelCountZ
-                   << " = " << (froxelCountX * froxelCountY * froxelCountZ) << " ("
-                   << getFroxelBufferEntryCount() - froxelCountX * froxelCountY * froxelCountZ
-                   << " lost)";
+#ifndef NDEBUG
+        slog.d << "Froxel: " << viewport.width << "x" << viewport.height << " / "
+               << froxelDimension.x << "x" << froxelDimension.y << io::endl
+               << "Froxel: " << froxelCountX << "x" << froxelCountY << "x" << froxelCountZ
+               << " = " << (froxelCountX * froxelCountY * froxelCountZ)
+               << " (" << getFroxelBufferEntryCount() - froxelCountX * froxelCountY * froxelCountZ << " lost)"
+               << io::endl;
+#endif

        mFroxelCountX = froxelCountX;
        mFroxelCountY = froxelCountY;
@@ -710,7 +712,9 @@ void Froxelizer::froxelizeAssignRecordsCompress() noexcept {
        const size_t lightCount = entry.count();

        if (UTILS_UNLIKELY(offset + lightCount >= RECORD_BUFFER_ENTRY_COUNT)) {
-            DLOG(INFO) << "out of space: " << i << ", at " << offset;
+#ifndef NDEBUG
+            slog.d << "out of space: " << i << ", at " << offset << io::endl;
+#endif
            // note: instead of dropping froxels we could look for similar records we've already
            // filed up.
            do {
@@ -232,6 +232,46 @@ template UTILS_PUBLIC mat3f MaterialInstance::getParameter<mat3f>      (const ch

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

+template<>
+inline void FMaterialInstance::setConstantImpl<bool>(std::string_view const name, bool const& value) {
+    std::optional<uint32_t> id = mMaterial->getMutableConstantId(name);
+    FILAMENT_CHECK_PRECONDITION(id.has_value()) << "No mutable constant with name " << name;
+    mConstants.set(*id, value);
+}
+
+template<typename T, typename>
+void MaterialInstance::setConstant(const char* name, size_t nameLength, T const& value) {
+    downcast(this)->setConstantImpl({ name, nameLength }, value);
+}
+
+// Explicit template instantiation of our supported types.
+//
+// Mutable spec constants will probably only ever allow bools, but it's nice to keep the API
+// forwards-compatible.
+template UTILS_PUBLIC void MaterialInstance::setConstant<bool>(const char* name, size_t nameLength, bool const& v);
+
+// ------------------------------------------------------------------------------------------------
+
+template<>
+inline bool FMaterialInstance::getConstantImpl<bool>(std::string_view const name) const {
+    std::optional<uint32_t> id = mMaterial->getMutableConstantId(name);
+    FILAMENT_CHECK_PRECONDITION(id.has_value()) << "No mutable constant with name " << name;
+    return mConstants[*id];
+}
+
+template<typename T, typename>
+T MaterialInstance::getConstant(const char* name, size_t nameLength) const {
+    return downcast(this)->getConstantImpl<T>({ name, nameLength });
+}
+
+// Explicit template instantiation of our supported types.
+//
+// Mutable spec constants will probably only ever allow bools, but it's nice to keep the API
+// forwards-compatible.
+template UTILS_PUBLIC bool MaterialInstance::getConstant<bool>(const char* name, size_t nameLength) const;
+
+// ------------------------------------------------------------------------------------------------
+
 Material const* MaterialInstance::getMaterial() const noexcept {
    return downcast(this)->getMaterial();
 }
@@ -229,6 +229,11 @@ bool MaterialParser::getConstants(FixedCapacityVector<MaterialConstant>* contain
    return get<ChunkMaterialConstants>(container);
 }

+bool MaterialParser::getMutableConstants(
+        FixedCapacityVector<MaterialMutableConstant>* container) const noexcept {
+    return get<ChunkMaterialMutableConstants>(container);
+}
+
 bool MaterialParser::getPushConstants(CString* structVarName,
        FixedCapacityVector<MaterialPushConstant>* value) const noexcept {
    auto [start, end] = mImpl.mChunkContainer.getChunkRange(MaterialPushConstants);
@@ -751,6 +756,38 @@ bool ChunkMaterialConstants::unflatten(Unflattener& unflattener,
    return true;
 }

+bool ChunkMaterialMutableConstants::unflatten(Unflattener& unflattener,
+        FixedCapacityVector<MaterialMutableConstant>* materialConstants) {
+    assert_invariant(materialConstants);
+
+    // Read number of constants.
+    uint64_t numConstants = 0;
+    if (!unflattener.read(&numConstants)) {
+        return false;
+    }
+
+    materialConstants->reserve(numConstants);
+    materialConstants->resize(numConstants);
+
+    for (uint64_t i = 0; i < numConstants; i++) {
+        CString constantName;
+        bool defaultValue;
+
+        if (!unflattener.read(&constantName)) {
+            return false;
+        }
+
+        if (!unflattener.read(&defaultValue)) {
+            return false;
+        }
+
+        (*materialConstants)[i].name = std::move(constantName);
+        (*materialConstants)[i].defaultValue = defaultValue;
+    }
+
+    return true;
+}
+
 bool ChunkMaterialPushConstants::unflatten(Unflattener& unflattener,
        CString* structVarName,
        FixedCapacityVector<MaterialPushConstant>* materialPushConstants) {
@@ -49,6 +49,7 @@ class BufferInterfaceBlock;
 class SamplerInterfaceBlock;
 struct SubpassInfo;
 struct MaterialConstant;
+struct MaterialMutableConstant;
 struct MaterialPushConstant;

 class MaterialParser {
@@ -79,6 +80,8 @@ public:
    bool getShaderModels(uint32_t* value) const noexcept;
    bool getMaterialProperties(uint64_t* value) const noexcept;
    bool getConstants(utils::FixedCapacityVector<MaterialConstant>* value) const noexcept;
+    bool getMutableConstants(utils::FixedCapacityVector<MaterialMutableConstant>* value)
+        const noexcept;
    bool getPushConstants(utils::CString* structVarName,
            utils::FixedCapacityVector<MaterialPushConstant>* value) const noexcept;

@@ -237,6 +240,13 @@ struct ChunkMaterialConstants {
    static filamat::ChunkType const tag = filamat::MaterialConstants;
 };

+struct ChunkMaterialMutableConstants {
+    static bool unflatten(filaflat::Unflattener& unflattener,
+            utils::FixedCapacityVector<MaterialMutableConstant>* materialConstants);
+    using Container = utils::FixedCapacityVector<MaterialMutableConstant>;
+    static filamat::ChunkType const tag = filamat::MaterialMutableConstants;
+};
+
 struct ChunkMaterialPushConstants {
    static bool unflatten(filaflat::Unflattener& unflattener, utils::CString* structVarName,
            utils::FixedCapacityVector<MaterialPushConstant>* materialPushConstants);
@@ -187,7 +187,10 @@ FMaterial* PostProcessManager::PostProcessMaterial::getMaterial(FEngine& engine,
    if (UTILS_UNLIKELY(mSize)) {
        loadMaterial(engine);
    }
-    mMaterial->prepareProgram(Variant{ Variant::type_t(variant) });
+    mMaterial->prepareProgram(Variant{ Variant::type_t(variant) },
+            // TODO(exv): allow post process materials to use mutable spec constants?
+            Program::MutableSpecConstantsInfo(0)
+            );
    return mMaterial;
 }

@@ -423,7 +426,10 @@ UTILS_NOINLINE
 PipelineState PostProcessManager::getPipelineState(
        FMaterial const* const ma, PostProcessVariant variant) const noexcept {
    return {
-            .program = ma->getProgram(Variant{ Variant::type_t(variant) }),
+            .program = ma->getProgram(Variant{ Variant::type_t(variant) },
+                    // TODO(exv): allow post process materials to use mutable spec constants?
+                    Program::MutableSpecConstantsInfo(0)
+                    ),
            .vertexBufferInfo = mFullScreenQuadVbih,
            .pipelineLayout = {
                    .setLayout = {
@@ -42,12 +42,12 @@

 #include <private/utils/Tracing.h>

-#include <utils/JobSystem.h>
-#include <utils/Panic.h>
-#include <utils/Range.h>
-#include <utils/Slice.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
+#include <utils/JobSystem.h>
+#include <utils/Panic.h>
+#include <utils/Slice.h>
+#include <utils/Range.h>

 #include <algorithm>
 #include <functional>
@@ -246,7 +246,8 @@ void RenderPass::appendCommands(FEngine const& engine,
    for (Command const* first = curr, *last = curr + commandCount ; first != last ; ++first) {
        if (UTILS_LIKELY((first->key & CUSTOM_MASK) == uint64_t(CustomCommand::PASS))) {
            auto ma = first->info.mi->getMaterial();
-            ma->prepareProgram(first->info.materialVariant);
+            ma->prepareProgram(first->info.materialVariant,
+                    first->info.mi->getMutableSpecConstants());
        }
    }
 }
@@ -407,8 +408,8 @@ RenderPass::Command* RenderPass::instanceify(DriverApi& driver,
    }

    if (UTILS_UNLIKELY(firstSentinel)) {
-        // DLOG(INFO) << "auto-instancing, saving " << drawCallsSavedCount << " draw calls, out of "
-        //            << count;
+        //slog.d << "auto-instancing, saving " << drawCallsSavedCount << " draw calls, out of "
+        //       << count << io::endl;
        // we have instanced primitives
        // copy our instanced ubo data
        driver.updateBufferObjectUnsynchronized(mInstancedUboHandle, {
@@ -1098,7 +1099,8 @@ void RenderPass::Executor::execute(FEngine const& engine, DriverApi& driver,
                }

                assert_invariant(ma);
-                pipeline.program = ma->getProgram(info.materialVariant);
+                pipeline.program = ma->getProgram(info.materialVariant,
+                        info.mi->getMutableSpecConstants());

                if (UTILS_UNLIKELY(memcmp(&pipeline, &currentPipeline, sizeof(PipelineState)) != 0)) {
                    currentPipeline = pipeline;
@@ -27,11 +27,11 @@

 #include "private/backend/DriverApi.h"

-#include <utils/Logger.h>
 #include <utils/algorithm.h>
 #include <utils/bitset.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
+#include <utils/Log.h>
 #include <utils/ostream.h>

 #include <array>
@@ -291,16 +291,17 @@ void ResourceAllocator::gc(bool const skippedFrame) noexcept {
 UTILS_NOINLINE
 void ResourceAllocator::dump(bool const brief) const noexcept {
    constexpr float MiB = 1.0f / float(1u << 20u);
-    DLOG(INFO) << "# entries=" << mTextureCache.size() << ", sz=" << (float) mCacheSize * MiB
-               << " MiB"
-               << ", max=" << (float) mCacheSizeHiWaterMark * MiB << " MiB";
+    slog.d  << "# entries=" << mTextureCache.size()
+            << ", sz=" << (float)mCacheSize * MiB << " MiB"
+            << ", max=" << (float)mCacheSizeHiWaterMark * MiB << " MiB"
+            << io::endl;
    if (!brief) {
        for (auto const& it : mTextureCache) {
            auto w = it.first.width;
            auto h = it.first.height;
            auto f = FTexture::getFormatSize(it.first.format);
-            DLOG(INFO) << it.first.name << ": w=" << w << ", h=" << h << ", f=" << f
-                       << ", sz=" << (float) it.second.size * MiB;
+            slog.d << it.first.name << ": w=" << w << ", h=" << h << ", f=" << f << ", sz="
+                   << (float)it.second.size * MiB << io::endl;
        }
    }
 }
@@ -308,7 +309,7 @@ void ResourceAllocator::dump(bool const brief) const noexcept {
 ResourceAllocator::CacheContainer::iterator
 ResourceAllocator::purge(
        CacheContainer::iterator const& pos) {
-    // DLOG(INFO) << "purging " << pos->second.handle.getId() << ", age=" << pos->second.age;
+    //slog.d << "purging " << pos->second.handle.getId() << ", age=" << pos->second.age << io::endl;
    mBackend.destroyTexture(pos->second.handle);
    mCacheSize -= pos->second.size;
    return mTextureCache.erase(pos);
@@ -16,7 +16,7 @@

 #include "ResourceList.h"

-#include <utils/Logger.h>
+#include <utils/Log.h>

 #include <algorithm>

@@ -32,7 +32,7 @@ ResourceListBase::ResourceListBase(const char* typeName)
 ResourceListBase::~ResourceListBase() noexcept {
 #ifndef NDEBUG
    if (!mList.empty()) {
-        DLOG(INFO) << "leaked " << mList.size() << " " << mTypeName;
+        utils::slog.d << "leaked " << mList.size() << " " << mTypeName << utils::io::endl;
    }
 #endif
 }
@@ -20,7 +20,7 @@
 #include "details/Camera.h"

 #include <utils/Entity.h>
-#include <utils/Logger.h>
+#include <utils/Log.h>
 #include <utils/debug.h>

 using namespace utils;
@@ -36,7 +36,10 @@ FCameraManager::~FCameraManager() noexcept = default;
 void FCameraManager::terminate(FEngine& engine) noexcept {
    auto& manager = mManager;
    if (!manager.empty()) {
-        DLOG(INFO) << "cleaning up " << manager.getComponentCount() << " leaked Camera components";
+#ifndef NDEBUG
+        slog.d << "cleaning up " << manager.getComponentCount()
+               << " leaked Camera components" << io::endl;
+#endif
        Slice<Entity> const entities{ manager.getEntities(), manager.getComponentCount() };
        for (Entity const e : entities) {
            destroy(engine, e);
@@ -23,9 +23,9 @@

 #include <filament/LightManager.h>

-#include <utils/Logger.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
+#include <utils/Log.h>
 #include <utils/ostream.h>

 #include <math/fast.h>
@@ -230,7 +230,8 @@ void FLightManager::terminate() noexcept {
    auto& manager = mManager;
    if (!manager.empty()) {
 #ifndef NDEBUG
-        DLOG(INFO) << "cleaning up " << manager.getComponentCount() << " leaked Light components";
+        slog.d << "cleaning up " << manager.getComponentCount()
+               << " leaked Light components" << io::endl;
 #endif
        while (!manager.empty()) {
            Instance const ci = manager.end() - 1;
@@ -39,15 +39,14 @@
 #include <backend/DriverEnums.h>
 #include <backend/Handle.h>

+#include <utils/compiler.h>
+#include <utils/debug.h>
 #include <utils/EntityManager.h>
 #include <utils/FixedCapacityVector.h>
 #include <utils/Log.h>
-#include <utils/Logger.h>
+#include <utils/ostream.h>
 #include <utils/Panic.h>
 #include <utils/Slice.h>
-#include <utils/compiler.h>
-#include <utils/debug.h>
-#include <utils/ostream.h>

 #include <math/mat4.h>
 #include <math/scalar.h>
@@ -397,11 +396,10 @@ void RenderableManager::BuilderDetails::processBoneIndicesAndWights(Engine& engi
                }
 #ifndef NDEBUG
                else {
-                    LOG(WARNING) << "Warning of skinning: [entity=%" << entity.getId()
-                                 << ", primitive @ %" << primitiveIndex
-                                 << "] sum of bone weights of vertex=" << iVertex << " is "
-                                 << boneWeightsSum
-                                 << ", it should be one. Weights will be normalized.";
+                    slog.w << "Warning of skinning: [entity=%" << entity.getId()
+                        << ", primitive @ %" << primitiveIndex
+                        << "] sum of bone weights of vertex=" << iVertex << " is " << boneWeightsSum
+                        << ", it should be one. Weights will be normalized." << io::endl;
                }
 #endif

@@ -500,9 +498,9 @@ RenderableManager::Builder::Result RenderableManager::Builder::build(Engine& eng
        AttributeBitset const declared = downcast(entry.vertices)->getDeclaredAttributes();
        AttributeBitset const required = material->getRequiredAttributes();
        if ((declared & required) != required) {
-            LOG(WARNING) << "[entity=" << entity.getId() << ", primitive @ " << i
-                         << "] missing required attributes (" << required
-                         << "), declared=" << declared;
+            slog.w << "[entity=" << entity.getId() << ", primitive @ " << i
+                   << "] missing required attributes ("
+                   << required << "), declared=" << declared << io::endl;
        }

        // we have at least one valid primitive
@@ -728,8 +726,10 @@ void FRenderableManager::destroy(Entity const e) noexcept {
 void FRenderableManager::terminate() noexcept {
    auto& manager = mManager;
    if (!manager.empty()) {
-        DLOG(INFO) << "cleaning up " << manager.getComponentCount()
-                   << " leaked Renderable components";
+#ifndef NDEBUG
+        slog.d << "cleaning up " << manager.getComponentCount()
+               << " leaked Renderable components" << io::endl;
+#endif
        while (!manager.empty()) {
            Instance const ci = manager.end() - 1;
            destroyComponent(ci);
@@ -811,9 +811,9 @@ void FRenderableManager::setMaterialInstanceAt(Instance const instance, uint8_t
            // emitting many invalid warnings as the `declared` bitset is not populated yet.
            bool const isPrimitiveInitialized = !!primitives[primitiveIndex].getHwHandle();
            if (UTILS_UNLIKELY(isPrimitiveInitialized && (declared & required) != required)) {
-                LOG(WARNING) << "[instance=" << instance.asValue() << ", primitive @ "
-                             << primitiveIndex << "] missing required attributes (" << required
-                             << "), declared=" << declared;
+                slog.w << "[instance=" << instance.asValue() << ", primitive @ " << primitiveIndex
+                       << "] missing required attributes ("
+                       << required << "), declared=" << declared << io::endl;
            }
        }
    }
@@ -868,7 +868,7 @@ FColorGrading::FColorGrading(FEngine& engine, const Builder& builder) {
    }

    //std::chrono::duration<float, std::milli> duration = std::chrono::steady_clock::now() - now;
-    //DLOG(INFO) << "LUT generation time: " << duration.count() << " ms";
+    //slog.d << "LUT generation time: " << duration.count() << " ms" << io::endl;

    if (converted) {
        free(data);
@@ -54,14 +54,14 @@

 #include <utils/Allocator.h>
 #include <utils/CallStack.h>
+#include <utils/compiler.h>
+#include <utils/debug.h>
 #include <utils/Invocable.h>
-#include <utils/Logger.h>
+#include <utils/Log.h>
+#include <utils/ostream.h>
 #include <utils/Panic.h>
 #include <utils/PrivateImplementation-impl.h>
 #include <utils/ThreadUtils.h>
-#include <utils/compiler.h>
-#include <utils/debug.h>
-#include <utils/ostream.h>

 #include <math/vec3.h>
 #include <math/vec4.h>
@@ -127,7 +127,7 @@ Engine* FEngine::create(Builder const& builder) {
            instance->mOwnPlatform = true;
        }
        if (platform == nullptr) {
-            LOG(ERROR) << "Selected backend not supported in this build.";
+            slog.e << "Selected backend not supported in this build." << io::endl;
            delete instance;
            return nullptr;
        }
@@ -140,7 +140,6 @@ Engine* FEngine::create(Builder const& builder) {
                .forceGLES2Context = instance->getConfig().forceGLES2Context,
                .stereoscopicType = instance->getConfig().stereoscopicType,
                .assertNativeWindowIsValid = instance->features.backend.opengl.assert_native_window_is_valid,
-                .metalDisablePanicOnDrawableFailure = instance->getConfig().metalDisablePanicOnDrawableFailure,
        };
        instance->mDriver = platform->createDriver(sharedContext, driverConfig);

@@ -281,8 +280,8 @@ FEngine::FEngine(Builder const& builder) :
    // (it may not be the case)
    mJobSystem.adopt();

-    LOG(INFO) << "FEngine (" << sizeof(void*) * 8 << " bits) created at " << this << " "
-              << "(threading is " << (UTILS_HAS_THREADING ? "enabled)" : "disabled)");
+    slog.i << "FEngine (" << sizeof(void*) * 8 << " bits) created at " << this << " "
+           << "(threading is " << (UTILS_HAS_THREADING ? "enabled)" : "disabled)") << io::endl;
 }

 uint32_t FEngine::getJobSystemThreadPoolSize(Config const& config) noexcept {
@@ -317,8 +316,8 @@ void FEngine::init() {
    assert_invariant(mActiveFeatureLevel > FeatureLevel::FEATURE_LEVEL_0);
 #endif

-    LOG(INFO) << "Backend feature level: " << int(driverApi.getFeatureLevel());
-    LOG(INFO) << "FEngine feature level: " << int(mActiveFeatureLevel);
+    slog.i << "Backend feature level: " << int(driverApi.getFeatureLevel()) << io::endl;
+    slog.i << "FEngine feature level: " << int(mActiveFeatureLevel) << io::endl;


    mResourceAllocatorDisposer = std::make_shared<ResourceAllocatorDisposer>(driverApi);
@@ -545,7 +544,8 @@ void FEngine::shutdown() {
    // print out some statistics about this run
    size_t const wm = mCommandBufferQueue.getHighWatermark();
    size_t const wmpct = wm / (getCommandBufferSize() / 100);
-    DLOG(INFO) << "CircularBuffer: High watermark " << wm / 1024 << " KiB (" << wmpct << "%)";
+    slog.d << "CircularBuffer: High watermark "
+           << wm / 1024 << " KiB (" << wmpct << "%)" << io::endl;
 #endif

    DriverApi& driver = getDriverApi();
@@ -740,9 +740,9 @@ int FEngine::loop() {
    if (mPlatform == nullptr) {
        mPlatform = PlatformFactory::create(&mBackend);
        mOwnPlatform = true;
-        LOG(INFO) << "FEngine resolved backend: " << to_string(mBackend);
+        slog.i << "FEngine resolved backend: " << to_string(mBackend) << io::endl;
        if (mPlatform == nullptr) {
-            LOG(ERROR) << "Selected backend not supported in this build.";
+            slog.e << "Selected backend not supported in this build." << io::endl;
            mDriverBarrier.latch();
            return 0;
        }
@@ -760,7 +760,6 @@ int FEngine::loop() {
            .forceGLES2Context = mConfig.forceGLES2Context,
            .stereoscopicType =  mConfig.stereoscopicType,
            .assertNativeWindowIsValid = features.backend.opengl.assert_native_window_is_valid,
-            .metalDisablePanicOnDrawableFailure = mConfig.metalDisablePanicOnDrawableFailure,
    };
    mDriver = mPlatform->createDriver(mSharedGLContext, driverConfig);

@@ -1043,8 +1042,8 @@ UTILS_NOINLINE
 void FEngine::cleanupResourceList(ResourceList<T>&& list) {
    if (UTILS_UNLIKELY(!list.empty())) {
 #ifndef NDEBUG
-        DLOG(INFO) << "cleaning up " << list.size() << " leaked "
-                   << CallStack::typeName<T>().c_str();
+        slog.d << "cleaning up " << list.size()
+               << " leaked " << CallStack::typeName<T>().c_str() << io::endl;
 #endif
        list.forEach([this, &allocator = mHeapAllocator](T* item) {
            item->terminate(*this);
@@ -1241,10 +1240,11 @@ bool FEngine::destroy(const FMaterialInstance* p) {
                            << ri.asValue() << ", index=" << j << ")";
                } else {
                    if (UTILS_UNLIKELY(mi == p)) {
-                        LOG(ERROR) << "destroying MaterialInstance \"" << mi->getName()
-                                   << "\" which is still in use by Renderable (entity="
-                                   << entity.getId() << ", instance=" << ri.asValue()
-                                   << ", index=" << j << ")";
+                        slog.e  << "destroying MaterialInstance \""
+                                << mi->getName() << "\" which is still in use by Renderable (entity="
+                                << entity.getId() << ", instance="
+                                << ri.asValue() << ", index=" << j << ")"
+                                << io::endl;
                    }
                }
            }
@@ -49,7 +49,7 @@
 #include <utils/FixedCapacityVector.h>
 #include <utils/Hash.h>
 #include <utils/Invocable.h>
-#include <utils/Logger.h>
+#include <utils/Log.h>
 #include <utils/Panic.h>
 #include <utils/bitset.h>
 #include <utils/compiler.h>
@@ -169,16 +169,6 @@ template Material::Builder& Material::Builder::constant<int32_t>(const char*, si
 template Material::Builder& Material::Builder::constant<float>(const char*, size_t, float);
 template Material::Builder& Material::Builder::constant<bool>(const char*, size_t, bool);

-
-const char* toString(ShaderModel model) {
-    switch (model) {
-        case ShaderModel::MOBILE:
-            return "mobile";
-        case ShaderModel::DESKTOP:
-            return "desktop";
-    }
-}
-
 Material* Material::Builder::build(Engine& engine) const {
    std::unique_ptr<MaterialParser> materialParser = createParser(
        downcast(engine).getBackend(), downcast(engine).getShaderLanguage(),
@@ -197,11 +187,17 @@ Material* Material::Builder::build(Engine& engine) const {
    if (!shaderModels.test(static_cast<uint32_t>(shaderModel))) {
        CString name;
        materialParser->getName(&name);
-        char shaderModelsString[16];
-        snprintf(shaderModelsString, sizeof(shaderModelsString), "%#x", shaderModels.getValue());
-        LOG(ERROR) << "The material '" << name.c_str_safe() << "' was not built for "
-                   << toString(shaderModel) << ".";
-        LOG(ERROR) << "Compiled material contains shader models " << shaderModelsString << ".";
+        slog.e << "The material '" << name.c_str_safe() << "' was not built for ";
+        switch (shaderModel) {
+            case ShaderModel::MOBILE:
+                slog.e << "mobile.\n";
+                break;
+            case ShaderModel::DESKTOP:
+                slog.e << "desktop.\n";
+                break;
+        }
+        slog.e << "Compiled material contains shader models 0x"
+                << io::hex << shaderModels.getValue() << io::dec << "." << io::endl;
        return nullptr;
    }

@@ -221,10 +217,10 @@ Material* Material::Builder::build(Engine& engine) const {
            if (materialStereoscopicType != engineStereoscopicType) {
                CString name;
                materialParser->getName(&name);
-                LOG(WARNING) << "The stereoscopic type in the compiled material '"
-                             << name.c_str_safe() << "' is " << (int) materialStereoscopicType
-                             << ", which is not compatiable with the engine's setting "
-                             << (int) engineStereoscopicType << ".";
+                slog.w << "The stereoscopic type in the compiled material '" << name.c_str_safe()
+                        << "' is " << (int)materialStereoscopicType
+                        << ", which is not compatiable with the engine's setting "
+                        << (int)engineStereoscopicType << "." << io::endl;
            }
        }
    }
@@ -342,8 +338,24 @@ FMaterial::FMaterial(FEngine& engine, const Builder& builder,

    processBlendingMode(parser);
    processSpecializationConstants(engine, builder, parser);
+    processMutableSpecializationConstants(engine, builder, parser);
    processPushConstants(engine, parser);
    processDescriptorSets(engine, parser);
+
+    switch (mMaterialDomain) {
+        case filament::MaterialDomain::SURFACE:
+            mVariantBits = VARIANT_BITS;
+            break;
+        case filament::MaterialDomain::POST_PROCESS:
+            mVariantBits = POST_PROCESS_VARIANT_BITS;
+            break;
+        case filament::MaterialDomain::COMPUTE:
+            mVariantBits = 0;
+            break;
+    }
+    mCachedPrograms = FixedCapacityVector<backend::Handle<backend::HwProgram>>(
+            1 << (mVariantBits + mMaterialMutableConstants.size()));
+
    precacheDepthVariants(engine);

 #if FILAMENT_ENABLE_MATDBG
@@ -366,12 +378,9 @@ void FMaterial::invalidate(Variant::type_t variantMask, Variant::type_t variantV
        !mHasCustomDepthShader) {
        // it would be unsafe to invalidate any of the cached depth variant
        if (UTILS_UNLIKELY(!((variantMask & Variant::DEP) && !(variantValue & Variant::DEP)))) {
-            char variantMaskString[16];
-            snprintf(variantMaskString, sizeof(variantMaskString), "%#x", +variantMask);
-            char variantValueString[16];
-            snprintf(variantValueString, sizeof(variantValueString), "%#x", +variantValue);
-            LOG(WARNING) << "FMaterial::invalidate(" << variantMaskString << ", "
-                         << variantValueString << ") would corrupt the depth variant cache";
+            slog.w << io::hex << "FMaterial::invalidate("
+                   << +variantMask << ", " << +variantValue
+                   << ") would corrupt the depth variant cache" << io::endl;
        }
        variantMask |= Variant::DEP;
        variantValue &= ~Variant::DEP;
@@ -397,8 +406,8 @@ void FMaterial::terminate(FEngine& engine) {
                    << pos->second.size() << " instances still alive.";
        } else {
            if (UTILS_UNLIKELY(!pos->second.empty())) {
-                LOG(ERROR) << "destroying material \"" << this->getName().c_str_safe() << "\" but "
-                           << pos->second.size() << " instances still alive.";
+                slog.e << "destroying material \"" << this->getName().c_str_safe() << "\" but "
+                              << pos->second.size() << " instances still alive." << io::endl;
            }
        }
    }
@@ -449,13 +458,17 @@ void FMaterial::compile(CompilerPriorityQueue const priority,
    UserVariantFilterMask const variantFilter =
            ~variantSpec & UserVariantFilterMask(UserVariantFilterBit::ALL);

+    int mutableConstantVariations = 1 << mMaterialMutableConstants.size();
+
    if (UTILS_LIKELY(mEngine.getDriverApi().isParallelShaderCompileSupported())) {
        auto const& variants = isVariantLit() ?
                VariantUtils::getLitVariants() : VariantUtils::getUnlitVariants();
        for (auto const variant: variants) {
            if (!variantFilter || variant == Variant::filterUserVariant(variant, variantFilter)) {
                if (hasVariant(variant)) {
-                    prepareProgram(variant, priority);
+                    for (int spec = 0; spec < mutableConstantVariations; spec++) {
+                        prepareProgram(variant, Program::MutableSpecConstantsInfo(spec), priority);
+                    }
                }
            }
        }
@@ -496,6 +509,11 @@ FMaterialInstance* FMaterial::getDefaultInstance() noexcept {
    return mDefaultMaterialInstance;
 }

+bool FMaterial::isCached(Variant const variant,
+        const backend::Program::MutableSpecConstantsInfo mutableSpecConstants) const noexcept {
+    return bool(mCachedPrograms[getCachedProgramIndex(variant, mutableSpecConstants)]);
+}
+
 bool FMaterial::hasParameter(const char* name) const noexcept {
    return mUniformInterfaceBlock.hasField(name) ||
           mSamplerInterfaceBlock.hasSampler(name) ||
@@ -536,14 +554,15 @@ bool FMaterial::hasVariant(Variant const variant) const noexcept {
 }

 void FMaterial::prepareProgramSlow(Variant const variant,
+        const backend::Program::MutableSpecConstantsInfo mutableSpecConstants,
        backend::CompilerPriorityQueue const priorityQueue) const noexcept {
    assert_invariant(mEngine.hasFeatureLevel(mFeatureLevel));
    switch (getMaterialDomain()) {
        case MaterialDomain::SURFACE:
-            getSurfaceProgramSlow(variant, priorityQueue);
+            getSurfaceProgramSlow(variant, mutableSpecConstants, priorityQueue);
            break;
        case MaterialDomain::POST_PROCESS:
-            getPostProcessProgramSlow(variant, priorityQueue);
+            getPostProcessProgramSlow(variant, mutableSpecConstants, priorityQueue);
            break;
        case MaterialDomain::COMPUTE:
            // TODO: implement MaterialDomain::COMPUTE
@@ -552,6 +571,7 @@ void FMaterial::prepareProgramSlow(Variant const variant,
 }

 void FMaterial::getSurfaceProgramSlow(Variant const variant,
+        const backend::Program::MutableSpecConstantsInfo mutableSpecConstants,
        CompilerPriorityQueue const priorityQueue) const noexcept {
    // filterVariant() has already been applied in generateCommands(), shouldn't be needed here
    // if we're unlit, we don't have any bits that correspond to lit materials
@@ -562,25 +582,25 @@ void FMaterial::getSurfaceProgramSlow(Variant const variant,
    Variant const vertexVariant   = Variant::filterVariantVertex(variant);
    Variant const fragmentVariant = Variant::filterVariantFragment(variant);

-    Program pb{ getProgramWithVariants(variant, vertexVariant, fragmentVariant) };
+    Program pb{ getProgramWithVariants(variant, vertexVariant, fragmentVariant, mutableSpecConstants) };
    pb.priorityQueue(priorityQueue);
    pb.multiview(
            mEngine.getConfig().stereoscopicType == StereoscopicType::MULTIVIEW &&
            Variant::isStereoVariant(variant));
-    createAndCacheProgram(std::move(pb), variant);
+    createAndCacheProgram(std::move(pb), variant, mutableSpecConstants);
 }

 void FMaterial::getPostProcessProgramSlow(Variant const variant,
+        const backend::Program::MutableSpecConstantsInfo mutableSpecConstants,
        CompilerPriorityQueue const priorityQueue) const noexcept {
-    Program pb{ getProgramWithVariants(variant, variant, variant) };
+    Program pb{ getProgramWithVariants(variant, variant, variant, mutableSpecConstants) };
    pb.priorityQueue(priorityQueue);
-    createAndCacheProgram(std::move(pb), variant);
+    createAndCacheProgram(std::move(pb), variant, mutableSpecConstants);
 }

-Program FMaterial::getProgramWithVariants(
-        Variant variant,
-        Variant vertexVariant,
-        Variant fragmentVariant) const {
+Program FMaterial::getProgramWithVariants(Variant variant,
+        Variant vertexVariant, Variant fragmentVariant,
+        const backend::Program::MutableSpecConstantsInfo mutableSpecConstants) const {
    FEngine const& engine = mEngine;
    const ShaderModel sm = engine.getShaderModel();
    const bool isNoop = engine.getBackend() == Backend::NOOP;
@@ -641,29 +661,34 @@ Program FMaterial::getProgramWithVariants(
            mProgramDescriptorBindings[+DescriptorSetBindingPoints::PER_RENDERABLE]);
    program.descriptorBindings(+DescriptorSetBindingPoints::PER_MATERIAL,
            mProgramDescriptorBindings[+DescriptorSetBindingPoints::PER_MATERIAL]);
-    program.specializationConstants(mSpecializationConstants);
+    program.specializationConstants(mSpecializationConstants,
+            CONFIG_MAX_RESERVED_SPEC_CONSTANTS + mMaterialConstants.size(), mutableSpecConstants);

    program.pushConstants(ShaderStage::VERTEX, mPushConstants[uint8_t(ShaderStage::VERTEX)]);
    program.pushConstants(ShaderStage::FRAGMENT, mPushConstants[uint8_t(ShaderStage::FRAGMENT)]);

-    program.cacheId(hash::combine(size_t(mCacheId), variant.key));
+    program.cacheId(
+            hash::combine(size_t(mCacheId),
+                    hash::combine(variant.key, mutableSpecConstants.getValue())));

    return program;
 }

-void FMaterial::createAndCacheProgram(Program&& p, Variant const variant) const noexcept {
+void FMaterial::createAndCacheProgram(Program&& p, Variant const variant,
+        Program::MutableSpecConstantsInfo const mutableSpecConstants) const noexcept {
    FEngine const& engine = mEngine;
    DriverApi& driverApi = mEngine.getDriverApi();

    bool const isShared = isSharedVariant(variant);
+    size_t const cacheIndex = getCachedProgramIndex(variant, mutableSpecConstants);

    // Check if the default material has this program cached
    if (isShared) {
        FMaterial const* const pDefaultMaterial = engine.getDefaultMaterial();
        if (pDefaultMaterial) {
-            auto const program = pDefaultMaterial->mCachedPrograms[variant.key];
+            auto const program = pDefaultMaterial->mCachedPrograms[cacheIndex];
            if (program) {
-                mCachedPrograms[variant.key] = program;
+                mCachedPrograms[cacheIndex] = program;
                return;
            }
        }
@@ -672,17 +697,17 @@ void FMaterial::createAndCacheProgram(Program&& p, Variant const variant) const
    auto const program = driverApi.createProgram(std::move(p));
    driverApi.setDebugTag(program.getId(), mName);
    assert_invariant(program);
-    mCachedPrograms[variant.key] = program;
+    mCachedPrograms[cacheIndex] = program;

    // If the default material doesn't already have this program cached, and all caching conditions
    // are met (Surface Domain and no custom depth shader), cache it now.
    // New Materials will inherit these program automatically.
    if (isShared) {
        FMaterial const* const pDefaultMaterial = engine.getDefaultMaterial();
-        if (pDefaultMaterial && !pDefaultMaterial->mCachedPrograms[variant.key]) {
+        if (pDefaultMaterial && !pDefaultMaterial->mCachedPrograms[cacheIndex]) {
            // set the tag to the default material name
            driverApi.setDebugTag(program.getId(), mName);
-            pDefaultMaterial->mCachedPrograms[variant.key] = program;
+            pDefaultMaterial->mCachedPrograms[cacheIndex] = program;
        }
    }
 }
@@ -730,6 +755,14 @@ size_t FMaterial::getParameters(ParameterInfo* parameters, size_t count) const n
    return count;
 }

+std::optional<uint32_t> FMaterial::getMutableConstantId(std::string_view name) const noexcept {
+    auto const pos = mMutableSpecializationConstantsNameToIndex.find(name);
+    if (pos != mMutableSpecializationConstantsNameToIndex.end()) {
+        return pos->second;
+    }
+    return std::nullopt;
+}
+
 #if FILAMENT_ENABLE_MATDBG

 // Swaps in an edited version of the original package that was used to create the material. The
@@ -738,7 +771,7 @@ size_t FMaterial::getParameters(ParameterInfo* parameters, size_t count) const n
 // source strings, so here we trigger a rebuild of the HwProgram objects.
 void FMaterial::applyPendingEdits() noexcept {
    const char* name = mName.c_str();
-    DLOG(INFO) << "Applying edits to " << (name ? name : "(untitled)");
+    slog.d << "Applying edits to " << (name ? name : "(untitled)") << io::endl;
    destroyPrograms(mEngine); // FIXME: this will not destroy the shared variants
    latchPendingEdits();
 }
@@ -788,7 +821,9 @@ void FMaterial::onQueryCallback(void* userdata, VariantList* pActiveVariants) {

 #endif // FILAMENT_ENABLE_MATDBG

-[[nodiscard]] Handle<HwProgram> FMaterial::getProgramWithMATDBG(Variant const variant) const noexcept {
+[[nodiscard]] Handle<HwProgram> FMaterial::getProgramWithMATDBG(Variant const variant,
+        Program::MutableSpecConstantsInfo const mutableSpecConstants) const noexcept {
+    size_t cacheIndex = getCachedProgramIndex(variant, mutableSpecConstants);
 #if FILAMENT_ENABLE_MATDBG
    assert_invariant((size_t)variant.key < VARIANT_COUNT);
    std::unique_lock lock(mActiveProgramsLock);
@@ -803,13 +838,13 @@ void FMaterial::onQueryCallback(void* userdata, VariantList* pActiveVariants) {
    lock.unlock();
    if (isSharedVariant(variant)) {
        FMaterial const* const pDefaultMaterial = mEngine.getDefaultMaterial();
-        if (pDefaultMaterial && pDefaultMaterial->mCachedPrograms[variant.key]) {
-            return pDefaultMaterial->getProgram(variant);
+        if (pDefaultMaterial && pDefaultMaterial->mCachedPrograms[cacheIndex]) {
+            return pDefaultMaterial->getProgram(variant, mutableSpecConstants);
        }
    }
 #endif
-    assert_invariant(mCachedPrograms[variant.key]);
-    return mCachedPrograms[variant.key];
+    assert_invariant(mCachedPrograms[cacheIndex]);
+    return mCachedPrograms[cacheIndex];
 }

 void FMaterial::destroyPrograms(FEngine& engine,
@@ -822,7 +857,7 @@ void FMaterial::destroyPrograms(FEngine& engine,
        case MaterialDomain::SURFACE: {
            if (mIsDefaultMaterial || mHasCustomDepthShader) {
                // default material, or we have custom depth shaders, we destroy all variants
-                for (size_t k = 0, n = VARIANT_COUNT; k < n; ++k) {
+                for (size_t k = 0, n = cachedPrograms.size(); k < n; ++k) {
                    if ((k & variantMask) == variantValue) {
                        // Only destroy if the handle is valid. Not strictly needed, but we have a lot
                        // of variants, and this generates traffic in the command queue.
@@ -840,7 +875,7 @@ void FMaterial::destroyPrograms(FEngine& engine,
                UTILS_UNUSED_IN_RELEASE
                auto const UTILS_NULLABLE pDefaultMaterial = engine.getDefaultMaterial();

-                for (size_t k = 0, n = VARIANT_COUNT; k < n; ++k) {
+                for (size_t k = 0, n = cachedPrograms.size(); k < n; ++k) {
                    if ((k & variantMask) == variantValue) {
                        // Only destroy if the handle is valid. Not strictly needed, but we have a lot
                        // of variant, and this generates traffic in the command queue.
@@ -852,7 +887,7 @@ void FMaterial::destroyPrograms(FEngine& engine,
                                // During Engine::shutdown, auto-cleanup destroys the
                                // default material first
                                assert_invariant(!pDefaultMaterial ||
-                                        pDefaultMaterial->mCachedPrograms[k]);
+                                        pDefaultMaterial->mCachedPrograms[k & (VARIANT_COUNT - 1)]);
                                // we don't own this variant, skip, but clear the entry.
                                cachedPrograms[k].clear();
                                continue;
@@ -866,7 +901,7 @@ void FMaterial::destroyPrograms(FEngine& engine,
            break;
        }
        case MaterialDomain::POST_PROCESS: {
-            for (size_t k = 0, n = POST_PROCESS_VARIANT_COUNT; k < n; ++k) {
+            for (size_t k = 0, n = cachedPrograms.size(); k < n; ++k) {
                if ((k & variantMask) == variantValue) {
                    // Only destroy if the handle is valid. Not strictly needed, but we have a lot
                    // of variant, and this generates traffic in the command queue.
@@ -878,8 +913,13 @@ void FMaterial::destroyPrograms(FEngine& engine,
            break;
        }
        case MaterialDomain::COMPUTE: {
-            // Compute programs don't have variants
-            driverApi.destroyProgram(std::move(cachedPrograms[0]));
+            for (size_t k = 0, n = cachedPrograms.size(); k < n; ++k) {
+                // Only destroy if the handle is valid. Not strictly needed, but we have a lot
+                // of variant, and this generates traffic in the command queue.
+                if (cachedPrograms[k]) {
+                    driverApi.destroyProgram(std::move(cachedPrograms[k]));
+                }
+            }
            break;
        }
    }
@@ -1114,6 +1154,19 @@ void FMaterial::processSpecializationConstants(FEngine& engine, Builder const& b
    }
 }

+void FMaterial::processMutableSpecializationConstants(FEngine& engine, Builder const& builder,
+        MaterialParser const* const parser) {
+    // Older materials won't have a mutable constants chunk, but that's okay.
+    parser->getMutableConstants(&mMaterialMutableConstants);
+    for (size_t i = 0, c = mMaterialMutableConstants.size(); i < c; i++) {
+        auto& item = mMaterialMutableConstants[i];
+        // the key can be a string_view because mMaterialMutableConstants owns the CString
+        std::string_view const key{ item.name.data(), item.name.size() };
+        mMutableSpecializationConstantsNameToIndex[key] = i;
+        mDefaultMutableSpecializationConstants.set(i, item.defaultValue);
+    }
+}
+
 void FMaterial::processPushConstants(FEngine&, MaterialParser const* parser) {
    FixedCapacityVector<Program::PushConstant>& vertexConstants =
            mPushConstants[uint8_t(ShaderStage::VERTEX)];
@@ -1169,7 +1222,8 @@ void FMaterial::precacheDepthVariants(FEngine& engine) {
            }
            assert_invariant(Variant::isValidDepthVariant(variant));
            if (hasVariant(variant)) {
-                prepareProgram(variant);
+                // The default material shouldn't ever have mutable spec constants.
+                prepareProgram(variant, Program::MutableSpecConstantsInfo(0));
            }
        }
        return;
@@ -1182,9 +1236,16 @@ void FMaterial::precacheDepthVariants(FEngine& engine) {
        FMaterial const* const pDefaultMaterial = engine.getDefaultMaterial();
        assert_invariant(pDefaultMaterial);
        auto const allDepthVariants = VariantUtils::getDepthVariants();
+        int mutableConstantVariations = 1 << mMaterialMutableConstants.size();
        for (auto const variant: allDepthVariants) {
            assert_invariant(Variant::isValidDepthVariant(variant));
-            mCachedPrograms[variant.key] = pDefaultMaterial->mCachedPrograms[variant.key];
+            size_t defaultCacheIndex = pDefaultMaterial->getCachedProgramIndex(variant,
+                    Program::MutableSpecConstantsInfo(0));
+            for (int spec = 0; spec < mutableConstantVariations; spec++) {
+                size_t cacheIndex = getCachedProgramIndex(variant,
+                        Program::MutableSpecConstantsInfo(spec));
+                mCachedPrograms[cacheIndex] = pDefaultMaterial->mCachedPrograms[defaultCacheIndex];
+            }
        }
    }
 }
@@ -122,9 +122,8 @@ public:

    FEngine& getEngine() const noexcept  { return mEngine; }

-    bool isCached(Variant const variant) const noexcept {
-        return bool(mCachedPrograms[variant.key]);
-    }
+    bool isCached(Variant const variant,
+            const backend::Program::MutableSpecConstantsInfo mutableSpecConstants) const noexcept;

    void invalidate(Variant::type_t variantMask = 0, Variant::type_t variantValue = 0) noexcept;

@@ -132,26 +131,31 @@ public:
    // Must be called outside of backend render pass.
    // Must be called before getProgram() below.
    void prepareProgram(Variant const variant,
+            backend::Program::MutableSpecConstantsInfo const mutableSpecConstants,
            backend::CompilerPriorityQueue const priorityQueue = CompilerPriorityQueue::HIGH) const noexcept {
        // prepareProgram() is called for each RenderPrimitive in the scene, so it must be efficient.
-        if (UTILS_UNLIKELY(!isCached(variant))) {
-            prepareProgramSlow(variant, priorityQueue);
+        if (UTILS_UNLIKELY(!isCached(variant, mutableSpecConstants))) {
+            prepareProgramSlow(variant, mutableSpecConstants, priorityQueue);
        }
    }

-    // getProgram returns the backend program for the material's given variant.
+    // getProgram returns the backend program for the material's given variant and set of mutable
+    // spec constants.
    // Must be called after prepareProgram().
    [[nodiscard]]
-    backend::Handle<backend::HwProgram> getProgram(Variant const variant) const noexcept {
+    backend::Handle<backend::HwProgram> getProgram(Variant const variant,
+            backend::Program::MutableSpecConstantsInfo const mutableSpecConstants) const noexcept {
 #if FILAMENT_ENABLE_MATDBG
-        return getProgramWithMATDBG(variant);
+        return getProgramWithMATDBG(variant, mutableSpecConstants);
 #endif
-        assert_invariant(mCachedPrograms[variant.key]);
-        return mCachedPrograms[variant.key];
+        size_t index = getCachedProgramIndex(variant, mutableSpecConstants);
+        assert_invariant(mCachedPrograms[index]);
+        return mCachedPrograms[index];
    }

    [[nodiscard]]
-    backend::Handle<backend::HwProgram> getProgramWithMATDBG(Variant variant) const noexcept;
+    backend::Handle<backend::HwProgram> getProgramWithMATDBG(Variant variant,
+            backend::Program::MutableSpecConstantsInfo const mutableSpecConstants) const noexcept;

    bool isVariantLit() const noexcept { return mIsVariantLit; }

@@ -208,6 +212,12 @@ public:
    }
    size_t getParameters(ParameterInfo* parameters, size_t count) const noexcept;

+    uint32_t getMutableConstantCount() const noexcept { return mMaterialMutableConstants.size(); }
+    std::optional<uint32_t> getMutableConstantId(std::string_view name) const noexcept;
+    backend::Program::MutableSpecConstantsInfo getDefaultMutableConstants() const noexcept {
+        return mDefaultMutableSpecializationConstants;
+    }
+
    uint32_t generateMaterialInstanceId() const noexcept { return mMaterialInstanceId++; }

    void destroyPrograms(FEngine& engine,
@@ -261,34 +271,48 @@ public:
 private:
    bool hasVariant(Variant variant) const noexcept;
    void prepareProgramSlow(Variant variant,
+            backend::Program::MutableSpecConstantsInfo mutableSpecConstants,
            CompilerPriorityQueue priorityQueue) const noexcept;
    void getSurfaceProgramSlow(Variant variant,
+            backend::Program::MutableSpecConstantsInfo mutableSpecConstants,
            CompilerPriorityQueue priorityQueue) const noexcept;
    void getPostProcessProgramSlow(Variant variant,
+            backend::Program::MutableSpecConstantsInfo mutableSpecConstants,
            CompilerPriorityQueue priorityQueue) const noexcept;
    backend::Program getProgramWithVariants(Variant variant,
-            Variant vertexVariant, Variant fragmentVariant) const;
+            Variant vertexVariant, Variant fragmentVariant,
+            backend::Program::MutableSpecConstantsInfo mutableSpecConstants) const;

    void processBlendingMode(MaterialParser const* parser);

    void processSpecializationConstants(FEngine& engine, Builder const& builder,
            MaterialParser const* parser);

+    void processMutableSpecializationConstants(FEngine& engine, Builder const& builder,
+            MaterialParser const* parser);
+
    void processPushConstants(FEngine& engine, MaterialParser const* parser);

    void precacheDepthVariants(FEngine& engine);

    void processDescriptorSets(FEngine& engine, MaterialParser const* parser);

-    void createAndCacheProgram(backend::Program&& p, Variant variant) const noexcept;
+    void createAndCacheProgram(backend::Program&& p, Variant variant,
+            backend::Program::MutableSpecConstantsInfo mutableSpecConstants) const noexcept;

    inline bool isSharedVariant(Variant const variant) const {
        return (mMaterialDomain == MaterialDomain::SURFACE) && !mIsDefaultMaterial &&
               !mHasCustomDepthShader && Variant::isValidDepthVariant(variant);
    }

+    inline size_t getCachedProgramIndex(const Variant variant,
+            const backend::Program::MutableSpecConstantsInfo mutableSpecConstants) const noexcept {
+        return static_cast<size_t>(variant.key) |
+                (static_cast<size_t>(mutableSpecConstants.getValue()) << mVariantBits);
+    }
+
    // try to order by frequency of use
-    mutable std::array<backend::Handle<backend::HwProgram>, VARIANT_COUNT> mCachedPrograms;
+    mutable utils::FixedCapacityVector<backend::Handle<backend::HwProgram>> mCachedPrograms;
    DescriptorSetLayout mPerViewDescriptorSetLayout;
    DescriptorSetLayout mPerViewDescriptorSetLayoutVsm;
    DescriptorSetLayout mDescriptorSetLayout;
@@ -324,6 +348,7 @@ private:
    bool mHasCustomDepthShader = false;
    bool mIsDefaultMaterial = false;
    bool mSpecularAntiAliasing = false;
+    uint8_t mVariantBits;

    // reserve some space to construct the default material instance
    mutable FMaterialInstance* mDefaultMaterialInstance = nullptr;
@@ -348,6 +373,13 @@ private:
    // current specialization constants for the HwProgram
    utils::FixedCapacityVector<backend::Program::SpecializationConstant> mSpecializationConstants;

+    // Mutable constants defined by this Material.
+    utils::FixedCapacityVector<MaterialMutableConstant> mMaterialMutableConstants;
+    // A map from the Constant name to the mMutableMaterialConstant index
+    std::unordered_map<std::string_view, uint32_t> mMutableSpecializationConstantsNameToIndex;
+    // Default values for the mutable constants.
+    backend::Program::MutableSpecConstantsInfo mDefaultMutableSpecializationConstants;
+
    // current push constants for the HwProgram
    std::array<utils::FixedCapacityVector<backend::Program::PushConstant>,
            backend::Program::SHADER_TYPE_COUNT>
@@ -35,12 +35,12 @@
 #include <backend/Handle.h>

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

 #include <math/scalar.h>

@@ -63,6 +63,7 @@ FMaterialInstance::FMaterialInstance(FEngine& engine, FMaterial const* material,
                                     const char* name) noexcept
        : mMaterial(material),
          mDescriptorSet("MaterialInstance", material->getDescriptorSetLayout()),
+          mConstants(material->getDefaultMutableConstants()),
          mCulling(CullingMode::BACK),
          mShadowCulling(CullingMode::BACK),
          mDepthFunc(RasterState::DepthFunc::LE),
@@ -128,6 +129,7 @@ FMaterialInstance::FMaterialInstance(FEngine& engine,
          mTextureParameters(other->mTextureParameters),
          mDescriptorSet(other->mDescriptorSet.duplicate(
                "MaterialInstance", mMaterial->getDescriptorSetLayout())),
+          mConstants(other->mConstants),
          mPolygonOffset(other->mPolygonOffset),
          mStencilState(other->mStencilState),
          mMaskThreshold(other->mMaskThreshold),
@@ -340,7 +342,7 @@ float FMaterialInstance::getSpecularAntiAliasingThreshold() const noexcept {

 void FMaterialInstance::setDoubleSided(bool const doubleSided) noexcept {
    if (UTILS_UNLIKELY(!mMaterial->hasDoubleSidedCapability())) {
-        LOG(WARNING) << "Parent material does not have double-sided capability.";
+        slog.w << "Parent material does not have double-sided capability." << io::endl;
        return;
    }
    setParameter("_doubleSided", doubleSided);
@@ -383,18 +385,19 @@ void FMaterialInstance::use(FEngine::DriverApi& driver) const {
    if (UTILS_UNLIKELY(mMissingSamplerDescriptors.any())) {
        std::call_once(mMissingSamplersFlag, [this] {
            auto const& list = mMaterial->getSamplerInterfaceBlock().getSamplerInfoList();
-            LOG(WARNING) << "sampler parameters not set in MaterialInstance \""
-                         << mName.c_str_safe() << "\" or Material \""
-                         << mMaterial->getName().c_str_safe() << "\":";
+            slog.w << "sampler parameters not set in MaterialInstance \""
+                   << mName.c_str_safe() << "\" or Material \""
+                   << mMaterial->getName().c_str_safe() << "\":\n";
            mMissingSamplerDescriptors.forEachSetBit([&list](descriptor_binding_t binding) {
                auto const pos = std::find_if(list.begin(), list.end(), [binding](const auto& item) {
                    return item.binding == binding;
                });
                // just safety-check, should never fail
                if (UTILS_LIKELY(pos != list.end())) {
-                    LOG(WARNING) << "[" << +binding << "] " << pos->name.c_str();
+                    slog.w << "[" << +binding << "] " << pos->name.c_str() << '\n';
                }
            });
+            flush(slog.w);
        });
        mMissingSamplerDescriptors.clear();
    }
@@ -31,6 +31,7 @@

 #include <backend/DriverEnums.h>
 #include <backend/Handle.h>
+#include <backend/Program.h>

 #include <utils/BitmaskEnum.h>
 #include <utils/bitset.h>
@@ -66,7 +67,7 @@ public:
    void terminate(FEngine& engine);

    void commitStreamUniformAssociations(FEngine::DriverApi& driver);
-    
+
    void commit(FEngine& engine) const;

    void commit(FEngine::DriverApi& driver) const;
@@ -242,6 +243,10 @@ public:

    using MaterialInstance::setParameter;

+    const backend::Program::MutableSpecConstantsInfo getMutableSpecConstants() const noexcept {
+        return mConstants;
+    }
+
 private:
    friend class FMaterial;
    friend class MaterialInstance;
@@ -264,6 +269,12 @@ private:
    template<typename T>
    T getParameterImpl(std::string_view name) const;

+    template<typename T>
+    void setConstantImpl(std::string_view name, T const& value);
+
+    template<typename T>
+    T getConstantImpl(std::string_view name) const;
+
    // keep these grouped, they're accessed together in the render-loop
    FMaterial const* mMaterial = nullptr;

@@ -277,6 +288,7 @@ private:
    mutable DescriptorSet mDescriptorSet;
    UniformBuffer mUniforms;
    bool mHasStreamUniformAssociations = false;
+    backend::Program::MutableSpecConstantsInfo mConstants;

    backend::PolygonOffset mPolygonOffset{};
    backend::StencilState mStencilState{};
@@ -52,12 +52,12 @@

 #include <private/utils/Tracing.h>

-#include <utils/JobSystem.h>
-#include <utils/Logger.h>
-#include <utils/Panic.h>
 #include <utils/compiler.h>
-#include <utils/debug.h>
+#include <utils/JobSystem.h>
+#include <utils/Log.h>
 #include <utils/ostream.h>
+#include <utils/Panic.h>
+#include <utils/debug.h>

 #include <chrono>
 #include <limits>
@@ -155,10 +155,14 @@ FRenderer::FRenderer(FEngine& engine) :
 FRenderer::~FRenderer() noexcept {
    // There shouldn't be any resource left when we get here, but if there is, make sure
    // to free what we can (it would probably mean something when wrong).
+#ifndef NDEBUG
    size_t const wm = getCommandsHighWatermark();
    size_t const wmpct = wm / (mEngine.getPerFrameCommandsSize() / 100);
-    DLOG(INFO) << "Renderer: Commands High watermark " << wm / 1024 << " KiB (" << wmpct << "%), "
-               << wm / sizeof(Command) << " commands, " << sizeof(Command) << " bytes/command";
+    slog.d << "Renderer: Commands High watermark "
+    << wm / 1024 << " KiB (" << wmpct << "%), "
+    << wm / sizeof(Command) << " commands, " << sizeof(Command) << " bytes/command"
+    << io::endl;
+#endif
 }

 void FRenderer::terminate(FEngine& engine) {
@@ -459,9 +463,10 @@ void FRenderer::readPixels(FRenderTarget* renderTarget,

    // TODO: change the following to an assert when client call sites have addressed the issue.
    if (!renderTarget->supportsReadPixels()) {
-        LOG(WARNING) << "readPixels() must be called with a renderTarget with COLOR0 created with "
-                        "TextureUsage::BLIT_SRC. This precondition will be asserted in a later "
-                        "release of Filament.";
+        slog.w << "readPixels() must be called with a renderTarget with COLOR0 created with "
+                         "TextureUsage::BLIT_SRC.  This precondition will be asserted in a later "
+                         "release of Filament."
+                      << io::endl;
    }

    RendererUtils::readPixels(mEngine.getDriverApi(), renderTarget->getHwHandle(),
@@ -1476,9 +1481,7 @@ void FRenderer::renderJob(RootArenaScope& rootArenaScope, FView& view) {
    }
 #endif

-    //utils::io::sstream graphviz;
-    //fg.export_graphviz(graphviz, view.getName());
-    //DLOG(INFO) << graphviz.c_str();
+    //fg.export_graphviz(slog.d, view.getName());

    fg.execute(driver);

@@ -27,14 +27,14 @@
 #include <backend/DriverEnums.h>
 #include <backend/BufferDescriptor.h>

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

 #include <algorithm>
 #include <array>
@@ -120,8 +120,8 @@ VertexBuffer::Builder& VertexBuffer::Builder::attribute(VertexAttribute const at

        mImpl->mDeclaredAttributes.set(attribute);
    } else {
-        LOG(WARNING) << "Ignoring VertexBuffer attribute, the limit of "
-                     << MAX_VERTEX_ATTRIBUTE_COUNT << " attributes has been exceeded";
+        utils::slog.w << "Ignoring VertexBuffer attribute, the limit of " <<
+                MAX_VERTEX_ATTRIBUTE_COUNT << " attributes has been exceeded" << utils::io::endl;
    }
    return *this;
 }
@@ -25,12 +25,12 @@
 #include <backend/DriverEnums.h>
 #include <backend/Handle.h>

-#include <utils/Logger.h>
-#include <utils/Panic.h>
-#include <utils/StaticString.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
+#include <utils/Log.h>
+#include <utils/Panic.h>
 #include <utils/ostream.h>
+#include <utils/StaticString.h>

 #include <utility>
 #include <limits>
@@ -108,8 +108,9 @@ void DescriptorSet::commitSlow(DescriptorSetLayout const& layout,
    auto const unsetValidDescriptors = layout.getValidDescriptors() & ~mValid;
    if (UTILS_VERY_UNLIKELY(!unsetValidDescriptors.empty())) {
        unsetValidDescriptors.forEachSetBit([&](auto i) {
-            LOG(WARNING) << (layout.isSampler(i) ? "Sampler" : "Buffer") << " descriptor " << i
-                         << " of " << mName.c_str() << " is not set. Please report this issue.";
+            slog.w << (layout.isSampler(i) ? "Sampler" : "Buffer")
+                    << " descriptor " << i << " of " << mName.c_str() << " is not set. "
+                       "Please report this issue." << io::endl;
        });
    }
 }
@@ -130,8 +131,9 @@ void DescriptorSet::bind(FEngine::DriverApi& driver, DescriptorSetBindingPoints
    // assert_invariant(mDirty.none());
    if (UTILS_VERY_UNLIKELY(mDirty.any() && !mSetAfterCommitWarning)) {
        mDirty.forEachSetBit([&](uint8_t const binding) {
-            LOG(WARNING) << "Descriptor set (handle=" << mDescriptorSetHandle.getId()
-                         << ") binding=" << (int) binding << " was set between begin/endRenderPass";
+            utils::slog.w << "Descriptor set (handle=" << mDescriptorSetHandle.getId()
+                          << ") binding=" << (int) binding
+                          << " was set between begin/endRenderPass" << utils::io::endl;
        });
        mSetAfterCommitWarning = true;
    }
@@ -29,8 +29,6 @@

 #include "details/Texture.h"

-#include <utils/Logger.h>
-
 using namespace filament;
 using namespace backend;

@@ -78,9 +76,7 @@ protected:
    }

    void TearDown() override {
-        //utils::io::sstream graphviz;
-        //fg.export_graphviz(graphviz);
-        //DLOG(INFO) << graphviz.c_str();
+        //fg.export_graphviz(utils::slog.d);
    }

    Backend backend = Backend::NOOP;
@@ -111,9 +107,7 @@ TEST(DependencyGraphTest, Simple) {

    graph.cull();

-    //utils::io::sstream graphviz;
-    //graph.export_graphviz(graphviz);
-    //DLOG(INFO) << graphviz.c_str();
+    //graph.export_graphviz(utils::slog.d);

    EXPECT_FALSE(n2->isCulled());
    EXPECT_FALSE(n1->isCulled());
@@ -147,9 +141,7 @@ TEST(DependencyGraphTest, Culling1) {

    graph.cull();

-    //utils::io::sstream graphviz;
-    //graph.export_graphviz(graphviz);
-    //DLOG(INFO) << graphviz.c_str();
+    //graph.export_graphviz(utils::slog.d);

    EXPECT_TRUE(n1_0->isCulled());
    EXPECT_TRUE(n1_0->isCulledCalled());
@@ -190,9 +182,7 @@ TEST(DependencyGraphTest, Culling2) {

    graph.cull();

-    //utils::io::sstream graphviz;
-    //graph.export_graphviz(graphviz);
-    //DLOG(INFO) << graphviz.c_str();
+    //graph.export_graphviz(utils::slog.d);

    EXPECT_TRUE(n1_0->isCulled());
    EXPECT_TRUE(n1_0_0->isCulled());
--- a/Show More
+++ b/Show More