OpenGL ES: implement support for BGRA textures and reads.

ES requires GL_EXT_texture_format_BGRA8888 or GL_APPLE_texture_format_BGRA8888 to create BGRA8 internalFormat textures, and GL_EXT_read_format_bgra to read from them. Desktop GL can swizzle back and forth from RGBA8, so keep using RGBA8 if the extension is unavailable.

Intel's implementation of GL_EXT_texture_format_BGRA8888 on ES is broken, and won't create GL_BGRA8_EXT or GL_BGRA internalFormat textures, so disable the test there and modify another test to not use BGRA textures.

Change-Id: Ia81d9ff20e2849b00379f8e01fb5d2ecfa34bd53
Bug: dawn:596, dawn:1393
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/86744
Commit-Queue: Stephen White <senorblanco@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>

src/dawn/native/Toggles.cpp

@@ -147,6 +147,10 @@ namespace dawn::native {
               "Disables reading from depth/stencil textures which is unsupported on some "
               "platforms.",
               "https://crbug.com/dawn/667"}},
+            {Toggle::DisableBGRARead,
+             {"disable_bgra_read",
+              "Disables reading from BGRA textures which is unsupported on some platforms.",
+              "https://crbug.com/dawn/1393"}},
             {Toggle::DisableSampleVariables,
              {"disable_sample_variables",
               "Disables gl_SampleMask and related functionality which is unsupported on some "

src/dawn/native/Toggles.h

@@ -45,6 +45,7 @@ namespace dawn::native {
         DisableIndexedDrawBuffers,
         DisableSnormRead,
         DisableDepthStencilRead,
+        DisableBGRARead,
         DisableSampleVariables,
         UseD3D12SmallShaderVisibleHeapForTesting,
         UseDXC,

src/dawn/native/opengl/DeviceGL.cpp

@@ -55,7 +55,7 @@ namespace dawn::native::opengl {
 
     MaybeError Device::Initialize(const DeviceDescriptor* descriptor) {
         InitTogglesFromDriver();
-        mFormatTable = BuildGLFormatTable();
+        mFormatTable = BuildGLFormatTable(GetBGRAInternalFormat());
 
         return DeviceBase::Initialize(AcquireRef(new Queue(this, &descriptor->defaultQueue)));
     }
@@ -74,6 +74,10 @@ namespace dawn::native::opengl {
         bool supportsDepthStencilRead =
             gl.IsAtLeastGL(3, 0) || gl.IsGLExtensionSupported("GL_NV_read_depth_stencil");
 
+        // Desktop GL supports BGRA textures via swizzling in the driver; ES requires an extension.
+        bool supportsBGRARead =
+            gl.GetVersion().IsDesktop() || gl.IsGLExtensionSupported("GL_EXT_read_format_bgra");
+
         bool supportsSampleVariables = gl.IsAtLeastGL(4, 0) || gl.IsAtLeastGLES(3, 2) ||
                                        gl.IsGLExtensionSupported("GL_OES_sample_variables");
 
@@ -97,6 +101,7 @@ namespace dawn::native::opengl {
         SetToggle(Toggle::DisableIndexedDrawBuffers, !supportsIndexedDrawBuffers);
         SetToggle(Toggle::DisableSnormRead, !supportsSnormRead);
         SetToggle(Toggle::DisableDepthStencilRead, !supportsDepthStencilRead);
+        SetToggle(Toggle::DisableBGRARead, !supportsBGRARead);
         SetToggle(Toggle::DisableSampleVariables, !supportsSampleVariables);
         SetToggle(Toggle::FlushBeforeClientWaitSync, gl.GetVersion().IsES());
         // For OpenGL ES, we must use a placeholder fragment shader for vertex-only render pipeline.
@@ -112,6 +117,16 @@ namespace dawn::native::opengl {
         return result;
     }
 
+    GLenum Device::GetBGRAInternalFormat() const {
+        if (gl.IsGLExtensionSupported("GL_EXT_texture_format_BGRA8888") ||
+            gl.IsGLExtensionSupported("GL_APPLE_texture_format_BGRA8888")) {
+            return GL_BGRA8_EXT;
+        } else {
+            // Desktop GL will swizzle to/from RGBA8 for BGRA formats.
+            return GL_RGBA8;
+        }
+    }
+
     ResultOrError<Ref<BindGroupBase>> Device::CreateBindGroupImpl(
         const BindGroupDescriptor* descriptor) {
         DAWN_TRY(ValidateGLBindGroupDescriptor(descriptor));

src/dawn/native/opengl/DeviceGL.h

@@ -119,6 +119,7 @@ namespace dawn::native::opengl {
             const RenderPipelineDescriptor* descriptor) override;
 
         void InitTogglesFromDriver();
+        GLenum GetBGRAInternalFormat() const;
         ResultOrError<ExecutionSerial> CheckAndUpdateCompletedSerials() override;
         void DestroyImpl() override;
         MaybeError WaitForIdleForDestruction() override;

src/dawn/native/opengl/GLFormat.cpp

@@ -16,7 +16,7 @@
 
 namespace dawn::native::opengl {
 
-    GLFormatTable BuildGLFormatTable() {
+    GLFormatTable BuildGLFormatTable(GLenum internalFormatForBGRA) {
         GLFormatTable table;
 
         using Type = GLFormat::ComponentType;
@@ -71,8 +71,7 @@ namespace dawn::native::opengl {
         AddFormat(wgpu::TextureFormat::RGBA8Uint, GL_RGBA8UI, GL_RGBA_INTEGER, GL_UNSIGNED_BYTE, Type::Uint);
         AddFormat(wgpu::TextureFormat::RGBA8Sint, GL_RGBA8I, GL_RGBA_INTEGER, GL_BYTE, Type::Int);
 
-        // This doesn't have an enum for the internal format in OpenGL, so use RGBA8.
-        AddFormat(wgpu::TextureFormat::BGRA8Unorm, GL_RGBA8, GL_BGRA, GL_UNSIGNED_BYTE, Type::Float);
+        AddFormat(wgpu::TextureFormat::BGRA8Unorm, internalFormatForBGRA, GL_BGRA, GL_UNSIGNED_BYTE, Type::Float);
         AddFormat(wgpu::TextureFormat::RGB10A2Unorm, GL_RGB10_A2, GL_RGBA, GL_UNSIGNED_INT_2_10_10_10_REV, Type::Float);
         AddFormat(wgpu::TextureFormat::RG11B10Ufloat, GL_R11F_G11F_B10F, GL_RGB, GL_UNSIGNED_INT_10F_11F_11F_REV, Type::Float);
         AddFormat(wgpu::TextureFormat::RGB9E5Ufloat, GL_RGB9_E5, GL_RGB, GL_UNSIGNED_INT_5_9_9_9_REV, Type::Float);

src/dawn/native/opengl/GLFormat.h

@@ -35,7 +35,7 @@ namespace dawn::native::opengl {
     };
 
     using GLFormatTable = ityp::array<FormatIndex, GLFormat, kKnownFormatCount>;
-    GLFormatTable BuildGLFormatTable();
+    GLFormatTable BuildGLFormatTable(GLenum internalFormatForBGRA);
 
 }  // namespace dawn::native::opengl
 

src/dawn/native/opengl/supported_extensions.json

@@ -18,6 +18,8 @@
     "supported_extensions": [
         "GL_EXT_texture_compression_s3tc",
         "GL_EXT_texture_compression_s3tc_srgb",
-        "GL_OES_EGL_image"
+        "GL_OES_EGL_image",
+        "GL_EXT_texture_format_BGRA8888",
+        "GL_APPLE_texture_format_BGRA8888"
     ]
 }

src/dawn/tests/end2end/BindGroupTests.cpp

@@ -1601,7 +1601,7 @@ TEST_P(BindGroupTests, CreateWithDestroyedResource) {
         wgpu::TextureDescriptor textureDesc;
         textureDesc.usage = wgpu::TextureUsage::TextureBinding;
         textureDesc.size = {1, 1, 1};
-        textureDesc.format = wgpu::TextureFormat::BGRA8Unorm;
+        textureDesc.format = wgpu::TextureFormat::RGBA8Unorm;
 
         // Create view, then destroy.
         {

src/dawn/tests/end2end/TextureFormatTests.cpp

@@ -458,8 +458,12 @@ TEST_P(TextureFormatTest, RGBA8Unorm) {
 
 // Test the BGRA8Unorm format
 TEST_P(TextureFormatTest, BGRA8Unorm) {
-    // TODO(crbug.com/dawn/596): BGRA is unsupported on OpenGL ES; add workaround or validation
-    DAWN_SUPPRESS_TEST_IF(IsOpenGLES());
+    DAWN_TEST_UNSUPPORTED_IF(HasToggleEnabled("disable_bgra_read"));
+
+    // Intel's implementation of BGRA on ES is broken: it claims to support
+    // GL_EXT_texture_format_BGRA8888, but won't accept GL_BGRA or GL_BGRA8_EXT as internalFormat.
+    DAWN_SUPPRESS_TEST_IF(IsIntel() && IsOpenGLES() && IsLinux());
+
     uint8_t maxValue = std::numeric_limits<uint8_t>::max();
     std::vector<uint8_t> textureData = {maxValue, 1, 0, maxValue};
     std::vector<float> uncompressedData = {0.0f, 1.0f / maxValue, 1.0f, 1.0f};