Vulkan: Edge case test and fix for alpha channel masks

src/libANGLE/renderer/vulkan/ContextVk.cpp

@@ -378,7 +378,7 @@ void ContextVk::popDebugGroup()
     UNIMPLEMENTED();
 }
 
-void ContextVk::updateClearColorMask(const gl::BlendState &blendState)
+void ContextVk::updateColorMask(const gl::BlendState &blendState)
 {
     mClearColorMask =
         gl_vk::GetColorComponentFlags(blendState.colorMaskRed, blendState.colorMaskGreen,
@@ -444,7 +444,7 @@ void ContextVk::syncState(const gl::Context *context, const gl::State::DirtyBits
                 mPipelineDesc->updateBlendEquations(glState.getBlendState());
                 break;
             case gl::State::DIRTY_BIT_COLOR_MASK:
-                updateClearColorMask(glState.getBlendState());
+                updateColorMask(glState.getBlendState());
                 break;
             case gl::State::DIRTY_BIT_SAMPLE_ALPHA_TO_COVERAGE_ENABLED:
                 WARN() << "DIRTY_BIT_SAMPLE_ALPHA_TO_COVERAGE_ENABLED unimplemented";
@@ -555,7 +555,7 @@ void ContextVk::syncState(const gl::Context *context, const gl::State::DirtyBits
                 WARN() << "DIRTY_BIT_READ_FRAMEBUFFER_BINDING unimplemented";
                 break;
             case gl::State::DIRTY_BIT_DRAW_FRAMEBUFFER_BINDING:
-                updateClearColorMask(glState.getBlendState());
+                updateColorMask(glState.getBlendState());
                 break;
             case gl::State::DIRTY_BIT_RENDERBUFFER_BINDING:
                 WARN() << "DIRTY_BIT_RENDERBUFFER_BINDING unimplemented";

src/libANGLE/renderer/vulkan/ContextVk.h

@@ -163,6 +163,7 @@ class ContextVk : public ContextImpl
     gl::Error getIncompleteTexture(const gl::Context *context,
                                    gl::TextureType type,
                                    gl::Texture **textureOut);
+    void updateColorMask(const gl::BlendState &blendState);
 
   private:
     gl::Error initPipeline();
@@ -171,7 +172,6 @@ class ContextVk : public ContextImpl
                         vk::CommandBuffer **commandBufferOut,
                         bool *shouldApplyVertexArrayOut);
 
-    void updateClearColorMask(const gl::BlendState &blendState);
     void updateScissor(const gl::State &glState);
 
     RendererVk *mRenderer;

src/libANGLE/renderer/vulkan/FramebufferVk.cpp

@@ -390,13 +390,12 @@ gl::Error FramebufferVk::syncState(const gl::Context *context,
                         colorIndex, emulatedFormat.redBits > 0, emulatedFormat.greenBits > 0,
                         emulatedFormat.blueBits > 0, emulatedFormat.alphaBits > 0);
 
-                    // TODO(lucferron): Add a test to trigger edge case where the framebuffer
-                    // attachment would change but not the binding.
-                    // http://anglebug.com/2597
                     const angle::Format &sourceFormat =
                         renderTarget->getImageFormat().angleFormat();
                     mEmulatedAlphaAttachmentMask.set(
                         colorIndex, sourceFormat.alphaBits == 0 && emulatedFormat.alphaBits > 0);
+
+                    contextVk->updateColorMask(context->getGLState().getBlendState());
                 }
                 else
                 {

src/tests/gl_tests/ClearTest.cpp

@@ -106,6 +106,61 @@ TEST_P(ClearTest, RGBA8Framebuffer)
     EXPECT_PIXEL_NEAR(0, 0, 128, 128, 128, 128, 1.0);
 }
 
+// Test to validate that we can go from an RGBA framebuffer attachment, to an RGB one and still
+// have a correct behavior after.
+TEST_P(ClearTest, ChangeFramebufferAttachmentFromRGBAtoRGB)
+{
+    // TODO(lucferron): Diagnose and fix this on D3D9 and 11.
+    // http://anglebug.com/2685
+    ANGLE_SKIP_TEST_IF(IsD3D9() || IsD3D11());
+
+    ANGLE_GL_PROGRAM(program, angle::essl1_shaders::vs::Simple(),
+                     angle::essl1_shaders::fs::UniformColor());
+    setupQuadVertexBuffer(0.5f, 1.0f);
+    glUseProgram(program);
+    GLint positionLocation = glGetAttribLocation(program, angle::essl1_shaders::PositionAttrib());
+    ASSERT_NE(positionLocation, -1);
+    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
+    glEnableVertexAttribArray(positionLocation);
+
+    GLint colorUniformLocation =
+        glGetUniformLocation(program, angle::essl1_shaders::ColorUniform());
+    ASSERT_NE(colorUniformLocation, -1);
+
+    glUniform4f(colorUniformLocation, 1.0f, 1.0f, 1.0f, 0.5f);
+
+    glBindFramebuffer(GL_FRAMEBUFFER, mFBOs[0]);
+
+    GLTexture texture;
+    glColorMask(GL_TRUE, GL_FALSE, GL_TRUE, GL_TRUE);
+
+    glBindTexture(GL_TEXTURE_2D, texture);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, getWindowWidth(), getWindowHeight(), 0, GL_RGBA,
+                 GL_UNSIGNED_BYTE, nullptr);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
+
+    glClearColor(0.5f, 0.5f, 0.5f, 0.5f);
+    glClear(GL_COLOR_BUFFER_BIT);
+    ASSERT_GL_NO_ERROR();
+
+    // So far so good, we have an RGBA framebuffer that we've cleared to 0.5 everywhere.
+    EXPECT_PIXEL_NEAR(0, 0, 128, 0, 128, 128, 1.0);
+
+    // In the Vulkan backend, RGB textures are emulated with an RGBA texture format
+    // underneath and we keep a special mask to know that we shouldn't touch the alpha
+    // channel when we have that emulated texture. This test exists to validate that
+    // this mask gets updated correctly when the framebuffer attachment changes.
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, getWindowWidth(), getWindowHeight(), 0, GL_RGB,
+                 GL_UNSIGNED_BYTE, nullptr);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
+    ASSERT_GL_NO_ERROR();
+
+    glDrawArrays(GL_TRIANGLES, 0, 6);
+    ASSERT_GL_NO_ERROR();
+
+    EXPECT_PIXEL_RECT_EQ(0, 0, getWindowWidth(), getWindowHeight(), GLColor::magenta);
+}
+
 // Test clearing a RGB8 Framebuffer with a color mask.
 TEST_P(ClearTest, RGB8WithMaskFramebuffer)
 {