Vulkan: Add test and fix clear on RGB8 with color masks

src/libANGLE/renderer/vulkan/FramebufferVk.cpp

@@ -134,7 +134,7 @@ gl::Error FramebufferVk::clear(const gl::Context *context, GLbitfield mask)
     VkColorComponentFlags colorMaskFlags = contextVk->getClearColorMask();
     if (clearColor && (mActiveColorComponents & colorMaskFlags) != mActiveColorComponents)
     {
-        ANGLE_TRY(clearWithDraw(contextVk, colorMaskFlags));
+        ANGLE_TRY(clearWithDraw(context, colorMaskFlags));
 
         // Stencil clears must be handled separately. The only way to write out a stencil value from
         // a fragment shader in Vulkan is with VK_EXT_shader_stencil_export. Support for this
@@ -587,8 +587,10 @@ gl::Error FramebufferVk::clearWithClearAttachments(ContextVk *contextVk,
     return gl::NoError();
 }
 
-gl::Error FramebufferVk::clearWithDraw(ContextVk *contextVk, VkColorComponentFlags colorMaskFlags)
+gl::Error FramebufferVk::clearWithDraw(const gl::Context *context,
+                                       VkColorComponentFlags colorMaskFlags)
 {
+    ContextVk *contextVk             = vk::GetImpl(context);
     RendererVk *renderer             = contextVk->getRenderer();
     vk::ShaderLibrary *shaderLibrary = renderer->getShaderLibrary();
 
@@ -654,7 +656,18 @@ gl::Error FramebufferVk::clearWithDraw(ContextVk *contextVk, VkColorComponentFla
     vk::CommandBuffer *writeCommands = nullptr;
     ANGLE_TRY(appendWriteResource(renderer, &writeCommands));
 
+    // If the format of the framebuffer does not have an alpha channel, we need to make sure we does
+    // not affect the alpha channel of the type we're using to emulate the format.
+    // TODO(jmadill): Implement EXT_draw_buffers http://anglebug.com/2394
+    RenderTargetVk *renderTarget = mRenderTargetCache.getColors()[0];
+    ASSERT(renderTarget);
+
+    const vk::Format &imageFormat     = renderTarget->getImageFormat();
     VkClearColorValue clearColorValue = contextVk->getClearColorValue().color;
+    bool overrideAlphaWithOne =
+        imageFormat.textureFormat().alphaBits > 0 && imageFormat.angleFormat().alphaBits == 0;
+    clearColorValue.float32[3] = overrideAlphaWithOne ? 1.0f : clearColorValue.float32[3];
+
     drawCommands->pushConstants(pipelineLayout.get(), VK_SHADER_STAGE_FRAGMENT_BIT, 0,
                                 sizeof(VkClearColorValue), clearColorValue.float32);
 

src/libANGLE/renderer/vulkan/FramebufferVk.h

@@ -110,7 +110,7 @@ class FramebufferVk : public FramebufferImpl, public vk::CommandGraphResource
                                         bool clearColor,
                                         bool clearDepth,
                                         bool clearStencil);
-    gl::Error clearWithDraw(ContextVk *contextVk, VkColorComponentFlags colorMaskFlags);
+    gl::Error clearWithDraw(const gl::Context *context, VkColorComponentFlags colorMaskFlags);
     void updateActiveColorMasks(size_t colorIndex, bool r, bool g, bool b, bool a);
     RenderTargetVk *getColorReadRenderTarget() const;
 

src/tests/gl_tests/ClearTest.cpp

@@ -106,6 +106,31 @@ TEST_P(ClearTest, RGBA8Framebuffer)
     EXPECT_PIXEL_NEAR(0, 0, 128, 128, 128, 128, 1.0);
 }
 
+// Test clearing a RGB8 Framebuffer with a color mask.
+TEST_P(ClearTest, RGB8WithMaskFramebuffer)
+{
+    // TODO(lucferron): Figure out why this test fails on OSX / OpenGL.
+    // http://anglebug.com/2674
+    ANGLE_SKIP_TEST_IF(IsOSX() && IsDesktopOpenGL());
+    glBindFramebuffer(GL_FRAMEBUFFER, mFBOs[0]);
+
+    GLTexture texture;
+
+    glBindTexture(GL_TEXTURE_2D, texture);
+    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);
+
+    glColorMask(GL_TRUE, GL_TRUE, GL_FALSE, GL_TRUE);
+
+    // alpha shouldn't really be taken into account and we should find 255 as a result since we
+    // are writing to a RGB8 texture. Also, the
+    glClearColor(0.5f, 0.5f, 0.5f, 0.2f);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    EXPECT_PIXEL_NEAR(0, 0, 128, 128, 0, 255, 1.0);
+}
+
 TEST_P(ClearTest, ClearIssue)
 {
     glEnable(GL_DEPTH_TEST);