WebGL: GL_RGB emulation for IOSurface backed textures. [For reference only]

third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 330 matching lines @@
     ASSERT_NOT_REACHED();
 }
 
 DrawingBuffer::TextureParameters DrawingBuffer::chromiumImageTextureParameters()
 {
 #if OS(MACOSX)
     // A CHROMIUM_image backed texture requires a specialized set of parameters
     // on OSX.
     TextureParameters parameters;
     parameters.target = GC3D_TEXTURE_RECTANGLE_ARB;
-    parameters.internalColorFormat = GL_BGRA_EXT;
-    parameters.internalRenderbufferFormat = GL_RGBA8_OES;
-    parameters.colorFormat = GL_RGBA;
+    if (m_requestedAttributes.alpha) {
+        parameters.internalColorFormat = GL_BGRA_EXT;
+        parameters.internalRenderbufferFormat = GL_RGBA8_OES;
+        parameters.colorFormat = GL_RGBA;
+    } else {
+        parameters.internalColorFormat = GL_BGR_EXT;
+        parameters.internalRenderbufferFormat = GL_RGB8_OES;
+        parameters.colorFormat = GL_RGB;
+    }
     return parameters;
 #else
     return defaultTextureParameters();
 #endif
 }
 
 DrawingBuffer::TextureParameters DrawingBuffer::defaultTextureParameters()
 {
     TextureParameters parameters;
     parameters.target = GL_TEXTURE_2D;
@@ skipping 587 matching lines @@
     if (info->imageId) {
         m_gl->BindTexture(info->parameters.target, info->textureId);
         m_gl->ReleaseTexImage2DCHROMIUM(info->parameters.target, info->imageId);
         m_gl->DestroyImageCHROMIUM(info->imageId);
         info->imageId = 0;
     }
 }
 
 DrawingBuffer::TextureInfo DrawingBuffer::createTextureAndAllocateMemory(const IntSize& size)
 {
-    // TODO(erikchen): Add support for a CHROMIUM_image back buffer whose
-    // behavior mimics a texture with internal format GL_RGB.
-    // https://crbug.com/581777.
-    if (!m_requestedAttributes.alpha)
-        return createDefaultTextureAndAllocateMemory(size);
-
     if (!RuntimeEnabledFeatures::webGLImageChromiumEnabled())
         return createDefaultTextureAndAllocateMemory(size);
 
     // First, try to allocate a CHROMIUM_image. This always has the potential to
     // fail.
     TextureParameters parameters = chromiumImageTextureParameters();
     WGC3Duint imageId = m_gl->CreateGpuMemoryBufferImageCHROMIUM(size.width(), size.height(), parameters.internalColorFormat, GC3D_SCANOUT_CHROMIUM);
     if (!imageId)
         return createDefaultTextureAndAllocateMemory(size);
 
@@ skipping 49 matching lines @@
 
     if (m_antiAliasingMode == MSAAImplicitResolve)
         m_gl->FramebufferTexture2DMultisampleEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, target, m_colorBuffer.textureId, 0, m_sampleCount);
     else
         m_gl->FramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, target, m_colorBuffer.textureId, 0);
 
     m_gl->BindTexture(GL_TEXTURE_2D, m_texture2DBinding);
 }
 
 } // namespace blink