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

gpu/command_buffer/service/gles2_cmd_decoder.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
@@ skipping 665 matching lines @@
   // Restores the current state to the user's settings.
   void RestoreCurrentFramebufferBindings();
 
   // Sets DEPTH_TEST, STENCIL_TEST and color mask for the current framebuffer.
   void ApplyDirtyState();
 
   // These check the state of the currently bound framebuffer or the
   // backbuffer if no framebuffer is bound.
   // Check with all attached and enabled color attachments.
   bool BoundFramebufferHasColorAttachmentWithAlpha();
+  bool BoundFramebufferEmulatingRGB();
   bool BoundFramebufferHasDepthAttachment();
   bool BoundFramebufferHasStencilAttachment();
 
   error::ContextLostReason GetContextLostReason() override;
 
   // Overriden from ErrorStateClient.
   void OnContextLostError() override;
   void OnOutOfMemoryError() override;
 
   // Ensure Renderbuffer corresponding to last DoBindRenderbuffer() is bound.
@@ skipping 4007 matching lines @@
 }
 
 bool GLES2DecoderImpl::BoundFramebufferHasColorAttachmentWithAlpha() {
   Framebuffer* framebuffer =
       GetFramebufferInfoForTarget(GL_DRAW_FRAMEBUFFER_EXT);
   if (framebuffer)
     return framebuffer->HasAlphaMRT();
   return BackBufferHasAlpha();
 }
 
+bool GLES2DecoderImpl::BoundFramebufferEmulatingRGB() {
+  Framebuffer* framebuffer =
+      GetFramebufferInfoForTarget(GL_DRAW_FRAMEBUFFER_EXT);
+  if (framebuffer)
+    return framebuffer->EmulatingRGB();
+  return false;
+}
+
 bool GLES2DecoderImpl::BoundFramebufferHasDepthAttachment() {
   Framebuffer* framebuffer =
       GetFramebufferInfoForTarget(GL_DRAW_FRAMEBUFFER_EXT);
   if (framebuffer) {
     return framebuffer->HasDepthAttachment();
   }
   if (offscreen_target_frame_buffer_.get()) {
     return offscreen_target_depth_format_ != 0;
   }
   return back_buffer_has_depth_;
 }
 
 bool GLES2DecoderImpl::BoundFramebufferHasStencilAttachment() {
   Framebuffer* framebuffer =
       GetFramebufferInfoForTarget(GL_DRAW_FRAMEBUFFER_EXT);
   if (framebuffer) {
     return framebuffer->HasStencilAttachment();
   }
   if (offscreen_target_frame_buffer_.get()) {
     return offscreen_target_stencil_format_ != 0 ||
            offscreen_target_depth_format_ == GL_DEPTH24_STENCIL8;
   }
   return back_buffer_has_stencil_;
 }
 
 void GLES2DecoderImpl::ApplyDirtyState() {
+  if (BoundFramebufferEmulatingRGB()) {
+    Framebuffer* framebuffer =
+        GetFramebufferInfoForTarget(GL_DRAW_FRAMEBUFFER_EXT);
+    if (framebuffer->HasUninitializedDrawBuffers()) {
+      glClearColor(0.2f, 0.2f, 0.2f, 1.0f);
+      state_.SetDeviceColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_TRUE);
+      glClear(GL_COLOR_BUFFER_BIT);
+      glClearColor(state_.color_clear_red, state_.color_clear_green,
+                   state_.color_clear_blue, state_.color_clear_alpha);
+      framebuffer->SetDrawBuffersAsInitialized();
+      framebuffer_state_.clear_state_dirty = true;
+    }
+  }
+
   if (framebuffer_state_.clear_state_dirty) {
     bool have_alpha = BoundFramebufferHasColorAttachmentWithAlpha();
     state_.SetDeviceColorMask(state_.color_mask_red,
                               state_.color_mask_green,
                               state_.color_mask_blue,
                               state_.color_mask_alpha && have_alpha);
 
     bool have_depth = BoundFramebufferHasDepthAttachment();
     state_.SetDeviceDepthMask(state_.depth_mask && have_depth);
 
@@ skipping 11584 matching lines @@
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "base/macros.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu