[Command buffer] workaround the framebuffer completeness bug for Intel Mac

gpu/command_buffer/service/framebuffer_manager.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/framebuffer_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/logging.h"
@@ skipping 593 matching lines @@
 }
 
 bool Framebuffer::HasDepthAttachment() const {
   return attachments_.find(GL_DEPTH_ATTACHMENT) != attachments_.end();
 }
 
 bool Framebuffer::HasStencilAttachment() const {
   return attachments_.find(GL_STENCIL_ATTACHMENT) != attachments_.end();
 }
 
+bool Framebuffer::ReadBufferHasNoImage() const {
+  if (read_buffer_ == GL_NONE) {
+    return false;
+  }
+  AttachmentMap::const_iterator it = attachments_.find(read_buffer_);
+  if (it == attachments_.end()) {
+    return true;
+  }
+  return false;
+}
+
+bool Framebuffer::DrawBuffersHaveNoImage() const {
+  for (GLenum i = 0; i < manager_->max_draw_buffers_; ++i) {
+    if (draw_buffers_[i] == GL_NONE) {
+      continue;
+    }
+    const Attachment* attachment = GetAttachment(draw_buffers_[i]);
+    if (attachment) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool Framebuffer::ColorBuffersHaveImage() const {
+  for (GLenum i = 0; i < manager_->max_color_attachments_; i++) {
+    if (attachments_.find(GL_COLOR_ATTACHMENT0 + i) != attachments_.end())

[qiankun, 2016/11/11 15:30:48]

Why don't check attachment != NULL (i.e. attachments_.find(GL_COLOR_ATTACHMENT0
+ i)->second) here?

What's the difference of Drawbuffers and ColorBuffers? Aren't they same?

[yunchao, 2016/11/15 16:04:34]

It is unnecessary. see the other code like HasColorAttachment, etc. The
AttachmentMap will erase or attach the first and the second all together. 
Maybe the name is a little confusing, but draw buffers are per context, color
buffers are per fbo.

+      return true;
+  }
+  return false;
+}
+
 GLenum Framebuffer::GetReadBufferInternalFormat() const {
   if (read_buffer_ == GL_NONE)
     return 0;
   AttachmentMap::const_iterator it = attachments_.find(read_buffer_);
   if (it == attachments_.end()) {
     return 0;
   }
   const Attachment* attachment = it->second.get();
   if (attachment->EmulatingRGB()) {
     DCHECK_EQ(static_cast<GLenum>(GL_RGBA), attachment->internal_format());
@@ skipping 432 matching lines @@
 
 bool FramebufferManager::IsComplete(
     Framebuffer* framebuffer) {
   DCHECK(framebuffer);
   return framebuffer->framebuffer_complete_state_count_id() ==
       framebuffer_state_change_count_;
 }
 
 }  // namespace gles2
 }  // namespace gpu