Chromium implementation of discardBackbuffer WebGraphicsContext3D extension.

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.h

 // 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.
 
 #ifndef CONTENT_COMMON_GPU_CLIENT_WEBGRAPHICSCONTEXT3D_COMMAND_BUFFER_IMPL_H_
 #define CONTENT_COMMON_GPU_CLIENT_WEBGRAPHICSCONTEXT3D_COMMAND_BUFFER_IMPL_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 425 matching lines @@
       WGC3Dint yoffset,
       WGC3Dsizei width,
       WGC3Dsizei height,
       WGC3Denum format,
       WGC3Denum type,
       WGC3Denum access);
   virtual void unmapTexSubImage2DCHROMIUM(const void*);
 
   virtual void setVisibilityCHROMIUM(bool visible);
 
+  virtual void discardFramebufferEXT();

[apatrick_chromium, 2012/03/16 19:37:56]

This one takes some arguments.

[mmocny, 2012/03/16 20:25:20]

How closely should I duplicate the original arguments?

I assume target will simply be "WGC3Denum target", but I am not sure how best to
implement the attachements argument:

The only reference to values "COLOR_EXT" etc in our codebase is defined in
ANGLE, and WebGraphicsContext3D seems to use an Attributes struct of which
contains bools for these concepts.

Should I use an array of enum values and define these values somewhere, or use
something higher level?

On 2012/03/16 19:37:56, apatrick_chromium wrote:

[apatrick_chromium, 2012/03/16 21:08:19]

I think for the purposes of this patch, just make the signature:

void discardFramebufferEXT(WGC3Denum target, WGC3Dsizei numAttachments, const
WGC3Denum *attachments);

The constants are not used anywhere yet. But I think the appropriate place to
put them would be WebKit/Source/WebCore/platform/graphics/Extensions3D.h or
WebKit/Source/WebCore/platform/graphics/chromium/Extensions3DChromium.h. I don't
do a lot with WebKit though. You might want to check with someone more familiar
with it.

+  virtual void ensureFramebufferCHROMIUM();
+
   virtual void setMemoryAllocationChangedCallbackCHROMIUM(
       WebGraphicsMemoryAllocationChangedCallbackCHROMIUM* callback);
 
   virtual void copyTextureToParentTextureCHROMIUM(
       WebGLId texture, WebGLId parentTexture);
 
   virtual void rateLimitOffscreenContextCHROMIUM();
 
   virtual WebKit::WebString getRequestableExtensionsCHROMIUM();
   virtual void requestExtensionCHROMIUM(const char*);
@@ skipping 111 matching lines @@
 
 #ifdef FLIP_FRAMEBUFFER_VERTICALLY
   std::vector<uint8> scanline_;
   void FlipVertically(uint8* framebuffer,
                       unsigned int width,
                       unsigned int height);
 #endif
 };
 
 #endif  // CONTENT_COMMON_GPU_CLIENT_WEBGRAPHICSCONTEXT3D_COMMAND_BUFFER_IMPL_H_