Add support for ES3 MSAA.

include/gpu/gl/GrGLInterface.h

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef GrGLInterface_DEFINED
@@ skipping 211 matching lines @@
     GLPtr<GrGLLinkProgramProc> fLinkProgram;
     GLPtr<GrGLLoadIdentityProc> fLoadIdentity;
     GLPtr<GrGLLoadMatrixfProc> fLoadMatrixf;
     GLPtr<GrGLMapBufferProc> fMapBuffer;
     GLPtr<GrGLMatrixModeProc> fMatrixMode;
     GLPtr<GrGLPixelStoreiProc> fPixelStorei;
     GLPtr<GrGLQueryCounterProc> fQueryCounter;
     GLPtr<GrGLReadBufferProc> fReadBuffer;
     GLPtr<GrGLReadPixelsProc> fReadPixels;
     GLPtr<GrGLRenderbufferStorageProc> fRenderbufferStorage;
+
+#if !GR_GL_IGNORE_ES3_MSAA
+    //  On OpenGL ES there are multiple incompatible extensions that add support for MSAA
+    //  and ES3 adds MSAA support to the standard. On an ES3 driver we may still use the
+    //  older extensions for performance reasons or due to ES3 driver bugs. We want the function
+    //  that creates the GrGLInterface to provide all available functions and internally
+    //  we will select among them. They all have a method called glRenderbufferStorageMultisample*.
+    //  So we have separate function pointers for GL_IMG/EXT_multisampled_to_texture,
+    //  GL_CHROMIUM/ANGLE_framebuffer_multisample/ES3, and GL_APPLE_framebuffer_multisample
+    //  variations.
+    //
+    //  If a driver supports multiple GL_ARB_framebuffer_multisample-style extensions then we will
+    //  assume the function pointers for the standard (or equivalent GL_ARB) version have
+    //  been preferred over GL_EXT, GL_CHROMIUM, or GL_ANGLE variations that have reduced
+    //  functionality.
+
+    //  GL_EXT_multisampled_render_to_texture (preferred) or GL_IMG_multisampled_render_to_texture
+    GLPtr<GrGLRenderbufferStorageMultisampleProc> fRenderbufferStorageMultisampleES2EXT;
+    //  GL_APPLE_framebuffer_multisample
+    GLPtr<GrGLRenderbufferStorageMultisampleProc> fRenderbufferStorageMultisampleES2APPLE;
+#endif
+    //  This is used to store the pointer for GL_ARB/EXT/ANGLE/CHROMIUM_framebuffer_multisample or
+    //  the standard function in ES3+ or GL 3.0+.
     GLPtr<GrGLRenderbufferStorageMultisampleProc> fRenderbufferStorageMultisample;
+
     GLPtr<GrGLRenderbufferStorageMultisampleCoverageProc> fRenderbufferStorageMultisampleCoverage;
     GLPtr<GrGLResolveMultisampleFramebufferProc> fResolveMultisampleFramebuffer;
     GLPtr<GrGLScissorProc> fScissor;
     GLPtr<GrGLShaderSourceProc> fShaderSource;
     GLPtr<GrGLStencilFuncProc> fStencilFunc;
     GLPtr<GrGLStencilFuncSeparateProc> fStencilFuncSeparate;
     GLPtr<GrGLStencilMaskProc> fStencilMask;
     GLPtr<GrGLStencilMaskSeparateProc> fStencilMaskSeparate;
     GLPtr<GrGLStencilOpProc> fStencilOp;
     GLPtr<GrGLStencilOpSeparateProc> fStencilOpSeparate;
@@ skipping 87 matching lines @@
 
     // Per-GL func callback
 #if GR_GL_PER_GL_FUNC_CALLBACK
     GrGLInterfaceCallbackProc fCallback;
     GrGLInterfaceCallbackData fCallbackData;
 #endif
 
 };
 
 #endif