Implement support for KHR_blend_equation_advanced

src/gpu/gl/GrGLCaps.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGLCaps.h"
 
@@ skipping 278 matching lines @@
         fTwoSidedStencilSupport = (ctxInfo.version() >= GR_GL_VER(2,0));
         // supported on GL 1.4 and higher or by extension
         fStencilWrapOpsSupport = (ctxInfo.version() >= GR_GL_VER(1,4)) ||
                                   ctxInfo.hasExtension("GL_EXT_stencil_wrap");
     } else {
         // ES 2 has two sided stencil and stencil wrap
         fTwoSidedStencilSupport = true;
         fStencilWrapOpsSupport = true;
     }
 
+    if (ctxInfo.hasExtension("GL_KHR_blend_equation_advanced_coherent")) {

[Mark Kilgard, 2015/04/03 18:30:04]

can you also look for NV_blend_equation_advanced_coherent here?

there was a lengthy time interval (10 months, maybe more?) before KHR
standardization where NVIDIA shipped NV_blend_equation_advanced (all Fermi and
all Kepler GPUs, except K1) & NV_blend_equation_advanced_coherent (K1 and all
Maxwell GPUs)

The KHR extension is a proper subset of the NV extension with identical enum
values for tokens in both the NV and KHR version.  So you should be able to look
for either string.

Stating this in a comment would be good historical context.

[Chris Dalton, 2015/04/17 08:37:19]

Done.

+        fBlendEquationSupport = kAdvancedCoherent_BlendEquationSupport;
+    } else if (ctxInfo.hasExtension("GL_KHR_blend_equation_advanced")) {
+        fBlendEquationSupport = kAdvanced_BlendEquationSupport;
+    } else {
+        fBlendEquationSupport = kBasic_BlendEquationSupport;
+    }
+
     if (kGL_GrGLStandard == standard) {
         fMapBufferFlags = kCanMap_MapFlag; // we require VBO support and the desktop VBO
                                             // extension includes glMapBuffer.
         if (version >= GR_GL_VER(3, 0) || ctxInfo.hasExtension("GL_ARB_map_buffer_range")) {
             fMapBufferFlags |= kSubset_MapFlag;
             fMapBufferType = kMapBufferRange_MapBufferType;
         } else {
             fMapBufferType = kMapBuffer_MapBufferType;
         }
     } else {
@@ skipping 737 matching lines @@
     r.appendf("Two Format Limit: %s\n", (fTwoFormatLimit ? "YES": "NO"));
     r.appendf("Fragment coord conventions support: %s\n",
              (fFragCoordsConventionSupport ? "YES": "NO"));
     r.appendf("Vertex array object support: %s\n", (fVertexArrayObjectSupport ? "YES": "NO"));
     r.appendf("Use non-VBO for dynamic data: %s\n",
              (fUseNonVBOVertexAndIndexDynamicData ? "YES" : "NO"));
     r.appendf("Full screen clear is free: %s\n", (fFullClearIsFree ? "YES" : "NO"));
     r.appendf("Drops tile on zero divide: %s\n", (fDropsTileOnZeroDivide ? "YES" : "NO"));
     return r;
 }