Enable stencil clipping in mixed sampled render targets

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 330 matching lines @@
             ctxInfo.hasExtension("GL_OES_standard_derivatives");
     }
 
     // We need dual source blending and the ability to disable multisample in order to support mixed
     // samples in every corner case.
     if (fMultisampleDisableSupport && glslCaps->fDualSourceBlendingSupport) {
         // We understand "mixed samples" to mean the collective capability of 3 different extensions
         glslCaps->fMixedSamplesSupport =
             ctxInfo.hasExtension("GL_NV_framebuffer_mixed_samples") &&
             ctxInfo.hasExtension("GL_NV_sample_mask_override_coverage") &&
-            ctxInfo.hasExtension("GL_EXT_raster_multisample");
+            ctxInfo.hasExtension("GL_EXT_raster_multisample") &&
+            ctxInfo.hasExtension("GL_NV_sample_locations");

[Chris Dalton, 2015/09/22 08:35:24]

With our current plans to just put basic mixed samples support in the chromium
command buffer, it won't work to rope this extension in with mixed samples as
well. I'm afraid we're going to have to make a separate cap for sample
locations, and then check that specific cap before trying to use an MSAA stencil
clip.

     }
     // Workaround NVIDIA bug related to glInvalidateFramebuffer and mixed samples.
     if (kNVIDIA_GrGLDriver == ctxInfo.driver() && fShaderCaps->mixedSamplesSupport()) {
         fDiscardRenderTargetSupport = false;
         fInvalidateFBType = kNone_InvalidateFBType;
     }
 
     /**************************************************************************
      * GrCaps fields
      **************************************************************************/
@@ skipping 830 matching lines @@
         for (int p = 0; p < kGrSLPrecisionCount; ++p) {
             glslCaps->fFloatPrecisions[kGeometry_GrShaderType][p] = 
                                                glslCaps->fFloatPrecisions[kVertex_GrShaderType][p];
         }
     }
 }