Add cap and builder feature for multisample interpolation

src/gpu/glsl/GrGLSLCaps.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 "GrGLSLCaps.h"
 
 #include "GrContextOptions.h"
 
 ////////////////////////////////////////////////////////////////////////////////////////////
 
 GrGLSLCaps::GrGLSLCaps(const GrContextOptions& options) {
     fGLSLGeneration = k330_GrGLSLGeneration;
 
     fDropsTileOnZeroDivide = false;
     fFBFetchSupport = false;
     fFBFetchNeedsCustomOutput = false;
     fBindlessTextureSupport = false;
     fUsesPrecisionModifiers = false;
     fCanUseAnyFunctionInShader = true;
     fCanUseMinAndAbsTogether = true;
     fMustForceNegatedAtanParamToFloat = false;
     fFlatInterpolationSupport = false;
     fNoPerspectiveInterpolationSupport = false;
+    fMultisampleInterpolationSupport = false;
     fSampleVariablesSupport = false;
     fSampleMaskOverrideCoverageSupport = false;
     fVersionDeclString = nullptr;
     fShaderDerivativeExtensionString = nullptr;
     fFragCoordConventionsExtensionString = nullptr;
     fSecondaryOutputExtensionString = nullptr;
     fExternalTextureExtensionString = nullptr;
     fNoPerspectiveInterpolationExtensionString = nullptr;
+    fMultisampleInterpolationExtensionString = nullptr;
     fSampleVariablesExtensionString = nullptr;
     fFBFetchColorName = nullptr;
     fFBFetchExtensionString = nullptr;
     fAdvBlendEqInteraction = kNotSupported_AdvBlendEqInteraction;
 }
 
 SkString GrGLSLCaps::dump() const {
     SkString r = INHERITED::dump();
 
     static const char* kAdvBlendEqInteractionStr[] = {
@@ skipping 14 matching lines @@
     r.appendf("Drops tile on zero divide: %s\n", (fDropsTileOnZeroDivide ? "YES" : "NO"));
     r.appendf("Bindless texture support: %s\n", (fBindlessTextureSupport ? "YES" : "NO"));
     r.appendf("Uses precision modifiers: %s\n", (fUsesPrecisionModifiers ? "YES" : "NO"));
     r.appendf("Can use any() function: %s\n", (fCanUseAnyFunctionInShader ? "YES" : "NO"));
     r.appendf("Can use min() and abs() together: %s\n", (fCanUseMinAndAbsTogether ? "YES" : "NO"));
     r.appendf("Must force negated atan param to float: %s\n", (fMustForceNegatedAtanParamToFloat ?
                                                                "YES" : "NO"));
     r.appendf("Flat interpolation support: %s\n", (fFlatInterpolationSupport ?  "YES" : "NO"));
     r.appendf("No perspective interpolation support: %s\n", (fNoPerspectiveInterpolationSupport ?
                                                              "YES" : "NO"));
+    r.appendf("Multisample interpolation support: %s\n", (fMultisampleInterpolationSupport ?

[joshualitt, 2016/03/01 17:58:58]

Should we log the string? we don't do it for fb fetch support, but we do seem to
do it for kAdvBlendEqInteractionStr

[bsalomon, 2016/03/01 18:02:26]

Seems like it'd be nice to log both.

[joshualitt, 2016/03/01 18:02:45]

whoops, should have paid more attention, the string is either a nullptr or
"GL_OES_shader_multisample_interpolation", nvm

+                                                          "YES" : "NO"));
     r.appendf("Sample variables support: %s\n", (fSampleVariablesSupport ? "YES" : "NO"));
     r.appendf("Sample mask override coverage support: %s\n", (fSampleMaskOverrideCoverageSupport ?
                                                               "YES" : "NO"));
     r.appendf("Advanced blend equation interaction: %s\n",
               kAdvBlendEqInteractionStr[fAdvBlendEqInteraction]);
     return r;
 }
 
 void GrGLSLCaps::onApplyOptionsOverrides(const GrContextOptions& options) {
 }