Add gl_SampleMask functionality to fragment builders

src/gpu/glsl/GrGLSLCaps.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef GrGLSLCaps_DEFINED
 #define GrGLSLCaps_DEFINED
@@ skipping 36 matching lines @@
     bool bindlessTextureSupport() const { return fBindlessTextureSupport; }
 
     const char* versionDeclString() const { return fVersionDeclString; }
 
     const char* fbFetchColorName() const { return fFBFetchColorName; }
 
     const char* fbFetchExtensionString() const { return fFBFetchExtensionString; }
 
     bool dropsTileOnZeroDivide() const { return fDropsTileOnZeroDivide; }
 
+    bool sampleVariablesSupport() const { return fSampleVariablesSupport; }
+
+    bool sampleMaskOverrideCoverageSupport() const { return fSampleMaskOverrideCoverageSupport; }
+
     bool flatInterpolationSupport() const { return fFlatInterpolationSupport; }
 
     bool noperspectiveInterpolationSupport() const { return fNoPerspectiveInterpolationSupport; }
 
     AdvBlendEqInteraction advBlendEqInteraction() const { return fAdvBlendEqInteraction; }
 
     bool mustEnableAdvBlendEqs() const {
         return fAdvBlendEqInteraction >= kGeneralEnable_AdvBlendEqInteraction;
     }
 
@@ skipping 14 matching lines @@
 
     bool mustForceNegatedAtanParamToFloat() const { return fMustForceNegatedAtanParamToFloat; }
 
     // Returns the string of an extension that must be enabled in the shader to support
     // derivatives. If nullptr is returned then no extension needs to be enabled. Before calling
     // this function, the caller should check that shaderDerivativeSupport exists.
     const char* shaderDerivativeExtensionString() const {
         SkASSERT(this->shaderDerivativeSupport());
         return fShaderDerivativeExtensionString;
     }
+
+    const char* sampleVariablesExtensionString() const {
+        SkASSERT(this->sampleVariablesSupport());
+        return fSampleVariablesExtensionString;
+    }
     
     // Returns the string of an extension that will do all necessary coord transfomations needed
     // when reading the fragment position. If such an extension does not exisits, this function
     // returns a nullptr, and all transforms of the frag position must be done manually in the
     // shader.
     const char* fragCoordConventionsExtensionString() const {
         return fFragCoordConventionsExtensionString;
     }
 
     // This returns the name of an extension that must be enabled in the shader, if such a thing is
@@ skipping 38 matching lines @@
     void onApplyOptionsOverrides(const GrContextOptions& options) override;
 
     GrGLSLGeneration fGLSLGeneration;
     
     bool fDropsTileOnZeroDivide : 1;
     bool fFBFetchSupport : 1;
     bool fFBFetchNeedsCustomOutput : 1;
     bool fBindlessTextureSupport : 1;
     bool fUsesPrecisionModifiers : 1;
     bool fCanUseAnyFunctionInShader : 1;
+    bool fSampleVariablesSupport : 1;
+    bool fSampleMaskOverrideCoverageSupport : 1;
     bool fFlatInterpolationSupport : 1;
     bool fNoPerspectiveInterpolationSupport : 1;
 
     // Used for specific driver bug work arounds
     bool fCanUseMinAndAbsTogether : 1;
     bool fMustForceNegatedAtanParamToFloat : 1;
 
     const char* fVersionDeclString;
 
     const char* fShaderDerivativeExtensionString;
+    const char* fSampleVariablesExtensionString;
     const char* fFragCoordConventionsExtensionString;
     const char* fSecondaryOutputExtensionString;
     const char* fExternalTextureExtensionString;
     const char* fNoPerspectiveInterpolationExtensionString;
 
     const char* fFBFetchColorName;
     const char* fFBFetchExtensionString;
 
     AdvBlendEqInteraction fAdvBlendEqInteraction;
 
     GrSwizzle fConfigTextureSwizzle[kGrPixelConfigCnt];
     GrSwizzle fConfigOutputSwizzle[kGrPixelConfigCnt];
 
     friend class GrGLCaps;  // For initialization.
     friend class GrVkCaps;
 
     typedef GrShaderCaps INHERITED;
 };
 
 #endif