added support for glMinSampleShading

src/gpu/GrGeometryProcessor.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGeometryProcessor_DEFINED
 #define GrGeometryProcessor_DEFINED
 
 #include "GrPrimitiveProcessor.h"
 
 /**
  * A GrGeometryProcessor is a flexible method for rendering a primitive.  The GrGeometryProcessor
  * has complete control over vertex attributes and uniforms(aside from the render target) but it
  * must obey the same contract as any GrPrimitiveProcessor, specifically it must emit a color and
  * coverage into the fragment shader.  Where this color and coverage come from is completely the
  * responsibility of the GrGeometryProcessor.
  */
 class GrGeometryProcessor : public GrPrimitiveProcessor {
 public:
     GrGeometryProcessor()
         : fWillUseGeoShader(false)
-        , fLocalCoordsType(kUnused_LocalCoordsType) {}
+        , fLocalCoordsType(kUnused_LocalCoordsType)
+        , fSampleShading(0.0) {}
 
     bool willUseGeoShader() const override { return fWillUseGeoShader; }
 
     bool hasTransformedLocalCoords() const override {
         return kHasTransformed_LocalCoordsType == fLocalCoordsType;
     }
 
     bool hasExplicitLocalCoords() const override {
         return kHasExplicit_LocalCoordsType == fLocalCoordsType;
     }
 
+    /**
+     * Returns the minimum fraction of samples for which the fragment shader will be run. For
+     * instance, if sampleShading is 0.5 in MSAA16 mode, the fragment shader will run a minimum of
+     * 8 times per pixel. The default value is zero.
+     */
+    float getSampleShading() const override {
+        return fSampleShading;
+    }
+
 protected:
     /**
      * Subclasses call this from their constructor to register vertex attributes.  Attributes
      * will be padded to the nearest 4 bytes for performance reasons.
      * TODO After deferred geometry, we should do all of this inline in GenerateGeometry alongside
      * the struct used to actually populate the attributes.  This is all extremely fragile, vertex
      * attributes have to be added in the order they will appear in the struct which maps memory.
      * The processor key should reflect the vertex attributes, or there lack thereof in the
      * GrGeometryProcessor.
      */
@@ skipping 21 matching lines @@
 
     void setHasExplicitLocalCoords() {
         SkASSERT(kUnused_LocalCoordsType == fLocalCoordsType);
         fLocalCoordsType = kHasExplicit_LocalCoordsType;
     }
     void setHasTransformedLocalCoords() {
         SkASSERT(kUnused_LocalCoordsType == fLocalCoordsType);
         fLocalCoordsType = kHasTransformed_LocalCoordsType;
     }
 
+    void setSampleShading(float sampleShading) {
+        fSampleShading = sampleShading;
+    }
+
 private:
     bool fWillUseGeoShader;
     LocalCoordsType fLocalCoordsType;
+    float fSampleShading;
 
     typedef GrPrimitiveProcessor INHERITED;
 };
 
 #endif