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      1 /*
      2  * Copyright 2013 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef GrGeometryProcessor_DEFINED
      9 #define GrGeometryProcessor_DEFINED
     10 
     11 #include "GrPrimitiveProcessor.h"
     12 
     13 /**
     14  * A GrGeometryProcessor is a flexible method for rendering a primitive.  The GrGeometryProcessor
     15  * has complete control over vertex attributes and uniforms(aside from the render target) but it
     16  * must obey the same contract as any GrPrimitiveProcessor, specifically it must emit a color and
     17  * coverage into the fragment shader.  Where this color and coverage come from is completely the
     18  * responsibility of the GrGeometryProcessor.
     19  */
     20 class GrGeometryProcessor : public GrPrimitiveProcessor {
     21 public:
     22     GrGeometryProcessor(ClassID classID)
     23         : INHERITED(classID)
     24         , fWillUseGeoShader(false)
     25         , fLocalCoordsType(kUnused_LocalCoordsType)
     26         , fSampleShading(0.0) {}
     27 
     28     bool willUseGeoShader() const final { return fWillUseGeoShader; }
     29 
     30     bool hasExplicitLocalCoords() const final {
     31         return kHasExplicit_LocalCoordsType == fLocalCoordsType;
     32     }
     33 
     34     /**
     35      * Returns the minimum fraction of samples for which the fragment shader will be run. For
     36      * instance, if sampleShading is 0.5 in MSAA16 mode, the fragment shader will run a minimum of
     37      * 8 times per pixel. The default value is zero.
     38      */
     39     float getSampleShading() const final { return fSampleShading; }
     40 
     41 protected:
     42     void setWillUseGeoShader() { fWillUseGeoShader = true; }
     43 
     44     /**
     45      * If a GrFragmentProcessor in the GrPipeline needs localCoods, we will provide them in one of
     46      * three ways
     47      * 1) LocalCoordTransform * Position - in Shader
     48      * 2) LocalCoordTransform * ExplicitLocalCoords- in Shader
     49      * 3) A transformation on the CPU uploaded via vertex attribute
     50      */
     51     enum LocalCoordsType {
     52         kUnused_LocalCoordsType,
     53         kHasExplicit_LocalCoordsType,
     54         kHasTransformed_LocalCoordsType
     55     };
     56 
     57     void setHasExplicitLocalCoords() {
     58         SkASSERT(kUnused_LocalCoordsType == fLocalCoordsType);
     59         fLocalCoordsType = kHasExplicit_LocalCoordsType;
     60     }
     61     void setHasTransformedLocalCoords() {
     62         SkASSERT(kUnused_LocalCoordsType == fLocalCoordsType);
     63         fLocalCoordsType = kHasTransformed_LocalCoordsType;
     64     }
     65 
     66     void setSampleShading(float sampleShading) {
     67         fSampleShading = sampleShading;
     68     }
     69 
     70 private:
     71     bool fWillUseGeoShader;
     72     LocalCoordsType fLocalCoordsType;
     73     float fSampleShading;
     74 
     75     typedef GrPrimitiveProcessor INHERITED;
     76 };
     77 
     78 #endif
     79