1/* 2 * Copyright 2014 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 GrFragmentProcessor_DEFINED 9#define GrFragmentProcessor_DEFINED 10 11#include "GrProcessor.h" 12 13class GrCoordTransform; 14class GrGLSLCaps; 15class GrGLFragmentProcessor; 16class GrProcessorKeyBuilder; 17 18/** Provides custom fragment shader code. Fragment processors receive an input color (vec4f) and 19 produce an output color. They may reference textures and uniforms. They may use 20 GrCoordTransforms to receive a transformation of the local coordinates that map from local space 21 to the fragment being processed. 22 */ 23class GrFragmentProcessor : public GrProcessor { 24public: 25 GrFragmentProcessor() 26 : INHERITED() 27 , fWillUseInputColor(true) 28 , fUsesLocalCoords(false) {} 29 30 /** Implemented using GLFragmentProcessor::GenKey as described in this class's comment. */ 31 virtual void getGLProcessorKey(const GrGLSLCaps& caps, 32 GrProcessorKeyBuilder* b) const = 0; 33 34 /** Returns a new instance of the appropriate *GL* implementation class 35 for the given GrFragmentProcessor; caller is responsible for deleting 36 the object. */ 37 virtual GrGLFragmentProcessor* createGLInstance() const = 0; 38 39 /** Human-meaningful string to identify this GrFragmentProcessor; may be embedded 40 in generated shader code. */ 41 virtual const char* name() const = 0; 42 43 int numTransforms() const { return fCoordTransforms.count(); } 44 45 /** Returns the coordinate transformation at index. index must be valid according to 46 numTransforms(). */ 47 const GrCoordTransform& coordTransform(int index) const { return *fCoordTransforms[index]; } 48 49 const SkTArray<const GrCoordTransform*, true>& coordTransforms() const { 50 return fCoordTransforms; 51 } 52 53 /** Will this prceossor read the source color value? */ 54 bool willUseInputColor() const { return fWillUseInputColor; } 55 56 /** Do any of the coordtransforms for this processor require local coords? */ 57 bool usesLocalCoords() const { return fUsesLocalCoords; } 58 59 /** Returns true if this and other processor conservatively draw identically. It can only return 60 true when the two processor are of the same subclass (i.e. they return the same object from 61 from getFactory()). 62 63 A return value of true from isEqual() should not be used to test whether the processor would 64 generate the same shader code. To test for identical code generation use getGLProcessorKey*/ 65 bool isEqual(const GrFragmentProcessor& that) const { 66 if (this->classID() != that.classID() || 67 !this->hasSameTransforms(that) || 68 !this->hasSameTextureAccesses(that)) { 69 return false; 70 } 71 return this->onIsEqual(that); 72 } 73 74 /** 75 * This function is used to perform optimizations. When called the invarientOuput param 76 * indicate whether the input components to this processor in the FS will have known values. 77 * In inout the validFlags member is a bitfield of GrColorComponentFlags. The isSingleComponent 78 * member indicates whether the input will be 1 or 4 bytes. The function updates the members of 79 * inout to indicate known values of its output. A component of the color member only has 80 * meaning if the corresponding bit in validFlags is set. 81 */ 82 void computeInvariantOutput(GrInvariantOutput* inout) const; 83 84protected: 85 /** 86 * Fragment Processor subclasses call this from their constructor to register coordinate 87 * transformations. Coord transforms provide a mechanism for a processor to receive coordinates 88 * in their FS code. The matrix expresses a transformation from local space. For a given 89 * fragment the matrix will be applied to the local coordinate that maps to the fragment. 90 * 91 * When the transformation has perspective, the transformed coordinates will have 92 * 3 components. Otherwise they'll have 2. 93 * 94 * This must only be called from the constructor because GrProcessors are immutable. The 95 * processor subclass manages the lifetime of the transformations (this function only stores a 96 * pointer). The GrCoordTransform is typically a member field of the GrProcessor subclass. 97 * 98 * A processor subclass that has multiple methods of construction should always add its coord 99 * transforms in a consistent order. The non-virtual implementation of isEqual() automatically 100 * compares transforms and will assume they line up across the two processor instances. 101 */ 102 void addCoordTransform(const GrCoordTransform*); 103 104 /** 105 * If the prceossor will generate a result that does not depend on the input color value then it 106 * must call this function from its constructor. Otherwise, when its generated backend-specific 107 * code might fail during variable binding due to unused variables. 108 */ 109 void setWillNotUseInputColor() { fWillUseInputColor = false; } 110 111 /** 112 * Subclass implements this to support getConstantColorComponents(...). 113 */ 114 virtual void onComputeInvariantOutput(GrInvariantOutput* inout) const = 0; 115 116private: 117 /** 118 * Subclass implements this to support isEqual(). It will only be called if it is known that 119 * the two processors are of the same subclass (i.e. they return the same object from 120 * getFactory()). The processor subclass should not compare its coord transforms as that will 121 * be performed automatically in the non-virtual isEqual(). 122 */ 123 virtual bool onIsEqual(const GrFragmentProcessor&) const = 0; 124 125 bool hasSameTransforms(const GrFragmentProcessor&) const; 126 127 SkSTArray<4, const GrCoordTransform*, true> fCoordTransforms; 128 bool fWillUseInputColor; 129 bool fUsesLocalCoords; 130 131 typedef GrProcessor INHERITED; 132}; 133 134#endif 135