bsalomon | 6251d17 | 2014-10-15 10:50:36 -0700 | [diff] [blame] | 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 | |
| 13 | class GrCoordTransform; |
| 14 | |
| 15 | /** Provides custom fragment shader code. Fragment processors receive an input color (vec4f) and |
| 16 | produce an output color. They may reference textures and uniforms. They may use |
| 17 | GrCoordTransforms to receive a transformation of the local coordinates that map from local space |
| 18 | to the fragment being processed. |
| 19 | */ |
| 20 | class GrFragmentProcessor : public GrProcessor { |
| 21 | public: |
| 22 | GrFragmentProcessor() |
| 23 | : INHERITED() |
| 24 | , fWillReadDstColor(false) |
| 25 | , fWillUseInputColor(true) {} |
| 26 | |
| 27 | virtual const GrBackendFragmentProcessorFactory& getFactory() const = 0; |
| 28 | |
| 29 | int numTransforms() const { return fCoordTransforms.count(); } |
| 30 | |
| 31 | /** Returns the coordinate transformation at index. index must be valid according to |
| 32 | numTransforms(). */ |
| 33 | const GrCoordTransform& coordTransform(int index) const { return *fCoordTransforms[index]; } |
| 34 | |
| 35 | /** Will this prceossor read the destination pixel value? */ |
| 36 | bool willReadDstColor() const { return fWillReadDstColor; } |
| 37 | |
| 38 | /** Will this prceossor read the source color value? */ |
| 39 | bool willUseInputColor() const { return fWillUseInputColor; } |
| 40 | |
| 41 | /** Returns true if this and other prceossor conservatively draw identically. It can only return |
| 42 | true when the two prceossor are of the same subclass (i.e. they return the same object from |
| 43 | from getFactory()). |
| 44 | |
| 45 | A return value of true from isEqual() should not be used to test whether the prceossor would |
| 46 | generate the same shader code. To test for identical code generation use the prceossor' keys |
| 47 | computed by the GrBackendProcessorFactory. */ |
| 48 | bool isEqual(const GrFragmentProcessor& other) const { |
bsalomon | de258cd | 2014-10-15 19:06:21 -0700 | [diff] [blame^] | 49 | if (&this->getFactory() != &other.getFactory() || !this->hasSameTransforms(other)) { |
bsalomon | 6251d17 | 2014-10-15 10:50:36 -0700 | [diff] [blame] | 50 | return false; |
| 51 | } |
| 52 | bool result = this->onIsEqual(other); |
| 53 | #ifdef SK_DEBUG |
| 54 | if (result) { |
| 55 | this->assertTexturesEqual(other); |
| 56 | } |
| 57 | #endif |
| 58 | return result; |
| 59 | } |
| 60 | |
| 61 | protected: |
| 62 | /** |
| 63 | * Fragment Processor subclasses call this from their constructor to register coordinate |
bsalomon | de258cd | 2014-10-15 19:06:21 -0700 | [diff] [blame^] | 64 | * transformations. Coord transforms provide a mechanism for a processor to receive coordinates |
| 65 | * in their FS code. The matrix expresses a transformation from local space. For a given |
| 66 | * fragment the matrix will be applied to the local coordinate that maps to the fragment. |
| 67 | * |
| 68 | * When the transformation has perspective, the transformed coordinates will have |
| 69 | * 3 components. Otherwise they'll have 2. |
| 70 | * |
| 71 | * This must only be called from the constructor because GrProcessors are immutable. The |
| 72 | * processor subclass manages the lifetime of the transformations (this function only stores a |
| 73 | * pointer). The GrCoordTransform is typically a member field of the GrProcessor subclass. |
| 74 | * |
| 75 | * A processor subclass that has multiple methods of construction should always add its coord |
| 76 | * transforms in a consistent order. The non-virtual implementation of isEqual() automatically |
| 77 | * compares transforms and will assume they line up across the two processor instances. |
bsalomon | 6251d17 | 2014-10-15 10:50:36 -0700 | [diff] [blame] | 78 | */ |
| 79 | void addCoordTransform(const GrCoordTransform*); |
| 80 | |
| 81 | /** |
bsalomon | 98b33eb | 2014-10-15 11:05:26 -0700 | [diff] [blame] | 82 | * If the prceossor subclass will read the destination pixel value then it must call this |
| 83 | * function from its constructor. Otherwise, when its generated backend-specific prceossor class |
| 84 | * attempts to generate code that reads the destination pixel it will fail. |
bsalomon | 6251d17 | 2014-10-15 10:50:36 -0700 | [diff] [blame] | 85 | */ |
| 86 | void setWillReadDstColor() { fWillReadDstColor = true; } |
| 87 | |
| 88 | /** |
| 89 | * If the prceossor will generate a result that does not depend on the input color value then it |
| 90 | * must call this function from its constructor. Otherwise, when its generated backend-specific |
| 91 | * code might fail during variable binding due to unused variables. |
| 92 | */ |
| 93 | void setWillNotUseInputColor() { fWillUseInputColor = false; } |
| 94 | |
| 95 | private: |
bsalomon | de258cd | 2014-10-15 19:06:21 -0700 | [diff] [blame^] | 96 | /** |
| 97 | * Subclass implements this to support isEqual(). It will only be called if it is known that |
| 98 | * the two processors are of the same subclass (i.e. they return the same object from |
| 99 | * getFactory()). The processor subclass should not compare its coord transforms as that will |
| 100 | * be performed automatically in the non-virtual isEqual(). |
| 101 | */ |
| 102 | virtual bool onIsEqual(const GrFragmentProcessor&) const = 0; |
| 103 | |
| 104 | bool hasSameTransforms(const GrFragmentProcessor&) const; |
bsalomon | 6251d17 | 2014-10-15 10:50:36 -0700 | [diff] [blame] | 105 | |
| 106 | SkSTArray<4, const GrCoordTransform*, true> fCoordTransforms; |
| 107 | bool fWillReadDstColor; |
| 108 | bool fWillUseInputColor; |
| 109 | |
| 110 | typedef GrProcessor INHERITED; |
| 111 | }; |
| 112 | |
bsalomon | 6251d17 | 2014-10-15 10:50:36 -0700 | [diff] [blame] | 113 | #endif |