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| 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 c
olor (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 acco
rding to |
| 32 numTransforms(). */ |
| 33 const GrCoordTransform& coordTransform(int index) const { return *fCoordTran
sforms[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 t
he 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 { |
| 49 if (&this->getFactory() != &other.getFactory()) { |
| 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 registe
r coordinate |
| 64 * transformations. The processor subclass manages the lifetime of the trans
formations (this |
| 65 * function only stores a pointer). The GrCoordTransform is typically a memb
er field of the |
| 66 * GrProcessor subclass. When the matrix has perspective, the transformed co
ordinates will have |
| 67 * 3 components. Otherwise they'll have 2. This must only be called from the
constructor because |
| 68 * GrProcessors are immutable. |
| 69 */ |
| 70 void addCoordTransform(const GrCoordTransform*); |
| 71 |
| 72 /** |
| 73 * If the prceossor subclass will read the destination pixel value then it m
ust call this function |
| 74 * from its constructor. Otherwise, when its generated backend-specific prce
ossor class attempts |
| 75 * to generate code that reads the destination pixel it will fail. |
| 76 */ |
| 77 void setWillReadDstColor() { fWillReadDstColor = true; } |
| 78 |
| 79 /** |
| 80 * If the prceossor will generate a result that does not depend on the input
color value then it |
| 81 * must call this function from its constructor. Otherwise, when its generat
ed backend-specific |
| 82 * code might fail during variable binding due to unused variables. |
| 83 */ |
| 84 void setWillNotUseInputColor() { fWillUseInputColor = false; } |
| 85 |
| 86 private: |
| 87 /** Subclass implements this to support isEqual(). It will only be called if
it is known that |
| 88 the two prceossor are of the same subclass (i.e. they return the same ob
ject from |
| 89 getFactory()).*/ |
| 90 virtual bool onIsEqual(const GrFragmentProcessor& other) const = 0; |
| 91 |
| 92 SkSTArray<4, const GrCoordTransform*, true> fCoordTransforms; |
| 93 bool fWillReadDstColor; |
| 94 bool fWillUseInputColor; |
| 95 |
| 96 typedef GrProcessor INHERITED; |
| 97 }; |
| 98 |
| 99 /** |
| 100 * This creates an effect outside of the effect memory pool. The effect's destru
ctor will be called |
| 101 * at global destruction time. NAME will be the name of the created GrProcessor. |
| 102 */ |
| 103 #define GR_CREATE_STATIC_FRAGMENT_PROCESSOR(NAME, FP_CLASS, ARGS)
\ |
| 104 static SkAlignedSStorage<sizeof(FP_CLASS)> g_##NAME##_Storage;
\ |
| 105 static GrFragmentProcessor* NAME SkNEW_PLACEMENT_ARGS(g_##NAME##_Storage.get(),
FP_CLASS, ARGS); \ |
| 106 static SkAutoTDestroy<GrFragmentProcessor> NAME##_ad(NAME); |
| 107 |
| 108 #endif |
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