wangyix | 809e5af | 2015-09-09 12:58:32 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2015 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 | #include "effects/GrXfermodeFragmentProcessor.h" |
| 9 | |
| 10 | #include "GrFragmentProcessor.h" |
| 11 | #include "effects/GrConstColorProcessor.h" |
| 12 | #include "gl/GrGLBlend.h" |
| 13 | #include "gl/builders/GrGLProgramBuilder.h" |
| 14 | |
| 15 | |
| 16 | class GrComposeTwoFragmentProcessor : public GrFragmentProcessor { |
| 17 | public: |
| 18 | GrComposeTwoFragmentProcessor(const GrFragmentProcessor* src, const GrFragmentProcessor* dst, |
| 19 | SkXfermode::Mode mode) |
| 20 | : fMode(mode) { |
| 21 | // Only coefficient xfer modes are supported |
| 22 | SkASSERT(SkXfermode::kLastCoeffMode >= mode); |
| 23 | this->initClassID<GrComposeTwoFragmentProcessor>(); |
| 24 | SkDEBUGCODE(int shaderAChildIndex = )this->registerChildProcessor(src); |
| 25 | SkDEBUGCODE(int shaderBChildIndex = )this->registerChildProcessor(dst); |
| 26 | SkASSERT(0 == shaderAChildIndex); |
| 27 | SkASSERT(1 == shaderBChildIndex); |
| 28 | } |
| 29 | |
| 30 | const char* name() const override { return "ComposeShader"; } |
| 31 | |
| 32 | void onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override { |
| 33 | b->add32(fMode); |
| 34 | } |
| 35 | |
| 36 | SkXfermode::Mode getMode() const { return fMode; } |
| 37 | |
| 38 | protected: |
| 39 | bool onIsEqual(const GrFragmentProcessor& other) const override { |
| 40 | const GrComposeTwoFragmentProcessor& cs = other.cast<GrComposeTwoFragmentProcessor>(); |
| 41 | return fMode == cs.fMode; |
| 42 | } |
| 43 | |
| 44 | void onComputeInvariantOutput(GrInvariantOutput* inout) const override { |
| 45 | inout->setToUnknown(GrInvariantOutput::kWill_ReadInput); |
| 46 | } |
| 47 | |
| 48 | private: |
| 49 | GrGLFragmentProcessor* onCreateGLInstance() const override; |
| 50 | |
| 51 | SkXfermode::Mode fMode; |
| 52 | |
| 53 | GR_DECLARE_FRAGMENT_PROCESSOR_TEST; |
| 54 | |
| 55 | typedef GrFragmentProcessor INHERITED; |
| 56 | }; |
| 57 | |
| 58 | ///////////////////////////////////////////////////////////////////// |
| 59 | |
| 60 | class GrGLComposeTwoFragmentProcessor : public GrGLFragmentProcessor { |
| 61 | public: |
| 62 | GrGLComposeTwoFragmentProcessor(const GrProcessor& processor) {} |
| 63 | |
| 64 | void emitCode(EmitArgs&) override; |
| 65 | |
| 66 | private: |
| 67 | typedef GrGLFragmentProcessor INHERITED; |
| 68 | }; |
| 69 | |
| 70 | ///////////////////////////////////////////////////////////////////// |
| 71 | |
| 72 | GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrComposeTwoFragmentProcessor); |
| 73 | |
| 74 | const GrFragmentProcessor* GrComposeTwoFragmentProcessor::TestCreate(GrProcessorTestData* d) { |
| 75 | #if SK_ALLOW_STATIC_GLOBAL_INITIALIZERS |
| 76 | // Create two random frag procs. |
| 77 | // For now, we'll prevent either children from being a shader with children to prevent the |
| 78 | // possibility of an arbitrarily large tree of procs. |
| 79 | SkAutoTUnref<const GrFragmentProcessor> fpA; |
| 80 | do { |
| 81 | fpA.reset(GrProcessorTestFactory<GrFragmentProcessor>::CreateStage(d)); |
| 82 | SkASSERT(fpA); |
| 83 | } while (fpA->numChildProcessors() != 0); |
| 84 | SkAutoTUnref<const GrFragmentProcessor> fpB; |
| 85 | do { |
| 86 | fpB.reset(GrProcessorTestFactory<GrFragmentProcessor>::CreateStage(d)); |
| 87 | SkASSERT(fpB); |
| 88 | } while (fpB->numChildProcessors() != 0); |
| 89 | |
| 90 | SkXfermode::Mode mode = static_cast<SkXfermode::Mode>( |
| 91 | d->fRandom->nextRangeU(0, SkXfermode::kLastCoeffMode)); |
| 92 | return SkNEW_ARGS(GrComposeTwoFragmentProcessor, (fpA, fpB, mode)); |
| 93 | #else |
| 94 | SkFAIL("Should not be called if !SK_ALLOW_STATIC_GLOBAL_INITIALIZERS"); |
| 95 | return nullptr; |
| 96 | #endif |
| 97 | } |
| 98 | |
| 99 | GrGLFragmentProcessor* GrComposeTwoFragmentProcessor::onCreateGLInstance() const{ |
| 100 | return SkNEW_ARGS(GrGLComposeTwoFragmentProcessor, (*this)); |
| 101 | } |
| 102 | |
| 103 | ///////////////////////////////////////////////////////////////////// |
| 104 | |
| 105 | void GrGLComposeTwoFragmentProcessor::emitCode(EmitArgs& args) { |
| 106 | |
| 107 | GrGLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder(); |
| 108 | const GrComposeTwoFragmentProcessor& cs = args.fFp.cast<GrComposeTwoFragmentProcessor>(); |
| 109 | |
| 110 | // Store alpha of input color and un-premultiply the input color by its alpha. We will |
| 111 | // re-multiply by this alpha after blending the output colors of the two child procs. |
| 112 | // This is because we don't want the paint's alpha to affect either child proc's output |
| 113 | // before the blend; we want to apply the paint's alpha AFTER the blend. This mirrors the |
| 114 | // software implementation of SkComposeShader. |
| 115 | SkString inputAlpha("inputAlpha"); |
| 116 | fsBuilder->codeAppendf("float %s = %s.a;", inputAlpha.c_str(), args.fInputColor); |
| 117 | fsBuilder->codeAppendf("%s /= %s.a;", args.fInputColor, args.fInputColor); |
| 118 | |
| 119 | // declare outputColor and emit the code for each of the two children |
| 120 | SkString outputColorSrc(args.fOutputColor); |
| 121 | outputColorSrc.append("_src"); |
| 122 | fsBuilder->codeAppendf("vec4 %s;\n", outputColorSrc.c_str()); |
| 123 | this->emitChild(0, args.fInputColor, outputColorSrc.c_str(), args); |
| 124 | |
| 125 | SkString outputColorDst(args.fOutputColor); |
| 126 | outputColorDst.append("_dst"); |
| 127 | fsBuilder->codeAppendf("vec4 %s;\n", outputColorDst.c_str()); |
| 128 | this->emitChild(1, args.fInputColor, outputColorDst.c_str(), args); |
| 129 | |
| 130 | // emit blend code |
| 131 | SkXfermode::Mode mode = cs.getMode(); |
| 132 | fsBuilder->codeAppend("{"); |
| 133 | fsBuilder->codeAppendf("// Compose Xfer Mode: %s\n", SkXfermode::ModeName(mode)); |
| 134 | GrGLBlend::AppendPorterDuffBlend(fsBuilder, outputColorSrc.c_str(), |
| 135 | outputColorDst.c_str(), args.fOutputColor, mode); |
| 136 | fsBuilder->codeAppend("}"); |
| 137 | |
| 138 | // re-multiply the output color by the input color's alpha |
| 139 | fsBuilder->codeAppendf("%s *= %s;", args.fOutputColor, inputAlpha.c_str()); |
| 140 | } |
| 141 | |
| 142 | |
| 143 | const GrFragmentProcessor* GrXfermodeFragmentProcessor::CreateFromTwoProcessors( |
| 144 | const GrFragmentProcessor* src, const GrFragmentProcessor* dst, SkXfermode::Mode mode) { |
| 145 | if (SkXfermode::kLastCoeffMode < mode) { |
| 146 | return nullptr; |
| 147 | } |
| 148 | switch (mode) { |
| 149 | case SkXfermode::kClear_Mode: |
| 150 | SkDebugf("CreateFromTwoProcessors() should not be used with kClear_Mode. " |
| 151 | "Use GrConstColorProcessor.\n"); |
| 152 | return GrConstColorProcessor::Create(GrColor_TRANS_BLACK, |
| 153 | GrConstColorProcessor::kIgnore_InputMode); |
| 154 | break; |
| 155 | case SkXfermode::kSrc_Mode: |
| 156 | SkDebugf("CreateFromTwoProcessors() should not be used with kSrc_Mode. " |
| 157 | "Use the src processor directly.\n"); |
| 158 | return SkRef(src); |
| 159 | break; |
| 160 | case SkXfermode::kDst_Mode: |
| 161 | SkDebugf("CreateFromTwoProcessors() should not be used with kDst_Mode. " |
| 162 | "Use the dst processor directly.\n"); |
| 163 | return SkRef(dst); |
| 164 | break; |
| 165 | default: |
| 166 | return new GrComposeTwoFragmentProcessor(src, dst, mode); |
| 167 | } |
| 168 | } |