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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "effects/GrXfermodeFragmentProcessor.h"
#include "GrFragmentProcessor.h"
#include "effects/GrConstColorProcessor.h"
#include "gl/GrGLBlend.h"
#include "gl/builders/GrGLProgramBuilder.h"
class GrComposeTwoFragmentProcessor : public GrFragmentProcessor {
public:
GrComposeTwoFragmentProcessor(const GrFragmentProcessor* src, const GrFragmentProcessor* dst,
SkXfermode::Mode mode)
: fMode(mode) {
// Only coefficient xfer modes are supported
SkASSERT(SkXfermode::kLastCoeffMode >= mode);
this->initClassID<GrComposeTwoFragmentProcessor>();
SkDEBUGCODE(int shaderAChildIndex = )this->registerChildProcessor(src);
SkDEBUGCODE(int shaderBChildIndex = )this->registerChildProcessor(dst);
SkASSERT(0 == shaderAChildIndex);
SkASSERT(1 == shaderBChildIndex);
}
const char* name() const override { return "ComposeShader"; }
void onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override {
b->add32(fMode);
}
SkXfermode::Mode getMode() const { return fMode; }
protected:
bool onIsEqual(const GrFragmentProcessor& other) const override {
const GrComposeTwoFragmentProcessor& cs = other.cast<GrComposeTwoFragmentProcessor>();
return fMode == cs.fMode;
}
void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
inout->setToUnknown(GrInvariantOutput::kWill_ReadInput);
}
private:
GrGLFragmentProcessor* onCreateGLInstance() const override;
SkXfermode::Mode fMode;
GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
typedef GrFragmentProcessor INHERITED;
};
/////////////////////////////////////////////////////////////////////
class GrGLComposeTwoFragmentProcessor : public GrGLFragmentProcessor {
public:
GrGLComposeTwoFragmentProcessor(const GrProcessor& processor) {}
void emitCode(EmitArgs&) override;
private:
typedef GrGLFragmentProcessor INHERITED;
};
/////////////////////////////////////////////////////////////////////
GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrComposeTwoFragmentProcessor);
const GrFragmentProcessor* GrComposeTwoFragmentProcessor::TestCreate(GrProcessorTestData* d) {
#if SK_ALLOW_STATIC_GLOBAL_INITIALIZERS
// Create two random frag procs.
// For now, we'll prevent either children from being a shader with children to prevent the
// possibility of an arbitrarily large tree of procs.
SkAutoTUnref<const GrFragmentProcessor> fpA;
do {
fpA.reset(GrProcessorTestFactory<GrFragmentProcessor>::Create(d));
SkASSERT(fpA);
} while (fpA->numChildProcessors() != 0);
SkAutoTUnref<const GrFragmentProcessor> fpB;
do {
fpB.reset(GrProcessorTestFactory<GrFragmentProcessor>::Create(d));
SkASSERT(fpB);
} while (fpB->numChildProcessors() != 0);
SkXfermode::Mode mode = static_cast<SkXfermode::Mode>(
d->fRandom->nextRangeU(0, SkXfermode::kLastCoeffMode));
return SkNEW_ARGS(GrComposeTwoFragmentProcessor, (fpA, fpB, mode));
#else
SkFAIL("Should not be called if !SK_ALLOW_STATIC_GLOBAL_INITIALIZERS");
return nullptr;
#endif
}
GrGLFragmentProcessor* GrComposeTwoFragmentProcessor::onCreateGLInstance() const{
return SkNEW_ARGS(GrGLComposeTwoFragmentProcessor, (*this));
}
/////////////////////////////////////////////////////////////////////
void GrGLComposeTwoFragmentProcessor::emitCode(EmitArgs& args) {
GrGLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder();
const GrComposeTwoFragmentProcessor& cs = args.fFp.cast<GrComposeTwoFragmentProcessor>();
// Store alpha of input color and un-premultiply the input color by its alpha. We will
// re-multiply by this alpha after blending the output colors of the two child procs.
// This is because we don't want the paint's alpha to affect either child proc's output
// before the blend; we want to apply the paint's alpha AFTER the blend. This mirrors the
// software implementation of SkComposeShader.
const char* opaqueInput = nullptr;
const char* inputAlpha = nullptr;
if (args.fInputColor) {
inputAlpha = "inputAlpha";
opaqueInput = "opaqueInput";
fsBuilder->codeAppendf("float inputAlpha = %s.a;", args.fInputColor);
fsBuilder->codeAppendf("vec4 opaqueInput = vec4(%s.rgb / inputAlpha, 1);",
args.fInputColor);
}
// declare outputColor and emit the code for each of the two children
SkString outputColorSrc(args.fOutputColor);
outputColorSrc.append("_src");
fsBuilder->codeAppendf("vec4 %s;\n", outputColorSrc.c_str());
this->emitChild(0, opaqueInput, outputColorSrc.c_str(), args);
SkString outputColorDst(args.fOutputColor);
outputColorDst.append("_dst");
fsBuilder->codeAppendf("vec4 %s;\n", outputColorDst.c_str());
this->emitChild(1, opaqueInput, outputColorDst.c_str(), args);
// emit blend code
SkXfermode::Mode mode = cs.getMode();
fsBuilder->codeAppend("{");
fsBuilder->codeAppendf("// Compose Xfer Mode: %s\n", SkXfermode::ModeName(mode));
GrGLBlend::AppendPorterDuffBlend(fsBuilder, outputColorSrc.c_str(),
outputColorDst.c_str(), args.fOutputColor, mode);
fsBuilder->codeAppend("}");
// re-multiply the output color by the input color's alpha
if (inputAlpha) {
fsBuilder->codeAppendf("%s *= %s;", args.fOutputColor, inputAlpha);
}
}
const GrFragmentProcessor* GrXfermodeFragmentProcessor::CreateFromTwoProcessors(
const GrFragmentProcessor* src, const GrFragmentProcessor* dst, SkXfermode::Mode mode) {
if (SkXfermode::kLastCoeffMode < mode) {
return nullptr;
}
switch (mode) {
case SkXfermode::kClear_Mode:
return GrConstColorProcessor::Create(GrColor_TRANS_BLACK,
GrConstColorProcessor::kIgnore_InputMode);
break;
case SkXfermode::kSrc_Mode:
return SkRef(src);
break;
case SkXfermode::kDst_Mode:
return SkRef(dst);
break;
default:
return new GrComposeTwoFragmentProcessor(src, dst, mode);
}
}
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