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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 "GrGLBlend.h"
#include "gl/builders/GrGLFragmentShaderBuilder.h"
static bool append_porterduff_term(GrGLFragmentBuilder* fsBuilder, SkXfermode::Coeff coeff,
const char* colorName, const char* srcColorName,
const char* dstColorName, bool hasPrevious) {
if (SkXfermode::kZero_Coeff == coeff) {
return hasPrevious;
} else {
if (hasPrevious) {
fsBuilder->codeAppend(" + ");
}
fsBuilder->codeAppendf("%s", colorName);
switch (coeff) {
case SkXfermode::kOne_Coeff:
break;
case SkXfermode::kSC_Coeff:
fsBuilder->codeAppendf(" * %s", srcColorName);
break;
case SkXfermode::kISC_Coeff:
fsBuilder->codeAppendf(" * (vec4(1.0) - %s)", srcColorName);
break;
case SkXfermode::kDC_Coeff:
fsBuilder->codeAppendf(" * %s", dstColorName);
break;
case SkXfermode::kIDC_Coeff:
fsBuilder->codeAppendf(" * (vec4(1.0) - %s)", dstColorName);
break;
case SkXfermode::kSA_Coeff:
fsBuilder->codeAppendf(" * %s.a", srcColorName);
break;
case SkXfermode::kISA_Coeff:
fsBuilder->codeAppendf(" * (1.0 - %s.a)", srcColorName);
break;
case SkXfermode::kDA_Coeff:
fsBuilder->codeAppendf(" * %s.a", dstColorName);
break;
case SkXfermode::kIDA_Coeff:
fsBuilder->codeAppendf(" * (1.0 - %s.a)", dstColorName);
break;
default:
SkFAIL("Unsupported Blend Coeff");
}
return true;
}
}
void GrGLBlend::AppendPorterDuffBlend(GrGLFragmentBuilder* fsBuilder, const char* srcColor,
const char* dstColor, const char* outColor,
SkXfermode::Mode mode) {
SkXfermode::Coeff srcCoeff, dstCoeff;
SkXfermode::ModeAsCoeff(mode, &srcCoeff, &dstCoeff);
fsBuilder->codeAppendf("%s =", outColor);
// append src blend
bool didAppend = append_porterduff_term(fsBuilder, srcCoeff, srcColor, srcColor, dstColor,
false);
// append dst blend
SkAssertResult(append_porterduff_term(fsBuilder, dstCoeff, dstColor, srcColor, dstColor,
didAppend));
fsBuilder->codeAppend(";");
}
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