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/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "gl/GrGLXferProcessor.h"
#include "GrXferProcessor.h"
#include "gl/builders/GrGLFragmentShaderBuilder.h"
#include "gl/builders/GrGLProgramBuilder.h"
void GrGLXferProcessor::emitCode(const EmitArgs& args) {
if (!args.fXP.willReadDstColor()) {
this->emitOutputsForBlendState(args);
return;
}
GrGLXPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();
const char* dstColor = fsBuilder->dstColor();
if (args.fXP.getDstTexture()) {
bool topDown = kTopLeft_GrSurfaceOrigin == args.fXP.getDstTexture()->origin();
if (args.fXP.readsCoverage()) {
// We don't think any shaders actually output negative coverage, but just as a safety
// check for floating point precision errors we compare with <= here
fsBuilder->codeAppendf("if (all(lessThanEqual(%s, vec4(0)))) {"
" discard;"
"}", args.fInputCoverage);
}
const char* dstTopLeftName;
const char* dstCoordScaleName;
fDstTopLeftUni = args.fPB->addUniform(GrGLProgramBuilder::kFragment_Visibility,
kVec2f_GrSLType,
kDefault_GrSLPrecision,
"DstTextureUpperLeft",
&dstTopLeftName);
fDstScaleUni = args.fPB->addUniform(GrGLProgramBuilder::kFragment_Visibility,
kVec2f_GrSLType,
kDefault_GrSLPrecision,
"DstTextureCoordScale",
&dstCoordScaleName);
const char* fragPos = fsBuilder->fragmentPosition();
fsBuilder->codeAppend("// Read color from copy of the destination.\n");
fsBuilder->codeAppendf("vec2 _dstTexCoord = (%s.xy - %s) * %s;",
fragPos, dstTopLeftName, dstCoordScaleName);
if (!topDown) {
fsBuilder->codeAppend("_dstTexCoord.y = 1.0 - _dstTexCoord.y;");
}
fsBuilder->codeAppendf("vec4 %s = ", dstColor);
fsBuilder->appendTextureLookup(args.fSamplers[0], "_dstTexCoord", kVec2f_GrSLType);
fsBuilder->codeAppend(";");
}
this->emitBlendCodeForDstRead(args.fPB, args.fInputColor, dstColor, args.fOutputPrimary,
args.fXP);
// Apply coverage.
if (args.fXP.dstReadUsesMixedSamples()) {
if (args.fXP.readsCoverage()) {
fsBuilder->codeAppendf("%s *= %s;", args.fOutputPrimary, args.fInputCoverage);
fsBuilder->codeAppendf("%s = %s;", args.fOutputSecondary, args.fInputCoverage);
} else {
fsBuilder->codeAppendf("%s = vec4(1.0);", args.fOutputSecondary);
}
} else if (args.fXP.readsCoverage()) {
fsBuilder->codeAppendf("%s = %s * %s + (vec4(1.0) - %s) * %s;",
args.fOutputPrimary, args.fInputCoverage,
args.fOutputPrimary, args.fInputCoverage, dstColor);
}
}
void GrGLXferProcessor::setData(const GrGLProgramDataManager& pdm, const GrXferProcessor& xp) {
if (xp.getDstTexture()) {
if (fDstTopLeftUni.isValid()) {
pdm.set2f(fDstTopLeftUni, static_cast<GrGLfloat>(xp.dstTextureOffset().fX),
static_cast<GrGLfloat>(xp.dstTextureOffset().fY));
pdm.set2f(fDstScaleUni, 1.f / xp.getDstTexture()->width(),
1.f / xp.getDstTexture()->height());
} else {
SkASSERT(!fDstScaleUni.isValid());
}
} else {
SkASSERT(!fDstTopLeftUni.isValid());
SkASSERT(!fDstScaleUni.isValid());
}
this->onSetData(pdm, xp);
}
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