blob: 7a04f4bfd217a3b339fd4d86d858c68a120acf13 [file] [log] [blame]
* 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 "src/gpu/glsl/GrGLSLXferProcessor.h"
#include "include/gpu/GrTexture.h"
#include "src/gpu/GrShaderCaps.h"
#include "src/gpu/GrXferProcessor.h"
#include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
#include "src/gpu/glsl/GrGLSLProgramDataManager.h"
#include "src/gpu/glsl/GrGLSLUniformHandler.h"
// This is only called for cases where we are doing LCD coverage and not using in shader blending.
// For these cases we assume the the src alpha is 1, thus we can just use the max for the alpha
// coverage since src alpha will always be greater than or equal to dst alpha.
static void adjust_for_lcd_coverage(GrGLSLXPFragmentBuilder* fragBuilder,
const char* srcCoverage,
const GrXferProcessor& proc) {
if (srcCoverage && proc.isLCD()) {
fragBuilder->codeAppendf("%s.a = max(max(%s.r, %s.g), %s.b);",
srcCoverage, srcCoverage, srcCoverage, srcCoverage);
void GrGLSLXferProcessor::emitCode(const EmitArgs& args) {
if (!args.fXP.willReadDstColor()) {
adjust_for_lcd_coverage(args.fXPFragBuilder, args.fInputCoverage, args.fXP);
} else {
GrGLSLXPFragmentBuilder* fragBuilder = args.fXPFragBuilder;
GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
const char* dstColor = fragBuilder->dstColor();
bool needsLocalOutColor = false;
if (args.fDstTextureSamplerHandle.isValid()) {
bool flipY = kBottomLeft_GrSurfaceOrigin == args.fDstTextureOrigin;
if (args.fInputCoverage) {
// 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. We just
// check the rgb values of the coverage since the alpha may not have been set when
// using lcd. If we are using single channel coverage alpha will equal to rgb
// anyways.
// The discard here also helps for batching text draws together which need to read
// from a dst copy for blends. Though this only helps the case where the outer
// bounding boxes of each letter overlap and not two actually parts of the text.
fragBuilder->codeAppendf("if (all(lessThanEqual(%s.rgb, half3(0)))) {"
" discard;"
"}", args.fInputCoverage);
const char* dstTopLeftName;
const char* dstCoordScaleName;
fDstTopLeftUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
fDstScaleUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
fragBuilder->codeAppend("// Read color from copy of the destination.\n");
fragBuilder->codeAppendf("half2 _dstTexCoord = (half2(sk_FragCoord.xy) - %s) * %s;",
dstTopLeftName, dstCoordScaleName);
if (flipY) {
fragBuilder->codeAppend("_dstTexCoord.y = 1.0 - _dstTexCoord.y;");
fragBuilder->codeAppendf("half4 %s = ", dstColor);
fragBuilder->appendTextureLookup(args.fDstTextureSamplerHandle, "_dstTexCoord",
} else {
needsLocalOutColor = args.fShaderCaps->requiresLocalOutputColorForFBFetch();
const char* outColor = "_localColorOut";
if (!needsLocalOutColor) {
outColor = args.fOutputPrimary;
} else {
fragBuilder->codeAppendf("half4 %s;", outColor);
if (needsLocalOutColor) {
fragBuilder->codeAppendf("%s = %s;", args.fOutputPrimary, outColor);
// Swizzle the fragment shader outputs if necessary.
args.fXPFragBuilder, args.fOutputSwizzle, args.fOutputPrimary, args.fOutputSecondary);
void GrGLSLXferProcessor::emitOutputSwizzle(
GrGLSLXPFragmentBuilder* x, const GrSwizzle& swizzle, const char* outColor,
const char* outColorSecondary) const {
if (GrSwizzle::RGBA() != swizzle) {
x->codeAppendf("%s = %s.%s;", outColor, outColor, swizzle.c_str());
if (outColorSecondary) {
x->codeAppendf("%s = %s.%s;", outColorSecondary, outColorSecondary, swizzle.c_str());
void GrGLSLXferProcessor::setData(const GrGLSLProgramDataManager& pdm, const GrXferProcessor& xp,
const GrTexture* dstTexture, const SkIPoint& dstTextureOffset) {
if (dstTexture) {
if (fDstTopLeftUni.isValid()) {
pdm.set2f(fDstTopLeftUni, static_cast<float>(dstTextureOffset.fX),
pdm.set2f(fDstScaleUni, 1.f / dstTexture->width(), 1.f / dstTexture->height());
} else {
} else {
this->onSetData(pdm, xp);
void GrGLSLXferProcessor::DefaultCoverageModulation(GrGLSLXPFragmentBuilder* fragBuilder,
const char* srcCoverage,
const char* dstColor,
const char* outColor,
const char* outColorSecondary,
const GrXferProcessor& proc) {
if (proc.dstReadUsesMixedSamples()) {
if (srcCoverage) {
// TODO: Once we are no longer using legacy mesh ops, it will not be possible to even
// create a mixed sample with lcd so we can uncomment the below assert. In practice
// today this never happens except for GLPrograms test which can make one. skia:6661
// SkASSERT(!proc.isLCD());
fragBuilder->codeAppendf("%s *= %s;", outColor, srcCoverage);
fragBuilder->codeAppendf("%s = %s;", outColorSecondary, srcCoverage);
} else {
fragBuilder->codeAppendf("%s = half4(1.0);", outColorSecondary);
} else if (srcCoverage) {
if (proc.isLCD()) {
fragBuilder->codeAppendf("half lerpRed = mix(%s.a, %s.a, %s.r);",
dstColor, outColor, srcCoverage);
fragBuilder->codeAppendf("half lerpBlue = mix(%s.a, %s.a, %s.g);",
dstColor, outColor, srcCoverage);
fragBuilder->codeAppendf("half lerpGreen = mix(%s.a, %s.a, %s.b);",
dstColor, outColor, srcCoverage);
fragBuilder->codeAppendf("%s = %s * %s + (half4(1.0) - %s) * %s;",
outColor, srcCoverage, outColor, srcCoverage, dstColor);
if (proc.isLCD()) {
fragBuilder->codeAppendf("%s.a = max(max(lerpRed, lerpBlue), lerpGreen);", outColor);