1 /*
2 * Copyright 2014 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 "src/gpu/glsl/GrGLSLXferProcessor.h"
9
10 #include "src/gpu/GrShaderCaps.h"
11 #include "src/gpu/GrTexture.h"
12 #include "src/gpu/GrXferProcessor.h"
13 #include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
14 #include "src/gpu/glsl/GrGLSLProgramDataManager.h"
15 #include "src/gpu/glsl/GrGLSLUniformHandler.h"
16
17 // This is only called for cases where we are doing LCD coverage and not using in shader blending.
18 // For these cases we assume the the src alpha is 1, thus we can just use the max for the alpha
19 // coverage since src alpha will always be greater than or equal to dst alpha.
adjust_for_lcd_coverage(GrGLSLXPFragmentBuilder * fragBuilder,const char * srcCoverage,const GrXferProcessor & proc)20 static void adjust_for_lcd_coverage(GrGLSLXPFragmentBuilder* fragBuilder,
21 const char* srcCoverage,
22 const GrXferProcessor& proc) {
23 if (srcCoverage && proc.isLCD()) {
24 fragBuilder->codeAppendf("%s.a = max(max(%s.r, %s.g), %s.b);",
25 srcCoverage, srcCoverage, srcCoverage, srcCoverage);
26 }
27 }
28
29
emitCode(const EmitArgs & args)30 void GrGLSLXferProcessor::emitCode(const EmitArgs& args) {
31 if (!args.fXP.willReadDstColor()) {
32 adjust_for_lcd_coverage(args.fXPFragBuilder, args.fInputCoverage, args.fXP);
33 this->emitOutputsForBlendState(args);
34 } else {
35 GrGLSLXPFragmentBuilder* fragBuilder = args.fXPFragBuilder;
36 GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
37 const char* dstColor = fragBuilder->dstColor();
38
39 bool needsLocalOutColor = false;
40
41 if (args.fDstTextureSamplerHandle.isValid()) {
42 if (args.fInputCoverage) {
43 // We don't think any shaders actually output negative coverage, but just as a
44 // safety check for floating point precision errors we compare with <= here. We just
45 // check the rgb values of the coverage since the alpha may not have been set when
46 // using lcd. If we are using single channel coverage alpha will equal to rgb
47 // anyways.
48 //
49 // The discard here also helps for batching text draws together which need to read
50 // from a dst copy for blends. Though this only helps the case where the outer
51 // bounding boxes of each letter overlap and not two actually parts of the text.
52 fragBuilder->codeAppendf("if (all(lessThanEqual(%s.rgb, half3(0)))) {"
53 " discard;"
54 "}", args.fInputCoverage);
55 }
56 if (GrDstSampleTypeUsesTexture(args.fDstSampleType)) {
57 bool flipY = kBottomLeft_GrSurfaceOrigin == args.fDstTextureOrigin;
58
59 const char* dstTopLeftName;
60 const char* dstCoordScaleName;
61
62 fDstTopLeftUni = uniformHandler->addUniform(nullptr,
63 kFragment_GrShaderFlag,
64 kHalf2_GrSLType,
65 "DstTextureUpperLeft",
66 &dstTopLeftName);
67 fDstScaleUni = uniformHandler->addUniform(nullptr,
68 kFragment_GrShaderFlag,
69 kHalf2_GrSLType,
70 "DstTextureCoordScale",
71 &dstCoordScaleName);
72
73 fragBuilder->codeAppend("// Read color from copy of the destination.\n");
74 fragBuilder->codeAppendf("half2 _dstTexCoord = (half2(sk_FragCoord.xy) - %s) * %s;",
75 dstTopLeftName, dstCoordScaleName);
76
77 if (flipY) {
78 fragBuilder->codeAppend("_dstTexCoord.y = 1.0 - _dstTexCoord.y;");
79 }
80
81 fragBuilder->codeAppendf("half4 %s = ", dstColor);
82 fragBuilder->appendTextureLookup(args.fDstTextureSamplerHandle, "_dstTexCoord");
83 fragBuilder->codeAppend(";");
84 } else if (args.fDstSampleType == GrDstSampleType::kAsInputAttachment) {
85 fragBuilder->codeAppendf("half4 %s = ", dstColor);
86 fragBuilder->appendInputLoad(args.fDstTextureSamplerHandle);
87 fragBuilder->codeAppend(";");
88 }
89 } else {
90 needsLocalOutColor = args.fShaderCaps->requiresLocalOutputColorForFBFetch();
91 }
92
93 const char* outColor = "_localColorOut";
94 if (!needsLocalOutColor) {
95 outColor = args.fOutputPrimary;
96 } else {
97 fragBuilder->codeAppendf("half4 %s;", outColor);
98 }
99
100 this->emitBlendCodeForDstRead(fragBuilder,
101 uniformHandler,
102 args.fInputColor,
103 args.fInputCoverage,
104 dstColor,
105 outColor,
106 args.fOutputSecondary,
107 args.fXP);
108 if (needsLocalOutColor) {
109 fragBuilder->codeAppendf("%s = %s;", args.fOutputPrimary, outColor);
110 }
111 }
112
113 // Swizzle the fragment shader outputs if necessary.
114 this->emitWriteSwizzle(args.fXPFragBuilder, args.fWriteSwizzle, args.fOutputPrimary,
115 args.fOutputSecondary);
116 }
117
emitWriteSwizzle(GrGLSLXPFragmentBuilder * x,const GrSwizzle & swizzle,const char * outColor,const char * outColorSecondary) const118 void GrGLSLXferProcessor::emitWriteSwizzle(GrGLSLXPFragmentBuilder* x,
119 const GrSwizzle& swizzle,
120 const char* outColor,
121 const char* outColorSecondary) const {
122 if (GrSwizzle::RGBA() != swizzle) {
123 x->codeAppendf("%s = %s.%s;", outColor, outColor, swizzle.asString().c_str());
124 if (outColorSecondary) {
125 x->codeAppendf("%s = %s.%s;", outColorSecondary, outColorSecondary,
126 swizzle.asString().c_str());
127 }
128 }
129 }
130
setData(const GrGLSLProgramDataManager & pdm,const GrXferProcessor & xp,const GrTexture * dstTexture,const SkIPoint & dstTextureOffset)131 void GrGLSLXferProcessor::setData(const GrGLSLProgramDataManager& pdm, const GrXferProcessor& xp,
132 const GrTexture* dstTexture, const SkIPoint& dstTextureOffset) {
133 if (dstTexture) {
134 if (fDstTopLeftUni.isValid()) {
135 pdm.set2f(fDstTopLeftUni, static_cast<float>(dstTextureOffset.fX),
136 static_cast<float>(dstTextureOffset.fY));
137 pdm.set2f(fDstScaleUni, 1.f / dstTexture->width(), 1.f / dstTexture->height());
138 } else {
139 SkASSERT(!fDstScaleUni.isValid());
140 }
141 } else {
142 SkASSERT(!fDstTopLeftUni.isValid());
143 SkASSERT(!fDstScaleUni.isValid());
144 }
145 this->onSetData(pdm, xp);
146 }
147
DefaultCoverageModulation(GrGLSLXPFragmentBuilder * fragBuilder,const char * srcCoverage,const char * dstColor,const char * outColor,const char * outColorSecondary,const GrXferProcessor & proc)148 void GrGLSLXferProcessor::DefaultCoverageModulation(GrGLSLXPFragmentBuilder* fragBuilder,
149 const char* srcCoverage,
150 const char* dstColor,
151 const char* outColor,
152 const char* outColorSecondary,
153 const GrXferProcessor& proc) {
154 if (srcCoverage) {
155 if (proc.isLCD()) {
156 fragBuilder->codeAppendf("half3 lerpRGB = mix(%s.aaa, %s.aaa, %s.rgb);",
157 dstColor, outColor, srcCoverage);
158 }
159 fragBuilder->codeAppendf("%s = %s * %s + (half4(1.0) - %s) * %s;",
160 outColor, srcCoverage, outColor, srcCoverage, dstColor);
161 if (proc.isLCD()) {
162 fragBuilder->codeAppendf("%s.a = max(max(lerpRGB.r, lerpRGB.b), lerpRGB.g);", outColor);
163 }
164 }
165 }
166
167