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 "glsl/GrGLSLXferProcessor.h"
9
10 #include "GrShaderCaps.h"
11 #include "GrTexture.h"
12 #include "GrXferProcessor.h"
13 #include "glsl/GrGLSLFragmentShaderBuilder.h"
14 #include "glsl/GrGLSLProgramDataManager.h"
15 #include "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 return;
35 }
36
37 GrGLSLXPFragmentBuilder* fragBuilder = args.fXPFragBuilder;
38 GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
39 const char* dstColor = fragBuilder->dstColor();
40
41 bool needsLocalOutColor = false;
42
43 if (args.fDstTextureSamplerHandle.isValid()) {
44 bool flipY = kBottomLeft_GrSurfaceOrigin == args.fDstTextureOrigin;
45
46 if (args.fInputCoverage) {
47 // We don't think any shaders actually output negative coverage, but just as a safety
48 // check for floating point precision errors we compare with <= here. We just check the
49 // rgb values of the coverage since the alpha may not have been set when using lcd. If
50 // we are using single channel coverage alpha will equal to rgb anyways.
51 //
52 // The discard here also helps for batching text draws together which need to read from
53 // a dst copy for blends. Though this only helps the case where the outer bounding boxes
54 // of each letter overlap and not two actually parts of the text.
55 fragBuilder->codeAppendf("if (all(lessThanEqual(%s.rgb, half3(0)))) {"
56 " discard;"
57 "}", args.fInputCoverage);
58 }
59
60 const char* dstTopLeftName;
61 const char* dstCoordScaleName;
62
63 fDstTopLeftUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
64 kHalf2_GrSLType,
65 "DstTextureUpperLeft",
66 &dstTopLeftName);
67 fDstScaleUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
68 kHalf2_GrSLType,
69 "DstTextureCoordScale",
70 &dstCoordScaleName);
71
72 fragBuilder->codeAppend("// Read color from copy of the destination.\n");
73 fragBuilder->codeAppendf("half2 _dstTexCoord = (sk_FragCoord.xy - %s) * %s;",
74 dstTopLeftName, dstCoordScaleName);
75
76 if (flipY) {
77 fragBuilder->codeAppend("_dstTexCoord.y = 1.0 - _dstTexCoord.y;");
78 }
79
80 fragBuilder->codeAppendf("half4 %s = ", dstColor);
81 fragBuilder->appendTextureLookup(args.fDstTextureSamplerHandle, "_dstTexCoord",
82 kHalf2_GrSLType);
83 fragBuilder->codeAppend(";");
84 } else {
85 needsLocalOutColor = args.fShaderCaps->requiresLocalOutputColorForFBFetch();
86 }
87
88 const char* outColor = "_localColorOut";
89 if (!needsLocalOutColor) {
90 outColor = args.fOutputPrimary;
91 } else {
92 fragBuilder->codeAppendf("half4 %s;", outColor);
93 }
94
95 this->emitBlendCodeForDstRead(fragBuilder,
96 uniformHandler,
97 args.fInputColor,
98 args.fInputCoverage,
99 dstColor,
100 outColor,
101 args.fOutputSecondary,
102 args.fXP);
103 if (needsLocalOutColor) {
104 fragBuilder->codeAppendf("%s = %s;", args.fOutputPrimary, outColor);
105 }
106 }
107
setData(const GrGLSLProgramDataManager & pdm,const GrXferProcessor & xp,const GrTexture * dstTexture,const SkIPoint & dstTextureOffset)108 void GrGLSLXferProcessor::setData(const GrGLSLProgramDataManager& pdm, const GrXferProcessor& xp,
109 const GrTexture* dstTexture, const SkIPoint& dstTextureOffset) {
110 if (dstTexture) {
111 if (fDstTopLeftUni.isValid()) {
112 pdm.set2f(fDstTopLeftUni, static_cast<float>(dstTextureOffset.fX),
113 static_cast<float>(dstTextureOffset.fY));
114 pdm.set2f(fDstScaleUni, 1.f / dstTexture->width(), 1.f / dstTexture->height());
115 } else {
116 SkASSERT(!fDstScaleUni.isValid());
117 }
118 } else {
119 SkASSERT(!fDstTopLeftUni.isValid());
120 SkASSERT(!fDstScaleUni.isValid());
121 }
122 this->onSetData(pdm, xp);
123 }
124
DefaultCoverageModulation(GrGLSLXPFragmentBuilder * fragBuilder,const char * srcCoverage,const char * dstColor,const char * outColor,const char * outColorSecondary,const GrXferProcessor & proc)125 void GrGLSLXferProcessor::DefaultCoverageModulation(GrGLSLXPFragmentBuilder* fragBuilder,
126 const char* srcCoverage,
127 const char* dstColor,
128 const char* outColor,
129 const char* outColorSecondary,
130 const GrXferProcessor& proc) {
131 if (proc.dstReadUsesMixedSamples()) {
132 if (srcCoverage) {
133 // TODO: Once we are no longer using legacy mesh ops, it will not be possible to even
134 // create a mixed sample with lcd so we can uncomment the below assert. In practice
135 // today this never happens except for GLPrograms test which can make one. skia:6661
136 // SkASSERT(!proc.isLCD());
137 fragBuilder->codeAppendf("%s *= %s;", outColor, srcCoverage);
138 fragBuilder->codeAppendf("%s = %s;", outColorSecondary, srcCoverage);
139 } else {
140 fragBuilder->codeAppendf("%s = half4(1.0);", outColorSecondary);
141 }
142 } else if (srcCoverage) {
143 if (proc.isLCD()) {
144 fragBuilder->codeAppendf("half lerpRed = mix(%s.a, %s.a, %s.r);",
145 dstColor, outColor, srcCoverage);
146 fragBuilder->codeAppendf("half lerpBlue = mix(%s.a, %s.a, %s.g);",
147 dstColor, outColor, srcCoverage);
148 fragBuilder->codeAppendf("half lerpGreen = mix(%s.a, %s.a, %s.b);",
149 dstColor, outColor, srcCoverage);
150 }
151 fragBuilder->codeAppendf("%s = %s * %s + (half4(1.0) - %s) * %s;",
152 outColor, srcCoverage, outColor, srcCoverage, dstColor);
153 if (proc.isLCD()) {
154 fragBuilder->codeAppendf("%s.a = max(max(lerpRed, lerpBlue), lerpGreen);", outColor);
155 }
156 }
157 }
158
159