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 "GrXferProcessor.h"
12 #include "glsl/GrGLSLFragmentShaderBuilder.h"
13 #include "glsl/GrGLSLProgramDataManager.h"
14 #include "glsl/GrGLSLUniformHandler.h"
15 
emitCode(const EmitArgs & args)16 void GrGLSLXferProcessor::emitCode(const EmitArgs& args) {
17     if (!args.fXP.willReadDstColor()) {
18         this->emitOutputsForBlendState(args);
19         return;
20     }
21 
22     GrGLSLXPFragmentBuilder* fragBuilder = args.fXPFragBuilder;
23     GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
24     const char* dstColor = fragBuilder->dstColor();
25 
26     bool needsLocalOutColor = false;
27 
28     if (args.fXP.getDstTexture()) {
29         bool topDown = kTopLeft_GrSurfaceOrigin == args.fXP.getDstTexture()->origin();
30 
31         if (args.fInputCoverage) {
32             // We don't think any shaders actually output negative coverage, but just as a safety
33             // check for floating point precision errors we compare with <= here
34             fragBuilder->codeAppendf("if (all(lessThanEqual(%s, vec4(0)))) {"
35                                      "    discard;"
36                                      "}", args.fInputCoverage);
37         }
38 
39         const char* dstTopLeftName;
40         const char* dstCoordScaleName;
41 
42         fDstTopLeftUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
43                                                     kVec2f_GrSLType,
44                                                     kDefault_GrSLPrecision,
45                                                     "DstTextureUpperLeft",
46                                                     &dstTopLeftName);
47         fDstScaleUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
48                                                   kVec2f_GrSLType,
49                                                   kDefault_GrSLPrecision,
50                                                   "DstTextureCoordScale",
51                                                   &dstCoordScaleName);
52 
53         fragBuilder->codeAppend("// Read color from copy of the destination.\n");
54         fragBuilder->codeAppendf("vec2 _dstTexCoord = (sk_FragCoord.xy - %s) * %s;",
55                                  dstTopLeftName, dstCoordScaleName);
56 
57         if (!topDown) {
58             fragBuilder->codeAppend("_dstTexCoord.y = 1.0 - _dstTexCoord.y;");
59         }
60 
61         fragBuilder->codeAppendf("vec4 %s = ", dstColor);
62         fragBuilder->appendTextureLookup(args.fTexSamplers[0], "_dstTexCoord", kVec2f_GrSLType);
63         fragBuilder->codeAppend(";");
64     } else {
65         needsLocalOutColor = args.fShaderCaps->requiresLocalOutputColorForFBFetch();
66     }
67 
68     const char* outColor = "_localColorOut";
69     if (!needsLocalOutColor) {
70         outColor = args.fOutputPrimary;
71     } else {
72         fragBuilder->codeAppendf("vec4 %s;", outColor);
73     }
74 
75     this->emitBlendCodeForDstRead(fragBuilder,
76                                   uniformHandler,
77                                   args.fInputColor,
78                                   args.fInputCoverage,
79                                   dstColor,
80                                   outColor,
81                                   args.fOutputSecondary,
82                                   args.fXP);
83     if (needsLocalOutColor) {
84         fragBuilder->codeAppendf("%s = %s;", args.fOutputPrimary, outColor);
85     }
86 }
87 
setData(const GrGLSLProgramDataManager & pdm,const GrXferProcessor & xp)88 void GrGLSLXferProcessor::setData(const GrGLSLProgramDataManager& pdm, const GrXferProcessor& xp) {
89     if (xp.getDstTexture()) {
90         if (fDstTopLeftUni.isValid()) {
91             pdm.set2f(fDstTopLeftUni, static_cast<float>(xp.dstTextureOffset().fX),
92                       static_cast<float>(xp.dstTextureOffset().fY));
93             pdm.set2f(fDstScaleUni, 1.f / xp.getDstTexture()->width(),
94                       1.f / xp.getDstTexture()->height());
95         } else {
96             SkASSERT(!fDstScaleUni.isValid());
97         }
98     } else {
99         SkASSERT(!fDstTopLeftUni.isValid());
100         SkASSERT(!fDstScaleUni.isValid());
101     }
102     this->onSetData(pdm, xp);
103 }
104 
DefaultCoverageModulation(GrGLSLXPFragmentBuilder * fragBuilder,const char * srcCoverage,const char * dstColor,const char * outColor,const char * outColorSecondary,const GrXferProcessor & proc)105 void GrGLSLXferProcessor::DefaultCoverageModulation(GrGLSLXPFragmentBuilder* fragBuilder,
106                                                     const char* srcCoverage,
107                                                     const char* dstColor,
108                                                     const char* outColor,
109                                                     const char* outColorSecondary,
110                                                     const GrXferProcessor& proc) {
111     if (proc.dstReadUsesMixedSamples()) {
112         if (srcCoverage) {
113             fragBuilder->codeAppendf("%s *= %s;", outColor, srcCoverage);
114             fragBuilder->codeAppendf("%s = %s;", outColorSecondary, srcCoverage);
115         } else {
116             fragBuilder->codeAppendf("%s = vec4(1.0);", outColorSecondary);
117         }
118     } else if (srcCoverage) {
119         fragBuilder->codeAppendf("%s = %s * %s + (vec4(1.0) - %s) * %s;",
120                                  outColor, srcCoverage, outColor, srcCoverage, dstColor);
121     }
122 }
123