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
16void 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
88void 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
105void 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