GrGLSLXferProcessor.cpp revision 7ea439b2203855db97330b25945b87dd4b170b8b 
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 "GrXferProcessor.h"
11#include "glsl/GrGLSLFragmentShaderBuilder.h"
12#include "glsl/GrGLSLProgramDataManager.h"
13#include "glsl/GrGLSLUniformHandler.h"
14
15void GrGLSLXferProcessor::emitCode(const EmitArgs& args) {
16    if (!args.fXP.willReadDstColor()) {
17        this->emitOutputsForBlendState(args);
18        return;
19    }
20
21    GrGLSLXPFragmentBuilder* fragBuilder = args.fXPFragBuilder;
22    GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
23    const char* dstColor = fragBuilder->dstColor();
24
25    if (args.fXP.getDstTexture()) {
26        bool topDown = kTopLeft_GrSurfaceOrigin == args.fXP.getDstTexture()->origin();
27
28        if (args.fInputCoverage) {
29            // We don't think any shaders actually output negative coverage, but just as a safety
30            // check for floating point precision errors we compare with <= here
31            fragBuilder->codeAppendf("if (all(lessThanEqual(%s, vec4(0)))) {"
32                                     "    discard;"
33                                     "}", args.fInputCoverage);
34        }
35
36        const char* dstTopLeftName;
37        const char* dstCoordScaleName;
38
39        fDstTopLeftUni = uniformHandler->addUniform(GrGLSLUniformHandler::kFragment_Visibility,
40                                                    kVec2f_GrSLType,
41                                                    kDefault_GrSLPrecision,
42                                                    "DstTextureUpperLeft",
43                                                    &dstTopLeftName);
44        fDstScaleUni = uniformHandler->addUniform(GrGLSLUniformHandler::kFragment_Visibility,
45                                                  kVec2f_GrSLType,
46                                                  kDefault_GrSLPrecision,
47                                                  "DstTextureCoordScale",
48                                                  &dstCoordScaleName);
49        const char* fragPos = fragBuilder->fragmentPosition();
50
51        fragBuilder->codeAppend("// Read color from copy of the destination.\n");
52        fragBuilder->codeAppendf("vec2 _dstTexCoord = (%s.xy - %s) * %s;",
53                                 fragPos, dstTopLeftName, dstCoordScaleName);
54
55        if (!topDown) {
56            fragBuilder->codeAppend("_dstTexCoord.y = 1.0 - _dstTexCoord.y;");
57        }
58
59        fragBuilder->codeAppendf("vec4 %s = ", dstColor);
60        fragBuilder->appendTextureLookup(args.fSamplers[0], "_dstTexCoord", kVec2f_GrSLType);
61        fragBuilder->codeAppend(";");
62    }
63
64    this->emitBlendCodeForDstRead(fragBuilder,
65                                  uniformHandler,
66                                  args.fInputColor,
67                                  args.fInputCoverage,
68                                  dstColor,
69                                  args.fOutputPrimary,
70                                  args.fOutputSecondary,
71                                  args.fXP);
72}
73
74void GrGLSLXferProcessor::setData(const GrGLSLProgramDataManager& pdm, const GrXferProcessor& xp) {
75    if (xp.getDstTexture()) {
76        if (fDstTopLeftUni.isValid()) {
77            pdm.set2f(fDstTopLeftUni, static_cast<float>(xp.dstTextureOffset().fX),
78                      static_cast<float>(xp.dstTextureOffset().fY));
79            pdm.set2f(fDstScaleUni, 1.f / xp.getDstTexture()->width(),
80                      1.f / xp.getDstTexture()->height());
81        } else {
82            SkASSERT(!fDstScaleUni.isValid());
83        }
84    } else {
85        SkASSERT(!fDstTopLeftUni.isValid());
86        SkASSERT(!fDstScaleUni.isValid());
87    }
88    this->onSetData(pdm, xp);
89}
90
91