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      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 
     15 void 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(kFragment_GrShaderFlag,
     40                                                     kVec2f_GrSLType,
     41                                                     kDefault_GrSLPrecision,
     42                                                     "DstTextureUpperLeft",
     43                                                     &dstTopLeftName);
     44         fDstScaleUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
     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 
     74 void 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 void GrGLSLXferProcessor::DefaultCoverageModulation(GrGLSLXPFragmentBuilder* fragBuilder,
     92                                                     const char* srcCoverage,
     93                                                     const char* dstColor,
     94                                                     const char* outColor,
     95                                                     const char* outColorSecondary,
     96                                                     const GrXferProcessor& proc) {
     97     if (proc.dstReadUsesMixedSamples()) {
     98         if (srcCoverage) {
     99             fragBuilder->codeAppendf("%s *= %s;", outColor, srcCoverage);
    100             fragBuilder->codeAppendf("%s = %s;", outColorSecondary, srcCoverage);
    101         } else {
    102             fragBuilder->codeAppendf("%s = vec4(1.0);", outColorSecondary);
    103         }
    104     } else if (srcCoverage) {
    105         fragBuilder->codeAppendf("%s = %s * %s + (vec4(1.0) - %s) * %s;",
    106                                  outColor, srcCoverage, outColor, srcCoverage, dstColor);
    107     }
    108 }
    109