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      1 /*
      2  * Copyright 2015 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 #ifndef GrGLSLXferProcessor_DEFINED
      9 #define GrGLSLXferProcessor_DEFINED
     10 
     11 #include "glsl/GrGLSLProgramDataManager.h"
     12 #include "glsl/GrGLSLTextureSampler.h"
     13 
     14 class GrXferProcessor;
     15 class GrGLSLCaps;
     16 class GrGLSLUniformHandler;
     17 class GrGLSLXPBuilder;
     18 class GrGLSLXPFragmentBuilder;
     19 
     20 class GrGLSLXferProcessor {
     21 public:
     22     GrGLSLXferProcessor() {}
     23     virtual ~GrGLSLXferProcessor() {}
     24 
     25     typedef GrGLSLTextureSampler::TextureSamplerArray TextureSamplerArray;
     26     struct EmitArgs {
     27         EmitArgs(GrGLSLXPFragmentBuilder* fragBuilder,
     28                  GrGLSLUniformHandler* uniformHandler,
     29                  const GrGLSLCaps* caps,
     30                  const GrXferProcessor& xp,
     31                  const char* inputColor,
     32                  const char* inputCoverage,
     33                  const char* outputPrimary,
     34                  const char* outputSecondary,
     35                  const TextureSamplerArray& samplers,
     36                  const bool usePLSDstRead)
     37             : fXPFragBuilder(fragBuilder)
     38             , fUniformHandler(uniformHandler)
     39             , fGLSLCaps(caps)
     40             , fXP(xp)
     41             , fInputColor(inputColor)
     42             , fInputCoverage(inputCoverage)
     43             , fOutputPrimary(outputPrimary)
     44             , fOutputSecondary(outputSecondary)
     45             , fSamplers(samplers)
     46             , fUsePLSDstRead(usePLSDstRead) {}
     47 
     48         GrGLSLXPFragmentBuilder* fXPFragBuilder;
     49         GrGLSLUniformHandler* fUniformHandler;
     50         const GrGLSLCaps* fGLSLCaps;
     51         const GrXferProcessor& fXP;
     52         const char* fInputColor;
     53         const char* fInputCoverage;
     54         const char* fOutputPrimary;
     55         const char* fOutputSecondary;
     56         const TextureSamplerArray& fSamplers;
     57         bool fUsePLSDstRead;
     58     };
     59     /**
     60      * This is similar to emitCode() in the base class, except it takes a full shader builder.
     61      * This allows the effect subclass to emit vertex code.
     62      */
     63     void emitCode(const EmitArgs&);
     64 
     65     /** A GrGLSLXferProcessor instance can be reused with any GrGLSLXferProcessor that produces
     66         the same stage key; this function reads data from a GrGLSLXferProcessor and uploads any
     67         uniform variables required  by the shaders created in emitCode(). The GrXferProcessor
     68         parameter is guaranteed to be of the same type that created this GrGLSLXferProcessor and
     69         to have an identical processor key as the one that created this GrGLSLXferProcessor. This
     70         function calls onSetData on the subclass of GrGLSLXferProcessor
     71      */
     72     void setData(const GrGLSLProgramDataManager& pdm, const GrXferProcessor& xp);
     73 
     74 protected:
     75     static void DefaultCoverageModulation(GrGLSLXPFragmentBuilder* fragBuilder,
     76                                           const char* srcCoverage,
     77                                           const char* dstColor,
     78                                           const char* outColor,
     79                                           const char* outColorSecondary,
     80                                           const GrXferProcessor& proc);
     81 
     82 private:
     83     /**
     84      * Called by emitCode() when the XP will not be performing a dst read. This method is
     85      * responsible for both blending and coverage. A subclass only needs to implement this method if
     86      * it can construct a GrXferProcessor that will not read the dst color.
     87      */
     88     virtual void emitOutputsForBlendState(const EmitArgs&) {
     89         SkFAIL("emitOutputsForBlendState not implemented.");
     90     }
     91 
     92     /**
     93      * Called by emitCode() when the XP will perform a dst read. This method only needs to supply
     94      * the blending logic. The base class applies coverage. A subclass only needs to implement this
     95      * method if it can construct a GrXferProcessor that reads the dst color.
     96      */
     97     virtual void emitBlendCodeForDstRead(GrGLSLXPFragmentBuilder*,
     98                                          GrGLSLUniformHandler*,
     99                                          const char* srcColor,
    100                                          const char* srcCoverage,
    101                                          const char* dstColor,
    102                                          const char* outColor,
    103                                          const char* outColorSecondary,
    104                                          const GrXferProcessor&) {
    105         SkFAIL("emitBlendCodeForDstRead not implemented.");
    106     }
    107 
    108     virtual void onSetData(const GrGLSLProgramDataManager&, const GrXferProcessor&) = 0;
    109 
    110     GrGLSLProgramDataManager::UniformHandle fDstTopLeftUni;
    111     GrGLSLProgramDataManager::UniformHandle fDstScaleUni;
    112 };
    113 #endif
    114