Implement NVPR on GLES

src/gpu/gl/builders/GrGLProgramBuilder.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLProgramBuilder_DEFINED
 #define GrGLProgramBuilder_DEFINED
 
@@ skipping 22 matching lines @@
 */
 class GrGLProgramBuilder {
 public:
     enum ShaderVisibility {
         kVertex_Visibility   = 0x1,
         kGeometry_Visibility = 0x2,
         kFragment_Visibility = 0x4,
     };
 
     typedef GrGLProgramDataManager::UniformHandle UniformHandle;
+    typedef GrGLProgramDataManager::VaryingHandle VaryingHandle;
 
     // Handles for program uniforms (other than per-effect uniforms)
     struct BuiltinUniformHandles {
         UniformHandle       fViewMatrixUni;
         UniformHandle       fRTAdjustmentUni;
         UniformHandle       fColorUni;
         UniformHandle       fCoverageUni;
 
         // We use the render target height to provide a y-down frag coord when specifying
         // origin_upper_left is not supported.
         UniformHandle       fRTHeightUni;
 
         // Uniforms for computing texture coords to do the dst-copy lookup
         UniformHandle       fDstCopyTopLeftUni;
         UniformHandle       fDstCopyScaleUni;
         UniformHandle       fDstCopySamplerUni;
     };
 
     struct UniformInfo {
         GrGLShaderVar fVariable;
         uint32_t      fVisibility;
         GrGLint       fLocation;
     };
 
     // This uses an allocator rather than array so that the GrGLShaderVars don't move in memory
     // after they are inserted. Users of GrGLShaderBuilder get refs to the vars and ptrs to their
     // name strings. Otherwise, we'd have to hand out copies.
     typedef GrTAllocator<UniformInfo> UniformInfoArray;
 
+    struct SeparableVaryingInfo {
+        GrGLShaderVar fVariable;
+        GrGLint       fLocation;
+    };
+
+    typedef GrTAllocator<SeparableVaryingInfo> SeparableVaryingInfoArray;
+
     /** Generates a shader program.
      *
      * The program implements what is specified in the stages given as input.
      * After successful generation, the builder result objects are available
      * to be used.
      * @return true if generation was successful.
      */
     bool genProgram(const GrEffectStage* inColorStages[],
                     const GrEffectStage* inCoverageStages[]);
 
     // Below are the results of the shader generation.
 
     GrGLProgramEffects* getColorEffects() const { SkASSERT(fProgramID); return fColorEffects.get(); }
     GrGLProgramEffects* getCoverageEffects() const { SkASSERT(fProgramID); return fCoverageEffects.get(); }
     const BuiltinUniformHandles& getBuiltinUniformHandles() const {
         SkASSERT(fProgramID);
         return fUniformHandles;
     }
     GrGLuint getProgramID() const { SkASSERT(fProgramID); return fProgramID; }
     bool hasVertexShader() const { SkASSERT(fProgramID); return !fFragOnly; }
     int getTexCoordSetCount() const { SkASSERT(fProgramID); return fTexCoordSetCnt; }
     const UniformInfoArray& getUniformInfos() const { return fUniforms; }
+    const SeparableVaryingInfoArray& getSeparableVaryingInfos() const {
+        return fSeparableVaryingInfos;
+    }
 
     virtual ~GrGLProgramBuilder() {}
 
     /** Add a uniform variable to the current program, that has visibility in one or more shaders.
         visibility is a bitfield of ShaderVisibility values indicating from which shaders the
         uniform should be accessible. At least one bit must be set. Geometry shader uniforms are not
         supported at this time. The actual uniform name will be mangled. If outName is not NULL then
         it will refer to the final uniform name after return. Use the addUniformArray variant to add
         an array of uniforms. */
     GrGLProgramDataManager::UniformHandle addUniform(uint32_t visibility,
@@ skipping 15 matching lines @@
     /**
      * Shortcut for getUniformVariable(u).c_str()
      */
     const char* getUniformCStr(GrGLProgramDataManager::UniformHandle u) const {
         return this->getUniformVariable(u).c_str();
     }
 
     const GrGLContextInfo& ctxInfo() const;
 
     GrGLFragmentShaderBuilder* getFragmentShaderBuilder() { return &fFS; }
+    GrGpuGL* gpu() const { return fGpu; }
 
 protected:
     typedef GrTAllocator<GrGLShaderVar> VarArray;
     GrGLProgramBuilder(GrGpuGL*, const GrGLProgramDesc&);
 
-    GrGpuGL* gpu() const { return fGpu; }
-
     const GrGLProgramDesc& desc() const { return fDesc; }
 
     // Helper for emitEffects().
     void createAndEmitEffects(GrGLProgramEffectsBuilder*,
                               const GrEffectStage* effectStages[],
                               int effectCnt,
                               const GrGLProgramDesc::EffectKeyProvider&,
                               GrGLSLExpr4* inOutFSColor);
 
     // Generates a name for a variable. The generated string will be name prefixed by the prefix
     // char (unless the prefix is '\0'). It also mangles the name to be stage-specific if we're
     // generating stage code.
     void nameVariable(SkString* out, char prefix, const char* name);
 
     virtual bool compileAndAttachShaders(GrGLuint programId, SkTDArray<GrGLuint>* shaderIds) const;
 
     virtual void bindProgramLocations(GrGLuint programId);
     void resolveProgramLocations(GrGLuint programId);
 
     void appendDecls(const VarArray&, SkString*) const;
     void appendUniformDecls(ShaderVisibility, SkString*) const;
 
     SkAutoTUnref<GrGLProgramEffects> fColorEffects;
     SkAutoTUnref<GrGLProgramEffects> fCoverageEffects;
     BuiltinUniformHandles            fUniformHandles;
     bool                             fFragOnly;
     int                              fTexCoordSetCnt;
     GrGLuint                         fProgramID;
     GrGLFragmentShaderBuilder        fFS;
+    SeparableVaryingInfoArray        fSeparableVaryingInfos;
 private:
     class CodeStage : SkNoncopyable {
     public:
         CodeStage() : fNextIndex(0), fCurrentIndex(-1), fEffectStage(NULL) {}
 
         bool inStageCode() const {
             this->validate();
             return NULL != fEffectStage;
         }
 
@@ skipping 89 matching lines @@
     GrGLFullProgramBuilder(GrGpuGL*, const GrGLProgramDesc&);
 
    /** Add a varying variable to the current program to pass values between vertex and fragment
         shaders. If the last two parameters are non-NULL, they are filled in with the name
         generated. */
     void addVarying(GrSLType type,
                     const char* name,
                     const char** vsOutName = NULL,
                     const char** fsInName = NULL);
 
+    /** Add a separable varying input variable to the current program.
+     * A separable varying (fragment shader input) is a varying that can be used also when vertex
+     * shaders are not used. With a vertex shader, the operation is same as with other
+     * varyings. Without a vertex shader, such as with NV_path_rendering, GL APIs are used to
+     * populate the variable. The APIs can refer to the variable through the returned handle.
+     */
+    VaryingHandle addSeparableVarying(GrSLType type,
+                                      const char* name,
+                                      const char** vsOutName,
+                                      const char** fsInName);
+

[joshua.litt, 2014/08/25 17:00:05]

Since this only requires a fragment shader, does it make more sense to move this
to the base class?

[Chris Dalton, 2014/08/25 18:04:50]

It actually does require a vertex shader. Not for NVpr calls (those use
glProgramPathFragmentInputGenNV instead), but when drawing with standard GL
calls the separable varying value needs to be set by the vertex shader.

The base class is for making inputs that wouldn't require a vertex shader even
with the standard GL calls (i.e. by using the fixed-function texture coordinates
and glTexGen, which is not the case for separable varyings).

     GrGLVertexShaderBuilder* getVertexShaderBuilder() { return &fVS; }
 
 private:
     virtual void emitCodeBeforeEffects(GrGLSLExpr4* color, GrGLSLExpr4* coverage) SK_OVERRIDE;
 
     virtual GrGLProgramEffects* createAndEmitEffects(const GrEffectStage* effectStages[],
                                                      int effectCnt,
                                                      const GrGLProgramDesc::EffectKeyProvider&,
                                                      GrGLSLExpr4* inOutFSColor) SK_OVERRIDE;
 
@@ skipping 25 matching lines @@
                                                      int effectCnt,
                                                      const GrGLProgramDesc::EffectKeyProvider&,
                                                      GrGLSLExpr4* inOutFSColor) SK_OVERRIDE;
 
     virtual void emitCodeAfterEffects() SK_OVERRIDE {}
 
     typedef GrGLProgramBuilder INHERITED;
 };
 
 #endif