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Diffstat (limited to 'src/gpu/gl/builders/GrGLFragmentShaderBuilder.h')
-rw-r--r-- | src/gpu/gl/builders/GrGLFragmentShaderBuilder.h | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h b/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h new file mode 100644 index 0000000000..0f700bd94d --- /dev/null +++ b/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h @@ -0,0 +1,118 @@ +/* + * 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 GrGLFragmentShaderBuilder_DEFINED +#define GrGLFragmentShaderBuilder_DEFINED +#include "GrGLShaderBuilder.h" + +class GrGLProgramBuilder; + +class GrGLFragmentShaderBuilder : public GrGLShaderBuilder { +public: + typedef uint8_t DstReadKey; + typedef uint8_t FragPosKey; + + /** Returns a key for adding code to read the copy-of-dst color in service of effects that + require reading the dst. It must not return 0 because 0 indicates that there is no dst + copy read at all (in which case this function should not be called). */ + static DstReadKey KeyForDstRead(const GrTexture* dstCopy, const GrGLCaps&); + + /** Returns a key for reading the fragment location. This should only be called if there is an + effect that will requires the fragment position. If the fragment position is not required, + the key is 0. */ + static FragPosKey KeyForFragmentPosition(const GrRenderTarget* dst, const GrGLCaps&); + + GrGLFragmentShaderBuilder(GrGLProgramBuilder* program, const GrGLProgramDesc& desc); + + /** Returns the variable name that holds the color of the destination pixel. This may be NULL if + no effect advertised that it will read the destination. */ + const char* dstColor(); + + /** + * Use of these features may require a GLSL extension to be enabled. Shaders may not compile + * if code is added that uses one of these features without calling enableFeature() + */ + enum GLSLFeature { + kStandardDerivatives_GLSLFeature = 0, + kLastGLSLFeature = kStandardDerivatives_GLSLFeature + }; + + /** + * If the feature is supported then true is returned and any necessary #extension declarations + * are added to the shaders. If the feature is not supported then false will be returned. + */ + bool enableFeature(GLSLFeature); + + /** + * This returns a variable name to access the 2D, perspective correct version of the coords in + * the fragment shader. If the coordinates at index are 3-dimensional, it immediately emits a + * perspective divide into the fragment shader (xy / z) to convert them to 2D. + */ + SkString ensureFSCoords2D(const TransformedCoordsArray& coords, int index); + + + /** Returns a variable name that represents the position of the fragment in the FS. The position + is in device space (e.g. 0,0 is the top left and pixel centers are at half-integers). */ + const char* fragmentPosition(); + +private: + /* + * An internal call for GrGLFullProgramBuilder to use to add varyings to the vertex shader + */ + void addVarying(GrSLType type, + const char* name, + const char** fsInName); + + /* + * Private functions used by GrGLProgramBuilder for compilation + */ + void bindProgramLocations(GrGLuint programId); + bool compileAndAttachShaders(GrGLuint programId, SkTDArray<GrGLuint>* shaderIds) const; + void emitCodeBeforeEffects(); + void emitCodeAfterEffects(const GrGLSLExpr4& inputColor, const GrGLSLExpr4& inputCoverage); + + /** Enables using the secondary color output and returns the name of the var in which it is + to be stored */ + const char* enableSecondaryOutput(); + + /** Gets the name of the primary color output. */ + const char* getColorOutputName() const; + + /** + * Features that should only be enabled by GrGLFragmentShaderBuilder itself. + */ + enum GLSLPrivateFeature { + kFragCoordConventions_GLSLPrivateFeature = kLastGLSLFeature + 1, + kLastGLSLPrivateFeature = kFragCoordConventions_GLSLPrivateFeature + }; + + // Interpretation of DstReadKey when generating code + enum { + kNoDstRead_DstReadKey = 0, + kYesDstRead_DstReadKeyBit = 0x1, // Set if we do a dst-copy-read. + kUseAlphaConfig_DstReadKeyBit = 0x2, // Set if dst-copy config is alpha only. + kTopLeftOrigin_DstReadKeyBit = 0x4, // Set if dst-copy origin is top-left. + }; + + enum { + kNoFragPosRead_FragPosKey = 0, // The fragment positition will not be needed. + kTopLeftFragPosRead_FragPosKey = 0x1,// Read frag pos relative to top-left. + kBottomLeftFragPosRead_FragPosKey = 0x2,// Read frag pos relative to bottom-left. + }; + + bool fHasCustomColorOutput; + bool fHasSecondaryOutput; + bool fSetupFragPosition; + bool fTopLeftFragPosRead; + + friend class GrGLProgramBuilder; + friend class GrGLFullProgramBuilder; + + typedef GrGLShaderBuilder INHERITED; +}; + +#endif |