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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 #ifndef GrGLFragmentShaderBuilder_DEFINED |
| 9 #define GrGLFragmentShaderBuilder_DEFINED |
| 10 #include "GrGLShaderBuilder.h" |
| 11 |
| 12 class GrGLProgramBuilder; |
| 13 |
| 14 class GrGLFragmentShaderBuilder : public GrGLShaderBuilder { |
| 15 public: |
| 16 typedef uint8_t DstReadKey; |
| 17 typedef uint8_t FragPosKey; |
| 18 |
| 19 /** Returns a key for adding code to read the copy-of-dst color in service
of effects that |
| 20 require reading the dst. It must not return 0 because 0 indicates that t
here is no dst |
| 21 copy read at all (in which case this function should not be called). */ |
| 22 static DstReadKey KeyForDstRead(const GrTexture* dstCopy, const GrGLCaps&); |
| 23 |
| 24 /** Returns a key for reading the fragment location. This should only be cal
led if there is an |
| 25 effect that will requires the fragment position. If the fragment position
is not required, |
| 26 the key is 0. */ |
| 27 static FragPosKey KeyForFragmentPosition(const GrRenderTarget* dst, const Gr
GLCaps&); |
| 28 |
| 29 GrGLFragmentShaderBuilder(GrGLProgramBuilder* program, const GrGLProgramDesc
& desc); |
| 30 |
| 31 /** Returns the variable name that holds the color of the destination pixel.
This may be NULL if |
| 32 no effect advertised that it will read the destination. */ |
| 33 const char* dstColor(); |
| 34 |
| 35 /** |
| 36 * Use of these features may require a GLSL extension to be enabled. Shaders
may not compile |
| 37 * if code is added that uses one of these features without calling enableFe
ature() |
| 38 */ |
| 39 enum GLSLFeature { |
| 40 kStandardDerivatives_GLSLFeature = 0, |
| 41 kLastGLSLFeature = kStandardDerivatives_GLSLFeature |
| 42 }; |
| 43 |
| 44 /** |
| 45 * If the feature is supported then true is returned and any necessary #exte
nsion declarations |
| 46 * are added to the shaders. If the feature is not supported then false will
be returned. |
| 47 */ |
| 48 bool enableFeature(GLSLFeature); |
| 49 |
| 50 /** |
| 51 * This returns a variable name to access the 2D, perspective correct versio
n of the coords in |
| 52 * the fragment shader. If the coordinates at index are 3-dimensional, it im
mediately emits a |
| 53 * perspective divide into the fragment shader (xy / z) to convert them to 2
D. |
| 54 */ |
| 55 SkString ensureFSCoords2D(const TransformedCoordsArray& coords, int index); |
| 56 |
| 57 |
| 58 /** Returns a variable name that represents the position of the fragment in
the FS. The position |
| 59 is in device space (e.g. 0,0 is the top left and pixel centers are at ha
lf-integers). */ |
| 60 const char* fragmentPosition(); |
| 61 |
| 62 private: |
| 63 /* |
| 64 * An internal call for GrGLFullProgramBuilder to use to add varyings to the
vertex shader |
| 65 */ |
| 66 void addVarying(GrSLType type, |
| 67 const char* name, |
| 68 const char** fsInName); |
| 69 |
| 70 /* |
| 71 * Private functions used by GrGLProgramBuilder for compilation |
| 72 */ |
| 73 void bindProgramLocations(GrGLuint programId); |
| 74 bool compileAndAttachShaders(GrGLuint programId, SkTDArray<GrGLuint>* shader
Ids) const; |
| 75 void emitCodeBeforeEffects(); |
| 76 void emitCodeAfterEffects(const GrGLSLExpr4& inputColor, const GrGLSLExpr4&
inputCoverage); |
| 77 |
| 78 /** Enables using the secondary color output and returns the name of the var
in which it is |
| 79 to be stored */ |
| 80 const char* enableSecondaryOutput(); |
| 81 |
| 82 /** Gets the name of the primary color output. */ |
| 83 const char* getColorOutputName() const; |
| 84 |
| 85 /** |
| 86 * Features that should only be enabled by GrGLFragmentShaderBuilder itself. |
| 87 */ |
| 88 enum GLSLPrivateFeature { |
| 89 kFragCoordConventions_GLSLPrivateFeature = kLastGLSLFeature + 1, |
| 90 kLastGLSLPrivateFeature = kFragCoordConventions_GLSLPrivateFeature |
| 91 }; |
| 92 |
| 93 // Interpretation of DstReadKey when generating code |
| 94 enum { |
| 95 kNoDstRead_DstReadKey = 0, |
| 96 kYesDstRead_DstReadKeyBit = 0x1, // Set if we do a dst-copy-read. |
| 97 kUseAlphaConfig_DstReadKeyBit = 0x2, // Set if dst-copy config is alph
a only. |
| 98 kTopLeftOrigin_DstReadKeyBit = 0x4, // Set if dst-copy origin is top-
left. |
| 99 }; |
| 100 |
| 101 enum { |
| 102 kNoFragPosRead_FragPosKey = 0, // The fragment positition wil
l not be needed. |
| 103 kTopLeftFragPosRead_FragPosKey = 0x1,// Read frag pos relative to t
op-left. |
| 104 kBottomLeftFragPosRead_FragPosKey = 0x2,// Read frag pos relative to b
ottom-left. |
| 105 }; |
| 106 |
| 107 bool fHasCustomColorOutput; |
| 108 bool fHasSecondaryOutput; |
| 109 bool fSetupFragPosition; |
| 110 bool fTopLeftFragPosRead; |
| 111 |
| 112 friend class GrGLProgramBuilder; |
| 113 friend class GrGLFullProgramBuilder; |
| 114 |
| 115 typedef GrGLShaderBuilder INHERITED; |
| 116 }; |
| 117 |
| 118 #endif |
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