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      1 /*
      2  * Copyright 2012 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 GrGLEffectMatrix_DEFINED
      9 #define GrGLEffectMatrix_DEFINED
     10 
     11 #include "GrGLEffect.h"
     12 #include "SkMatrix.h"
     13 
     14 class GrTexture;
     15 class SkRandom;
     16 
     17 /**
     18  * This is a helper to implement a texture matrix in a GrGLEffect.
     19  */
     20 class GrGLEffectMatrix {
     21 public:
     22     typedef GrGLEffect::EffectKey EffectKey;
     23     /**
     24      * The matrix uses kKeyBits of the effect's EffectKey. A GrGLEffect may place these bits at an
     25      * arbitrary shift in its final key. However, when GrGLEffectMatrix::emitCode*() code is called
     26      * the relevant bits must be in the lower kKeyBits of the key parameter.
     27      */
     28     enum {
     29         kKeyBits = 2,
     30         kKeyMask = (1 << kKeyBits) - 1,
     31     };
     32 
     33     GrGLEffectMatrix() : fUni(GrGLUniformManager::kInvalidUniformHandle) {
     34         fPrevMatrix = SkMatrix::InvalidMatrix();
     35     }
     36 
     37     /**
     38      * Generates the key for the portion of the code emitted by this class's emitCode() function.
     39      * Pass a texture to make GrGLEffectMatrix automatically adjust for the texture's origin. Pass
     40      * NULL when not using the EffectMatrix for a texture lookups, or if the GrGLEffect subclass
     41      * wants to handle origin adjustments in some other manner. coordChangeMatrix is the matrix
     42      * from GrEffectStage.
     43      */
     44     static EffectKey GenKey(const SkMatrix& effectMatrix,
     45                             const SkMatrix& coordChangeMatrix,
     46                             const GrTexture*);
     47 
     48     /**
     49      * Emits code to implement the matrix in the VS. A varying is added as an output of the VS and
     50      * input to the FS. The varying may be either a vec2f or vec3f depending upon whether
     51      * perspective interpolation is required or not. The names of the varying in the VS and FS are
     52      * are returned as output parameters and the type of the varying is the return value. The suffix
     53      * is an optional parameter that can be used to make all variables emitted by the object
     54      * unique within a stage. It is only necessary if multiple GrGLEffectMatrix objects are used by
     55      * a GrGLEffect.
     56      */
     57     GrSLType emitCode(GrGLShaderBuilder*,
     58                       EffectKey,
     59                       const char* vertexCoords,
     60                       const char** fsCoordName, /* optional */
     61                       const char** vsCoordName = NULL,
     62                       const char* suffix = NULL);
     63 
     64     /**
     65      * This is similar to emitCode except that it performs perspective division in the FS if the
     66      * texture coordinates have a w coordinate. The fsCoordName always refers to a vec2f.
     67      */
     68     void emitCodeMakeFSCoords2D(GrGLShaderBuilder*,
     69                                 EffectKey,
     70                                 const char* vertexCoords,
     71                                 const char** fsCoordName, /* optional */
     72                                 const char** vsVaryingName = NULL,
     73                                 GrSLType* vsVaryingType = NULL,
     74                                 const char* suffix = NULL);
     75     /**
     76      * Call from a GrGLEffect's subclass to update the texture matrix. The matrix,
     77      * coordChangeMatrix, and texture params should match those used with GenKey.
     78      */
     79     void setData(const GrGLUniformManager& uniformManager,
     80                  const SkMatrix& effectMatrix,
     81                  const SkMatrix& coordChangeMatrix,
     82                  const GrTexture*);
     83 
     84 private:
     85     enum {
     86         kIdentity_Key   = 0,
     87         kTrans_Key      = 1,
     88         kNoPersp_Key    = 2,
     89         kGeneral_Key    = 3,
     90     };
     91 
     92     GrGLUniformManager::UniformHandle fUni;
     93     GrSLType                          fUniType;
     94     SkMatrix                          fPrevMatrix;
     95 };
     96 
     97 #endif
     98