Line data    Source code

       1             : /*
       2             :  * Copyright 2017 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 GrBlurredEdgeFragmentProcessor_DEFINED
       9             : #define GrBlurredEdgeFragmentProcessor_DEFINED
      10             : 
      11             : #include "GrFragmentProcessor.h"
      12             : 
      13             : /**
      14             :  * Shader for managing a blurred edge for a shadow.
      15             :  *
      16             :  * There are two blurring modes supported: Gaussian blur function and smoothstep function.
      17             :  *
      18             :  * If the primitive supports an implicit distance to the edge, the radius of the blur is specified
      19             :  * by r & g values of the color in 14.2 fixed point. For spot shadows, we increase the stroke width
      20             :  * to set the shadow against the shape. This pad is specified by b, also in 6.2 fixed point.
      21             :  * The a value represents the max final alpha.
      22             :  *
      23             :  * When not using implicit distance, then b in the input color represents the input to the
      24             :  * blur function, and r the max final alpha.
      25             :  *
      26             :  */
      27           0 : class GrBlurredEdgeFP : public GrFragmentProcessor {
      28             : public:
      29             :     enum Mode {
      30             :         kGaussian_Mode,
      31             :         kSmoothstep_Mode,
      32             : 
      33             :         kLastMode = kSmoothstep_Mode
      34             :     };
      35             :     static const int kModeCnt = kLastMode + 1;
      36             : 
      37             :     static sk_sp<GrFragmentProcessor> Make(Mode mode = kGaussian_Mode) {
      38             :         return sk_sp<GrFragmentProcessor>(new GrBlurredEdgeFP(mode));
      39             :     }
      40             : 
      41           0 :     const char* name() const override { return "BlurredEdge"; }
      42             : 
      43           0 :     Mode mode() const { return fMode; }
      44             : 
      45             : private:
      46             :     GrBlurredEdgeFP(Mode mode)
      47             :         : INHERITED(kNone_OptimizationFlags)
      48             :         , fMode(mode) {
      49             :         // enable output of distance information for shape
      50             :         this->setWillUseDistanceVectorField();
      51             : 
      52             :         this->initClassID<GrBlurredEdgeFP>();
      53             :     }
      54             : 
      55             :     GrGLSLFragmentProcessor* onCreateGLSLInstance() const override;
      56             : 
      57             :     void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override;
      58             : 
      59             :     bool onIsEqual(const GrFragmentProcessor&) const override;
      60             : 
      61             :     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
      62             : 
      63             :     Mode   fMode;
      64             : 
      65             :     typedef GrFragmentProcessor INHERITED;
      66             : };
      67             : 
      68             : #endif