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 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 const char* name() const override { return "BlurredEdge"; } 42 43 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 69
