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 GrConvolutionEffect_DEFINED 9 #define GrConvolutionEffect_DEFINED 10 11 #include "Gr1DKernelEffect.h" 12 #include "GrInvariantOutput.h" 13 14 /** 15 * A convolution effect. The kernel is specified as an array of 2 * half-width 16 * + 1 weights. Each texel is multiplied by it's weight and summed to determine 17 * the output color. The output color is modulated by the input color. 18 */ 19 class GrConvolutionEffect : public Gr1DKernelEffect { 20 21 public: 22 23 /// Convolve with an arbitrary user-specified kernel 24 static GrFragmentProcessor* Create(GrTexture* tex, 25 Direction dir, 26 int halfWidth, 27 const float* kernel, 28 bool useBounds, 29 float bounds[2]) { 30 return new GrConvolutionEffect(tex, dir, halfWidth, kernel, useBounds, bounds); 31 } 32 33 /// Convolve with a Gaussian kernel 34 static GrFragmentProcessor* CreateGaussian(GrTexture* tex, 35 Direction dir, 36 int halfWidth, 37 float gaussianSigma, 38 bool useBounds, 39 float bounds[2]) { 40 return new GrConvolutionEffect(tex, dir, halfWidth, gaussianSigma, useBounds, bounds); 41 } 42 43 virtual ~GrConvolutionEffect(); 44 45 const float* kernel() const { return fKernel; } 46 47 const float* bounds() const { return fBounds; } 48 bool useBounds() const { return fUseBounds; } 49 50 const char* name() const override { return "Convolution"; } 51 52 enum { 53 // This was decided based on the min allowed value for the max texture 54 // samples per fragment program run in DX9SM2 (32). A sigma param of 4.0 55 // on a blur filter gives a kernel width of 25 while a sigma of 5.0 56 // would exceed a 32 wide kernel. 57 kMaxKernelRadius = 12, 58 // With a C++11 we could have a constexpr version of WidthFromRadius() 59 // and not have to duplicate this calculation. 60 kMaxKernelWidth = 2 * kMaxKernelRadius + 1, 61 }; 62 63 protected: 64 65 float fKernel[kMaxKernelWidth]; 66 bool fUseBounds; 67 float fBounds[2]; 68 69 private: 70 GrConvolutionEffect(GrTexture*, Direction, 71 int halfWidth, 72 const float* kernel, 73 bool useBounds, 74 float bounds[2]); 75 76 /// Convolve with a Gaussian kernel 77 GrConvolutionEffect(GrTexture*, Direction, 78 int halfWidth, 79 float gaussianSigma, 80 bool useBounds, 81 float bounds[2]); 82 83 GrGLSLFragmentProcessor* onCreateGLSLInstance() const override; 84 85 void onGetGLSLProcessorKey(const GrGLSLCaps&, GrProcessorKeyBuilder*) const override; 86 87 bool onIsEqual(const GrFragmentProcessor&) const override; 88 89 void onComputeInvariantOutput(GrInvariantOutput* inout) const override { 90 // If the texture was opaque we could know that the output color if we knew the sum of the 91 // kernel values. 92 inout->mulByUnknownFourComponents(); 93 } 94 95 GR_DECLARE_FRAGMENT_PROCESSOR_TEST; 96 97 typedef Gr1DKernelEffect INHERITED; 98 }; 99 100 #endif 101
