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/*
* Copyright 2012 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrConvolutionEffect_DEFINED
#define GrConvolutionEffect_DEFINED
#include "Gr1DKernelEffect.h"
#include "GrInvariantOutput.h"
/**
* A convolution effect. The kernel is specified as an array of 2 * half-width
* + 1 weights. Each texel is multiplied by it's weight and summed to determine
* the output color. The output color is modulated by the input color.
*/
class GrConvolutionEffect : public Gr1DKernelEffect {
public:
/// Convolve with an arbitrary user-specified kernel
static sk_sp<GrFragmentProcessor> Make(GrTexture* tex,
Direction dir,
int halfWidth,
const float* kernel,
bool useBounds,
float bounds[2]) {
return sk_sp<GrFragmentProcessor>(
new GrConvolutionEffect(tex, dir, halfWidth, kernel, useBounds, bounds));
}
/// Convolve with a Gaussian kernel
static sk_sp<GrFragmentProcessor> MakeGaussian(GrTexture* tex,
Direction dir,
int halfWidth,
float gaussianSigma,
bool useBounds,
float bounds[2]) {
return sk_sp<GrFragmentProcessor>(
new GrConvolutionEffect(tex, dir, halfWidth, gaussianSigma, useBounds, bounds));
}
virtual ~GrConvolutionEffect();
const float* kernel() const { return fKernel; }
const float* bounds() const { return fBounds; }
bool useBounds() const { return fUseBounds; }
const char* name() const override { return "Convolution"; }
enum {
// This was decided based on the min allowed value for the max texture
// samples per fragment program run in DX9SM2 (32). A sigma param of 4.0
// on a blur filter gives a kernel width of 25 while a sigma of 5.0
// would exceed a 32 wide kernel.
kMaxKernelRadius = 12,
// With a C++11 we could have a constexpr version of WidthFromRadius()
// and not have to duplicate this calculation.
kMaxKernelWidth = 2 * kMaxKernelRadius + 1,
};
protected:
float fKernel[kMaxKernelWidth];
bool fUseBounds;
float fBounds[2];
private:
GrConvolutionEffect(GrTexture*, Direction,
int halfWidth,
const float* kernel,
bool useBounds,
float bounds[2]);
/// Convolve with a Gaussian kernel
GrConvolutionEffect(GrTexture*, Direction,
int halfWidth,
float gaussianSigma,
bool useBounds,
float bounds[2]);
GrGLSLFragmentProcessor* onCreateGLSLInstance() const override;
void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override;
bool onIsEqual(const GrFragmentProcessor&) const override;
void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
// If the texture was opaque we could know that the output color if we knew the sum of the
// kernel values.
inout->mulByUnknownFourComponents();
}
GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
typedef Gr1DKernelEffect INHERITED;
};
#endif
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