GPU-based Gaussian blur.
This is a first stab at implementing a GPU-based
Gaussian blur in Ganesh. The convolution shader is implemented as a new
filtering mode. There are several known issues:
- no support for blur types other than "normal"
- FBO truncation problem at high zoom values
- uses bilinear for upsampling instead of Mitchell
Review URL: http://codereview.appspot.com/4645082/
git-svn-id: http://skia.googlecode.com/svn/trunk@1830 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/include/GrContext.h b/gpu/include/GrContext.h
index a8810f9..0c873ee 100644
--- a/gpu/include/GrContext.h
+++ b/gpu/include/GrContext.h
@@ -490,6 +490,21 @@
void writePixels(int left, int top, int width, int height,
GrPixelConfig, const void* buffer, size_t stride);
+ /**
+ * Performs a 1D convolution over a rectangle of pixels. Set
+ * imageIncrement to (1/w, 0) for a convolution in X, (0, 1/h) for a
+ * convolution in Y, where w, h are the texture dimensions.
+ * @param srcTexture the texture to read from
+ * @param dstRect the destination rectangle
+ * @param imageIncrement the displacement between pixel samples
+ * @param kernel the convolution kernel (kernelWidth elements)
+ * @param kernelWidth the width of the convolution kernel
+ */
+ void convolveRect(GrTexture* srcTexture,
+ const SkRect& dstRect,
+ float imageIncrement[2],
+ const float* kernel,
+ int kernelWidth);
///////////////////////////////////////////////////////////////////////////
// Helpers
diff --git a/gpu/include/GrSamplerState.h b/gpu/include/GrSamplerState.h
index d10d8c4..c7a4f2b 100644
--- a/gpu/include/GrSamplerState.h
+++ b/gpu/include/GrSamplerState.h
@@ -21,6 +21,8 @@
#include "GrTypes.h"
#include "GrMatrix.h"
+#define MAX_KERNEL_WIDTH 25
+
class GrSamplerState {
public:
enum Filter {
@@ -39,6 +41,10 @@
* between texels in x and y spaced 4 texels apart.)
*/
k4x4Downsample_Filter,
+ /**
+ * Apply a separable convolution kernel.
+ */
+ kConvolution_Filter
};
/**
@@ -148,6 +154,9 @@
const GrRect& getTextureDomain() const { return fTextureDomain; }
bool hasTextureDomain() const {return SkIntToScalar(0) != fTextureDomain.right();}
Filter getFilter() const { return fFilter; }
+ int getKernelWidth() const { return fKernelWidth; }
+ const float* getKernel() const { return fKernel; }
+ const float* getImageIncrement() const { return fImageIncrement; }
bool isGradient() const {
return kRadial_SampleMode == fSampleMode ||
@@ -220,6 +229,19 @@
fRadial2PosRoot = posRoot;
}
+ void setConvolutionParams(int kernelWidth, const float* kernel, float imageIncrement[2]) {
+ GrAssert(kernelWidth >= 0 && kernelWidth <= MAX_KERNEL_WIDTH);
+ fKernelWidth = kernelWidth;
+ if (NULL != kernel) {
+ memcpy(fKernel, kernel, kernelWidth * sizeof(float));
+ }
+ if (NULL != imageIncrement) {
+ memcpy(fImageIncrement, imageIncrement, sizeof(fImageIncrement));
+ } else {
+ memset(fImageIncrement, 0, sizeof(fImageIncrement));
+ }
+ }
+
static const GrSamplerState& ClampNoFilter() {
return gClampNoFilter;
}
@@ -237,6 +259,11 @@
GrScalar fRadial2Radius0;
bool fRadial2PosRoot;
+ // These are undefined unless fFilter == kConvolution_Filter
+ int fKernelWidth;
+ float fKernel[MAX_KERNEL_WIDTH];
+ float fImageIncrement[2];
+
static const GrSamplerState gClampNoFilter;
};