GPU编程对图像进行高斯模糊

前段时间，写程序的时候写了几段shader如下：

// 对图像进行高斯模糊uniformsampler2DuSourcImg;// 要进行模糊的源图像uniformvec2pixelSize;// 如果纹理大小为800*600, 则为(1.0/800.0, 1.0/600.0)uniform floatGaussian_a; // 高斯函数的参数auniform floatGaussian_c; // 高斯函数的参数cuniform floatRANGE;// 模糊范围，比如3*3，则RANGE为3const float e = 2.71828183;//标准高斯函数，令a或c为参数，可以简化float Gaussian(float x){return Gaussian_a * pow(e, -x*x/(Gaussian_c*Gaussian_c) );}void main(){vec2 halfPixelSize = pixelSize.xy / 2.0;vec3 cOut = vec3(0.0, 0.0, 0.0);vec2 texCoordSample = gl_TexCoord[0].st;float gaussTotal = 0.0;float x,y;float temp;for (y=-RANGE; y<=RANGE; y+=1.0){for (x=-RANGE; x<=RANGE; x+=1.0){// 这一行是在GPU中进行计算，而在实际的程序中如果a,c,RANGE的值已经确定，// 可以在CPU中预先计算处所要的权重值，直接代入即可temp = Gaussian( sqrt( x*x + y*y ) );gaussTotal += temp;cOut += temp * vec3( texture2D(uSourcImg, texCoordSample + vec2(x,y) * pixelSize) );}}cOut /= gaussTotal;//调试用：不模糊，输出原图像//cOut = vec3(texture2D(uSourcImg, gl_TexCoord[0].st));gl_FragColor = vec4(cOut, 1.0);}

 

下面是对图像进行水平和垂直两个方向的模糊，请参考gamerendering网站上的说明：

 

X方向：

// 对图像进行水平方向的模糊uniform sampler2D uSourcImg; // 要进行模糊的源图像const float blurSize = 1.0/800.0; // 如果源图像的大小为 800*600 void main(void){vec2 vTexCoord = gl_TexCoord[0].st;vec4 sum = vec4(0.0);// blur in X (horizontal)// take nine samples, with the distance blurSize between themsum += texture2D(uSourcImg, vec2(vTexCoord.x - 4.0 * blurSize, vTexCoord.y)) * 1.0/47.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x - 3.0 * blurSize, vTexCoord.y)) * 2.0/47.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x - 2.0 * blurSize, vTexCoord.y)) * 3.0/47.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x - blurSize, vTexCoord.y)) * 10.0/47.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x , vTexCoord.y)) * 15.0/47.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x + blurSize, vTexCoord.y)) * 10.0/47.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x + 2.0 * blurSize, vTexCoord.y)) * 3.0/47.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x + 3.0 * blurSize, vTexCoord.y)) * 2.0/47.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x + 4.0 * blurSize, vTexCoord.y)) * 1.0/47.0;#if 0//只是权重不同，根据情况选用，这些权重值也可以通过高斯函数预先计算得出sum += texture2D(uSourcImg, vec2(vTexCoord.x - 4.0*blurSize, vTexCoord.y)) * 1.0/25.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x - 3.0*blurSize, vTexCoord.y)) * 2.0/25.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x - 2.0*blurSize, vTexCoord.y)) * 3.0/25.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x - blurSize, vTexCoord.y)) * 4.0/25.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x , vTexCoord.y)) * 5.0/25.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x + blurSize, vTexCoord.y)) * 4.0/25.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x + 2.0*blurSize, vTexCoord.y)) * 3.0/25.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x + 3.0*blurSize, vTexCoord.y)) * 2.0/25.0;sum += texture2D(uSourcImg, vec2(vTexCoord.x + 4.0*blurSize, vTexCoord.y)) * 1.0/25.0;#endifgl_FragColor = sum;}

 Y方向：

// 对图像进行垂直方向的模糊uniform sampler2D uBlurXTex;// 已经经过水平模糊的图像const float blurSize = 1.0/600.0; // 如果源图像的大小为 800*600 void main(void){vec2 vTexCoord = gl_TexCoord[0].st;vec4 sum = vec4(0.0);// blur in y (vertical)// take nine samples, with the distance blurSize between themsum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y - 4.0 * blurSize)) * 1.0/47.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y - 3.0 * blurSize)) * 2.0/47.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y - 2.0 * blurSize)) * 3.0/47.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y - blurSize)) * 10.0/47.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y )) * 15.0/47.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y + blurSize)) * 10.0/47.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y + 2.0 * blurSize)) * 3.0/47.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y + 3.0 * blurSize)) * 2.0/47.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y + 4.0 * blurSize)) * 1.0/47.0;#if 0//只是权重不同，根据情况选用，这些权重值也可以通过高斯函数预先计算得出sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y - 4.0*blurSize)) * 1.0/25.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y - 3.0*blurSize)) * 2.0/25.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y - 2.0*blurSize)) * 3.0/25.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y - blurSize)) * 4.0/25.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y )) * 5.0/25.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y + blurSize)) * 4.0/25.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y + 2.0*blurSize)) * 3.0/25.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y + 3.0*blurSize)) * 2.0/25.0;sum += texture2D(uBlurXTex, vec2(vTexCoord.x, vTexCoord.y + 4.0*blurSize)) * 1.0/25.0;#endifgl_FragColor = sum;}