径向模糊效果

最先在这里看到:http://www.gamerendering.com/2008/12/20/radial-blur-filter/

这效果在鬼泣4中切换场景时见过, 极品飞车12的运动模糊也有这种感觉.

原理:

确定一个中心点(如0.5, 0.5), 跟当前像素连一条线. 以当前像素为中心, 在线上的附近像素进行采样, 最后取一下平均值.

代码翻译成HLSL:

// This texture should hold the image to blur. sampler2D Texture0; // some const, tweak for best look const float fSampleDist; const float fSampleStrength; // some sample positions float samples[10] = { -0.08, -0.05, -0.03, -0.02, -0.01, 0.01, 0.02, 0.03, 0.05, 0.08 }; float4 ps_main( float2 texCoord : TEXCOORD0 ) : COLOR { // 0.5,0.5 is the center of the screen // so substracting uv from it will result in // a vector pointing to the middle of the screen float2 dir = 0.5 - texCoord; // calculate the distance to the center of the screen float dist = length(dir); // normalize the direction (reuse the distance) dir /= dist; // this is the original colour of this pixel // using only this would result in a nonblurred version float4 color = tex2D(Texture0, texCoord); float4 sum = color; // take 10 additional blur samples in the direction towards // the center of the screen for (int i = 0; i < 10; ++i) { sum += tex2D(Texture0, texCoord + dir * samples[i] * fSampleDist); } // we have taken eleven samples sum /= 11.0; // weighten the blur effect with the distance to the // center of the screen ( further out is blurred more) float t = saturate(dist * fSampleStrength); //Blend the original color with the averaged pixels return lerp(color, sum, t); }

两个参数, 动态调整的话可以产生极品飞车12那种速度感(也算是第一人称运动模糊的简单实现吧).

这是RM里的效果: