source: GTP/trunk/App/Demos/Illum/Ogre/Media/PMDemo/PathMap.hlsl @ 2217

uniform float4x4 WorldViewProj;
uniform float4 prmAtlasTilesHalfPixel;
uniform sampler2D filteredAtlasSampler : register(s0);
uniform sampler2D clusterWeightIndexSampler : register(s1);
uniform sampler2D clusterWeightSampler : register(s2);
uniform float allClusterCount; 
uniform float clusterCount;

struct vsInputWalk
{
    float4 pos                  : POSITION;
    float2 tex                  : TEXCOORD0;
    float2 texAtlas             : TEXCOORD1;
};

struct vsOutputWalk
{
    float4 pos                  : POSITION;
    float2 tex                  : TEXCOORD0;
    float2 texAtlas             : TEXCOORD1;
};


vsOutputWalk vsWalk(vsInputWalk input)
{
        vsOutputWalk output = (vsOutputWalk)0;
        output.pos = mul(WorldViewProj, input.pos);
        output.tex = input.tex;
        output.texAtlas = input.texAtlas;       
        return output;
}

float4  psWalk(vsOutputWalk input) : COLOR
{
        int2 prmAtlasTiles = prmAtlasTilesHalfPixel.xy;
        float2 atlasHalfPixel = prmAtlasTilesHalfPixel.zw;
        
        float3 col = 0;
        for(int iCluster = 0; iCluster < 32; iCluster++)
        {
                float2 prmTexPos = float2(
                        (input.texAtlas.x + (iCluster % prmAtlasTiles.x)) / prmAtlasTiles.x,
                        1.0 - (input.texAtlas.y + (iCluster / prmAtlasTiles.x)) / prmAtlasTiles.y) + atlasHalfPixel;

                float weightIndex = tex2D(clusterWeightIndexSampler, float2(((float)iCluster + 0.5) / clusterCount, 0.5)).r;
                float weight = tex2D(clusterWeightSampler, float2((weightIndex + 0.5)/allClusterCount, 0.5)).r;
                //weight = 0.0002 + 0.000000000001 * weight;
                float3 val = tex2D(filteredAtlasSampler, prmTexPos).xyz;
                col += val.xyz * weight;                
        }
        
        return float4(col * 300, 1);
}