source: GTP/branches/IllumWPdeliver2008dec/IlluminationWP/demos/Standalone/PathMap [DirectX]/computeWeights.fx @ 3255

#define SAMPLECUTDIST2 0.01
#define WEIGHTCUTOFF 0.01

int nRadionColumns;

texture radions;
sampler radionSampler = sampler_state
{
   Texture = <radions>;
   MinFilter = Point;
   MagFilter = Point;
   MipFilter = None;
};


struct vsInputComputeWeights
{
    float4      pos                     : POSITION;
    float2      tex                     : TEXCOORD0;
};

struct vsOutputComputeWeights
{
    float4      pos                     : POSITION;
    float2      tex                     : TEXCOORD0;
};

vsOutputComputeWeights
        vsComputeWeights(vsInputComputeWeights input)
{
    vsOutputComputeWeights output = (vsOutputComputeWeights)0;
    output.pos = input.pos;
    
    output.tex = (input.pos + 1.0) / 2.0;
    output.tex.y = 1.0 - output.tex.y;
    
    //output.tex = input.tex;
    return output;
}

float4
        psComputeWeights(vsOutputComputeWeights input) : COLOR0
{
        float dataColumnWidth = 1.0 / (float)nRadionColumns;
        int bushIndex = input.tex.x * 4096 + input.tex.y * nRadionColumns * 4096;
        int werx = bushIndex % nRadionColumns;
        int wery = bushIndex / nRadionColumns;
        float3 pos = tex2D(radionSampler, float2((werx + 0.25) * dataColumnWidth, (wery  + 0.5) / 4096.0) ).xyz;
        float3 dir = tex2D(radionSampler, float2((werx + 0.75) * dataColumnWidth, (wery  + 0.5) / 4096.0) ).xyz;
        /*
        float3 diff = lightPos - pos;
        float dist2 = dot(diff, diff);
        if(dist2 < SAMPLECUTDIST2)
                dist2 = SAMPLECUTDIST2;
        diff = normalize(diff);
        float cosa = - dot(lightDir, diff);
        float cosb = dot(dir, diff);    
        
        float4 occProjPos = mul(float4(pos, 1), occWorldToProjMatrix);  
        occProjPos /= occProjPos.w;
        float2 occTexPos = mul( occProjPos.xyw, occProjToTexMatrix);
        float visibility = tex2Dproj(depthMapSampler, float4(occTexPos, occProjPos.z - 0.1, 1) );

        float3 lightToPos = pos - lightPos;
        float actualDepth = length(lightToPos);

        float ret;
        if(  visibility < 0.5 || cosa < 0 || cosb < 0)
                ret = 0.0;
        else
                ret = pow(cosa, 9) * cosb / dist2;

        if(ret < 0.000001)
                ret = 0.0;
//      if(ret > WEIGHTCUTOFF)
//              ret = WEIGHTCUTOFF;
        */
        
        
        float3 diff = lightPos - pos;
        float dist2 = dot(diff, diff);
        if(dist2 < SAMPLECUTDIST2)
                dist2 = SAMPLECUTDIST2;
        diff = normalize(diff);
        float cosa = max(dot(lightDir, -diff), 0);
        float cosb = max(dot(dir, diff), 0);
        float ret = pow(cosa, 9) * cosb / dist2;
        return ret;
        
        return float4(ret, ret, ret, ret);
//      return float4((wery  + 0.5) / 4096.0, werx, werx, 1);
//      return float4(actualDepth, 1, 1, 1);
}

technique ComputeWeights{
        pass P0
    {
        VertexShader = compile vs_3_0 vsComputeWeights();
        PixelShader  = compile ps_3_0 psComputeWeights();
    }
}
/*
float4
        psAggregateWeights(vsOutputComputeWeights input, in int rid : VPOS) : COLOR0
{
        float sumWeight = 0.0;
        float sumProb = 0.0000001;
        
        int iRadion = clusterStarts[rid];
        float2 wTex = float2((iRadion / 4096 + 0.5) * dataColumnWidth,
                                                 (iRadion % 4096  + 0.5) / 4096.0) );
        while(iRadion < clusterStarts[rid+1])
        {
                sumWeight += tex2Dlod(weightSampler, float4(wTex, 0, 1));
                float sumProb += 1.0;
                wTex.y += 1.0 / 4096.0;
        }
        return (sumWeight / sumProb).xxxx;
}

technique AggregateWeights{
        pass P0
    {
        VertexShader = compile vs_3_0 vsComputeWeights();
        PixelShader  = compile ps_3_0 psAggregateWeights();
    }
}
*/