source: GTP/trunk/App/Demos/Illum/Ogre/Media/materials/GTPPathMap/PathMapWeightCompute.hlsl @ 2403

#define SAMPLECUTDIST2 0.01
#define WEIGHTCUTOFF   0.01
#define DIST_BIAS      0.005

uniform int nRadionColumns;
uniform float3 lightPos;
uniform float3 lightDir;
uniform float lightPower;
uniform float4 lightColor;
uniform float clusterCount;
uniform float4x4 lightViewProj;
uniform float lightFarPlane;
uniform float4 lightAttenuation;
uniform float spotLightFalloff;
uniform float lightAngleCos;

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 = input.tex;
    output.tex.y = 1.0 - output.tex.y;
   
    return output;
}

float4 psComputeWeights(vsOutputComputeWeights input,
                                                uniform sampler2D radionSampler : register(s0),
                                                uniform sampler2D shadowMap : register(s1)) : 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;
        dir = normalize(dir);
        
        float3 diff = lightPos - pos;
        float dist2 = dot(diff, diff);
        float dist = sqrt(dist2);
        diff = normalize(diff);
        float cosb = max(dot(dir, diff), 0);    
        
        float visibility = 0;
        float4 lightVPos = mul(lightViewProj, float4(pos,1));
                
        //if( lightVPos.z  > 0.0)
        //{     
        lightVPos /= lightVPos.w;
                //float d = length(lightVPos.xy);
                
                //if(d <= 1.0)
        {
                        float dist = dist / lightFarPlane;
                        lightVPos.xy = (lightVPos.xy + 1.0) / 2.0;
                        lightVPos.y = 1.0 - lightVPos.y;
                        float storedDist = tex2D(shadowMap, lightVPos.xy).r;
                        visibility = dist < storedDist + DIST_BIAS;
                }
   // }
    //visibility = 1.0 - visibility;
    visibility = 1.0 + 0.00001 * visibility;
        float spotFalloff = (dot(-diff, normalize(lightDir)) - lightAngleCos) / (1.0 - lightAngleCos);
        //spotFalloff = saturate(dot(normalize(pos - lightPos), normalize(lightDir))) + 0.0000000001 * lightAngleCos;
        spotFalloff = 1.0 + spotFalloff * 0.000000001;
        spotFalloff = pow(saturate(spotFalloff), spotLightFalloff);
                
        visibility *= spotFalloff / (lightAttenuation.y + dist * lightAttenuation.z + dist2 * lightAttenuation.w);
        
        float4 ret = visibility * cosb * lightPower * lightColor;
        return ret;
}

float4 psComputeWeightsPoint(vsOutputComputeWeights input,
                                                uniform sampler2D radionSampler : register(s0),
                                                uniform samplerCUBE shadowMap : register(s1)) : 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;
        dir = normalize(dir);
        
        float3 diff = lightPos - pos;
        float dist2 = dot(diff, diff);
        float dist = sqrt(dist2);
        diff = normalize(diff);
        float cosb = max(dot(dir, diff), 0);    
        
        float visibility = 1;
        float4 lightVPos = mul(lightViewProj, float4(pos,1));
        
        float distNorm = dist / lightFarPlane;
        float storedDist = texCUBE(shadowMap, float3(-diff.xy, diff.z)).r;
        dist -= DIST_BIAS;
        visibility = (distNorm <= storedDist);
          
        //visibility = 1.0 + 0.00001 * visibility;              
        visibility *=  1.0 / (lightAttenuation.y + dist * lightAttenuation.z + dist * dist * lightAttenuation.w);
        
        float4 ret = visibility * cosb * lightPower * lightColor;
        return ret;
}

float4 psSumWeights(vsOutputComputeWeights input,
                                        uniform sampler2D radionSampler       : register(s0),
                                        uniform sampler2D entryPointCountSampler : register(s1),
                                        uniform sampler2D allWeightsSampler   : register(s2)) : COLOR0
{
        float halfPixel = 0.5 / clusterCount;
        float iCluster = input.tex.x + halfPixel;
        int entryPointCount = tex2D(entryPointCountSampler, float2(iCluster, 0.25));
        int currentEntryPoint = tex2D(entryPointCountSampler, float2(iCluster, 0.75));
        //sum entrypoint weights
        float3 weight = 0;
        float clusterRad = 0;
        for(int i = 0; i < entryPointCount; i++)
        {
                
                float dataColumnWidth = 1.0 / (float)nRadionColumns;
                int werx = currentEntryPoint % nRadionColumns;
                int wery = currentEntryPoint / nRadionColumns;
                float2 coord1 = float2((werx + 0.5) * dataColumnWidth, (wery  + 0.5) / 4096.0);
                float2 coord2 = coord1 + float2(0.25 * dataColumnWidth, 0);
                float3 w = tex2Dlod(allWeightsSampler, float4(coord1, 0, 0)).rgb;
                float radrad = tex2Dlod(radionSampler, float4(coord2, 0, 0)).a;         
                weight += w * radrad;           
                clusterRad += radrad;
                currentEntryPoint++;
        }       
        
        if(clusterRad >= 0)
                weight /= clusterRad;
        else
                weight = 0;
   
        return float4(weight, 1);
}

void EntryPointDisplayVS(float4 position :POSITION0,
                                                 float4 color :COLOR0,
                                                 uniform float4x4 worldViewProj,
                                                 out float4 hPos:POSITION,
                                                 out float2 texCoord: TEXCOORD0)
{
        hPos = mul(worldViewProj, position);
        texCoord = color.xy;
}

float4 EntryPointDisplayPS(float2 texCoord : TEXCOORD0,
                                                        uniform sampler2D weightTexture : register(s0)):COLOR0
{
        //return texCoord.y;
        return texCoord.r;
}