source: GTP/trunk/App/Demos/Illum/PathMap/bushToAtlas.fx @ 1480

float cutNearness2;// 100.0

struct vsInputBushToAtlas
{
    float4      pos                     : POSITION;
    float2      tex                     : TEXCOORD0;
    float3      normal          : NORMAL;
};


struct vsOutputBushToAtlas
{
    float4      pos                     : POSITION;
    float2      tex                     : TEXCOORD0;
    float4      worldPos        : TEXCOORD1;
    float3      normal          : TEXCOORD2; 
    float4 occProjPos   : TEXCOORD3;
};

vsOutputBushToAtlas
        vsRenderBushToAtlas(vsInputBushToAtlas input)
{
    vsOutputBushToAtlas output = (vsOutputBushToAtlas)0;
    
        output.pos.xy=float2(2,-2)*input.tex-float2(1,1);
        output.pos.y=-1*output.pos.y; //Texture space to screen space.
    output.pos.z=0;
    output.pos.w=1;
  
    output.worldPos = mul(input.pos, modelToWorldMatrix);
    output.normal = mul(inverseTransposedModelToWorldMatrix, float4(input.normal, 0));
        output.occProjPos = mul(output.worldPos, occWorldToProjMatrix);     
    output.tex = input.tex;

    return output;
}

float4
        psRenderBushToAtlas(vsOutputBushToAtlas input) : COLOR0
{
        input.occProjPos /= input.occProjPos.w;
        float2 occTexPos = mul(input.occProjPos.xyw, occProjToTexMatrix);
        
        input.normal = normalize(input.normal);
        float3 diff = lightPos - input.worldPos.xyz;
        float4 retVal = float4(0, 0, 0, 1);
        float3 diffDir = normalize(diff);
        float cosa = dot(diffDir, input.normal);
        float cosb = -dot(diffDir, normalize(lightDir));
        float dist2 = dot(diff, diff);

        float visibility = tex2Dlod(depthMapSampler, float4(occTexPos, input.occProjPos.z, 0) );
        float formFactor;
        if( cosa > 0.0)
        {
                if( cosb < 0.01 && cosb > -0.1)
                        cosb =  0.01;
                float nearness = cosb * cosb * dist2;
                if( nearness < cutNearness2)
                {
                        float e2 = dist2 * (1.0 - cosb * cosb);
                        float dist2dash = e2 + cutNearness2;
                        formFactor = cosa * sqrt(cutNearness2 / dist2dash ) / dist2dash;
                }
                else
                        formFactor = cosa * cosb / dist2;
                        
                if( cosb > 0.0)
                {
                        retVal = float4(lightPower * formFactor * visibility, 1);
                }
        }
        return retVal;// + float4(0.3, 0, 0, 1);
}

technique BushToAtlas{
        pass P0
    {
        VertexShader = compile vs_3_0 vsRenderBushToAtlas();
        PixelShader  = compile ps_3_0 psRenderBushToAtlas();
    }
}