source: GTP/trunk/App/Demos/Illum/Illumination Networks Demo [OpenGL]/src/IllumIteratePrograms.cg @ 845

#define D 128
#define N 512

struct VertexOut
{
        float4 VertexPosition           :POSITION;
        float2 TexCoord                         :TEXCOORD;
};


/*
  Vertex program for cloud rendering 
*/
VertexOut VertexProgram( float4 Position :POSITION,
                                                float2 Texcoord: TEXCOORD
                                                )                                                                       
{
        VertexOut Out;  
        
        Out.VertexPosition=Position;
        Out.TexCoord=Texcoord;
        
        return Out;     
}

/*
  Fragment program for cloud rendering 
*/
float3 FragmentProgram( VertexOut       In,
                                                uniform samplerRECT IllumTexture,
                                                uniform samplerRECT TauTexture,
                                                uniform samplerRECT VisMap,                                             
                                                uniform samplerRECT DirectIllum,
                                                uniform samplerRECT Phase,
                                                uniform float3 Alb_Op,
                                                uniform float3 SkyColor
                                                ):COLOR
{       
        float3 Color=float3(0,0,0);
        
        int particle=floor(In.TexCoord.x);
        int direction=floor(In.TexCoord.y);             
        
        int vp=floor(texRECT(VisMap,float2(particle,direction)).r);
        
        if(vp<N)
        {
                        Color=texRECT(DirectIllum,float2(vp,direction));
                        float ds=texRECT(VisMap,float2(particle,direction)).g;
                        float tau=texRECT(TauTexture,float2(particle,1)).r;
                        //tau=5.0;
                        //ds=0.1;
                        //if(ds<0.1)ds=0.1;
                        float alpha=1-exp(-ds*tau);
                        //float alpha=Alb_Op.y;
                
                        float3 I=texRECT(IllumTexture,float2(vp,direction));
                        //Color+=I.rgb*(1-Alb_Op.y);
                        Color+=I.rgb*(1-alpha);
                                                
                        for(int d=0;d<D;d++)
                        {
                                I=texRECT(IllumTexture,float2(vp,d));
                                //Color+=I.rgb*Alb_Op.z*texRECT(Phase,float2(d,direction)).r;
                                Color+=I.rgb*alpha*Alb_Op.z*texRECT(Phase,float2(d,direction)).r;
                        }
                        
                                        
        }
        else
        {
                //Color=float3(2.2,2.9,4.5);    
                Color=SkyColor; 
        }
        
        return  Color;  
}