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

#define D 128

struct VertexOut
{
        float4 VertexPosition           :POSITION;
        float2 TexCoord                         :TEXCOORD;
        int ID                                          :TEXCOORD1;
};


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

/*
  Fragment program for cloud rendering 
*/
float3 FragmentProgram( VertexOut       In,
                                                uniform samplerRECT LVisMap,
                                                uniform samplerRECT Phase,
                                                uniform float4 LightDirsWeights,
                                                uniform float3 LightRad,
                                                uniform float3 LightRad2,
                                                uniform float2 Alb_Op):COLOR
{       
        float3 Color=float3(0,0,0);     
        
        int direction=floor(In.TexCoord.y);
        int negDir=D-1-direction;
        int particle=In.ID;
        
        float a_o=Alb_Op.x*Alb_Op.y;            
        
        //Light1                        
        int LDir=floor(LightDirsWeights.x);             
        float isvisible=texRECT(LVisMap,float2(particle,0)).r;
        
        //Scattering
        Color+=isvisible*a_o*texRECT(Phase,float2(LDir,negDir)).r*LightRad;
        //Transmittance 
        if(direction==LDir)
        {
                //Color+=LightRad*(1-Alb_Op.y)*isvisible;
                Color+=LightRad*isvisible;
        }
                
        //Light2                        
        int LDir2=floor(LightDirsWeights.y);            
        
        isvisible=texRECT(LVisMap,float2(particle,1)).r;
        //isvisible=1;
        
        //Scattering
        Color+=isvisible*a_o*texRECT(Phase,float2(LDir2,negDir)).r*LightRad2;
        //Transmittance 
        if(direction==LDir2)
        {
                //Color+=LightRad2*(1-Alb_Op.y)*isvisible;
                Color+=LightRad2*isvisible;
        }       
                
        
        ///Emission
        //Color+=float3(0.01,0.01,0.01);        
                
        return Color;
}