source: GTP/branches/IllumWPdeliver2008dec/IlluminationWP/demos/Standalone/Hierarchical Systems Demo [OpenGL]/src/Psystem_Multiply_Forward.cg @ 3255

struct VertexOut
{
        float4 VertexPosition           :POSITION;
        float2 TexCoord                         :TEXCOORD;
        float4 Position                         :TEXCOORD1;
        float4 EyePosition                      :TEXCOORD2;
        float2 BbSizeAngleCos           :TEXCOORD3;
        float4 LightSpacePos            :TEXCOORD4;     
        float4 Color                            :COLOR0;
};


//
//  Vertex program for displaying particle system with rectangle rendertexture 
//
VertexOut VertexProgram( float4 Position :POSITION,
                                                float4 Texcoord: TEXCOORD,
                                                float4 Color:COLOR0,
                                                uniform float4x4 LightModelViewProj,
                                                uniform float3 LightPosition,
                                                uniform float3 EyePosition,
                                                uniform float4x4 ModelViewProj  :state.matrix.mvp
                                                )                                                                       
{
        VertexOut Out;  
                        
        Out.Color=Color;
        
        Out.VertexPosition=mul(ModelViewProj, Position);
        Out.TexCoord=Texcoord.xy;
        
        Out.LightSpacePos=mul(LightModelViewProj, Position);
        Out.LightSpacePos.xyz=Out.LightSpacePos.xyz/Out.LightSpacePos.w;
        Out.LightSpacePos.xyz=(Out.LightSpacePos.xyz+1.0)/2.0;
                
        float3 LightToPoint=normalize(Position.xyz-LightPosition);
        float3 PointToEye=normalize(EyePosition-Position.xyz); 
        Out.BbSizeAngleCos.y=(dot(LightToPoint,PointToEye)+1.0)/2.0;
        
        return Out;     
}

//
//  Fragment program for displaying particle system with rectangle rendertexture
//
void FragmentProgram(   VertexOut       In,
                                                uniform samplerRECT FrontTexture,
                                                uniform samplerRECT Illum1,
                                                uniform samplerRECT PhaseTexture,
                                                uniform float Albedo,
                                                uniform float Transparency,
                                                uniform float Symmetry,
                                                uniform float3 LightColor,
                                                float4 out Color:COLOR                                          
                                        )
{       
        float2 illumUV=In.LightSpacePos.xy*256; 
        float z=In.LightSpacePos.z;
        
        float3 start;
        float3 end;
        float3 temp;    
                        
        float density=texRECT(FrontTexture,In.TexCoord*256).a;//density 
        
        float4 planes=float4(0.33,0.5,0.66,1);          
        float t;
        if(z<planes.x)
        {                               
                start=float3(1,1,1);
                end=texRECT(Illum1,illumUV).r;
                t=z/planes.x;
                temp=lerp(start,end,t); 
        }                       
        if(z<planes.y&&z>=planes.x)
        {                               
                start=texRECT(Illum1,illumUV).r;
                end=texRECT(Illum1,illumUV).g;
                t=(z-planes.x)/(planes.y-planes.x);
                temp=lerp(start,end,t);                 
        }       
                if(z>=planes.y&&z<planes.z)
        {                               
                start=texRECT(Illum1,illumUV).g;
                end=texRECT(Illum1,illumUV).b;
                t=(z-planes.y)/(planes.z-planes.y);
                temp=lerp(start,end,t);                                 
        }
        if(z>=planes.z)
        {                                       
                start=texRECT(Illum1,illumUV).b;
                end=texRECT(Illum1,illumUV).a;
                t=(z-planes.z)/(1-planes.z);
                temp=lerp(start,end,t);                         
        }                       
                float phase=texRECT(PhaseTexture,float2(Symmetry,In.BbSizeAngleCos.y)*256);
                float realdens=density*Transparency;
                
                float scatter=realdens*Albedo;
                float outcol=temp*phase*scatter;
                
                float scateeredforward=scatter*texRECT(PhaseTexture,float2(Symmetry,1)*256);                            
                Color=float4(LightColor*outcol*In.Color.rgb,1-realdens+scateeredforward/6.28);
                        
}