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

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*2.0-1.0;
        
        return Out;     
}

/*
  Fragment program for cloud rendering 
*/
float4 FragmentProgram( VertexOut       In):COLOR
{
        float4 Color;
        float2 UV=In.TexCoord;
        float g2=UV.x*UV.x;
        float phase=3*(1-g2)*(1+UV.y*UV.y)/2/(2+g2)/pow((1+g2-2*(UV.y)*(UV.x)),1.5);
        Color=float4(phase,1,1,1);
        
        return Color;
}