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

struct VertexOut
{
        float4 VertexPosition           :POSITION;
        float2 TexCoord                         :TEXCOORD;
        float4 Position                         :TEXCOORD2;
        float4 Color                            :COLOR0;
};


/*
  Vertex program for displaying particle system with rectangle rendertexture 
*/
VertexOut VertexProgram( float4 Position :POSITION,
                                                float4 Texcoord: TEXCOORD,
                                                float4 Color:COLOR0,
                                                float3 BillboardSize: NORMAL,
                                                uniform float4x4 ModelViewProj  :state.matrix.mvp
                                                )                                                                       
{
        VertexOut Out;  
        
        Out.Color=Color;
        
        Out.VertexPosition=mul(ModelViewProj, Position);
        Out.TexCoord=Texcoord.xy;
        
        Out.Position=Out.VertexPosition;
        Out.Position.x=Texcoord.w;
        Out.Position.z=(Out.Position.z/Out.Position.w+1)/2;
        Out.Position.y=Out.Position.z-0.5*Out.Position.x;
        
        return Out;     
}

/*
  Fragment program for displaying particle system with rectangle rendertexture
*/
void FragmentProgram(   VertexOut       In,
                                                uniform sampler2D Texture,
                                                uniform sampler2D frontTexture,
                                                out float4 Color:COLOR
                                                )
{
        float d=tex2D(frontTexture,In.TexCoord).r;      
        float d2=1.0-d;
        
        float frontDepth;
        float backDepth;
        
        frontDepth=In.Position.y+d*In.Position.x;
        backDepth=In.Position.y+d2*In.Position.x;       
                        
        if(d==1)
        {
                frontDepth=1;
                backDepth=0;
        }
        backDepth=1-backDepth;
        
        Color=float4(frontDepth,backDepth,0,tex2D(Texture,In.TexCoord).r*0.17*In.Color.a);      
        //Color=float4(frontDepth,backDepth,0,1-backDepth-frontDepth);  
}