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);
			
}