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 float3 LightPosition,
						uniform float3 EyePosition,
						uniform float4x4 ModelViewProj	:state.matrix.mvp,
						uniform float4x4 ModelViewMatrix:state.matrix.modelview
						)									
{
	VertexOut Out;	
			
	Out.Color=Color;
	
	Out.VertexPosition=mul(ModelViewProj, Position);
	Out.TexCoord=Texcoord.xy;
		
	Out.Position=Out.VertexPosition;
	Out.BbSizeAngleCos.x=Texcoord.z;
	
	float3 LightToPoint=normalize(Position.xyz-LightPosition);
	float3 PointToEye=normalize(EyePosition-Position.xyz); 
	Out.BbSizeAngleCos.y=(dot(LightToPoint,PointToEye)+1)/2;
	
	Out.EyePosition=mul(ModelViewMatrix, Position);
	
	Out.Position.xyz=(Out.Position.xyz/Out.Position.w+1)/2;
	
	return Out;	
}

//
//  Fragment program for displaying particle system with rectangle rendertexture
//
void FragmentProgram(	VertexOut	In,
						uniform samplerRECT FrontTexture,
						uniform samplerRECT ObjTexture,
						uniform samplerRECT PhaseTexture,
						uniform float Albedo,
						uniform float Transparency,
						uniform float Symmetry,
						uniform float3 LightColor,
						float4 out Color:COLOR						
					)
{		
	
	float objdepth=texRECT(ObjTexture,In.Position.xy*512).r;
	In.TexCoord*=256;
	
	float depth=texRECT(FrontTexture,In.TexCoord).r;
	float density=1;
		
	if(depth.x==1)
	{
		Color=float4(0,0,0,1);	
	}
	else
	{					
		float size=0.5*In.BbSizeAngleCos.x;
		float frontdepth=-In.EyePosition.z-size+texRECT(FrontTexture,In.TexCoord).r*size;
		float backdepth=-In.EyePosition.z-size+(1-texRECT(FrontTexture,In.TexCoord).g)*size;
		
		float d=backdepth-frontdepth;
		float o=-objdepth-frontdepth;		
		
		density*=texRECT(FrontTexture,In.TexCoord).a;//density	
		density*=saturate(o/d);	
					
		float phase=texRECT(PhaseTexture,float2(Symmetry,In.BbSizeAngleCos.y)*256);
		float realdens=density*Transparency;
		float outcol=realdens*phase*Albedo;
			
		Color=float4(LightColor*outcol*In.Color.rgb,1-realdens);
	}
		
}