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;
}