sampler indirectTexture: register(s0);
sampler sourceTexture: register(s1);
sampler visibilityTexture: register(s2);

uniform float epsilonX;
uniform float epsilonY;
uniform float sourceTextureSize;
uniform float numSamples;
uniform float sqrtNumSamples;

float4 main_fp(float2 texCoord: TEXCOORD0, 
               float2 subTexCoord: TEXCOORD1): COLOR
{
   float4 ocolor = float4(0.0, 0.0, 0.0, 0.0);	
   float2 epsilon = float2(epsilonX, epsilonY);  
   float4 value = tex2D(indirectTexture, subTexCoord).xyzw;
   float2 coords = texCoord - ( value.xy - epsilon );

   if (value.w != 0.0) 
   {	
        float2 unifcoord;
        float2 scale;
        unifcoord = (texCoord - value.xy) * float2(sourceTextureSize, sourceTextureSize); 
        scale = coords * float2(sourceTextureSize, sourceTextureSize) / float2(sqrtNumSamples, sqrtNumSamples);
	float2 newcoord = float2(1.0, 1.0) - value.zw + scale;
	ocolor = tex2D(sourceTexture, newcoord).xyzw;
	
	if (ocolor.w != 0.0)
	{
		float4 visibility = tex2D(visibilityTexture, subTexCoord).xyzw;
		float greyRange = 12.9107;
		float absGreyMin = abs(min(-6.47313, 0.0));
		visibility.xyzw = (visibility.xyzw * float4(greyRange, greyRange, greyRange, greyRange)) - float4(absGreyMin, absGreyMin, absGreyMin, absGreyMin);
		float e = lerp(visibility.x, visibility.y, unifcoord.x);
		float f = lerp(visibility.w, visibility.z, unifcoord.x);
		float g = lerp(e, f, unifcoord.y);
		ocolor.xyz =  g * ( ocolor.xyz );
	}
	// Debugging values...
	//ocolor.xyz = float3( epsilon.x, epsilon.y, 0.0 );
	//ocolor.xyz = float3( unifcoord.x, unifcoord.y, 0.0 );
	//ocolor.xyz =  float3( unifcoord.x, 0.0, 0.0 );
	//ocolor.xyz = float3( 0.0, unifcoord.y, 0.0 );
	//ocolor.xyz = float3( g, g, g );
	//ocolor.xyz = visibility.xyz;
	//ocolor.w = 1.0;
   }

   return  ocolor;
}