/* A simple surface shader to compute occlusion (a.k.a geometric
   exposure) using a point cloud file. This shader was created by 3Delight Team and modified by Jorge Pimentel(www.jorgepimentel.com), in order to have more control over the occlusion shadeop. */ 

surface ptc_occlusion(
	string ptc_file = "default.ptc";
	float biasValue = 0.1;
	float clampValue = 0;
	string hitsidesValue = "both";
	float samplebaseValue = 1;
	float maxdistValue = 0;
	float maxsolidangleValue = 0.5; )
{
	normal Nf = faceforward( normalize(N), I );

	Ci = 1 - occlusion( P, Nf, 
		"filename", ptc_file, "pointbased", 1,
		"bias", biasValue, "clamp", clampValue, "hitsides", "both", "samplebase", 1 , "maxdist", maxdistValue, "maxsolidangle", maxsolidangleValue  );
}