/*
 * emboss(): Use a texture map to perturb the surface normal.
 */

displacement 
emboss (string texname = "";
	float	depth     = 1.0)
{

	float	magnitude;
	point P2;

	P2 = transform("shader", P);
	
	magnitude = texture(texname);
	
	P2 = P - normalize(N) * (magnitude) * depth;
	N = calculatenormal(P2);
  	P = P2;

}