/****************************
Displacement Shader
(c) Mad Processor, 2009

As with all baking-compatible
shaders, one should not use 
the faceforward() call.

In-House disp workflow is 0.5-based, meaning
that a magnitude of 0.5 does nothing, 0 goes inward,
1 goes outward.
*****************************/

displacement lm_disp(
			    float Km = 1.5;
			    string texname = "";
			    float offset = -0.5;
			    )
{
  float surface_mag, layer_mag;
  point Ndiff;

 	if(texname != "")
		//surface_mag = float texture( texname, "fill", 0.5, s, t );
		surface_mag = float texture( texname, "fill", 0.5 );
	else surface_mag = 0.5;

  Ndiff = normalize(N) - normalize(Ng);
  //P += (-0.5)*Km*normalize(N);
  P += (surface_mag+offset)*Km*normalize(N);
  //P += (surface_mag-0.5*offset)*Km*normalize(N);
  //P += ((Km * surface_mag+offset) * normalize(N));
  N = normalize(calculatenormal(P)) + Ndiff;
}