/* Code based on a shader by Larry Gritz */

displacement DisplacementMap (float Km = 1;
		  string disp_space = "object",
                         mapname="";)
{
    point Psh, Nsh;

    if (mapname != "") {
      /* get P, N in object (or whatever) space */
      Psh = transform (disp_space, P);
      Nsh = normalize (ntransform (disp_space, N));
      /* displace in object space */
      Psh += Km * texture (mapname) * Nsh;
      /* transform back */
      P = transform (disp_space, "current", Psh);
      N = calculatenormal (P);
    }
}