/* Assignment 5         */
/* Digital Lighting/tv  */
/* Spring 96            */
/* Mark Fontana         */


/* gives slightly curled edges to a bilinear patch to make it look
   a little more like a sheet of paper                             */

displacement papercurl(float radius = 0.56, curlheight = 2.2)
{
  float ss, tt, dist;

  ss = s-0.5;
  tt = t-0.5;
  dist = sqrt(ss*ss+tt*tt);
  if (dist >= radius)
     P += normalize(N)*(dist-radius)*(dist-radius)*curlheight;
  N = calculatenormal(P);
}