#include "rmannotes.sl"
surface tongue(float Km = .02, Ks = .9, Kd = .5, Ka = .01,
              roughness = .1, bumps = 180; color specularcolor = 1)

{
  point diff_N,V,Nf;
  float flatness = 1, magnitude;
  color paper;  
  
  paper = color (.45,.167,.167);
  
  /* calculate displacement & color, etc. */

  diff_N = normalize(N) - normalize(Ng);
  P += -Km * noise (s * bumps, t * bumps) * normalize(N);
  N = normalize(calculatenormal(P)) + diff_N;
  Nf = faceforward(normalize(N), I);
  V = -normalize(I);

  paper = paper * Ka * ambient() +
          paper * Kd * diffuse(Nf) +
          specularcolor * Ks * specular(Nf, V, roughness);
  Oi = Os;
  Ci = Os * paper;

}