#include "rmannotes.sl"

surface tomshader2(float Ka = 0.4, Kd = 0.4, Ks = 0.6, roughness = 0.2;
                color specularcolor = 1)
{
  color surface_color, layer_color;
  color surface_opac, layer_opac;
  float ss, tt;
  float row;
  float fuzz = 0.05;
  float freq = 6;
  point Nf, V;

  /* background layer (layer 0) */

  surface_color = color (0.2, 0.6, 0.8); /* grey */
  surface_opac = 1;

  /* layer #1 */

  ss = repeat(s, 6);
  tt = repeat(t, 4);
  layer_color = color (0,0,1);
  layer_opac = pulse(0.35, 0.65, 0.02, ss);
  surface_color = blend(surface_color, layer_color, layer_opac);
  surface_opac = union(surface_opac, layer_opac);
  
  /* layer #2 */
 
  ss = repeat(s, 6);
  tt = repeat(t, 12);
  layer_color = color (.8,.9,.1);
  layer_opac = pulse(0.35, 0.65, 0.1, tt);
  layer_opac *= 0.5; 
  surface_color = blend(surface_color, layer_color, layer_opac);
  surface_opac = union(surface_opac, layer_opac);

  /* layer #3 */

  ss = repeat(s, 6);
  tt = repeat(t, 4);
  layer_color = color (1,1,0);
  layer_opac = pulse(0.45, 0.55, 0.02, ss);
  surface_color = blend(surface_color, layer_color, layer_opac);
  surface_opac = union(surface_opac, layer_opac);
  layer_opac *= 1;

  /* layer #4 */

  ss = repeat(s, 12);
  tt = repeat(t, 8);
  layer_color = color (.8,.1,.6);
  layer_opac = pulse(0.48, 0.52, 0.0, ss);
  surface_color = blend(surface_color, layer_color, layer_opac);
  surface_opac = union(surface_opac, layer_opac);
  layer_opac *= 1;

  /* layer 5 */

  ss = repeat(s, freq);
  tt = repeat(t, freq);
  row = whichtile(t, freq);
  if (even(row))
    ss = mod(ss + 1, 1);
  layer_color = color (1,.5,0);
  layer_opac = intersection(pulse(0.35, 0.65, fuzz, ss), 
                            pulse(0.35, 0.65, fuzz, tt));
  layer_opac *= .55;
  surface_color = blend(surface_color, layer_color, layer_opac);

  /* illum */

  Nf = faceforward(normalize(N), I);
  V = -normalize(I);
  surface_color = surface_color * (Ka * ambient() + Kd * diffuse(Nf))
    + specularcolor * Ks * specular(Nf, V, roughness);

  /* output */

  Oi = surface_opac;
  Ci = surface_color * surface_opac;
}