#include "rmannotes.sl"

surface surf2_1(float Ka = 0.5, Kd = 0.5, Ks = 0.5, roughness = 0.15;
		color specularcolor = 1)
{
  color surface_color, layer_color;
  color surface_opac, layer_opac;
  float ss, tt;
  point Nf, V;

  /* background layer (layer 0) */

  surface_color = color  (0.3, 0.15, 0.1);
  surface_opac = Os;

  /* layer #1 */

  ss = repeat(s, 12);
  tt = repeat(t, 12);
  layer_color = color (1, 0.95, 0.1); 
  layer_opac = union(pulse(0.35, 0.65, 0.02, ss),
		     pulse(0.35, 0.65, 0.02, tt));
  surface_color = blend(surface_color, layer_color, layer_opac);
  surface_opac = union(surface_opac, layer_opac);
  
  /* illum for all layers */

  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;
}