#include "rmannotes.sl"

surface surface_shader()
{  color surface_color, layer_color;
  color surface_opac, layer_opac;
  float ss, tt;
  float fuzz = 0.05;
  float freq = 4;

  /* background layer */

  surface_color = color (0.1,1,0);
  surface_opac = 1;

  /* layer 1 */

  ss = repeat(s, freq);
  tt = repeat(t, freq);
  layer_color = color (.5,.5,.5);
  layer_opac = pulse (0.5, 0.55, fuzz, tt);
  layer_opac = .5;
  surface_color = blend(surface_color, layer_color, layer_opac);

  /* layer 2 */

  ss = repeat(s,2);
  tt = repeat(t,2);
  layer_color = color (0.1,0,.1);
  layer_opac = pulse(0.2, 0.8, fuzz, tt);
  layer_opac *= 0.9;
  surface_color = blend(surface_color, layer_color, layer_opac);

  /* layer 3 */

  ss = repeat(s,2);
  tt = repeat(t,2);
  layer_color = color (1,1,0);
  layer_opac = pulse(0.46, 0.47, fuzz, tt);
  layer_opac *= 1;
  surface_color = blend(surface_color, layer_color, layer_opac);

 /* layer 4 */

  ss = repeat(s,2);
  tt = repeat(t,2);
  layer_color = color (1,1,0);
  layer_opac = pulse(0.53, 0.54, fuzz, tt);
  layer_opac *= 1;
  surface_color = blend(surface_color, layer_color, layer_opac);

  /* layer 5 */

  ss = repeat(s,freq);
  tt = repeat(t,freq);
  layer_color = color (1,1,1);
  layer_opac = pulse(0.45, 0.5, fuzz, tt);
  layer_opac *= 1;
  surface_color = blend(surface_color, layer_color, layer_opac);

  /* output */

  Oi = surface_opac;
  Ci = surface_color * surface_opac;
}