#include "rmannotes.sl"

surface demo()
{
  float fuz = 0.05;
  color surface_color = 1;

  /* tile coords */
  float freq = 4;
  float ss = repeat(s, freq);
  float tt = repeat(t, freq);

  float col = whichtile(s, freq);
  float row = whichtile(t, freq);

  float bomb = noise(col * 10 + 0.5, row * 10 + 0.5);

  /* rotate coords */
  float tmps = ss, tmpt = tt;
  float Rot = udn(bomb * 777, -60, 60);
  rotate2d(tmps, tmpt, radians(Rot), 0.5, 0.5, ss, tt);

  /* scale each feature randomly */
  float sc = udn(bomb * 3824, .33, 2);
  ss = (ss-0.5)*sc + 0.5;
  tt = (tt-0.5)*sc + 0.5;

  /* add noise to feature samples - same for every feature */
  ss += .25 * snoise(ss*6 + 437);
  tt += .25 * snoise(tt*6 + 298);
  
  /* add noise to layer color - same for each tile */
  color layer_color = udn2(ss*6+312, tt*6+252, 0,1);

  float d = distance(point(.5,.5,0), point(ss,tt,0));
  color layer_opac = 1 - smoothstep(0.3-fuz, 0.3, d);
  surface_color = blend(surface_color, layer_color, layer_opac);

  Ci = surface_color;
}