#include "rmannotes.sl"

surface diff()
{
  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 d = distance(point(.5,.5,0), point(ss,tt,0));
  float R = 0.3;
  
  color layer_color = color "hsv" (cellnoise(row*10 + 321),
                                   1,
				   udn2(s*4 + 321, t*4 +984, 0.5, 1.0));

  /* add noise to feature samples - different for every feature */
  d += .25 * snoise2(ss*3 + row*10 + 298, tt*3 + col*10 + 832);

  color layer_opac = 1 - smoothstep(R-fuz, R, d);
  surface_color = blend(surface_color, layer_color, layer_opac);

  Ci = surface_color;
}