#include <rmannotes.sl>
displacement tidles(float  Km = 0.1, fuzz = 0.5, sfreq = 55,
tfreq = 30)
{ float  ss, tt, row, col;
  float  radius, d, noi, x, y, z, q, half_width;
  float  surface_mag, layer_mag, tot_mag;
  point  center;

  surface_mag = 0;

  ss = s;
  tt = t;
  row = whichtile(tt, tfreq);
  col = whichtile(ss, sfreq);
  ss = repeat(ss, sfreq);
  tt = repeat(tt, tfreq);

  center = (0.15, 0.15, 0);
  radius = 1.25;
  half_width = 0.05;
  for (x = -1; x <= 1; x += 1)
  {
    for (y = -1; y <= 1; y += 1)
    {
     z = ss - x;
     q = tt - y;

  noi = noise((col + x) * sfreq + 0.25, (row + y) * tfreq + 0.25);

  z = z + udn(noi * 6789, -0.25, 0.25);
  q = q + udn(noi * 3456, -0.25, 0.25);

  radius = 0.25 + udn(noi * 456, -0.1, 0.1);


  d = distance(center * udn(noi * 56, -0.1, 0.1), (z, q, 0))/32;
  tot_mag = pulse(radius - half_width, radius + half_width, fuzz, d);
  layer_mag = tot_mag;
  surface_mag = mix(surface_mag, layer_mag, layer_mag);
}}
  
  P += Km * surface_mag * normalize(N);
  N = calculatenormal(P);
}