#include "rmannotes.sl"

displacement wavegrid(float freq, phase)
{
  float Km = 0.1;
  float magnitude, layer_mag;
  float tile_s, tile_t;
  float d;


  magnitude = 0;

  tile_s = repeat(s, 4);
  tile_t = repeat(t, 4);

/*vertical and horizontal bars, non-intersecting */

  layer_mag = pulse(tile_s, .35, .65, .05);
  magnitude = max(magnitude, layer_mag);

  layer_mag = pulse(tile_t, .35, .65, .05);
  magnitude = max(magnitude, layer_mag);

  rotate2d(s, t, 45, .5, .5, tile_s, tile_t);

/*lower height ring, non-interfering*/

  layer_mag = pulse(distance((.5, .5, 0), (tile_s, tile_t, 0)),
		    .35, .45, .01);
  layer_mag *= .5;
  magnitude = max(magnitude, layer_mag);

/*points, interfering (added on top of bars)*/

  layer_mag = 1 - smoothstep(.0, .1,
			     distance((.5, .5, 0), (tile_s, tile_t, 0)));
  layer_mag *= .5;
  magnitude += layer_mag;
  
  d = distance((s, t, 0), (1.7, -.4, 0));
  layer_mag = sin(d * 1 * PI * freq + phase);
  layer_mag *= 1;
  magnitude += layer_mag;

/* compute dispalcement */

  P += -Km * magnitude * normalize(N);
  N = calculatenormal(P);
}