#include "rmannotes.sl"

displacement
dmultirings(float frequency = 3)
{
 float tile_s, tile_t;
 float low, hi, fuzz, d, dd, max_d;
 point center, p; 
 float magnitude, layer_mag;
 float Km = 0.2; 
 float ring;

 fuzz = 0.05;
 magnitude = 0;

 rotate2d(s,t, 45, 0.6, 0.6, tile_s, tile_t);

 tile_s = repeat(tile_s, frequency );
 tile_t = repeat(tile_t, frequency );

 low = 0.35;
 hi  = 0.65;
 
 p = (0, 0, 0);
 center = (0.5, 0.5, 0);
 max_d = distance (center, p);

 p = (s, t, 0);
 d = distance (center, p);
 
 dd = (low/2)*d/max_d;

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

 layer_mag = pulse (distance ((tile_s, tile_t, 0), (d, d, 0)), 0.3, 0.4, fuzz);
 layer_mag *= d/max_d;
 magnitude = max(magnitude, layer_mag);

 rotate2d(tile_s,tile_t, 180, 0.5, 0.5, tile_s, tile_t);
 
 layer_mag = pulse (distance ((tile_s, tile_t, 0), (d, d, 0)), 0.3, 0.4, fuzz);
 layer_mag *= d/max_d;
 magnitude += layer_mag;

 
 ring= 1- smoothstep(.28, .47, distance((0.5, 0.5, 0), (s, t, 0)));

 if(ring!=0) 
 magnitude *= 2*(1-d/max_d)*ring;
 else {
  magnitude = 0;
}

 layer_mag = smoothstep(0.3, 0.5, distance((.5,.5,0), (s,t,0))/max_d);

 layer_mag *= 2*ring;
 layer_mag *= sin(2*PI*max_d/d);


 layer_mag *= .5;
 magnitude += layer_mag;
 
 rotate2d(tile_s, tile_t, 45, 0.5, 0.5, tile_s, tile_t);
 
/* to define a varying width of the pulse */
 low = d/(max_d *2);
 hi  = d/max_d;

 /* a layer having varying width of line patterns */

 layer_mag = pulse (tile_s, low, hi, fuzz);
 layer_mag *= hi/frequency;
 magnitude += layer_mag;

 /* a layer having varying width of line patterns */

 layer_mag = pulse (tile_t, low, hi, fuzz);
 layer_mag *= hi/frequency;
 magnitude += layer_mag; 

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

}