#include "rmannotes.sl"

displacement dwater(float phase = 0, omega =.7, lambda = 2, 
                    octave = 8)
{
  float magnitude;
  float layer_mag;
  float Km = 0.04;

  float freq;
  float d;
  float i,o,l;
  point a = (0,0,0);
  point PP;
  
  PP = transform("shader",P);
  l=1;o=1;
  for (i=0;i<octave; i+=1)
    {
      a+= o* ((point noise(l*PP)) - point(1,1,1)) ;
      l*= lambda;
      o*= omega;
    }


  magnitude = 0;

  /* source #1, located at (0,0,0) with frequency = 3 */

  freq = 75;
  d = distance(point(s,t,0), (.55, 1, 0)) + udn(P, -.5, .5);
  layer_mag = sin(d * 2 * PI * freq + phase);
  magnitude += layer_mag;

  /* source #2, located at (1.7,-.4,0), more subtle, frequency = 5 */

  freq = 50;
  d = distance(point(s,t,0), (.4, .9, 0))  + udn(P, -.25, .25);
  layer_mag = sin(d * 2 * PI * freq + phase);
  layer_mag *= .5;
  magnitude += layer_mag;

  /* displace */

  P += -Km * a  * magnitude * t / 2.5 * normalize(N);
  
  N = calculatenormal(P);
}