/* turb.sl
 *
 * shader for viewing simple turbulence
 *
 */
#include "rmannotes.sl"

surface turb(float turbfreq = 2)
{
  point PP;
  float turb, f;
  float maxfreq = 6;
  
  PP = transform("shader", P) * turbfreq;

  turb = 0;
  for (f = 1; f < maxfreq; f *= 2) 
    turb += abs(snoise(PP * f)) / f;

  Ci = turb;
}