#include "rmannotes.sl")

surface mistfall(color mistc = color(.6, .6, .6); float maxFreq = 6, phase = 0, 
              omega =.7, lambda = 2, octave = 8, trans = 0.7)
{
  float turb, f, l, o, a;
  point pp;

  pp = transform("shader", P);

  l=1;o=1;
  a = 0;
  for (f = 1; f <= octave; f+=1)
    {
      a+= o* ((noise(l*pp)) ) / f ;
      l*= lambda;
      o*= omega;
    }
  turb = 0;
  for (f = 1; f < maxFreq; f *= 2) 
    turb += abs(snoise(s * f, t * f)) / f;

  Oi = trans * a * turb;
  Ci = mix(mistc, color(.1, .1, .3), trans * turb * a); 
  P -= turb * a * normalize(N) * udn (pp * 3, -.5, .5);
  N = calculatenormal (N);
}