/* fin2.sl, from the pinchers of some bug
*
* decription: 
*
* param: complexity , Km, density
*
* complexity and densiti control turbulence, Km contols overall displacement
*
* author: Heath Hanlin
*/


#include "rmannotes.sl"

displacement fin2(float complexity = 10,Km = .1, density = .5)

{

float surface_mag = 0,layer_mag = 0;
float ss,tt;
point Nf, V, PP, Ndiff;
float width, cutoff, fade, f, turb, maxfreq = 16;

/* turbie */


 PP = transform("shader", P) * density;

  width = filterwidth_point(PP);
  cutoff = clamp(0.1 / width, .1, maxfreq);

  turb = 0;
  for (f = 1; f < 0.5 * cutoff; f *= 2) 
    turb += abs(snoise(PP * f)) / f;
  fade = clamp(10 * (cutoff - f) / cutoff, 6, 10);
  turb += fade * abs(snoise(PP * f)) / f;

  turb *= -0.5;


/* layer 1 */

tt = float noise(t * complexity * turb);
layer_mag = smoothstep(.1, .3, tt) * -.3;
surface_mag += layer_mag;

/* layer 2 */

ss = float noise(s * complexity * turb);
layer_mag = smoothstep(.6, .9, ss) * -.3;
surface_mag += layer_mag;

/* layer 3 */

tt = float noise(PP * complexity * turb - .2);
layer_mag = smoothstep(.3, .6, tt)* -.3;
surface_mag += layer_mag;


/* output */

Ndiff = normalize(N) - normalize(Ng);
P += P * Km * surface_mag * normalize(N);
N = normalize(calculatenormal(P)) + Ndiff;

}