/* fin3.sl
 *
 * displacement for the wood shader
 *
 */
#include "rmannotes.sl"

displacement fin3(float ringscale = 10, Km = .01)
{
  float surface_mag = 0,layer_mag = 0;
  point Nf, V, PP, Ndiff;
  float r, tmps, tmpt, ss, tt;
  float col, row, noi, freq = 100;
  float fuzz = .04;
  point center;
  float radius;
  float d;

 /* layer 1 */

  PP = transform("shader", P);
  PP += noise(PP) * 0.5;
  r = distance((0,ycomp(PP),zcomp(PP)), (0,0,0));

  r = repeat(r + noise(r), ringscale); 
  
  layer_mag = smoothstep(0,0.8,r) - smoothstep(0.83,1,r);
  surface_mag += layer_mag;


 /* layer 2*/

  ss = s + snoise(3 + 912) * 5;
  tt = t + snoise(3 + 333) * 5;

  col = whichtile(s, freq);
  row = whichtile(t, freq);
  noi = noise(col * 30  + 0.5, row * 30 + 0.5);

  tmps = repeat(s, freq) + udn(noi * 500, -0.35, 0.35);
  tmpt = repeat(t, freq) + udn(noi * 450, -0.35, 0.35);

  rotate2d(tmps, tmpt, radians(udn(noi * 777, 0, 360)), 0.3, 0.3, ss, tt);
  center = (0.5, 0.5, 0);
  radius = .7;          
  d = distance(center, (ss, tt, 0));
  
  layer_mag = 1 - smoothstep(radius - fuzz, radius, d);
   
  surface_mag += layer_mag;

  /* output */

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