/*Wooksang's irregular wood shader for Digital lighting*/ 

#include "rmannotes.sl" 
surface
irregular_metal(
	       float Ks = 0.2, Kd=1, Ka = 0.1,roughness=0.1;
	       color first = color(0.194,0.163,0.125);
	       color second = color(0.980,0.921,0.943);
	       color third = color(1,1,1);
	       color specularcolor = 1;
	       float number = 7) 
{

/*basic setting*/

  color surface_color, layer_color; 
  float surface_opac, layer_opac; 
  float d,col,row,ss,tt,noi;  
  float freq,i;
  vector V;
  normal Nf;

  Nf=faceforward(normalize(N),I);
  V=-normalize(I);
  surface_color = first;
/* basic options */

for(i=2;i<=number;i +=1)
{
  freq = i;
  col = whichtile(s,freq);
  row = whichtile(t,freq);
  noi = noise(col+0.7,row+0.7)*noise(i*10+0.5);

  ss = repeat(s,freq)+udn(noi*1300,-0.41,0.41);
  tt = repeat(t,freq)+udn(noi*236,-0.41,0.41);
  d = distance(point(0.5,0.5,0),point(ss,tt,0));

/* layer #1 */
  layer_color = second;
  layer_opac = (1-smoothstep(0.075*noise(ss*120,tt*170),0.12*noise(ss*60,tt*70),d))/number/freq*5;

  surface_color = blend(surface_color, layer_color, layer_opac); 
}
/* layer #2 */
  layer_color = third;
  layer_opac =clamp(1- noise(s*60,t*60),0.3,0.7);
  surface_color = blend(surface_color, layer_color, layer_opac); 

/* output */
  Oi=Os;
  Ci=surface_color*(Ka*ambient()+ (1-layer_opac)*Kd*diffuse(Nf))+specularcolor*layer_opac*Ks*specular(Nf,-V,roughness);
}