/* cubes.sl */
#include "rmannotes.sl"

surface cubes(float Ka = 0.2, Kd = 0.4, Ks = 0.6, roughness = 0.1,
	      r = 0.5, freq = 6)
{
  color surface_color=1, layer_color, layer_opac;
  normal Nf = faceforward(normalize(N), I);
  vector V = -normalize(I);

  point PP = transform("shader", P); /* transform P to shader space */

  PP += vector snoise(PP*10) * 0.1;

  float x = xcomp(PP), y = ycomp(PP), z = zcomp(PP);

  float xx = repeat(x,freq);
  float yy = repeat(y,freq);
  float zz = repeat(z,freq);

  float col = whichtile(x,freq);
  float row = whichtile(y,freq);
  float pla = whichtile(z,freq);
  color c = color cellnoise(point(col,row,pla));

  /* float d = max(abs(xx)-r, abs(yy)-r, abs(zz)-r); */
  float d = (xx-0.5)*(xx-0.5)+(yy-0.5)*(yy-0.5)+(zz-0.5)*(zz-0.5) - r*r;

  if(d>0) { surface_color = color (1,0,0); }
  else { surface_color = c; }

  float ds = distance(point(0.5,0.5,0.5), point(xx, yy, zz));
  float max_height = .1;
  float layer_mag = max_height * clamp(1-ds/r,0,1);
  float surface_mag = layer_mag;
  vector Nn = normalize(Nf);
  P += Nn * (surface_mag / length(vtransform("shader", Nn)));
  N = calculatenormal(P);
  Nf = faceforward (normalize(N),I);

  surface_color = surface_color * (Ka * ambient() + Kd * diffuse(Nf)) +
    Ks * specular(Nf, V, roughness);

  /* output */

  Oi = Os;
  Ci = Os * surface_color;
}