/* 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 */

  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 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 = color (0,0,1); }

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

  /* output */

  Oi = Os;
  Ci = Os * surface_color;
}