#include "rmannotes.sl"
surface hj( float Ka = 0.4, Kd = 0.4;
	    float Ks = 0.6, roughness = 0.175; color specularcolor = .5)

{ 
color paper, ink;
  float paper_opac;
  float rect1, rect2, rect3;
  float ss, tt;
  float col, row;
  float fuzz = 0.05;
  float freq=6;
  point Nf, V;

  /* init */

  Nf = faceforward(normalize(N), I);
  V = -normalize(I);

  paper =1;

  /*rotate*/

  rotate2d(s, t, radians(45), .5, .5, ss, tt);
  

  /* rect 1 */ 

  s = repeat(s, 4);
  t = repeat(t, 4);
 
  ink = color (.107,.434,.485);
  rect1= intersection(pulse(0.1, 0.6, fuzz, s),pulse(0.1, 0.6, fuzz, t));
  paper= mix(paper, ink, rect1);


  /* shift even rows 1/2 tile */

  col = whichtile(ss, freq);

  if (even(col))
    tt = mod(tt * freq + 0.5, 1);
  else
    tt = repeat(tt, freq);
  ss = repeat(ss, freq);

  /* rect 2 */ 

  ink = color (.105,.010,.194);
  rect2= intersection(pulse(0.2, 0.8, fuzz, ss),pulse(0.2, 0.8, fuzz, tt));
  paper= mix(paper, ink, rect2);

  /* rect 3 */

  ink = color (.652,.365,.365);
  rect3 = intersection(pulse(0.35, 0.65, fuzz, ss),pulse(0.35, 0.65, fuzz, tt));
  paper = mix(paper, ink, rect3);

  /*plastic Illum */

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

  /* output */

  Ci = paper;
}