/* experimental.sl "improved version"
 * Tom Suchan Assignment5: 1a.
 * multi-layer experimental shader
 * user can set parmeters for the "scale" and backgound wash colors
 */
#include "rmannotes.sl"

surface experimental(string wash = ""; string scale = "";
         float Ka = .5, Kd = .5, Ks = 1, roughness = 0.5; 
         color specularcolor = 1;)
{  
  color paper, ink, one, two;
  float paper_opac, ink_opac;
  float fuzz = 0.05;
  float ss, tt;
  point center;
  float radius, d;
  float freq = 5; 
  float row, col;
  float circle1, circle2;
  point Nf, V;

  /* paper */

  paper_opac = 1;
  Nf = faceforward(normalize(N), I);
  V = -normalize(I);

if(wash == "RG"){ /* a vertical wash from violet to green */
    one = color(1, 0, 1);
    two = color(0, 1, 0);
}
else
if(wash == "WY"){ /* a horizontal wash from white to yellow */
    one  = color(1, 1, 1);
    two  = color(1, 1,0);
}
else{
    one = color(.3, .6, .2);
    two = color(0, 1, .5);
}    
  paper = mix(one, two, t );

  /* repeat pattern */

  tt = repeat(t, freq);
  ss = repeat(s, freq);
  col = whichtile(s, freq);
  row = whichtile(t, freq);
  rotate2d(s, t, radians(45), 0.5, 0.5, ss, tt);

  
  /* vertical bar */
  
  if (even(row) && odd(col) ||
      even(col) && odd(row)) {

  ink = color (1, 1, 0);
  ink_opac = pulse(0.35, 0.65, fuzz, ss);
  paper = mix(paper, ink, ink_opac);
  
  /* horizontal bar */
  
  ink = color (1, 0, 0);
  ink_opac = pulse(0.35, 0.65, fuzz, tt);
  paper = mix(paper, ink, ink_opac);
  }
  else{

  /*disk*/
  
  ink = color(0, 0, 1);
  center = (0.5, 0.5, 0); 
  radius = 0.35;           
  d = distance(center, (ss, tt, 0));
  ink_opac = 1 - smoothstep(radius - fuzz, radius + fuzz, d);
  paper = mix(paper, ink, ink_opac);
  }
  
  /*scale layer*/    
   
  radius = 0.45;           

  if(scale == "W") /* white scales */
    ink = color(1,1,1); 

  else if(scale == "B") /* black scales */
    ink = color(0, 0,0);

  else 
    ink = color(.3, 1, .4);

  /* first circle */
  
  ss = repeat(s, freq);
  tt = repeat(t, freq);
  center = (.5, .5, 0);
  d = distance(center, (ss, tt, 0));
  circle1 = 1 - smoothstep(radius - fuzz, radius + fuzz, d);

  /* second circle */

  ss = repeat(s, freq);
  tt = repeat(t, freq);
  center = (.65, .5, 0);
  d = distance(center, (ss, tt, 0));
  circle2 = 1 - smoothstep(radius - fuzz, radius + fuzz, d);

  /* use difference of two circles to create moon */

  ink_opac = difference(circle1, circle2);
  paper = mix(paper, ink, ink_opac);

  /* mini_disc */
  
  radius = 0.10;           
  ink = color(1,1,1); 

  ss = repeat(s, freq);
  tt = repeat(t, freq);
  center = (.8, .5, 0);
  d = distance(center, (ss, tt, 0));
  ink_opac = 1 - smoothstep(radius - fuzz, radius + fuzz, d);
  paper = mix(paper, ink, ink_opac);


   /* illumination */

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

  /* output */


  Oi = paper_opac;
  Ci = paper_opac * paper;
}