/* Assignment 1, part 2 */
/* Digital Lighting/tv  */
/* Spring 96            */
/* Mark Fontana         */

#include "/usr/local/accad/shaders/rmannotes.sl"


/* procedural texture of a single 50's style "binky" star & plastic shading */


surface binky(float hfreq = 1, vfreq = 1, width = 0.04,
              Ka = 0.5, Kd = 0.5, Ks = 0.5, roughness = 0.1;
              color specularcolor = 1)
{
  point Nf = faceforward(normalize(N), I);
  point V  = normalize(-I);

  color surface_color, layer_color;
  float layer_opac;
  float fuzz = 0.005, half_width, d;
  point p1, p2;

  /* background layer */

  surface_color = Cs;
  Oi = 1;

  /* layers for the 5 lines in the binky */
  
  s = mod(s*hfreq, 1);
  t = mod(t*vfreq, 1);

  layer_color = color "rgb" (1, 1, .8);
  half_width = width/2;

  p1 = (0.5, 0.05, 0);   
  p2 = (0.5, 0.12, 0);   
  d = ptlined(p1, p2, (s, t, 0));
  layer_opac = 1 - smoothstep(half_width - fuzz, half_width, d);
  surface_color = mix(surface_color, layer_color, layer_opac);

  p1 = (0.60, 0.12, 0);  
  p2 = (0.55, 0.17, 0);  
  d = ptlined(p1, p2, (s, t, 0));
  layer_opac = 1 - smoothstep(half_width - fuzz, half_width, d);
  surface_color = mix(surface_color, layer_color, layer_opac);

  p1 = (0.40, 0.12, 0);  
  p2 = (0.45, 0.17, 0);  
  d = ptlined(p1, p2, (s, t, 0));
  layer_opac = 1 - smoothstep(half_width - fuzz, half_width, d);
  surface_color = mix(surface_color, layer_color, layer_opac);

  p1 = (0.55, 0.23, 0);  
  p2 = (0.60, 0.27, 0);  
  d = ptlined(p1, p2, (s, t, 0));
  layer_opac = 1 - smoothstep(half_width - fuzz, half_width, d);
  surface_color = mix(surface_color, layer_color, layer_opac);

  p1 = (0.45, 0.23, 0);  
  p2 = (0.40, 0.27, 0);  
  d = ptlined(p1, p2, (s, t, 0));
  layer_opac = 1 - smoothstep(half_width - fuzz, half_width, d);
  surface_color = mix(surface_color, layer_color, layer_opac);

  /* output color */

  Ci = surface_color;
  Ci = Oi*(Ci*(Ka*ambient() +       /* plastic illumination */
                  Kd*diffuse(Nf)) +
                  specularcolor*Ks*specular(Nf, V, roughness));
}