# include "rmannotes.sl"

surface body(float tfreq = 1,
                Km = 0.2,
                Ka = 0.1,
                Kd = 0.3,
                Ks = 0.4,
                roughness = .1;
           color specularcolor = 1)
{
  color surface_color,layer_color;
  color surface_opac, layer_opac;
  point Nf, PP, V;
  float  turbulence, f;
  float maxfreq = 4;
  float cutoff, width, fade;
  
  PP = transform("shader", P) * tfreq;
  
   Nf = faceforward(normalize(N),I);
   V = normalize(-I);
   surface_color = noise(PP);
   surface_opac = Os;

/* layer1 */
   layer_color = color (0.3);

    
   width = filterwidth_point(P);
   cutoff = clamp(0.5 / width, 0, maxfreq);

   turbulence = 0;
   for (f = 1; f < 0.5 * cutoff; f *= 2) 
   turbulence += abs(snoise(P * f)) / f;
 
   fade = clamp(2 * (cutoff - f) / cutoff, 0, 1);
   turbulence += fade * abs(snoise(P * f)) / f;

   layer_opac = turbulence;


   surface_color = blend(surface_color, layer_color, layer_opac);

   surface_opac = union(surface_opac, layer_opac);

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


  
   Oi = surface_opac;
   Ci = surface_opac * surface_color;

}