/*  
 *  ass6_4.sl
 *  
 *  Description:
 *      The displacement shader that generates regular pattern using sine and
 *      cosine functiion.
 *
 *  Parameters: freq, Km
 * 
 *  Author:  Akanee  Mahasith
 *
 */

#include "rmannotes.sl"

displacement ass6_4(float Km = 0.02;
                    float freq = 30;
                   )
 
{
   float  surface_mag, layer_mag;
   float  ss, tt;
   float  fuzz = .05;
   

   /* background layer */

   surface_mag = 0;
 
   /* layer 1 */

   layer_mag = sin(t * freq);
   surface_mag += layer_mag;

   /* layer 2 */
  
   layer_mag = sin(s * freq);
   surface_mag = min(surface_mag, layer_mag); 

   /* displace */
                
   P -= Km * surface_mag * normalize(N);
   N  = calculatenormal(P);
}