/*
 * photon.C : photon implementation
 */

#include <photon.H>
#include <error.h>

void CPhoton::FindRS(double *r, double *s, COORDSYS *coord,
		     BSDFFLAGS flag, float n)
{
  double phi, theta;

  // Determine angles

  VectorToSphericalCoord(&m_dir, coord, &phi, &theta);

  // Compute r,s

  if(flag == BRDF_DIFFUSE_COMPONENT)
  {
    *s = phi / (2 * M_PI);
    double tmp = cos(theta);
    *r = - tmp*tmp + 1;
  }
  else if(flag == BRDF_GLOSSY_COMPONENT)
  {
    *s = phi / (2 * M_PI);
    *r = pow(cos(theta), n+1);
  }
  else
  {
    Error("CPhoton::FindRS", "Component %i not implemented yet", flag);
  }
}