Function AnisotropicBlinn__eval

tutorials/pathtracer/pathtracer_device.cpp:427–436

! Evaluates the power cosine distribution. \param wh is the half * vector */

/*! Evaluates the power cosine distribution. \param wh is the half
 *  vector */
inline float AnisotropicBlinn__eval(const AnisotropicBlinn* This, const Vec3fa& wh)
{
  const float cosPhiH   = dot(wh, This->dx);
  const float sinPhiH   = dot(wh, This->dy);
  const float cosThetaH = dot(wh, This->dz);
  const float R = sqr(cosPhiH)+sqr(sinPhiH);
  if (R == 0.0f) return This->norm2;
  const float n = (This->nx*sqr(cosPhiH)+This->ny*sqr(sinPhiH))*rcp(R);
  return This->norm2 * powf(abs(cosThetaH), n);
}

/*! Samples the distribution. \param s is the sample location
 *  provided by the caller. */