ccl_device_forceinline bool point_intersect_test(const float4 point,
                                                 const float3 P,
                                                 const float3 dir,
                                                 float *t)
{
  const float3 center = float4_to_float3(point);
  const float radius = point.w;

  const float rd2 = 1.0f / dot(dir, dir);

  const float3 c0 = center - P;
  const float projC0 = dot(c0, dir) * rd2;
  const float3 perp = c0 - projC0 * dir;
  const float l2 = dot(perp, perp);
  const float r2 = radius * radius;
  if (!(l2 <= r2)) {
    return false;
  }

  const float td = sqrt((r2 - l2) * rd2);
  const float t_front = projC0 - td;
  const float t_back = projC0 + td;

  const bool valid_front = (0.0f <= t_front) & (t_front <= *t);
  const bool valid_back = (0.0f <= t_back) & (t_back <= *t);

  /* check if there is a first hit */
  const bool valid_first = valid_front | valid_back;
  if (!valid_first) {
    return false;
  }

  *t = (valid_front) ? t_front : t_back;
  return true;
}