template<typename T> Vector3<T> RandomUnitVector3()
{
  while (true)
  {
    Vector3<T> ret;
    for (i64 c = 0; c < ret.ElementCount; ++c)
      ret[c] = (T)(RandFloat() * 2 - 1);
    T len = Mag(ret);
    if (len < 1.0 && len > 0.01)
      return ret / len;
  }
}