code: public Point getPointAt(double t)
  	{
  		if (Double.isNaN(t))
  			return null;
  		return new Point(origin.x + t * direction.x, origin.y + t * direction.y, origin.z + t * direction.z);
  	}
docs: Gets the {@link Point} at the specified distance.
  
  @param t the distance
  @return the point at the distance t