// TODO: Cache.
    public void RemoveBody(RayCastingBody body)
    {
        Debug.Assert(bodyList.Contains(body));

        bodyList.Remove(body);
    }
    // Include body into calculation.
    // TODO: Cache.
    public void AddBody(RayCastingBody body)
    {
        Debug.Assert(!bodyList.Contains(body), "The body is already added.");

        bodyList.Add(body);
    }