public Pos getCenter() {
        switch(shape) {
            case O : return new Pos(0,0);
            case I : return rotation % 2 == 0 ? new Pos(1,0) : new Pos(0,1);
            default: switch (rotation) {
                case 0: return new Pos(1,0);
                case 3: return new Pos(0,1);
                default: return new Pos(1,1);
            }
        }
    }