White Grid: 0, 0, 3, 3|3, 0, 6, 3|6, 0, 9, 3|12, 0, 15, 3|0, 3, 3, 6|3, 3, 6, 6|12, 3, 15, 6|6, 6, 9, 9|9, 6, 12, 9|9, 9, 12, 12