2ad27044a6
Instead of incrementing and then doubling, calculate the child tile range by doubling and then incrementing.
With this change, tile coord [0, 0, 0] has the four following children:
[1, 0, 0] [1, 1, 0]
[1, 0, 1] [1, 1, 1]
Without this change, tile coord [0, 0, 0] had the nine following children:
[1, 0, 0] [1, 1, 0] [1, 2, 0]
[1, 0, 1] [1, 1, 1] [1, 2, 1]
[1, 0, 2] [1, 1, 2] [1, 2, 2]