A 2D index or something.
A SepTree is an index much like a QuadTree over 2D points. Sep points to the number 7, because there are 7 smaller tiles (hexagonals/hexes) for each bigger tile. Unlike a QuadTree it does not tesselate perfectly, as the smaller hexes needs to be rotated a small angle in order to fit into a bigger tile.
Each tiling of 7 hexes is indexed as follows:
1 2
3 4 5
6 7
Note that 0 is not used.
(I) means impemented
- Create index from keys (I)
- Get keys from index (I)
- Index point in space
- Get point from index