Bounding boxes of polygons could overlap. Ask the AABB tree for all possible candidates.
Might be faster than searching for the closest triangle, that requires traversing the whole depth of the tree every time.
1) Octree is built directly from the triangle mesh by checking
overlap of a triangle with an octree cell. This shall produce
a tighter octree with less dense cells.
2) The same method is used for both the adaptive / support cubic infill,
where for the support cubic infill the non-overhang triangles are
ignored.
The AABB tree is no more used.
3) Optimized extraction of continuous infill lines in O(1) instead of O(n^2)
