Note: This project was superceded by https://github.com/anvaka/ngraph.forcelayout. You can still use it as a reference for your own understanding of oct-trees, but ngraph.forcelayout contains more efficient implementation that can work for arbitrary number of dimensions. Quad Tree data structure for Barnes-Hut simulation in 3d space. Technically it should be named OctTree, since it's not a quad tree. But for parity with 2d interface it's currently called quadtree. Let me know if you think it should be changed :).