Particles Tests - 3

This animation shows the evolution of a data structure used, amongst other, to accelerate the computation of reciprocical forces between particles in computer simulations. For the more curious, those kind of tree-structures are called ["Bounding Volume Hierarchies"](https://en.wikipedia.org/wiki/Bounding_volume_hierarchy), and this visualization shows the bounding boxes of all hierarchy levels following ten particles in a 200k particles simulation (scattered in a sphere and being atracted to each other, therefore roughly oscillating around the global center). Those latest models are just the results of me testing stuff to update and improve a small C++ particle simulations code I previously used to create [this model ("Need some space?")](https://sketchfab.com/3d-models/need-some-space-d6521362b37b48e3a82bce4911409303). I've made the code a bit more robust and easier to setup, tweak, and run... And I've just fixed some huge memory leaks and drastically improved its performance, Yipiii !