Hi Ivan,
A couple of extra bit of info from the dev side.
We do expand the AABB bounds by around 10% for shapes - that way we don’t have to change the tree for small movements which helps speed things up.
SAP can struggle with performance for SceneQueries - essentially they aren’t generally inserted into a broadphase since they can’t be collided with, only collide with other things. This means a lot of searching and probable cache thrashing while searching.
SAP can also get into issues when there are a lot of overlaps on one axis even when the objects are really far apart, so you pay a cost for a large result set initially which then gets filtered out.
Specifically on your diagram, for a SAP structure - that square won’t be the search domain - it will have *all* the search space between the points along each axis - so more of a cross shape which then gets compared to filter out collisions. For updates then you would search for the X axis difference (for all Y), and Y axis difference (for all X), then filter out the X, Y and finally the overlap for X and Y.
Hope this all helps. Let us know if you need any specific advice when you are ready.
Geoff