I'm currently working on a 2D shoot them up type of game, and I'm using a quad tree for my collision detections. I wrote a working quad tree that correctly pushes my actors into the nodes/leaves they belong to in the tree. However I've got a few problems. Firstly, how do I actually use my quadtree to select against which other objects an object should test collisions ? I'm unsure about how this is done. Which brings up a second question. Say I have an object in node that is not a neighbor of another node, but that the object is large enough that it spans a few node, how can I check for an actual collision, since I'm guessing the tree might consider it's not close enough to collide with objects in a "far away" node ? Should objects that don't completely fit in a node be kept in the parent node ?
This is the type of game I am making:
Most of the objects are of different sizes and moving arround.
I've read a good number of blogs/articles about quadtrees but most just explain how to build a tree which is not really what I'm looking for. Any help/info is welcome.
Thanks.