Quad-Tree

I've been searching around for the logic behind QuadTrees, and trying to implement my own QuadTree algorithm.  What's the basic logic behind QuadTrees?

You have your choice of depth-first or breadth-first searching. This isn't new stuff, Dijkstra was doing this shit back in the 50s. At each node, check to see if the bounding volume of the node (and thus all of its children) intersects with the camera's view frustrum. If it does not, you do not need to traverse any further on that branch of the tree and you do not need to render any of the geometry located within the leaf nodes of that branch.