Revision Complex

Draw a dot on the screen using the mouse. As you add more and more dots, the screen will start subdividing into 4 sections. This is a quadtree. As more points are added, each subdivision will again subdivide. The maximum number of points before a section of the quadtree divides is 4 - the fifth point will divide it.

An important note here: each subdivision contains up to 4 points. So the entire screen is one section at first. The fifth point will divide the three into 4 new sections, in addition to the first. The 4 points assigned to the full screen remain in their own section. That is why it might seem like you can add more than 4 points to each section. Really, they are contained in the larger section which holds the four subdivisions.