The “highly intelligent” tablet as an efficient pointing device for interactive graphics (Preliminary Report)

Described is a simple, efficient algorithm for determining the nearest displayed point on a screen to an arbitrary cursor position. The algorithm seems particularly appropriate for interactive systems using a data tablet with a “smart” controller. The algorithm is based on partitioning the screen among the currently displayed points and minimally modifing this structure as points are added and deleted. Finding the nearest point for cursor position consists then of moving through this partitioning structure until the region is determined. A divide-and-conquer method is used for both inclusion testing in a particular region and also for speeding the search for the proper nearest point.