Delete Operation

Delete the spatial object. The object to be deleted is selected by positioning the mouse somewhere near it, say at point p and then clicking it. Since it is impossible to position the mouse exactly on the object being deleted, the actual object to be deleted is obtained by using the nearest neighbor operation which is implemented by the incremental nearest neighbor algorithm. This causes a modification to be made to the algorithm when the spatial object has extent and area (e.g., a rectangle) and the point p is inside the object. In particular, for the purpose of the incremental nearest neighbor algorithm, the distance from the point p to all objects that contain p is zero. However we need to distinguish between them anyway, and thus the distance from p to the nearest boundary of an object that contains p is used as a secondary discriminator on the ordering for the ranking.