RELATING A POINT OF SELECTION TO AN OBJECT IN A GRAPHICS¹DISPLAY SYSTEM

摘要

In a system and process for picking three dimensional objects from images depicted on a video display the displayed objects are selectively rerendered. During such rerendering the object pixels are compared in depth to the data in a Z buffer 9 for determining visibility. The number and size of the objects subject to rerendering by the rasterization processor 2 is constrained by using the front end graphics processor 1 to define object extents and by rerendering only extents which have been clipped to the boundaries of the pick window. The rerendering operation does not alter the three dimensional graphics image stored in and repetitively scanned from the frame buffer 3. Selection between multiple objects within the pick window can include a weighted comparison using a pick plane memory 20 to store visibility data by object.