source files: [xc]cmr.[ch]
(SEND <cmr> :CLEAR-ZBUFFER)
This message clears the zbuffer area corresponding to the camera viewport. It may or may not clear the zbuffer area outside the camera viewport, depending on the implementation. On many machines, clearing the zbuffer is an expensive operation -- it may involve setting three megabytes of RAM! -- so you should normally try to do it only once per frame.