orpheus@reed.UUCP (P. Hawthorne) (01/30/91)
Is the priority sort algorithm general for all cases?
I ask this question because I am coming to believe there may be a flaw
in the classical algorithm for priority sort.
The same anomaly occurs in at least two similar applications I have
used. One of the applications is my own, another is a commercial flight
simulator. I suspect it occurs in others as well, although I have not been
able to check it out. It does not occur when using a depth buffer.
Since my application uses a textbook implementation, and works
perfectly if you overlook this flaw, and other implementations share it, I
suspect it is actually a flaw in the algorithm.
Specifically, it occurs with surfaces on aircraft. One of the surfaces
around the cockpit that should be obscured is occasionally visible. The
cockpit, it may be worth noting, is at the center of at least one axis in
the modeling coordinate system for the aircraft, due to the symmetrical
nature of aircraft.
I would try to solve this myself if I had more time to devote, but I
was wondering if the solution had already been found.
orpheus@reed