What is clipping range?
Most 3D graphics programs that rely on hardware accelerated hidden surface removal always have a finite depth range. Vizard uses hardware z-buffering exclusively for hidden surface removal, as do most other rendering APIs. As such, you can use the viz.clip() command to fine tune the range. Keep in mind your depth resolution (the minimum distance the computer can distinguish in depth) will be spread over this range. You’re noticing that far objects are disappearing.
