home *** CD-ROM | disk | FTP | other *** search
- Xref: sparky comp.graphics:9052 alt.3d:900
- Newsgroups: comp.graphics,alt.3d
- Path: sparky!uunet!orca!orca!pmartz
- From: pmartz@dsd.es.com (Paul Martz)
- Subject: Re: Why 3D clipping?
- Message-ID: <1992Aug21.165147.10499@dsd.es.com>
- Sender: usenet@dsd.es.com
- Nntp-Posting-Host: bambam-gw
- Reply-To: pmartz@dsd.es.com (Paul Martz)
- Organization: Evans & Sutherland Computer Corp., Salt Lake City, UT
- References: <6w#nlg+.thinman@netcom.com>
- Distribution: na
- Date: Fri, 21 Aug 92 16:51:47 GMT
- Lines: 22
-
- In article <6w#nlg+.thinman@netcom.com>, thinman@netcom.com (Technically Sweet) writes:
- > Why does a 3D object painter need to do 3D clipping?
- > Is it necessary, or just a faster way of rejecting
- > off-screen objects & polygons?
-
- (Smartass answer:) If your "screen" is a 3D display device (and there
- are such beasts), it is required to clip in Z just as you would XY.
-
- > [ ... ]
- >
- > The nature of my software is that almost all objects will be on-screen
- > almost all the time, so the efficient rejection thing is moot.
-
- If some objects are so far away in Z as to be irrelevant, it would be
- more efficient to clip them in Z. Furthermore, if the Z value of an
- object puts it behind the eyepoint, it also makes sense to clip it.
- (Depending on your transformation pipe, attempting to draw objects
- behind the eyepoint could result in garbage on the screen.)
- --
-
- -paul pmartz@dsd.es.com
- Evans & Sutherland
-