Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!gem.mps.ohio-state.edu!ginosko!uunet!brunix!jfh
From: jfh@brunix (John Forbes Hughes)
Newsgroups: comp.graphics
Subject: Re: Vector Clipping
Message-ID: <13260@brunix.UUCP>
Date: 22 Aug 89 14:10:40 GMT
References: <4670@tekig5.PEN.TEK.COM> <378@maytag.waterloo.edu>
Sender: news@brunix.UUCP
Reply-To: jfh@euclid.UUCP (John Forbes Hughes)
Distribution: na
Organization: Brown University Department of Computer Science
Lines: 31

In article <378@maytag.waterloo.edu> lhf@Self.UUCP (Luiz H. deFigueiredo) writes:
>In article <4670@tekig5.PEN.TEK.COM> peteru@tekig5.PEN.TEK.COM (Peter Uchytil) writes:
>>Hi, I need an algorithm that will do vector clipping.  Ideally it would
>>work like this: give it the clipping window and the endpoints of the 
>>vector and it gives you the new endpoints back.  There must be an 
>>algorithm of this type somewhere out there.  Can someone point me in the
>>right direction?  Thanks!
>
>How about one of the text books like
> Newman & Sproll, Foley & van Dan, Baker, Harrison, etc...
>They all explain the Choen-Sutherland algorithm for vector clipping.

   The new edition of Foley and van Dam (now 'Foley, van Dam, Feiner, and 
Hughes') contains not only Cohen-Sutherland, but also the Cyrus-Beck/Liang-
Barsky algorithms, which are more efficient, in that the average number of 
intersections computed is smaller than that for C-S. 
   We also describe the Nicholl-Lee-Nicholl algorithm, which is the most 
efficient, but involves a great deal of code, because of its case-by-case 
analysis. If you are truly fascinated by these, let me know and I can fax you 
the relevant pages of the text (or send you the words, but not the pictures, 
via e-mail). 
   One interesting question: only C-S does 3D clipping. How hard is it to 
generalize NLN-clipping to 3D?

-John Hughes, Mathematics and Computer Science Dept's., Brown University
CSnet:   jfh@cs.brown.edu@relay.cs.net
ARPAnet: jfh@CS.BROWN.EDU
BITNET:  jfh@browncs		
UUCP:   ...!{decvax,allegra}!brunix!jfh
   "I was in this prematurely air-conditioned supermarket and there were 
   all these aisles..." -L. Childs