Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!sgi!shinobu!odin!bedlam.asd.sgi.com!davis
From: davis@bedlam.asd.sgi.com (Tom Davis)
Newsgroups: comp.graphics
Subject: Re: Clipping triangle against box
Keywords: Cannonical, 3D triangle, clipping,
Message-ID: <1991May13.224345.29026@odin.corp.sgi.com>
Date: 13 May 91 22:43:45 GMT
References: <1991May13.164136.23998@shograf.com>
Sender: news@odin.corp.sgi.com (Net News)
Reply-To: davis@bedlam.asd.sgi.com (Tom Davis)
Organization: Silicon Graphics, Inc., Mountain View, CA.
Lines: 12

I'll bet the general polygon clipping algorithm can't be simplified too
much, even for a triangle against a clipping box.  Lots of extra edges
get added.  For example, if you clip the triangle ABC against the
box -1.0 <= x, y, z <= 1.0, where A = (-1.2, 1.2, 0.0), B = (1.2, 0.0, -1.2),
and C = (0.0, -1.2, 1.2), you'll get a 9-sided figure.

Of course I never \\proved// anything, but I do recall looking
for the same sort algorithm you're seeking, and I gave up when I
found this example.

  -- Tom Davis
     Silicon Graphics