Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!mailrus!iuvax!chiuk
From: chiuk@iuvax.cs.indiana.edu (Kenneth Chiu)
Newsgroups: comp.graphics
Subject: Re: point in volume?
Message-ID: <60728@iuvax.cs.indiana.edu>
Date: 28 Sep 90 16:07:09 GMT
References: <11800013@uxh.cso.uiuc.edu>
Organization: Indiana University, Bloomington
Lines: 20

In article <11800013@uxh.cso.uiuc.edu> thender@uxh.cso.uiuc.edu writes:
 >Currently we are needing a routine to find
 >if a point is in a volume.
 >
 >The volume in question has two  restrictive constraints that
 >should make the job easier.
 >
 >       1.  it is always 6 sided
 >       2.  each side is made up of 4 points which may
 >           or may not be planar.  the definition of the
 >           surface defined by the four points is also not
 >           defined yet.

Depending on the exact definition of the sides, you may find it possible
to test the point against all six surface normals.  If the signs are all
the same, then it is inside.  In the general case, it only works for
convex volumes.

Of course, your surface normals must all agree to either point outside or
inside.