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From: thender@uxh.cso.uiuc.edu
Newsgroups: comp.graphics
Subject: RE: point in volume?
Message-ID: <11800014@uxh.cso.uiuc.edu>
Date: 28 Sep 90 16:57:00 GMT
Lines: 43
Nf-ID: #N:uxh.cso.uiuc.edu:11800014:000:1549
Nf-From: uxh.cso.uiuc.edu!thender    Sep 28 11:57:00 1990




Yesterday I posted a question about a point in a volume.  One of the
things that I did not make clear is that the side can be concave.
Therefore, we need a general test.  We also left the method for defining
a surface up to you.  We felt this would give more leaway.  As things
stand now we will break the 4 points into 2 triangles, and then do a
similar operation to the point in the polygon.  However, the point in
the polygon routine posted here was new to us.  Therefore we felt there
may be something more computationally desirable out there for a point
in a volume.

Todd Henderson
CFD Lab U. of Illinois


===========yesterdays note==========================

There has been quite a bit of discussion on the idea of a
point in a polygon.  Currently we are needing a routine to find
if a point is in a volume.  We feel that the point in a polygon
concept could certainly be extended to a volume, however we were
wondering if there was a better approach that could be used.

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.

             (i.e. it is a distorted cube basically)

Any comments, references, or help would be greatly appreciatted by
the CFD Lab at the University of Illinois.


comments can be posted here or e-mailed to:
 
        hender@uicfda.aae.uiuc.edu