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From: carter@IASTATE.EDU (Carter Michael Brannon)
Newsgroups: comp.graphics
Subject: Re:  Ray tracing Superquadrics
Keywords: raytracing
Message-ID: <1990Oct30.155452@IASTATE.EDU>
Date: 30 Oct 90 21:54:52 GMT
References: <28825@boulder.Colorado.EDU> <1990Oct29.150528.11257@eye.com> <3684@idunno.Princeton.EDU>
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Reply-To: carter@IASTATE.EDU (Carter Michael Brannon)
Organization: Iowa State University
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     I was just digging through my literature and finally came up with
the reference that was
stuck in the back of my mind.  I cannot vouch for the speed of this
method, but here's the ref.

Kalra, Devendra, and Alan H. Barr, "Guaranteed Ray Intersections with
Implicit Surfaces,"
  Computer Graphics, Vol. 23, No. 3, July 1989.

This method uses Lipschitz conditions to intersect ANY implicit surface.
It always finds the
closest (or subsequent) intersection points -- even in badly behaved
functions.  There are
also some really neat pictures of blended objects in the paper.

--
Michael B. Carter