Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!ukma!psuvm.bitnet!cunyvm!ndsuvm1!ndsuvax!nctingue
From: nctingue@ndsuvax.UUCP (Mark Tinguely)
Newsgroups: comp.graphics
Subject: Re: Raytracing speedups....
Message-ID: <1982@ndsuvax.UUCP>
Date: 16 Dec 88 14:40:12 GMT
Reply-To: nctingue@ndsuvax.UUCP (Mark Tinguely)
Distribution: na
Organization: North Dakota State University  Fargo, ND
Lines: 21


>In article <907@cmx.npac.syr.edu> gefuchs@top.cis.syr.edu (Gill E. Fuchs) writes:
>>   Would there be problems with secondary rays? (reflected,refracted)

In article <5796@saturn.ucsc.edu> easterb@ucscb.UCSC.EDU (William K. Karwin) writes:
>Casting a secondary ray would be equivalent
>to changing the viewpoint of the scene, and so would require another
>entire set of 2d bounding boxes to be created.  This would have
>to happen during runtime, because you could not predict secondary rays.

I don't want to put words in anyone's mouth but I think the intention
of the secondary ray is to PROJECT the secodary ray into 2D space, then
check the orginal bounding boxes. This is a crude test because the ray
could be moving away from the object, not toward it in the projected axis,
but it would help to eliminate those object not near the ray in the other
two axises.

Mark Tinguely
--
Mark Tinguely           North Dakota State University,  Fargo, ND  58105
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