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From: johng@neptune.uucp (John A. Gregor)
Newsgroups: comp.graphics
Subject: Re: A Ray Tracer Accelerator: ???
Message-ID: <1990Nov30.044217.17525@scion.CS.ORST.EDU>
Date: 30 Nov 90 04:42:17 GMT
References: <2010@ucf-cs.UCF.EDU> <4381@idunno.Princeton.EDU>
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Reply-To: johng@oce.orst.edu (John A. Gregor)
Organization: College of Oceanography, Oregon State Univ., Corvallis, Or.
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In article <4381@idunno.Princeton.EDU> markv@acm.Princeton.EDU (Mark VandeWettering) writes:
>
>Hmmm.  This probably bears looking into.  Any comments?

Well, to add another data point, the Wavefront software has both a "trace
object" and a "shadow object" associated with each object being rendered.

The trace object is the object used in reflections.  Usually, these
objects are left undefined, or point to a lower complexity, but
similarly shaped, object.  Since shadows and objects appearing as
reflections are typically small and are there to provide visual cues
and since Wavefront's running time is decidedly non-linear to number of
polygons in the scene, this is a win.

Also, you can achieve some neat tricks using this.  You can have an
object cast a shadow from a completely different object (e.g. a kitten
casting a lion's shadow) or appearing as something else in mirrors.
Using the same object with a different offset or scale can lead to some
pretty neat effects occasionally also.

-John
-- 
John Gregor

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