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From: mberger@RELAY.NSWC.NAVY.MIL
Newsgroups: comp.sys.sgi
Subject: Re:  Shadows in C
Message-ID: <9104021009.aa07529@VGR.BRL.MIL>
Date: 2 Apr 91 15:12:15 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 11

The spider demo has a shadow capability.

Also, The Iris Universe magazine (winter 1989) has an article title:
   casting shadows on flat surfaces

A paragraph from the article states:
   The easiest way to flatten an object is to use the scal function.  If
   the ground is the plane formed by the x and z axes (y=0) then:
   scale(1.0,0.0,1.0) could be used to create a shadow from a light shining
   straight down the y axis.
If you can't find the article I could FAX it to you.