Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!texsun!csccat!ncmicro!chris
From: chris@ncmicro.lonestar.org (Chris Arps)
Newsgroups: comp.graphics
Subject: Re: Texture mapping onto 3-D objects
Message-ID: <258@ncmicro.lonestar.org>
Date: 20 Dec 90 17:42:23 GMT
References: <1737@winnie.fit.edu> <2674@gould.doc.ic.ac.uk>
Organization: NC Microproducts, Inc. Richardson, Tx
Lines: 29

Hows about this?  

Get the ray to object intersection point via your favorite
ray tracing method.

Then compute an inverse transform so that the point on 
the object can be mapped back the the screen.  Once you have the
point on the screen(x,y), use it as the index into your source 2D image.  

This will give you the texture/color value for the point on the
object that you are ray tracing.  

This is a simple approach and would probably need some multi-pixel
sampling of the 2D texture in order to anti-alias the resulting
spheres texture.  You will probably have to trace more than one
ray per pixel to get smooth texture maps.

I have not implemented this but have heard of it being used.
Hope it is worth something!

P.S. I just got my hands on a program that will map GIF files
onto 3d complex objects (Pixar's Renderman).  I will
be posting some PC animations using this to alt.binaries.multimedia
real soon.
-- 
Chris Arps  ***THIS SPACE FOR RENT*** *New Music*SONIC YOUTH*FAITH NO MORE*
NC/Scientific Software, Musican,      *SOCIAL DISTORTION*PETER HAMILL*YELLO
Animator, 4 Dogs,2 Birds,1 cat,1 fish *Old Music*SPIRIT*MMANN*VDGG*HENDRIX
Concerning computers - "Anything slower than instantaneous is intolerable!"