Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cwjcc!gatech!prism!vsserv!geomag!prem
From: prem@geomag.fsu.edu (Prem Subrahmanyam)
Newsgroups: comp.graphics
Subject: Procedural Bump-mapping.
Message-ID: <201@vsserv.scri.fsu.edu>
Date: 20 Sep 89 18:41:45 GMT
Sender: news@vsserv.scri.fsu.edu
Reply-To: prem@geomag.gly.fsu.edu (Prem Subrahmanyam)
Organization: Florida State University Computing Center
Lines: 20


   I am going to attempt to employ a few procedural bump-map textures
   to DBW_Render (I have no idea how they will turn out).  I would like
   to start with some basics, like maybe a "golf-balling" algorithm 
   that will give the surface small, spherical pits.  Also, a "cross- 
   hatching" one would be nice as well, one that would produce furrows
   in a surface.  These should work for both planar surfaces as well as
   spherical ones.  So, here's the basic request....given a point, the
   normal to the surface at that point as well, how can I perturb the
   normal, position of the point, etc. to create reasonable bump-maps.

   One that I'd particularly like to reproduce is found in an old issue
   of IEEE Computer Graphics & Applications....the one with the Martian
   Magnolia in it.  Well, there's this cross-hatching on the spheres on 
   the previous page.  These would be very nice to try to implement in
   DBW_Render.  Can anyone point me to real code (or at least pseudocode)
   that will tell me how to generate these types of textures?  Eventually,
   with all these textures, bump-mapping, etc. in tow, DBW will be the 
   most kick-butt ray-tracer available to the general public.
   ---Prem Subrahmanyam