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: Re: Texture mapping
Keywords: Texture mapping, convex quadrilaterals, triangles
Message-ID: <170@vsserv.scri.fsu.edu>
Date: 6 Sep 89 14:21:15 GMT
References: <9119@pyr.gatech.EDU>
Sender: news@vsserv.scri.fsu.edu
Reply-To: prem@geomag.UUCP (Prem Subrahmanyam)
Organization: Florida State University Computing Center
Lines: 26


   I would strongly recommend obtaining copies of both DBW_Render and
   QRT, as both have very good texture mapping routines.  DBW uses 
   absolute spatial coordinates to determine texture, while QRT uses
   a relative position per each object type mapping.  DBW has some
   really interesting features, like sinusoidal reflection to simulate
   waves, a turbulence-based marble/wood texture based on the wave
   sources defined for the scene.  It as well has a brick texture,
   checkerboard, and mottling (turbulent variance of the color intensity).
   Writing a texture routine in DBW is quite simple, since you're provided
   with a host of tools (like a turbulence function, noise function, color
   blending, etc.). I have recently created a random-color texture that 
   uses the turbulence to redefine the base color based on the spatial point
   given, which it then blends into the object's base color using the color
   blend routines.  Next will be a turbulent-color marble texture that will
   modify the marble vein coloring according to the turbulent color.  Also
   in the works are random color checkerboarding (this will require a little
   more thought), variant brick height and mortar color (presently they are
   hard-wired), the list is almost endless.  I would think the ideal ray-tracer
   would be one that used QRT's user-definable texture patches which are then
   mapped onto the object, as well as DBW's turbulence/wave based routines.
   The latter would have to be absolute coordinate based, while the former can
   use QRT's relative position functions.  In any case, getting copies of both 
   of these would be the most convenient, as there's no reason to reinvent the
   wheel.
   ---Prem Subrahmanyam