Newsgroups: comp.graphics Path: utzoo!utgpu!watserv1!maytag!mks.com!david From: david@mks.com (David Rowley) Subject: Re: Scene Description Standard Date: Thu, 2 May 91 14:15:48 GMT Message-ID: <1991May2.141548.28966@mks.com> Organization: Mortice Kern Systems, Waterloo, Ontario, CANADA References: <248@rins.ryukoku.ac.jp> <1991May1.135548.27865@mks.com> In article bcorrie@csr (Brian Corrie) writes: >david@mks.com (David Rowley) writes: > >>Is the RIB format simply a Renderman program compiled into a bytestream ? >>If it is a reasonable subset, perhaps it could be used. Unfortunately >>it is not documented (or even really discussed) in Upstill's Renderman >>Companion. > >From what I understand, the RIB format is just a scene description, without >all of the control flow and other constructs of the C binding. It is still >quite rich geometrically, so you are right, most PD type renderers will not >be able (mine included 8-) to handle most of the more sophisticated primtives. >Unfortunate, but NURBS and CSG are the best ways to describe many objects. >Polygons just don't cut it for a lot of things. Where can I get a description of the RIB format ? It could be used as a standard format, since RenderMan is likely to be fairly popular. Like it or not. A RIB translator could transform the more complicated RIB primitives into simpler ones that all renderers could understand. (polygons, triangles, whatever). >I agree. I actually thought RIB had the programming constructs as well, until >recently. Without them RIB is JAF (Just Another Format 8-), rich as it may >be. Although it's just another format, it has some high-powered backing, and isn't likely to go away any day soon. >>One person mentioned a lisp-style format. This is more what I had >>in mind. It should be something that can be parsed in a simple manner. >>It should be trivial to write a filter to convert the standard format >>to the specific input format of a renderer. The main point being >>keep it as simple, yet extensible, as possible. You shouldn't >>need Yacc to parse it. Someone pointed me to P3D from Pittsburgh Supercomputing Center, which is based on a simple lisp interpreter. It comes close, but I still think a programmatic approach embedded within the scene description language is a liability. Programs should be used to *generate* this stuff. The reason I like the lisp-style *syntax* is that it is easy to parse. -- ll // // ,~/~~\' David Rowley /ll/// //l' `\\\ Mortice Kern Systems Inc. / l //_// ll\___/ 35 King Street North, Waterloo, ON, Canada N2J 2W9 O_/ 519/884-2251, FAX 519/884-8861, david@mks.com