special.html
The Materials and Geometry Format
Version 1.0, May 1995
Greg Ward, Lawrence Berkeley Laboratory, [email protected]Introduction
What makes MGF special?
There are three principal reasons to use MGF as an input language for lighting simulation and physically-based rendering:
- It's the only existing format that describes materials physically.
- It is endorsed by the Illuminating Engineering Society of North America (IESNA) as part of their LM-63-1995 standard for luminaire data.
- It's easy and fun to support since it comes with a standard parser and sample scenes and objects at the web site, http://radsite.lbl.gov/mgf/HOME.html.
This notion of extensibility is a cornerstone of the format, and it goes well beyond the extensibility of other languages because is guarantees that new versions of the standard will not break existing programs, and the new information will be used as much as possible. Other languages either require that all translators stay up to date with the latest standard, or allow forward compatibility by simply ignoring new entities. In MGF, if NURBS are added at some point and the translator or loader does not handle them directly, the new version of the parser will automatically convert them to smoothed polygons without changing a single line of the calling program. It is merely necessary to link to the new library, and all the new entities are supported.