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From: u87rpb@ecs.oxford.ac.uk
Newsgroups: comp.graphics
Subject: Re: Scene Description Standard
Message-ID: <9105081606.AA03837@uk.ac.oxford.ecs.booth18.ecs>
Date: 8 May 91 16:06:07 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
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David Rowley wrote:

> I took the postscript interpreter part of GNU's Ghostscript,
> and hacked up an interface for Rayshade.

I've got a half finished Forth interpreter which I added to the
PRT ray tracer that was posted at the end of last year. It's one
of the easiest languages to parse (as has been mentioned) whilst
at the same time allowing parametric definitions for geometry and
texture (and whatever else you might need).

To save time parsing, I decided that the Forth code should be
converted *once* into a byte stream (a la RenderMan) which could
be interpreted very quickly by the renderer itself. The main reason
for this was to prevent backtracking through the (ASCII) source whilst
rendering, and also to prevent duplicate effort in a parallel
environment (there's no point having 50 Sun's all doing a parse job
on the same program).

When the renderer itself starts, the program is first interpreted to
build the object database, and also to insert hooks for procedural
texturing. If an object in the database has a hook for texturing, that
`word' is then called with the relevant object parameters on the forth
stack whenever that object is intercepted.

I've not done any work on this since January, but it sounds like a
sound idea, so it's definitely something that I'll carry on with next
time I have some spare time...

Ray.