Subject: Re: VR mechanical animation

From: [email-masked] (Lance Norskog)
Date: Fri, 21 Feb 92 20:11:35 PST

} 
} Care to give us more details on this, Lance?

Oof!  I spent last winter designing an overly complex dataflow
system for doing the real-time interaction part.  It's called
5D: 3D + Time (the fourth dimension) + fun stuff like sound.

What's running is a simplified version of that.  You create
nodes in an arithmetic graph (constant numbers, mouse X & Y,
arithmetic operators, points, etc.).  Separately, you create
a tree of graphics operations which take their parameters
from these nodes.  The graph is executed in sequence.  The 
tree is then drawn.  If the arithmetic makes the point values change,
the picture changes shape. 

There are multiple arithmetic graphs and multiple
trees of graphics commands.  Different graphs are run from
different clocks.  Subclocks off the main clock (vertical retrace)
or just asynchronous events fired by nodes in the arithmetic
graphs ("a switch just went on, make a light flash").

That's the essence.  This real-time graphics (& sound, eventually)
engine will become a low-level piece of a larger system.
Scheme (simple LISP) programs will rearrange the graphs
asynchronously.  Some of the arithmetic nodes can be small
LISP programs that compute values on the fly.  The LISP
intepreters talk to each other (in LISP) over network
communications.  Scheme is an excellent choice for this
job: it has code-as-data, several excellent free implementations,
and a library of cool packages.

SUN's NeWS system does this in Postscript, and it is useable
over a modem (unlike X) because applications are split apart
at high levels instead of low.  Messaging thus communicates
things like "change number X to 42" instead of 500 line
drawing commands.

I have the time and knowledge to write about 1/50'th of 5D.
It's not intended as a VR toy, but as a VR/hypermedia 
replacement for X.  I'm trying to get together a demo that will
attract attention & funding.

Lance Norskog

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From: [email-masked] (Lance Norskog)
Date: Thu, 19 Mar 92 10:07:50 PST

Now, if you put one speaker above the ear and one below,
THAT would make it easier to do vertical effects.

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From: [email-masked] (Lance Norskog)
Date: Mon, 23 Mar 92 21:55:05 PST

The OFF stuff on decwrl comes with a read/write library.

Lance