Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site brl-tgr.ARPA
Path: utzoo!watmath!clyde!burl!mgnetp!ihnp4!zehntel!hplabs!hao!seismo!brl-tgr!gwyn
From: gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>)
Newsgroups: net.graphics
Subject: Re: Gray scale information sought
Message-ID: <4316@brl-tgr.ARPA>
Date: Wed, 29-Aug-84 11:42:28 EDT
Article-I.D.: brl-tgr.4316
Posted: Wed Aug 29 11:42:28 1984
Date-Received: Tue, 4-Sep-84 08:05:56 EDT
References: <1747@uw-june>
Organization: Ballistics Research Lab
Lines: 31

At BRL I have extended (upward compatibly!) UNIX plot(4) format
and associated utilities to add color and 3-D primitives.  Here
is how this was done:

Plot(4) format extensions:
	`C' followed by red, green, blue values, one byte each
	from 0..255.  Video displays use these directly as RGB;
	hardcopy uses complementary colors for obvious reasons.
	E.g. yellow on a color video display is encoded
		C <255> <255> <0>
	Initial color is assumed to be (0,0,0), and black-and-
	white device interpreters ignore all color commands.
	(Therefore it is not wise to generate a "background"
	colored draw in place of a move-to.)

	`L', `M', `N', `P', `S' are just like their lower-case
	equivalents but have Z values added after X and Y.  A
	two-dimensional display device interpreter ignores all
	Z coordinates, and a three-dimensional device interpreter
	will assume Z==0 when it reads two-dimensional primitives.

I can mail a manual page to interested parties; contact me at
gwyn@brl-vld.arpa or {decvax,esquire,research}!brl-bmd!gwyn.

We have a Megatek 7000-series device interpreter that allows
interactive viewing of colored 3-D displays; it needs further
work but is pretty nifty.

I would hope that anyone else extending UNIX plot would stick
to a compatible scheme rather than introducing yet another
variation.