			DTM DEMONSTRATION PROGRAMS

The following programs are all a part of a set of programs that illustrate the
use of the DTM library.  They have been written to give you an opportunity to 
examine the general use of DTM library as well as provide some typical
applications of the Scientific Data Set (SDS), the Surface Description
Language (SDL), and the View Control (VCTRL) message classes.  These programs
are provided for demo purposes only and are intended to demonstrate DTM.  They
are not meant to be particularly useful applications, nor are they going to be
extensively supported.

The programs are:

SIMPLE_READER and SIMPLE_WRITER:
		These VERY simple programs show the basics of sending and
		receiving messages.  Some useful hints on using DTM can be
		found in the source code.

GRAVITY:	A simple program that calculates a gravitational field of
		a point mass centered in a volume of space.  The field is
		written as an SDS via the supplied output port.

CIRCLE:		A program that will generate an SDL output that describes
		a circle made up of the specified number of line segments.

TRANSFORMS:	A program that generates view control matrix for an
		translation of (3,4,5) from the origin and a rotation of
		45 degrees about the x-axis.  The resulting matrix is thus:
				M = Rx(45) * T(3,4,5)

DEMOS:		A demonstration program that allows for reading and writing
		of data via DTM ports.  Use this program in conjuction with
		those just described and with other programs and utilities
		like READIT.

Typing the name of the program alone will display a usage message that
describes what command line arguments are necessary to successfully run
the program.  In general, these programs will not work unless all of the
ports required have been connected.


MAKING THE EXECUTABLE DEMOS:
To create the executable versions of these programs from their source code
originals, a makefile has been included.  To make the specific demo program,
simply type "make programname" or "make all".  Note: you must have the
environment variable DTM set to the directory that contains the include files 
and library archive for the files to make.


SAMPLE RUNS OF THESE PROGRAMS:
Here are some script uses of these programs:


# Simplest example available - this sends a text string from one processes
# to another.  The port number 7777 is arbitrary and since the host
# component of the address is missing the local host is assumed.  These
# processes can be started in any order.
simple_reader -DTMIN :7777 &
simple_writer -DTMOUT :7777 -msg "this is a test string" &

# This one will generate a circle made from 20 line segments and send the
# points and colors to the demo program running on the same machine via
# port 7777.
circle -DTMOUT :7777 -segments 20 &
demos -DTMIN :7777 &

# Transforms will send the view control matrix to the demo program where
# the values will be displayed on stderr.
transforms -DTMOUT :9876 &
demos -DTMIN :9876 &
