TRACER BOUNDS MODULE
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	Author: Lars M Bishop, National Center 
                for Computational  Electronics
		University of Illinois at Urbana-Champaign
	Date: 18 January 1993

	bishop@viz1.ceg.uiuc.edu
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Tracer Bounds:
-------------
	 Tracer Volume Bounds - This module takes in a 3D Uniform 4 vector
Byte field, and adds a white frame to the edges.  It is designed to be applied
to a volume of data right before it is sent to the tracer module, and
allows the addition of lines that look like the geometry viewer's volume 
bounds, which are normally inaccessible to volume-traced data.
	It also includes the ability to fill in the min X,Y, or Z walls,
as the original volume bounds module does.

The Inputs:
----------

Input Field: Field 3D Uniform 4-Vector Byte - A colorized volume of data
	that is ready to be sent to the tracer, to which volume bounds
	are to be added.

The Outputs:
-----------

Output Field: As above, with volume bounds added.

The Parameters:
--------------

Thickness : Adjusts the thickness (in elements) of the frame
	that is added to the data.
Opacity Scale : This is an important port - The tracer opacity
	adjustment should not be adjusted when using this module,
	as it will not only affect the opacity of the data, but
	also that of the frame.  This adjustment adjusts the
	opacity of the data only, leaving the frame totally
	opaque.
Min X : Adds an opaque wall along the plane of minimum x.
Min Y : Adds an opaque wall along the plane of minimum y.
Min Z : Adds an opaque wall along the plane of minimum z.

Example Network:
---------------

  Generate Colormap        Read Field
          |                    |
          |                    |
          -----------   --------
                    |   |
                  Colorizer
                      |
                      |
                Tracer Bounds
                      |
                      |
                    Tracer
                      |  
                      |
               Display Tracker


Known Problems/Bugs/Limitations:
-------------------------------

Only works with Uniform Data, not with Rectilinear

Rather Slow.

The Min X/Y/Z walls should be gridded, not solid.