Tracer can be run from any CLI or SHELL.  It must be passed certain
arguments to function properly:

   Tracer objectfile viewoptsfile screenmode

The object file and viewopts file are detailed below.  The screen mode is a
value between 1 and 4.  Each value corresponds to one of the following four
screen resolutions:

   1  =  320x200
   2  =  320x400
   3  =  640x200
   4  =  640x400

As the trace progresses, each pixel on the screen will turn white to
indicate that the pixel has been traced.  When the entire trace is finished,
the actual image's RGB data will be saved out as three individual files.
Each one will be appended with a separate extension, ".red", ".grn" or
".blu".  Programs such as The Art Department, or the public domain View can
be used to create a viewable picture from these RGB files.

The ViewOpts File

This file contains the necessary information to view an object.  The
contents of an example follows:

0 0 50
0 0 0
0.25
-50 50 50
1000 1000
-750
500

NOTE: These values have rather technical meanings.  Therefore, you want to
read through the article before trying to alter any viewing option files.

The first three numbers define a position in 3-D space for the camera.  The
next three numbers are the position of the point at which the camera is
looking.  The next value is a scaling value which controls what portion of
the screen to use for the trace.  A value of 1.0 would specify the entire
screen, while a value of 0.25 (as in the case above) would specify to use
only a quarter of the screen.

The following three values are the location of the light source.  The next
two values are the horizontal and vertical size of the view window.  This is
essentially the window through which you view your 3-D world.  The next
value is the position of the "ground" on the Y axis.  And the last value is
the position of the "center of projection" on the Z axis.  This value, in
conjunction with the horizontal and vertical sizes of the view window,
control zooming and field of view (refer to the article for more information
on this topic).

The GEO Object File

A sample GEO file follows:

3DG1
4
10 10 0
10 -10 0
-10 -10 0
-10 10 0
3 0 1 2 13
3 2 3 0 13

The first line of the file is used to indentify the file as a GEO object.
This line should be "3DG1" for Tracer to recognize it.  The next number is
the number of vertices contained in the object.  However many vertices there
are in the object defines how many of the following lines are vertex
positions in 3-D space.  In this example, there are four vertices, hence
the four lines following the "4" are vertex locations.  The remaining lines
in the file are polygon descriptions.  The first # of the polygon description
is the number of vertices contained in the polygon.  The remaining numbers,
except for the last, are vertex numbers which indicate which vertices in the
preceeding list are used for the polygon description.  The last number is a
color code:

0 = black
1 = blue
2 = green
3 = unused
4 = red
5 = unused
6 = brown
7 = grey
8 = black
9 = blue
10 = green
11 = unused
12 = red
13 = unused
14 = yellow
15 = white