I wrote this demo program while trying my hand at line and
circle generation.  It has a few more options than the earlier version.

Also, the iswind() problem is now solved for those of you who allow
logins from other than the console.

Line drawing is done using Bresenham's line algorithm.
Circles are drawn using a modification to Bresenham's circle algorithm
so that they appear round.  I use an aspect ratio of 3/2.
I had to generalize Bresenham's circle algorithm to generate the
ellipses.  Getting it right was very tricky.
To make it worse, I  tried to make it more efficient by performing
strength reduction on the code.  The result, is that the algorithm
is not easy to follow.  The meak of heart should not try to
modify it, (or even look at it).

The lines and circles are first drawn to an array in memory, and
then wrastop() is used to copy it to the screen.  It would be faster
to draw directly to the video memory, (but I have not made the 
hardware modification necessary to do so).  Perhaps it's time to get
that vidpal and mgr.

This code is placed in the public domain, with the hope it can be used
in real programs :-).

Thomas Tkacik
tkacik@kyzyl.mi.org

