
*****************************************
*					*
*	Hi System Software, 1995	*
*	   Spira, Version 1.0		*
*					*
*****************************************

To view this file under Windows, maximize
the window for convenience.

General description
-------------------

This program uses a parameter file to draw flying ellypses on the
screen in EGA/VGA graphic modes.  A slight variation of parameters
may result in a very different picture, and the users may adjust
the parameters to get a show satisfying their aesthetic demands.
The resulting patterns may influence the mental processes of the
observer, being either sedative, or mobilizing, or irritating, or
pleasing.  Since image generation stops when a key is pressed on
the keyboard or a mouse action is detected, it may be used as a
screen saver under DOS or Windows.

The program was written to work on any IBM compatible personal
computer under MS DOS.  By default, it uses the 640x480 VGA graphic
mode with 16 colors; to choose the 640x350 EGA screen, put the -e
switch in the command line starting the program.


Installation and usage
----------------------

The distribution package contains the following files:

	SPIRA.EXE	the program
	SPIRA.TXT	this document
	*.SPI		sample parameter files

To install, copy the file SPIRA.EXE into any directory you like
(those indicated in the PATH environment variable in your
AUTOEXEC.BAT file are preferable).  It would be convenient to place
the sample parameter files in a special directory (folder) where you
may put your own parameter files in the future.

To run the program, use the following DOS command line:

[drive:][path]SPIRA [-e] [drive:][path]filename[.ext]

You don't need to indicate the drive and path for the program
if they are contained in the PATH variable.  The drive and path of
the parameter file may be omitted if you start the program in the
directory containing the parameter file.  The default extension is
.SPI, but you may use any other extension as well, in which case
it must be indicated in the command line.

If Spira is run without parameters, or the command line contains
an error, a brief information screen is displayed.

In some shell programs (like Norton Commander) and under Windows
and Windows'95, you can associate the extension .SPI with SPIRA.EXE,
so that the program will be run with a parameter file when you point
at it and press [Enter], or double-click it with the mouse.

Since Spira is a DOS program, it cannot be indicated as a Windows
screen saver using the Control Panel.  However, there is a possibility
to make Spira a screen saver under Windows 3.1x manually editing the
files SYSTEM.INI (section [boot]) and WIN.INI (section [windows]) in
the Windows directory.  The following lines should be added/replaced:

WIN.INI

[windows]
ScreenSaveActive=1
ScreenSaveTimeOut=120	; secs before running screensaver

SYSTEM.INI

[boot]
scrnsave.exe=drive:\path\spira.exe [-e] drive:\path\file[.ext]

You will need to restart Windows for the parameters take effect.

Note, that you must indicate the full path for both SPIRA.EXE and
the parameter file in this case.

This procedure does not work under Windows'95.  However, you can first
install any Windows screen saver and then change the scrnsave.exe= line
in the [boot] section of the file SYSTEM.INI to

scrnsave.exe=drive:\path\spira.exe [-e] drive:\path\file[.ext]

This will start Spira instead of the previously installed Windows screen
saver.  Windows'95 does not need to restart to accept the new settings.
This methods will also work under Windows 3.1x.

A more simple way is associate Spira with a key combination, and
start it manually whenever you have to pause your work with the
computer.


Parameters
----------

The basic figure drawn by Spira on the screen is the ellypse
with the axes A and B (in pixels) with the center moving from
the point (FX,FY) in the foreplane to the point of perspective
with the screen coordinates (PX,PY), or back, and rotating as
a whole.

Every line of the parameter file contains a pair key=value;
the lines that cannot be interpreted are treated as comments,
as well as any text after the recognized key=value pair.

Key	Value		Def	Meaning
---	-----		---	-------

A	real		200	first radius of an ellypse
B	real		50	second radius of an ellypse
NW	real		1024	time points to draw an ellypse
NN	real		100	time points to rotate the ellypse
NV	int<62000	8192	lifetime of an ellypse
V	real		5	speed of incoming/outgoing movement
D	0, 1		1	movement direction: 0 outgoing, 1 incoming
M	0, 1		1	switching off style: 0 abrupt, 1 fading
BS	int<32000	3000	ellypse points visible together
DT	int		0	delay cycles between successive time points
N	int<=50		1	maximum number of ellypses
P	int<32000	0	inverse probability of a new ellypse appearing
C	int 1-15, A, R	15	drawing color; A sets different colors for
				different ellypses; R sets random colors
				for each drawing point
PX,PY	int, R, C	R	the coordinates of point of perspective;
				R means random within the screen;
				C means centered
FX,FY	int, R, C	R	the coordinates of an ellypse's center
				in the foreplane; R means random within the
				screen; C means centered

Parameters are case-insensitive.  The values that haven't been specified
are assigned by default.

You may experiment with the parameters as you like and save the files with
the parameters producing the most interesting patterns on the screen.
Please note:  a very slight change in the parameters may result in a
quite different screen pattern.


Support
-------

Spira is FREEWARE.  You may distribute is as you like, but
you may not solve it or prevent others from using it.

Any comments and questions direct to Paul Jones:

pjones@fly.triniti.troitsk.ru

The most interesting combinations of parameters may be sent in
too, for including into the distribution package.  If you wish,
you may include information about yourself in the parameter files
(as comments).

The new versions to appear are to be distributed through
HiLight:

http://www.geocities.com/CapeCanaveral/9321/hilight.htm

Thank you for using Spira.  Enjoy it, and be creative!
