Intro
-----
These are macros for vi which produce text stereograms.  I wrote them a
couple of years ago (while bored), and didn't comment them at all.
Consequently, I can't remember how they work, so don't even ask!

They have been tested with `vim' and `elvis' and seem to work okay...  i
don't know about other version of the editor.

Quick start
-----------
type the following:
   vi sample
   :so .exrc
   g   (then wait....)   z

Usage
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There's a sample file called `sample' - the macros are rather fussy about how
this source file is arranged.

The pattern to turn into a stereogram is held in the first 25 lines, made up
of asterisks and spaces.  It is not necessary for all lines to be 80
characters wide - indeed, it is permitted to have blank lines here.

Line 26 contains a row of `=' signs - this should not be changed (I can't
remember why)

Lines 28 to 53 contain random characters - this is where the stereogram is
generated.  these lines, too, shouldn't be altered.

press `g' to start the macro.  when it stops, press `z' to clean away
left-over garbage.

(the result of using these macros on `sample' is shown in the file `result' -
i don't recommend trying to view it in a small font (such as in an x-window))

Little things to note
---------------------
 o  it seems that `|' has a special function in macros - to use the standard
    vi `|' command it needs to be escaped with `^V|'
 o  the recursive part of the code has a trailing `0', so vi doesn't barf at
    the idea of recursion

Future - i might need some encouragement with these!
------
 o  would be nice to not have to do the clean-up command seperately (`z'),
    but i don't know how to make the recursive macro terminate cleanly - so
    the whole thing stops with a `not found' error.
 o  i've started work on multiple-layer stereograms, as this version will
    only make pictures with two layers (boo!)
 o  i wrote it through a vt220 terminal, so it's pretty much geared to a
    80x25 display - this might change in the future


    Comments and suggestions are welcome!
    cheers - matthew flint, 27th July 1997  (matthew@philtrum.demon.co.uk)