Xpgs is the name given to this suite of programs.

Its main purpose is the generation of Single-Image Random Dots Stereograms,
commonly known as SIRDS, RDS or autostereograms.

There have a number of these dotty poster on sale in your high street
shops (or shopping malls). This is a freeware distribution that produces
such images and is written to run using X11R5 (or X11R4) graphics
on any computer with an ANSI C compiler and Xlib.

The main program (xpgs) reads in a 3D dataset which describes an object
and outputs an animation of the object rotating about an arbitrary axis.
A frame can be saved in a compressed format, as a XBitMap or as a
PostScript file ready to print.

The second program (vpgs) can view the saved output from the previous
program and it can also read the MindImage RLE format.

The finally program (3dtopolyh) is a utility to convert some data formats
to the required form taken by xpgs.


This suite of programs is an updated version of xps with various
improvements and changes:

* The new name xpgs is to avoid confusion with an ancient program
 called xps.

* Faster filling algorithm for z buffer.

* The aforementioned compressed save.

* A new viewer program (vpgs) to look at saved frames or RLE files

* An implementation of the algorithm given by Thimbleby, Inglis & Witten
 in their paper "Displaying 3D Images: Algorithms for SIRDS" (see also
 a recent issue of the New Scientist).
 An improvement is made on their routine with a proper hidden surface
 removal routine.

* A SHIMMER mode to aid newbies at viewing SIRDS.

* A utility (3dtopolyh) to convert various 3D formats.

This set of programs will be put onto alt.3d in a tar.gz.uu form,
alt.sources in a shar'd form and wuarchive.wustl.edu (128.252.135.4)
in /pub/xpgs.


  Any reactions, sugestions, hacks, contributions, constructive
  criticisms, donations of large amounts of money, etc. would 
  be most welcomed.
  Send your responses to

        Peter Chang - peterc@v2.ph.man.ac.uk
        Gareth Richards - gareth@h2.ph.man.ac.uk