Editing RSF School and Workshop, Vancouver 2006 (section)

=== Joe Dellinger: Vplot graphics language - past, present, and future ===

Vplot is the graphical language used by the Stanford Exploration Project's "SEPlib" seismic processing system. Application programs such as "Graph", "Wiggle", and "Grey" write out specifications for plots in "vplot format". The appropriate vplot "pen" filter then reads in the vplot file and
produces the desired plot on the corresponding graphical device.

Vplot was originally created to allow consistent plotting on any of a dozen or so different graphical devices, each of which could only be accessed
using its own unique and proprietary programming interface. With so many devices (and now ones arriving every few months!), writing a separate version
of each plotting program for each device would have been completely impractical. Today, however, that is exactly what we do: most graphical programs directly support "X", "postscript", and/or "bitmaps".

Vplot is still in use today at least partly because the challenge of supporting so many different incompatible devices imposed a discipline that
produced a flexible and powerful internal programming logic. Even with the universe of plotting devices now collapsed down to only 3, vplot has been
useful enough in making those 3 compatible to survive.

In my talk I will explain the "vplot virtual device" and show how it was meant to be used. I will show what I think are the "good ideas" vplot
contains that even today have not been replicated in other systems. Foremost among these is the "4th canonical graphical device", the "capture the changes I've made and turn that back into a new figure" device ("vppen"). I will also show useful features in vplot that should still be used, but have been forgotten.

Finally, I will discuss "where should we go from here". If we wish to use vplot with Madagascar, now is our chance to update it!