> If all we expect the back end to do is draw lines and text, then
> it seems to me that we have to do a lot of work in Octave to recreate
> the things that tools like gnuplot can already do (drawing axes,
> automatic placement of tic marcs, drawing different line styles,
> hidden line removal, etc.). That seems like a waste to me. So is
> there a general purpose graphics library that can help with this?
Yes, it's called OpenGL. I haven't done the 3d plot yet (as you might
imagine, OpenGL excels at 3D; hidden line removal can be done in a variety
of ways in OpenGL) but Workshop has line styles and everything in there. As
a matter of fact, Christophe's patch to GL2PS was to properly support
stipples for postscript output.
The screenshot
http://www.math.mcgill.ca/loisel/octave-workshop/screenshot-windows-0.10.png
showcases some of these basic features.
Sebastien Loisel