Hi,
here is the first pay-off of my 3D box refactoring after last GSoC. I'm proud to introduce Inkscape's first diffident steps into the 3rd dimension: Perspective paths. :)
The new feature is implemented as a Live Path Effect, and contrary to what I had expected it's actually quite usable. ;-) Here is a screenshot of what it looks like with some text added to the two sides of a 3D box:
http://www.rzuser.uni-heidelberg.de/~malbert/images/teaser_3D_LPE.png
Note that the original path is still editable (also note Johan's great new feature of highlighing paths!). The effect can take as input any path but if you want to give it a try then it's probably best to use it with text first (converted to paths, of course) because this makes it easier to interpret the visual result.
Please keep in mind that it's only meant as a proof-of-concept. The UI needs to be refined, functionality to be added, and above all the perspective is not yet interactively adaptable (mainly because LPEs can't take arbitrary SPObjects as parameters); at present the effect just grabs the first existing perspective from the document. So a workaround would be to draw a 3D box, modify its perspective and reapply the LPE to the path. It should then use the updated perspective (provided that it's the first one occurring in the document defs).
Have fun using this. :)
Cheers, Max
P.S.: Apart from my GSoC application (which still needs to be submitted) this is likely to be the last thing you'll hear from me for the next six weeks or so. I need to drastically reduce the time invested for coding and mailing list interaction (as much fun as it is), otherwise I risk my remaining exams to badly go down the drain, which I really don't want to happen.