[Edu-sig] Vpython 4.0

[Arthur]

Making a long story as short as I can:

Taking on the project of getting vpython to numpy compatibility (think I 
got there) brought me for the first time to a serious look at vpython 
4.0 beta, which I had been avoiding, knowing it was buggy.

Bugs, aside - turns out it is a major step forward, implementing 
transparency, texturing, advanced lighting, among other cool features - 
including some undocumented features that are intended to make vpython 
accessible to other GUI toolkits (from what I gather).

Anybody interested might run the texture_and_lighting.py demo to get a 
feel for some of the new capabilities.  Very cool.

The only deal killing bug seems to be the one related to 
mouse.getclick() crashes, on Windows.

So I thought I'd have a look, getting quickly way over my C++ head, 
finding that a mouse click event  involved code that included shared 
pointers, signals and slots, threads,and the direct manipulation of the 
Python GIL. Way over my C++ head.

I tried to follow the code and on a gander decided to see what would 
happen if  I cut out the direct Python gil manipulation, having some 
clue/instinct that there was some conflict between that and what the 
boost::shared_ptr library was doing in managing object life cycles.

And with that one change (simple changing a call from "py_pop" to "pop" 
to short-circuit going into the gil code), the demo that was 
consistently crashing, the diople.py demo,  now seems stable

Which of course seems too good to be true, because presumably Jonathan 
Brandmeyer, the CS student author of this, had some specific reasons to 
be messing with the Python gil, and I don't know what I may be breaking, 
on what platforms, by my fix, if it is in fact a fix at all.

Or else I'm a genius, or lucky, or something.

Anybody willing to jump in here, to any extent, to have a look see?

Art