Sucess! I got the voronoi tesseleation working to my satisfaction. Turned out that I'd caused myself a three day diversion by making the tolerance at which vertices were merged too large, but feels very good to have something that will run.
I ran randomised tests upto 2million cases without any trouble, but I've yet to test it heavily with regular shapes.
hmm... didnt get much done on friday but went on a binge sunday morning after the pub on the gui, the trick to this seams to be too much green and blacks dark chocolate (better than coffee for coding sprees). Apparently there's not any caffeine in chocolate, but something in there works just as well (tho others say 150g of chocolate is the same as a cup of coffee). The stange this is that although I dont rembember the first few hours it seems to work really well. You can now click on output geometry and it selects the component that created it in the other window. You can also ask it output a specific subset with fixed inputs but random changes each time, for example you can see a window from a house generated 10 times in a row. The last addition on sunday was being able to output the current tesselation to maya easily.
Debugging information rendered out in maya:
Tommorow I move onto the roads!
Update I couldn't resist checking the regular tesselation (eg square roads) and it failed when the points where in a random order (nasty crash somewhere) but was ok for a regular ordering, so i'm happy: