Ok, I think I've got the silhouette extraction working. This is for the Isodraw-ish type stuff, anyone interested in that might want to look at the PDF attached below to see if that's doing the right thing.

I thought I'd better make these as another layer of edges that sit on top of the regular ones, rather than trying to make edges kind of alternate between thick and thin on the fly. With them layered on top it will probably be easier to do touchups by erasing the thick ones and then still having the regular ones underneath.

In Adobe Reader you can use the Layers left-side pane to turn on/off different sections, this one has the background bitmap, regular lines, then silhouette lines.

It looks like this:





- Michael