Hi Martin,

> This certainly looks very good but I have a hard time understanding the rule that
> requires to continue the thick horizontal line into the object. It's an aesthetical choice isn't it?
> It looks good and helps even more to understand the shape but it seems to be impossible
> to put into an algorithm.




If I understand correctly, it's a rule about all sihouettes being accented, regardless of whether they are inside the "outer outline" of the object or not.

It should not be hard to put this one into an algorithm, because the same geometric silhouette condition does hold through that entire edge - it's a silhouette edge because of the 2 surfaces that the edge belongs to, one surface normal points towards the viewer, while the other surface normal points away from the viewer.

It has to do with looking at surface normals, not at what's going on in the 2D screen space image...

- Michael