Hi PaQ,

> No the flip/flip dont resolve the problem.

What about if you go and look at it from the other side, can you see it on the other side or is missing from both sides?

Missing from both sides most likely means triangulation failure due to some degenerate too-close-together points in the n-gon.


> I'm wondering if its maybe a side effect of the special
> exporter for creating this famous wireframe hack.

No, it shouldn't be related to that - that segment generator thing didn't change anything about how mesh vertices are created.

You've just got a case here where the points from the trimming edge ended up close to the points from the untrimmed underlying surface refinement but not quite close enough for them to be get merged into a single point. It's probably something I could tune up a bit, but it's a pretty delicate area because glomming points together too much can mess things up also.

- Michael