[Gmsh] Something wrong with edge loop

[Peter Wainwright]

Hi,

I'm importing a STEP model, generated using a C++ program using
OpenCASCADE, consisting of triangular NURBS patches.  Of course, these
are really rectangular but each has one degenerate edge.

I got a lot of errors "Something wrong with edge loop".  It turns out
that GEdgeLoop::GEdgeLoop(const std::list<GEdge*> &cwire) will often
miss the degenerate edge.  For example, if the edge list contains AB,
BC, CA, CC in that order, then the edge loop will close as AB+BC+CA and
CC will be skipped.  We would fall through to the end of nextOne(),
which should never happen.

Thus nextOne() should check for a degenerate edge and process it before
moving on (in the same way that it already checks for seams). I've
attached a patch which does this.


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