[Gmsh] creating ruled surfaces bounded by Bsplines and how to obtain intersections

[charles quarra]

Hi,

I'm just learning gmsh from the tutorial, and I have some questions
regarding gmsh geometry design,

I have two Bsplines with common start and end points that are not coplanar
to each other. A ruled surface cannot be created with a loop from these two
Bsplines because the loop needs to have at least 3 lines.

My initial idea was to define a third line by creating a third Bspline,
whose start point and end point where the middle points of the two original
Bsplines, thus producing 3 loops of 3 lines each, and I would be able to
create a ruled surface from those loops

But how could I create such third Bspline? I don't understand how the
"split" line functionality in gmsh works. (It doesn't seem to be mentioned
in the tutorial either), basically it seems to ask for a "split point" but
when I click somewhere on the line nothing happens. If I add a point that
intersects the line somewhere the selection of that point seems to work,
but then I click 'e' to finish selection and nothing happens; when I hover
on each side of the line both are labeled as the original line, so no split
seems to actually happen

I tried to find how to intersect the original Bsplines with a plane, but I
couldn't find that functionality anywhere

Any ideas?

thanks
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