[Gmsh] The Control of OCC BSpline points on the intersection edge

[Christophe Geuzaine]

> On 10 Mar 2020, at 17:55, Jun Fang <hapfang at gmail.com> wrote:
> 
> Dear GMSH users,
> 
> By applying the BooleanIntersection between a volume and a curved surface, I can get a decent BSpline intersection curve loop on the surface. The problem I am facing is that the  BooleanIntersection by default gives me an “extra” point on the intersection edge, which I don’t want (for good reasons). 

Can you elaborate?

> A screenshot is posted below. The ‘Cylinder 23(OCC)’ is the outcome of Boolean intersection. What I need are the four points (22, 23, 24, 25) and four associated BSpline curves on the Surface. Somehow, I couldn’t get rid of the extra point (26), which is located at the z max position of Surface 23(OCC). My guess is that the additional point is kinda of a reference point created by the  BooleanIntersection function.
> 
> Is it possible to workaround this issue? I know Compound BSpline could potentially merge curves (i.e. connecting BSplines 27 and 28 here into one), but it only works for the built-in CAD kernel. Is there an equivalent function for OCC kernel? Any comments/suggestions are appreciated.
> 

If you don't want the point in the 1D mesh, can't you just use the "Compound Curve" meshing constraint?

Christophe


> <image.png>
> 
> Thanks very much,
> 
> Jun
> 
> -- 
> Jun Fang, Ph.D. - Argonne National Laboratory - (630)252-4561
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine