Connecting surface control points?

Hello all,

I’ve been wondering about this potential capability for years, and I am wondering if anyone has any pointers. In yacht design we are often working on surfaces that have continuity in some areas, and no continuity in others (kinks that turn into smooth surfaces). Historically a work-around has been to collapse points so they are almost coincidental, however the surfaces near these points is quite horrible. An alternative approach would be to create two surface whose order in the edge direction is the same, and make sure that the control points are identical. This would make sure there is no gap between the surfaces, and would allow for continuity where needed, and not in other places. Anyone have any idea how to “connect” two surfaces in this way? A plugin anyone?


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if you try ORCA, you can place a chine along a surface isocurve…but that does not fully satisfy most needs as a chine should be able to be placed precisely where the architect wants it to be. This issue is not yet resolved as far as I know in Rhino. Another method is to introduce one or two more isocurves in the area where you want the chine, then bunch their control points together where you wish the chine to exist. letting the control points remain where they fall beyond the needed chine area and the surface will show a chine that fades out as it progresses (usually) forward. I have used this method in the past but don’t like it as it introduces far greater opportunity for unfairness that is difficult to work out. I have reached out to this community and to McNeil with the basic question of placing chines where we want them and not necessarily along isocurves but have not heard a reply. Hang in there, these guys are good and our collective question will find an answer. Cheers, Rob

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You don’t need orca3d for chines, just use the InsertKink command. Another command that can be used to connect surfaces, with varying levels of continuity is MatchSrf.


The math of NURBS surfaces (which Rhino uses) preclude tangency discontinuities except along an isocurve.