Tween Curve to match to part of a curve between two curves how is it done?

I have three curves of similar shape the middle one has a gap so tween curve springs to mind but how does one get the ‘tween’ to coincide with that partial curve ?

refine cowling for smash.3dm (311.5 KB)

Why would you use TweenCurves in that situation?
BlendCrv seems a much more likely command.

BTW - The existing curves are really messy and have way, way too many control points to make decent surfaces.

I have used FitCrv to refine them (see other post) and thought it right and proper to take the revised curve before and after the gappy one to create a better transition curve in keeping with the two either side, as FitCrv does change slightly the curvature, so Tween is bound to flow better when it comes to skinning.

There are also times anyway when I want a tween to be at an exact spot.
refine cowling for smash.3dm (707.8 KB)
attached the refined curves using rebuild for the verticals (except one at ‘A’)


But that’s not how the command works.
The Help file article describes the methods used.
Start TweenCurves and tap F1

if I want a curve tweening between two and going through an exact spot what do I use ?
I see sample points in the help, no video which would help greatly in understanding what that para is saying. If thats the way then I need to youtube it I suppose.



I’m not aware of a command that will do that.

To get close, I’d use a BlendCrv and Join to close the gap, then maybe a Lofted surface between that polycurve and the complete curves on either side.
Then maybe extract another isocurve from that surface that coincides with one end of the gap you filled.

No matter what you do, it will be an approximation and you’ll need to be satisfied it’s close enough.

It could be programmed to do it, or so I would think. Tween through point option in its options.
Any clever souls wish to have a go ?

To be honest Tween through point is something that WOULD be needed from time to time.

Another way is create many tweens, and choose nearest, or nearest pair and tween those and so on until one finds one within tolerance, but thats theoretically a bit 2nd grade !

As the gap curve no longer bears an exact relationship to those either side, I think Tween is technically the correct way of ensuring the three flow nicely for when the surfacing is done.


Sorry for the late answer… Create a Loft surface between the two curves in question, then ExtractIsocurve in the U direction at the point where you need the TweenCurve. That’s basically what TweenCurves does in the background anyway.

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Thanks for the workaround, must try and remember that when staring at Tween curve options. if someone could add an option though it would be good.

Meanwhile I have added that to my word doc of useful commands I can search on key words and find it.