why the skin twisted??

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it is a very simple vellum system, only one hair constraints, one solver.

When opening the subdivision of the vellum post processor, some part of the rope's skin twisted.
Both subdivision method comes the same result.

If using a subdivision node downstream, it appears normal.

How to get a "right" skin in vellum post processor?
Thank you very much.
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Edited by hign - April 23, 2024 09:10:29

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Sounds like the subdivision is using the catmull clark algorithm on the quaterion orientation attribute naively. This attribute defines the twist on the curves when skinning. If you just want noodles, you can probably remove the orientation attribute created by the simulation. Otherwise, the only fix is to not subdivide the orient as a quaternion. If you decompose the orient to a normal and up vector, the subdivision will still be mostly valid and won't result in flips. I would file a bug too.
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tanks for your reply.

i checked @orient, at the twisted point, it seems ok,
but when post processed, it goes wrong.

if delete @orient, twist problem happens.

hope for the bug be fixed.

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