Post vellum hair Problem —— hair clump makes the hair rotate abnormally?

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I have been using vellum to simulate hair. After I have simulated the hair, I found that the wrong hair appears on the correct guide line, and the hair rotates strangely.
So I started a test
First I create a sphere, and create a guide line from the sphere, after using guidegroom and guidedeform to create the necessary attributes and adding animation, then in a new geo, I use hairgen and hairclump to create hairs and tie the hairs together.
Then there is a problem with hairclump! Rotate the sphere, the hair will rotate abnormally.
Image Not Found

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It seems to be related to the tangent attribute of hairclump.
Changing the shape method from ‘extrude and blend’ to ‘linear blend’ can solve this problem, but I don’t want to do this because it will change the hair styling. Is there a better solution?
File is
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Edited by nausicaa - 2020年7月31日 08:48:34

Attachments:
CH($RU~$VZ67)N2@K_%})@G.jpg (34.7 KB)
sfsfasdfasf.mov (11.1 MB)
T4~FL`Z%}%V`KOFUQ@ZQ7]7.jpg (34.3 KB)
hair rotate.hip (522.5 KB)

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Yep, looks pretty broken.

Fortunately the old hairclump node seems more stable. (I see a little bit of wiggle, but not to the degree of twisting seen in hairclump::2.0)

Edit:
do you mind if I submit this as a bug, or did you already?
Edited by jsmack - 2020年7月31日 14:47:22

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hair rotate_downgrade.hip (861.0 KB)

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what about linear blend instead of extrude and blend Method ?

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hair rotate_linear.hiplc (522.0 KB)

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also in this tute:

https://www.sidefx.com/tutorials/controlling-clumps/ [www.sidefx.com]

at 6:30 he talks about blend method, might be of interest to you.
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Thank you for your help, I believe I have learned a lot from it.
I haven't submit this bug.
Edited by nausicaa - 2020年8月4日 21:47:07
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Unfortunately, although hairclump in the ball rotation test is better than hairclump::2.0.
But on very complex hairs, hairclump's hair rotation error is much more than hairclump::2.0.
Edited by nausicaa - 2020年8月4日 21:46:58
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Sounds like clumping isn't usable on animated grooms. Are you able to deform a static groom using animated guides/or the skin? I don't think I've ever used a live groom in practice, there's always some problem that requires going with a deformer route.
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There are so many bug with Houdini's hair that surprised me.Houdini 's extrude and blend Method is the default option, but static modeling can only be used.
Hey jsmack,I tried,but guidedeformer is too slow.
Edited by nausicaa - 2020年8月5日 05:43:34
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