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Cloth Jumps at Start
#1
Hello!

When I hit play to simulate, the cloth jumps the moment it starts playing. It starts it out at an incorrect spot.

I followed the steps from the 'ObiCloth en capa' video.

What could I do to prevent the jumping?

Thank you!

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#2
(22-12-2022, 04:01 AM)brootas Wrote: Hello!

When I hit play to simulate, the cloth jumps the moment it starts playing. It starts it out at an incorrect spot.
What could I do to prevent the jumping?

Hi!

It's difficult to tell with no information regarding your character setup, but the video looks as if one or more of the transforms in your character's hierarchy have non-unit (slightly smaller than 1) scale. This will make the reference pose of your cloth shrink on startup, making the cloth "jump" inwards.

Re-export your character with proper scale. This video might help:
https://www.youtube.com/watch?v=5j7k_tJU...Kn&index=2

(22-12-2022, 04:01 AM)brootas Wrote: I followed the steps from the 'ObiCloth en capa' video.

Afaik, we don't have any video with that name. Could you link to the video you've followed?

kind regards,
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#3
Quote:Afaik, we don't have any video with that name. Could you link to the video you've followed?

Here's the tutorial I followed: https://youtu.be/9OihQv2NlHI?list=PLnCR8...HdzlzdwEr4


Quote:It's difficult to tell with no information regarding your character setup, but the video looks as if one or more of the transforms in your character's hierarchy have non-unit (slightly smaller than 1) scale. This will make the reference pose of your cloth shrink on startup, making the cloth "jump" inwards.

Re-export your character with proper scale. This video might help:
https://www.youtube.com/watch?v=5j7k_tJU...Kn&index=2

It's a rig I created in Maya with Advanced Skeleton. That's helpful to know what might be causing it so I know what to look for. Thanks!
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#4
(22-12-2022, 01:32 PM)brootas Wrote: Here's the tutorial I followed: https://youtu.be/9OihQv2NlHI?list=PLnCR8...HdzlzdwEr4

Hi,

This is not an official tutorial, just a video I recorded for a specific user. It's marked as hidden in Youtube and doesn't appear anywhere.


(22-12-2022, 01:32 PM)brootas Wrote: It's a rig I created in Maya with Advanced Skeleton. That's helpful to know what might be causing it so I know what to look for. Thanks!

In Unity, check the scale values of all transforms in your character's hierarchy: If any of them is other than 1 on all axis, that's the issue. Otherwise I'd have to take a closer look at your character setup to figure out what's wrong.

As to how to correctly export the character from Maya's Advanced Skeleton I can't help much as I'm not familiar with it, but you should find info online on how to export it.

kind regards,
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#5
Okay, so I found more information. I no longer think it's an Obi issue, but it affects my Obi cloth, and I'm not sure how to fix it.

When I export from Maya, the rig and animated file are exported from the same Maya file, and are in the exact same pose. As you can see, Unity has some sort of rest pose that's in a slightly different position, so that when I play, it bounces from that rest pose into the first pose of the animation, and causes a shockwave in the cloth.

I'm using Rokoko to do mocap retargeting, so the workflow I've found is using Humanoid in Unity, and I can use the clips from Rokoko or from Maya; the animation will work from either.

Personally, my main packages are Modo / ZBrush / Maya; not a lot of Unity.

If anyone has any ideas, I'd be grateful for the assist! Thanks!

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#6
(05-01-2023, 07:53 PM)brootas Wrote: Okay, so I found more information. I no longer think it's an Obi issue, but it affects my Obi cloth, and I'm not sure how to fix it.

When I export from Maya, the rig and animated file are exported from the same Maya file, and are in the exact same pose. As you can see, Unity has some sort of rest pose that's in a slightly different position, so that when I play, it bounces from that rest pose into the first pose of the animation, and causes a shockwave in the cloth.

Hi!

I'd guess that your bind pose and your animation's first frame are different, take a look at your root transform's pos/rot values in Unity when you enable the animation clip, check if those are identical to your bind pose.

One approach you could follow if you want to avoid cloth "shockwaves" even when there's sudden jumps in the animation is to use animation events to increase your solver's damping (or reduce your skin constraint's radius) temporarily at the start, then reset them when the animation has started.
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