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UE5 Root motion regression

I migrated a few assets to an empty UE5 project to play with motion warping and before I could even get that far, I noticed that the root motion of the animation is broken in UE5. Here is a couple before and after gifs of the same animation

Preview in UE4

Exact same animation in UE5

Just to rule out like a versioning issue with the uasset, I even tried reimporting from the original fbx source file, and the issue remains. This seems like a pretty significant root motion regression, but I’m assuming it’s not busted across the board, as I think the UE5 valley demo uses root motion. Anyone have an idea what’s going on here?

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I’m not sure if I’d call it a regression but I’m having odd behaviour as well. I had a bunch of animations that were authored with the sk_mannequin and so were not facing the correct default direction on the pawn. So I manually rotated the root and retargeted these animations to the new skeleton and edited the root motion so it goes in the correct direction. This works fine in UE4 but in UE5 all the animations are facing the correct direction but the root motion for some reason applies in the original (wrong) direction.

I dunno if I’m explaining this right but it is annoying anyway.

I think it’s to do with this change. Diff from 4.26

Building from source to see

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Looks to me like the motion is still there, but on the wrong axis of movement.

To confirm you can highlight the root bone, slide the animation to the same frame on both engines, and look at the bone’s acrual distance.

And if that’s correct, the post above could be the issue since it deals with rotation (can’t read the image on mobile. They still haven’t patched the forum… )

Let us know what you find. If you’d like, we’d also be happy to take a look if you can share your animation asset.

-Laurent

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@LDelayen I am having trouble getting the engine compiled off the UE5 EA branch, but I had filed a bug yesterday and linked to a sample project with the asset in question. Would be greatly appreciated if you took a look. I know of a number of people running into this issue in the various places I’ve asked about it. I suspect it has to do with a rotation on the root bone that our character has as well. I’ve been trying to get our animators to get rid of it but they tell me they aren’t quite sure how yet.

@LDelayen I’ve confirmed that the change pictured above is responsible for the change in root motion behavior. Here is a video of each code path in use. It first shows the fixed code path(taken from 4.26, and then a static switch to use the new UE5 code which exhibits the issue)

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Thank you @JSwigart , we’re looking into it and should have a fix available shortly!

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Thanks to change it ! I had the same issue

A fix for this has been submitted. If you’re building from source, this should be fixed by updating to latest on GitHub. Otherwise, it will be available in the next official release. Thank you @JSwigart for reporting.

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Excellent. Thanks!

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