Ragdoll physics don't work with mirrored skeletal mesh

Not sure if this is a bug or if it is not allowed to mirror a skeletal mesh. If I mirror a skeletal mesh and I activate ragdoll physics on it it goes crazy. This also happens when I mirror a parent component instead or the actor.

Is there an other way that allows me to mirror it? If I make a mirrored skeletal mesh in 3ds max do I have to create physic asset, etc. again for it?

Hi Davision,

Please explain what you mean when you say you mirror a skeletal mesh… Do you mean within the 3D graphics program where you mirror, for instance, the left side of your skeleton to/from the right side? Please answer this and provide detailed repro steps for mirroring a parent component.

Thanks,

.

In editor you can do right click on a skeletal mesh then you can select transform and then select mirror X which will just set the X scale to *-1, so like x 2 becomes x-2 scale. This is what I did. When using ragdoll physics on any skeletal mesh that has a scale with “-”, so a mirrored skeletal mesh the ragdoll physics will not work and just go crazy.

With your clarification, I was able to reproduce the way the physics affects the skeletal mesh when mirrored vs when it is not mirrored and have entered the following bug report: JIRA [UE-24002]. Should this issue be addressed in a future release of the engine, we will notify you and the Answerhub community with an update to this post.

Thanks for helping to improve Unreal 4!

This has not been fixed in UE 4.15 , are there any news on this ?

Here is a picture from the UE4 VR template, using the character hands. The hand on the right is mirrored with 1, -1, 1 and it clearly shows bones getting flipped on the physics asset.

This particular bug, UE-24002, has been marked as “Won’t Fix.” However, the feature request for Animation Mirroring, UEAP-41, is still listed as “TO DO” for a future release of the engine. At that time, this issue will likely be resolved in the course of implementing this feature. If not, we will reopen this ticket.

Thanks for the update!

So that means in the case of VR hands that should use physics you need import 2 versions (mirrored and not mirrored) then setup 2 physics assets, then make 2 animations blueprints. How does does animation mirroring help in this case?

I think it suxx that UD-24002 won’t be fixed. This is imo quite a bad move, since it will require you to have 2 animation blueprints and thus have to maintain the same code two places. One for each hand.