Physics blend jitter when scaling up bones

Development Character & Animation
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1

I blend physics into the animation of our characters when they are hit, however when I scale up character bones in the animation blueprint, they jitter when the blend weight is inbetween 0 and 1.

Scaled bone jitter video:


I don’t really know what I am doing wrong, I have played with the collision settings of the physics asset but with no success. It also seems that if I scale up the head of the character instead of the torso the head doesn’t spaz out which is weird.

Would really appreciate any help on this, since physics blending looks awesome on hit, but so does scaling up the bones as our characters get stronger. It would be a shame to have to do one or the other.

Blend blueprint

93718-blueprint.png
93718-blueprint.png946×326 56.4 KB

Blend timeline

93719-timeline.png
93719-timeline.png1141×384 28.2 KB

Bone scaling

93720-anim+blueprint.png

2

Hi miracle7,

I’m looking into your issue and I am seeing similar results. I just want to get some additional info.

Could you enable the ShowCollision console command during PIE and post a closeup screenshot of the meshes arm collision?

Also, please post the Details panel setup for both of the Transform(Modify)Bone nodes in the Anim BP.

3

Thank you for the prompt response :slight_smile:

Here is a video of before and after bone scaling with wireframe and collision enabled: - YouTube

I also recorded a video of the transition in slow motion with wireframe and collision shown after bone scaling so you can see what is going on inside: - YouTube

Here is a close up screenshot of the arm as is, and with collision/wireframe enabled. It appears that it is twisted:

94066-twisted+arm.png
94066-twisted+arm.png863×370 353 KB

94067-arm+wireframe+collision.png
94067-arm+wireframe+collision.png793×390 127 KB

As for anim BP nodes, they are both like this:

94069-animbpnode1.png
94069-animbpnode1.png713×499 14.5 KB

94070-animbpnode2.png
94070-animbpnode2.png715×497 14.5 KB

4

Hi miracle7,

Sorry for the delay. I wanted to make sure that you were seeing exactly the same thing I was with the Physics Bodies. If you notice, they aren’t being scaled with the bones. This could be the cause of the issue. So I’ve created JIRA UE-32025 and our developers will be investigating further.

We will post back here with updates as we have them.

Cheers,

TJ

5

Thanks TJ.

Wondering if there is any progress on this or a place where I can view the status of 32025 myself?

6

Hi miracle7,

This is still being investigated.

That JIRA number is currently used for tracking purposes only. We are working on a way to make some bugs publicly track-able but that is some time off. We will announce when it launches.

7

If this bug could be fixed sooner, my company could proceed forward with our work. Any way to expedite / elevate this issue? (I’ve already voted for the issue on JIRA)

8

Hi janimationd,

Finding other users that are interested in this fix (maybe on the forums) and having them also vote would be the best way. I have also made a comment on the internal JIRA to let the devs know this is a blocker for your project.

I know you found this on the public bug tracker but for ease of access here is a direct link: JIRA UE-32025