How to Play Animation On specific Bone Which is break from skeletal mesh?

I can break bone by calling BreakConstraint + SimulatePhysical
But How can I play animation on the bone which is break from skeletal mesh…!!?

Hi Chen,

Apologies for the delay. I could have sworn that I replied here.

As far as I know, there isn’t a way to do that out of the box. That “limb” that you detach is still being controlled by the AnimBP for the character. The only way that I can think is to do a layered blend per bone in your AnimBP, but that hardly seems like a viable solution.

What is the end result that you’re looking for? Perhaps there is a better way to do it than “Break Constraint”

-Matt W.

Yes, you can try Physical Animation to apply keyframe animation onto a physical simulation regardless the constrains were broken or not. The PhysicalAnimation applies Physical Animation Data which was applied to the physical assets to give the strength how difficult/easy the physical simulation could affect the keyframe animation.

With PhysicalAnimation working the mesh/bones need to be always simulating physics that will prevent the mesh penetrating ground while playing keyframe animations

But things becomes complicated if you also want your character has proper looking crawl animation playing after falling down. I think the challenge becomes how to natually blend an arbitrary pose to a Crawling animation. You might need to rotate the Pelvis bone to a proper orientation first to better match the upcoming crawling animation. Also you might need to prevent the character penetrating into a bumppness ground while crawling, so PhysicalAnimation is also a good way to go

Here’s a simplest BP and Video example shows the pumping leg 3 seconds after the guy falling down.

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Thank for your reply~!
I try to use layered blend on limb and body.
But It look like so strange…!!

I need to predict the direction of the fall.
So I can play suitable for animation.
And I alse need to use IK avoid bones penetrating the ground

Hey Chen,

It may be better to go the route of creating multiple skeletal meshes of different body parts(what used to be called a “gore mesh”) and detaching them based on hit location. (There is a pretty good tutorial series on this)

Can you tell me exactly what you want to happen? I need to know the general idea before moving forward. I can only assume that you want to detach the leg and have them fall over. That is different than my initial thinking on this, so we need to get on the same page.

-Matt W.

I look forward to When I detach leg, character falls down naturally. Then character can crawl on the ground and leg is still pumping~!
I hope that it’s not too much demand ~XD

Thank for your reply and example. I try this BP to test. It success that pumping leg. But the body twists slightly. Something can I do to avoid body to twist?

I guess that’s because of bit “unstable” simulation between the rigid bodies? You might need to increase the simulation parameters, tweak the constrains to get more stable simulation or disable the bodies collisions in betweens where get undesired twisting.