Stop physics bones from moving left/right up/down (local space)


I’m desperately trying to prevent physics driven bones from moving left/right up/down and only have them move forward/backward and rotate.

Imagine a piece of paper. Hold it “flat” in front of you in mid air. Let go of it. Now this is an exaggerated statement :slight_smile: but the paper CANNOT move up/down, it can move left/right and forward/backwards, to get down, it need to rotate a bit and start moving in the allowed axes.

Imagine the same for a, lets say, a snake. I’ll animate the head, and i want to tail to move with the head.

In physics editor I’ve set up the ragdoll.

In the character BP I turn physics sim on from tail1 and all below on begin event.

Now I would like to force the tail bones to not move on two of their 3 axes.


This one from the UE doc does not seem to exist in the normal blueprint space.

I’ve tried looping through all the bones affected, per frame, then get the velocity of the bones and convert them to local bone space, invert the local velocities on Y(LeftRight) and Z(UpDown) and apply them as force.
(which is hard without the above - and I want to avoid having sockets on all bones in the hierarchy)

Doesn’t really work.

Any idea why I can’t get a bone location without sockets? Seems weird.