Sockets SHIFTING!?

I’m getting an intermittent shifting of either my sockets or the items attached to the sockets on my characters. In particular, this is noticeable in the weapons the character is holding. It feels as if the socketed item is lagging behind the animation by 0.5 - 1.5 frames.

A little background: My project is a port from UDK. I’m using the same assets and merely changing materials and textures to suit UE4’s rendering. All of my weapons, characters, 1p-arms…etc are all 100% solid in both 3DStudioMax and UDK. There is no disconnect what-so-ever between the weapon, the socket, the animation or anything at all. It’s all solid.

In UE4 I see the weapon shifting around in his hands. Again, same mesh, same skeleton, same socket and same animations.

Here’s the weird thing, this amount of shifting appears to grow worse over time as I use the editor and bring in new animations or make edits to blueprints and things. The honest truth is I simply cannot tell what is actually a “cause” for this to start happening because as soon as I close and reopen the editor, the shifting around seems to either completely go away or get so miniscule that I fail to notice…but this is happening and it always comes back.

I’ve made a video displaying what I’m seeing and showing all of the aspects of it that I have figured out at this point. It’s a tad bit long but even in the video I can’t find a cause and sometimes it does not appear to do it, then it appears really bad and then it’s gone again. I’m not going to upload the video unless you guys feel you would like to see it.

I cannot tell if the weapon is shifting away from the socket or if the socket is shifting away from the bone. It looks like the weapon is moving away from the socket, but it’s hard to confirm because of the way the socket’s position marker renders in relation to its bone.

All I know is that this isn’t my imagination, it totally sucks and is freaking me out something fierce. I spent several years worth of effort and learning over the course of this project developing this system of a very secure connection between the weapons and the character that’s holding them. Even a pixel shift is beyond unacceptable to me and is driving me up the wall.

My biggest fear right now is that you won’t be able to reproduce this and come back and tell me that there’s nothing wrong and no further investigation is necessary. If that’s the case, I will upload my video and my assets to you so you can see my method of setting things up but it’s simply an extra bone to control the weapons that the hands get linked to. All the weapon meshes have their roots aligned to that bone and are attached with sockets. Everything else to line it all up is done on the animation side.

You say you’re using a second “weapon bone”? Try adding a copy bone node in your AnimGraph to force it to track the hand bone. What could be happening is that some of the engine’s procedural anim control (blending, additives, partial physics simulation, IK, whatever) is causing the disconnect since UE itself isn’t being told “always synchronise these bones”. I use weapon bones and had that issue with my aim offsets.