ik_hand_gun bone ignoring animation

[Xavier_B_Johnson]

I am begging you guys, I’m at my wits end. I’ve googled and searched the forums and no one else seems to be running into this problem:

I created this animation in Maya:

I use the ik_hand_gun bone to move the weapon. This allows the character to shift his grip on the weapon, which is necessary for this animation to work.

however, when I import the animation into unreal, the ik bones refuse to translate (they look like they are still rotating, but something is locking them in place!):

I haven’t done anything with a control rig or re targeting, this is just a simple animation test. But the CRAZY thing is THIS:

when I create a “new” skeleton based on the Mannequin skeletal mesh, the animation works as intended.

I cannot overstate: these are the SAME ANIMATION, re-imported for two identical skeletons that are EXACTLY THE SAME.

The only thing I can think is that Epic embedded some code somewhere that keeps the ik bones locked in place on the default mannequin skeleton, but why? and how do I disable it? There HAS to be a setting somewhere that I am missing. Why else would Unreal take two identical skeletons with identical animations and ignore key frames from one but not the other?

Can anyone tell me why this is?

A few caveats:

1. Yes, re importing the skeleton, and the skelmesh and all of the animations fixes the problem. But that’s not a sustainable solution, especially because I am a freelance animator, and I can’t tell my clients they have to completely re-import all their existing assets. I need to find whatever setting is causing ik_hand_gun to not translate and disable it.

2. Yes, I know it is more common to simply parent the weapon to the hand_r bone, but that would be impossible for this kind of animation, where the grip is shifting, because if you attach the weapon directly to the hand, you can’t adjust the grip on the weapon as I am trying to do. (this is also an issue with bolt-action rifles, where you need to work the bolt with your right hand)

Project Download Link: Dropbox - AxeTest.zip - Simplify your life

[FrankieV]

I use Motionbuilder so I’m going to take a guess based on observations made in that application.

In Motionbuilder all the IK joints need to be parented to their IK group followed by being parented to the root joint. once in place each of the corresponding IK handles needs to be “link” constrained to it’s mate. In other words the IK is driven by it’s mate but does not generate the key frames necessary to export the animation to Unreal so when imported the IK will have no animations applied to them.
In Motionbuilder to generate the keys is easy enough as the IK handles can be add to the character rig so when the animations are plotted from the control rig the key frames for the IK handles are also generated constrained or not.
As I recalled I also make use of 3ds Max so to included the IK when exporting I have to set the exporter to bake animations so that the constrained objects also generates keyframes as Unreal does not support constrained behaviour.

[Xavier_B_Johnson]

Yes, this is accurate, I know normally keyframes are not directly applied to the ik bones and they are instead constrained to their mates, but I made sure to deliberately bake out all IK down to the bones within Maya before exporting.

I know the keyframes are being exported properly because when I re-import the animation on a new skeleton it works perfectly, but the default skeleton doesn’t seem to recognize it.

[Xavier_B_Johnson]

I figured it out! I knew there had to be a setting for this!

There is a hidden setting in the skeleton editor under “Options” called “Show Retargeting Options”

enable it, then scroll down to you IK bones and set them to “Animation” (notice how the Pelvis is set to Animation as well? Looks like this is what let’s it translate around, we want the same thing for our ik nodes)

Now save your skeleton and presto! It works!

I was THIS close to giving up. Now I can animate my IK bones directly in maya, this will make retargeting 1000x easier, and will allow for much more natural feeling weapon animations.

[Leomerya12]

Bravo!