The fabrik node is causing the engine to crash after some weird behavior on the ik result. I recorded the situation:
You can see on the first part on the video, the solver is not being applied, but when I select the preview instance in the anim bp editor, it then gets applied correctly. then when I exit the game, the whole engine crashes with the following error:
It says bone index contains nan, but the fabrik node doesn’t work by manually entering bone names by hand, and this is the default manny skeleton, so I don’t think it is my mistake. I tried turning multithreaded animations off in the project settings, but that had no effect.
I’m starting to think that this might be a bug in the fabrik node, but am I missing anything?
Did you ever solve this? I have a similar problem Assertion failed: !Pose[BoneIndex].ContainsNaN() [File:D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Public\BonePose.h] [Line: 571]
I solved, I exported fbx from UE, then imported to Blender to delete the affected bones that were showing NaN. Then reimport to ue and the error was gone.
If you’re using Effector Transform in Bone Space in FABRIK, here’s the issue and how to fix it:
The problem is that FABRIK records zero coordinates for the Effector Transform when it’s in Bone Space.
To fix this, after assigning the bone in the editor, manually store the location of that bone in a variable. Then, feed that variable into the Effector Transform input of FABRIK.
This ensures FABRIK receives valid local-space coordinates and starts working correctly from the first frame.
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