I have been working on a character for a project of mine and have encountered a few issues.


I am using Blender version 2.90.1 and Unreal Engine version 4.25.4.

Model description:

Clothing: 3 shirt pieces (both arms and the collar), a waistcoat, trousers, shoes, and a tie.
Base: The head and hands (exported from MakeHuman).
It looks like this:
enter image description hereenter image description here

Animations I need imported:

Now he is animated, he has:

  • A Blinking Animation (a shape key named "blink" that changes from 0 to 1)
  • The Main Idle Animation (standard rig with IK) (Currently this is being exported and imported fine)
  • Basic Eye Movement (armature with "Track To" bone constraint). It should be noted that the eyes need to have the basic eye movement but also move with the main idle animation, so that if the head is moved the eyes follow with it while looking around.
    These all work as intended inside of Blender but apparently Unreal cannot import shape keys or bone constraints.

What I need to know:

  • Is there a way to package the shape key animation in an FBX file and import to Unreal Engine?
  • Is there a way to export the eye movement to an FBX file and import into UE4?
  • If I cannot use constraints for the eye movement, what is a simple way to achieve the desired effect without them?

Additional Info:

This is the armature that controls the eye movement:
The armature for controlling eye movement.
The bones "eye.R" and "eye.L" both have a Track To bone constraint. With these settings (Except for the bone being .R not .L):
enter image description here

As for the shape key animation, it starts the animation looking like this:
enter image description here
Then at frame 63 it is set to 1:
enter image description here
And then at frame 66 it is set back to 0.
In the graph editor I added a "Cycle" F-Curve modifier to make this blinking motion repeat, those settings look like this:
enter image description here
To quickly show how the animation looks in blender I'll link this video

  • $\begingroup$ The blinking is fixed now! I exported with "Apply Modifiers" unchecked and then reimported after the initial import, that fixed the issue! $\endgroup$ Nov 1, 2020 at 20:20
  • $\begingroup$ Unfortunatelly you can't export any constraint. You have to recreate it in UE4 with Animation Blueprint. $\endgroup$
    – FFeller
    Nov 1, 2020 at 20:24

1 Answer 1


The usual workflow to export animation with constraints is to perform the animation in Blender, then select all deforming bones and bake the animation (Pose mode, pose menu, animation, bake action), visual transform, delete constraints.

In this way you'll export an armature with no constraints that can be accepted by all others softwares.

Be sure to perform the bake on a copy of your file, because it's a destructive edit.

  • $\begingroup$ Good to know that, while you can't really export constraints sysems from a DCC to a game engine, you can build constraints in the game engine (sort of). I.E. if you need your character to be able to eye track things dynamically in-game, there are systems for that. But at the end of the day, whatever animation you make in your DCC needs to be baked into simple bone transforms and shapekeys before exporting. $\endgroup$
    – Lauloque
    Nov 29, 2021 at 15:20

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