I've created a track with skeletal animation. I have a bone, that has Spline IK constraint, which target is bezier curve. This bezier curve has curve modifier, which target is also bezier. All I need is export animation of this track working into fbx for UE4, but after inserting keyframes, nothing happens. I also notices, that locaton and translation of bones changes only visualy after I move the Spline IK's bezier curve. I' ve tried many of variations, but nothing helps. enter image description here

And this is what I have in UE. enter image description here
It has a gap and it is something like skewed. It is the best I have achieve

  • 1
    So there is no problem with Spline IK animation in Blender but you have problems to export it into .fbx, correct? – Jaroslav Jerryno Novotny Aug 21 '15 at 13:14
  • Yes, animation is great, but when I export to fbx there are big lags or nothing at all – A. Akzhigitov Aug 21 '15 at 13:23
  • Did you apply Loc-Rot-Scale? – Samoth Apr 17 '16 at 19:44
up vote 1 down vote accepted

If the track is made from pieces parented to bones:

  • Select all track pieces
  • Object > Animation > Bake Action
  • Check all the boxes and hit OK
  • Now the animation is baked and should export without problems.

If the track is single piece deformed by Armature modifier:

  • You will have to bake the animation of bones (same as above but bake to Pose)
  • Or convert it into Shapekey animation with this script. This will also export fine.
  • This is what I've got after baking imgur.com/fMbWPSI. Whithout baking everything is fine, but not for import. – A. Akzhigitov Aug 21 '15 at 14:28
  • Maybe I ve done something wrong? – A. Akzhigitov Aug 21 '15 at 14:29

This is a scaling artifact that happens when Y-stretch is enabled. The bones scale get applied additively down the chain, because the bones are parented to each other, resulting in an odd shape.

What you need to do is: Copy the SplineIK bone chain, delete the SplineIK constraint in this new chain and unparent all the bones from each other. Than add copy transform constraints to every bone in the chain, targeting the matching bone in the SplineIKchain. Make this new chain deform the mesh and disable deform for all the bones in the original splineIK bone chain.

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