Spline IK bake and export problem

Hi there!

I’m having some trouble with SplineIK. I made a rope with bones, animated on a curve. I used spline IK and at the end I baked it before exporting. Everything works well in Blender before exporting, but after I export it (DAE, FBX, whatever) the result is completely different as it should be.

I attached the blend file. It includes the animated rope with bones and the exported/imported result as well.

Could someone help me solve this?

Thank you

G

Attachments

rope.blend (5.43 MB)

I’m running into the same problem as well and came across your various posts on it. curious if there’d been any further developments.

as a small contribution, it specifically occurs if you want the bone chain to stretch to the spline. if the bones don’t stretch, the animation bakes/exports fine.

UPDATE: in case it helps anyone, I came up with a bit of a hack work around.

what appears to be happening during baking/export is that the bone Y stretching is getting applied additively down the spline ik chain.

if you’re just wanting to bake inside blender, you can get around this pretty easily by turning off inherit scale on each of the spline ik bones.

however if you’re like me and want to export an fbx, its a little more involved. fbx does not respect the inherit scale bone property. what I did to get around this was make a duplicate of my bone chain, and completely blow away the parenting relationships within the chain. then I added copy transform constraints on each bone in the duplicate unparented chain to its corresponding bone in the spline ik chain. this results in a set of bones that behave exactly like the spline ik chain but don’t have any of the scale inheritance issues. skin your geo to these bones and you’re good to go.

3 Likes