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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.

In the video you can see the difference between the correct animation (selected in pose mode) and the baked/exported/imported one.

https://www.youtube.com/watch?v=VIEfzo7iqjo

Could someone help me solve this?

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This is a scaling artifact that happens when Y-stretch is enabled. The bone scales 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, disable deform for all the bones in the original splineIK bone chain and enable only deform bones in export.

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  • $\begingroup$ Going to play with this, but quick question: does the bone's "Inherit Scale" option affect this? Seems like it should be taken into account during bake, avoiding the need for this solution. $\endgroup$ – Philip Guin Feb 15 at 21:06
  • $\begingroup$ I think that didn't work for me, that's why I had to use this workaround :/ $\endgroup$ – Kati Knitt Feb 27 at 16:19
  • $\begingroup$ I posted a bug about this, got marked as a Known Issue. Here’s to hoping they address this soon. developer.blender.org/T73863 $\endgroup$ – Philip Guin Feb 27 at 23:34

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