Today I tried to join one curve object to another as a shape key, but the function is greyed out in the menu. Is "Join as Shapes" not supported for curve objects?

Both objects have the same number of verts/points. Actually, one was made by duplicating the other, so they have the same curve resolution and everything.

Currently Blender's manual does not mention a lack of support for curve objects:

Join as Shapes (Transfer Mix)

Transfer the current resulting shape from a different object.

Select the object to copy, then the object to copy into. Use this action and a new shape key will be added to the active object with the current mix of the first object.

Most of the functionality of Shape Keys holds true for both meshes and curves. So I'm surprised by this. I also tested this on other curve objects, and the result is the same. Also, I verified that Join as Shapes is still working as expected on mesh objects.

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    $\begingroup$ I can only say that from my experience it doesn't seem to work. But it's not just the Join as Shapes functionality. If you e.g. simply join two curves that have shape keys this really messes them up and shape keys get lost - whereas two mesh objects join perfectly fine and the shapes and shape keys are preserved. $\endgroup$ Jul 12, 2022 at 5:56
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    $\begingroup$ @GordonBrinkmann That is an interesting observation... thanks for sharing. I just tested it, and got pretty bizarre results myself. Almost like the Z axis became the X axis for the newly added part of the geometry. $\endgroup$
    – Mentalist
    Jul 12, 2022 at 14:03
  • $\begingroup$ Yss, and for example if you join two mesh objects, let's say the first with one shape key and the other with two then the merged object has two or three (depending on the keys' names, keys with the same name will be merged). But with curve objects, the shape keys of one object are lost after merging. $\endgroup$ Jul 12, 2022 at 19:25


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