Mangled normals while morphing (blend shapes) when hard edges are present

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Hello,

We are having an issue with exporting of Normals when the geometry contains some hard edges (multiple normal per vertex). The issue only happens when there are blend shapes (aka morph targets) present. In the exported FBX file, when the normal are exported as eByControlPoint, everything is fine, but when we have some hard edges the exported FBX has normal eByPolygonVertex, the normals get mangled and reimporting it in Maya shows the same.

Any help would be greatly appreciated. I’d be happy to attach a simple animated (morphed) cube as an example.

Thanks!