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Incorrect import when a skinned mesh has vertices unassigned

Asset Importers


When importing fbx with a skinned mesh that has vertices not assigned to any joint, they get arbitrarily get set to 1.

1. Open 'UnassignedVertices.fbx' in Maya/Max/Blender etc.
2. Play animation and notice that some vertices are unaffected by bones
3. Import fbx in Unity, Play animation

Expected result: Animation plays the same, unassigned vertices are supported

Actual results: Animation is incorrect, but you get a warning:
'ImportFBX Warnings: Mesh 'XYX' has # (out of #) vertices with no weight and bone assigned (they will be assigned to bone #0 with weight 1).

  1. Response avatar

    Resolution Note:

    For runtime optimizations we either skin the complete mesh or nothing at all. To do skinning on the complete mesh we need a weight and a bone for every vertex. When a vertex does not have a weight and a bone assigned we assign one for the user - as shown by the warning message. It is impossible to guess the correct bone that follows the users intend. The first bone is a best guess that I imagine solves it for most cases. But it is really something that should be authored by the user.

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