Maniphest T90832

FBX export: Vertices deformed with Subdivision Surface export option
Closed, Archived
Actions

Assigned To
None
Authored By
Roberto O (Roberto_Van_Rotterdam)
Aug 21 2021, 5:40 PM
Tags
  • BF Blender
Subscribers
Philipp Oeser (lichtwerk)
Roberto O (Roberto_Van_Rotterdam)

Description

System Information
Operating system: Win10 Pro 19043.1165
Graphics card: GeForce GTX 970

Blender Version
Broken: 2.93.2
Worked: unknown

Short description of error
Vertices do not export correctly when choosing the 'Subdivision Surface' export option for FBX.
Loading the exported FBX file in Blender, Assimp Viewer, and my renderer produce identical results.

Assimp import result


Blender result

Expected import result

Exact steps for others to reproduce the error

  1. Open attached blender file
  2. go to File->Export->FBX
  3. select 'Export Subdivision Surface' from Geometry section
  4. export

Notice than when you re-import the file, the vertices are all messed up.

Blender file:

Defect.blend3 MBDownload

Related Objects

Event Timeline

Roberto O (Roberto_Van_Rotterdam) created this task.Aug 21 2021, 5:40 PM
Philipp Oeser (lichtwerk) closed this task as Archived.Aug 24 2021, 2:35 PM
Philipp Oeser (lichtwerk) added a subscriber: Philipp Oeser (lichtwerk).

This is because of the shapekeys (rather than the SubD export option)

First of all: there are broken drivers on the shapekeys:

WARN (bke.anim_sys): source/blender/blenkernel/intern/anim_sys.c:3594 BKE_animsys_eval_driver: invalid driver - key_blocks["Elbow_L"].value[0]
WARN (bke.anim_sys): source/blender/blenkernel/intern/anim_sys.c:3594 BKE_animsys_eval_driver: invalid driver - key_blocks["Elbow_R"].value[0]
WARN (bke.anim_sys): source/blender/blenkernel/intern/anim_sys.c:3594 BKE_animsys_eval_driver: invalid driver - key_blocks["Mouth_Lip_Pucker_top"].value[0]
WARN (bke.anim_sys): source/blender/blenkernel/intern/anim_sys.c:3594 BKE_animsys_eval_driver: invalid driver - key_blocks["Mouth_Lip_Pucker_bottom"].value[0

Does not really harm, just noting.

You have run into a similar situation as T68282: Deleting shape keys causes mesh to explode, I assume there have been modeling modifications on the mesh after adding the shapekey(s) that changed vertex count / topology?
This can have bad consequences for shapekeys.

So the fix in your case is:

  • open your file
  • select all vertices
  • select the Basis shapekey
  • from the menus, execute Vertex > Blend from Shape
  • export FBX

This is not considered a bug though. will close (of course feel free if issues persist)