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Blender 2.8 FBX exporter doesn't "preserve volume" or scale of second mesh from animated FBX file.
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Description

System Information
Operating system: Windows 10
Graphics card: Nvidia 1050 TI

Blender Version
Broken: (example: 2.80, edbf15d3c044, master, 2018-11-28, as found on the splash screen)
Blender 2.80
Worked: (optional)

Short description of error
The cylinder of the revolver shrinks in scale after it's exported to FBX. Although I toggled "Preserve Volume", it appears that Blender FBX's exporter applies it once to the revolver mesh, but ignores it for the cylinder mesh.

Here's how the animation is supposed to look:
https://cdn.discordapp.com/attachments/607260974088454154/627367561499115559/swagfire.mp40001-0035.mp4
Here's how the animation looks when reimported:
https://cdn.discordapp.com/attachments/605246613379612675/627394105609027594/test.mp4

Exact steps for others to reproduce the error

  1. Select the cylinder mesh ("revolvercylinder"), gun mesh ("gun"), and armature ("gun_bones") together.
  2. Export the blend file as an FBX file.
  3. Import the exported .fbx file into blender and see the shrunken cylinder.

Based on the default startup or an attached .blend file (as simple as possible).
Blend file


Exported fbx file:

Details

Type
Bug

Event Timeline

swagnol (gnawli) updated the task description. (Show Details)
swagnol (gnawli) renamed this task from Blender 2.8 FBX exporter doesn't "preserve volume" or scale of animated FBX file. to Blender 2.8 FBX exporter doesn't "preserve volume" or scale of second mesh from animated FBX file. .Sep 29 2019, 5:08 AM
swagnol (gnawli) raised the priority of this task from Needs Triage by Developer to Unbreak Now!.
swagnol (gnawli) updated the task description. (Show Details)
Evan Wilson (EAW) lowered the priority of this task from Unbreak Now! to Needs Triage by Developer.Sep 29 2019, 11:16 AM

Hello,

Please do not set priorities for your own bug reports. That is for the developers to decide.

Hello,
Please do not set priorities for your own bug reports. That is for the developers to decide.

I'm sorry about that, I'll wait for it.

Germano Cavalcante (mano-wii) lowered the priority of this task from Needs Triage by Developer to Confirmed, Low.

I can confirm.
To reproduce the problem simply open the attached file, export FBX and import the FBX file (in another file).
I don't know if this is a known limitation however.

I can confirm.
To reproduce the problem simply open the attached file, export FBX and import the FBX file (in another file).
I don't know if this is a known limitation however.

I tried finding a work around by setting "Maintain Volume" and "Limit Scale" in Bone constraints, but those never worked. Also tried parenting the mesh to the revolver, but that never worked too.

Bone envelope and preserve volumes are totally incompatible options for FBX export, those add advanced behavior to the Armature modifier that is in no way possible in FBX. When you disable those in your orig .blend file, you get the same shrinking, so there is no bug in FBX exporter here, it’s the rig that needs to be fixed to prevent that shrinking.

Bone envelope and preserve volumes are totally incompatible options for FBX export, those add advanced behavior to the Armature modifier that is in no way possible in FBX. When you disable those in your orig .blend file, you get the same shrinking, so there is no bug in FBX exporter here, it’s the rig that needs to be fixed to prevent that shrinking.

Forgive me for asking this, but how would you fix the rig? I just parented three bones to the primary one.

Bone envelope and preserve volumes are totally incompatible options for FBX export, those add advanced behavior to the Armature modifier that is in no way possible in FBX. When you disable those in your orig .blend file, you get the same shrinking, so there is no bug in FBX exporter here, it’s the rig that needs to be fixed to prevent that shrinking.

Forgive me for asking this, but how would you fix the rig? I just parented three bones to the primary one.

This user helped me out
https://blender.stackexchange.com/questions/157178/rigged-blender-model-doesnt-preserve-volume-when-exported-as-fbx