Maniphest T78857

Alembic export crashes Blender when an object is importing the .abc file.
Closed, Duplicate
Actions

Assigned To
None
Authored By
Lukas Tönne (lukastoenne)
Jul 12 2020, 12:51 PM
Tags
  • BF Blender
  • Alembic
Subscribers
Lukas Tönne (lukastoenne)
Richard Antalik (ISS)
Sybren A. Stüvel (sybren)

Description

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 446.14

Blender Version
Broken: version: 2.83.2, branch: master, commit date: 2020-07-09 05:50, hash: rB239fbf7d936f
Worked: (newest version of Blender that worked as expected)

Short description of error
Alembic export operator crashes when a mesh with a MeshSequenceCache modifier using the same cache file is in the scene.

Exact steps for others to reproduce the error
See the attached file for a quick repro setup:

AbcCrash.zip292 KBDownload

  1. Scene has a mesh to be exported (here a simple subdiv cube with a wave mod to actually export geometry)
  2. Export to an alembic file.
  3. Scene has a 2nd mesh with a MeshSequenceCache modifier (IsSequence setting enabled). This loads the .abc file exported above.
  4. Run the abc exporter again. Make sure the "Selected objects only" option is disabled, so it will try to export both the original and the reimported mesh.

Blender crashes when trying to export to the same file it is importing at the same time.

Expected: Blender should exclude the imported object from cache exports, and/or suspend the MeshSequenceCache modifier (also for performance reasons if it isn't exported).

Event Timeline

Lukas Tönne (lukastoenne) created this task.Jul 12 2020, 12:51 PM
Lukas Tönne (lukastoenne) added a project: Alembic.
Lukas Tönne (lukastoenne) added a comment.Jul 12 2020, 1:05 PM

I found that after reloading it sometimes stops crashing. In that case deleting the original import object with the MeshSequenceCache and creating a new one seems to repro the crash again. This makes me think it may depend on the arbitrary order of objects in blend data lists.

Richard Antalik (ISS) changed the task status from Needs Triage to Needs Information from User.Jul 13 2020, 8:26 PM
Richard Antalik (ISS) added a subscriber: Richard Antalik (ISS).

I wasn't able to reproduce crash while following steps. However those are not very exact.

I need to change path to .abc file in mesh sequence cache, so the file will "reload". If this is problem please update your steps to take this into account

Sybren A. Stüvel (sybren) closed this task as a duplicate of T76412: Crash, when ALEMBIC Input File internally has changed.Jul 16 2020, 6:05 PM
Sybren A. Stüvel (sybren) added a subscriber: Sybren A. Stüvel (sybren).

This is a limitation of the Alembic library.