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Bone driver leading to cyclic dependency (used to work in 2.79)
Open, Waiting for Developer to ReproducePublic


System Information
Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 419.67

Blender Version
Broken: version: 2.80 (sub 69), branch: master, commit date: 2019-05-18 09:53, hash: rB7fd015bb70b2
Worked: 2.79b

Short description of error
When the scale transform value of a bone is driven by its rotation value, a cyclic dependency is reported in the console (and it slows down script execution).
This scenario used to work in Blender 2.79 without cyclic dependency.

Exact steps for others to reproduce the error

  • Open the following blend file, it just contain a bone with a driver: rotation.x -> scale.y:

  • See the error message in the console



Event Timeline

Brecht Van Lommel (brecht) lowered the priority of this task from Needs Triage by Developer to Waiting for Developer to Reproduce.

As far as I know this case is not considered a bug. While in some situations it might work, in general there is an actual dependency cycle here both in 2.79 and 2.80.

lucas veber (lucky3) added a comment.EditedMay 18 2019, 2:02 PM

It would be sad if it's not considered as a bug. Most 3D softwares out there can do this... it would be quite a limitation for rigging :'-(
Blender riggers were so happy to hear that 2.8 dependency graph is supposed to be more powerful than Blender 2.79 one... In this case it would be a regression.