Hair Dynamics Strange Behaviour #80438

New Issue

Discko · 2020-09-03T19:40:57+02:00

Discko commented

2020-09-03 19:40:57 +02:00

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce RTX 2080 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 451.67

Broken: version: 2.90.0, branch: master, commit date: 2020-08-31 11:26, hash: 0330d1af29

I have not seen hair behave this way before. For this example file, I have simply used the default hair dynamics settings. I have a bake in the file attached, and you can try bake yourself to replicate the issue. The hair will fly all over the place, it is not colliding with anything and I cannot figure out what is causing the issue. It was recommended by a developer that I post the issue here for others to have a look, many thanks.
HairProb.blend

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce RTX 2080 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 451.67 Broken: version: 2.90.0, branch: master, commit date: 2020-08-31 11:26, hash: `0330d1af29` I have not seen hair behave this way before. For this example file, I have simply used the default hair dynamics settings. I have a bake in the file attached, and you can try bake yourself to replicate the issue. The hair will fly all over the place, it is not colliding with anything and I cannot figure out what is causing the issue. It was recommended by a developer that I post the issue here for others to have a look, many thanks. [HairProb.blend](https://archive.blender.org/developer/F8836868/HairProb.blend)

Discko commented

2020-09-03 19:40:57 +02:00

Added subscriber: @Discko

Discko commented

2020-09-06 22:34:14 +02:00

HairProb.blend

Interesting test, on the left is a singular strand of the problematic hair - gyrating around and doing it's own thing. In the middle is a brand new UV sphere with a new particle system completely at default settings, behaves normally - On the right is another new UV sphere, with the same particle system as the odd behaving hair - but it behaves fine

[HairProb.blend](https://archive.blender.org/developer/F8848200/HairProb.blend) Interesting test, on the left is a singular strand of the problematic hair - gyrating around and doing it's own thing. In the middle is a brand new UV sphere with a new particle system completely at default settings, behaves normally - On the right is another new UV sphere, with the same particle system as the odd behaving hair - but it behaves fine

Sebastian Parborg commented

2020-09-07 18:11:16 +02:00

Added subscriber: @ZedDB

Sebastian Parborg commented

2020-09-07 18:11:16 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Sebastian Parborg commented

2020-09-07 18:11:16 +02:00

I can reproduce this.

It seems like the simulated hair will start freaking out if it is edited into a "C" shape:
recording.mp4

I'm guessing that the cloth/hair springs gets bad initial values somehow perhaps. I haven't looked into it deeply yet though.

I can reproduce this. It seems like the simulated hair will start freaking out if it is edited into a "C" shape: [recording.mp4](https://archive.blender.org/developer/F8851136/recording.mp4) I'm guessing that the cloth/hair springs gets bad initial values somehow perhaps. I haven't looked into it deeply yet though.

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Hair Dynamics Strange Behaviour #80438