Bug / Crash Three bugs in FluidKarmanVortex Scene

[Chua Polar]

Environment: Win10, Unity 2022.1.0b4.2571, Obi FLuid 6.4 with Burst Solver, FluidKarmanVortex scene.
1. Warning of setting the velocity of a kinematic body. See the file of waring1.
2. Job access out range error. See the file of error1.
3. The particle advected by the fluid will disappear a few times after the scene started. The particles will quickly disappear after being emitted. See the image.

Images: https://drive.google.com/drive/folders/1...sp=sharing

[josemendez]

Environment: Win10, Unity 2022.1.0b4.2571, Obi FLuid 6.4 with Burst Solver, FluidKarmanVortex scene.
1. Warning of setting the velocity of a kinematic body. See the file of waring1.
2. Job access out range error. See the file of error1.
3. The particle advected by the fluid will disappear a few times after the scene started. The particles will quickly disappear after being emitted. See the image.

Images: https://drive.google.com/drive/folders/1...sp=sharing

Hi,

Thanks for the report! another user recently reported the exact same error, we were unable to reproduce it but this was his latest message to us:

"Hey, quick update; It seems it broke with the newer Unity 2021.2 updates, and not with the ObiFluid update. I apologize for thinking it was the ObiFluid update that broke it. It's broken in Unity 2021.2.10, working fine in 2021.2.7. Thanks for your help, hopefully Unity will get it fixed in an update soon."

So far this looks like a bug in Unity, or one of the Burst packages. We're still investigating and trying to reproduce it. My advice would be to try Unity 2021.2.7 or older, as it seems Burst broke somewhere between 2021.2.8 and 2021.2.10.

Also keep in mind that beta versions (2022.1.0b4.2571) should not be used for production.

let me know if I can be of further help,

[Chua Polar]

Hi,

Thanks for the report! another user recently reported the exact same error, we were unable to reproduce it but this was his latest message to us:

"Hey, quick update; It seems it broke with the newer Unity 2021.2 updates, and not with the ObiFluid update. I apologize for thinking it was the ObiFluid update that broke it. It's broken in Unity 2021.2.10, working fine in 2021.2.7. Thanks for your help, hopefully Unity will get it fixed in an update soon."

So far this looks like a bug in Unity, or one of the Burst packages. We're still investigating and trying to reproduce it. My advice would be to try Unity 2021.2.7 or older, as it seems Burst broke somewhere between 2021.2.8 and 2021.2.10.

Also keep in mind that beta versions (2022.1.0b4.2571) should not be used for production.

let me know if I can be of further help,

Thanks for your patience! 
Did you mean that exactly the three problems or just the burst job error, what about the other 2?

[josemendez]

Thanks for your patience! 
Did you mean that exactly the three problems or just the burst job error, what about the other 2?

All 3 errors are the same one. If an error is happening at runtime, that means the simulation is broken: advection won't work, particles might disappear, etc.

Until we can determine the cause (which is likely to be a bug in Burst and/or Unity), using an older Unity version is recommended.

[Chua Polar]

All 3 errors are the same one. If an error is happening at runtime, that means the simulation is broken: advection won't work, particles might disappear, etc.

Until we can determine the cause (which is likely to be a bug in Burst and/or Unity), using an older Unity version is recommended.

Thanks, I will post later when I transfer to a valid unity version.

[Chua Polar]

I find that when I turn the backend to Oni, the other 2 bugs remain.

[josemendez]

I find that when I turn the backend to Oni, the other 2 bugs remain.

Hi,

I'm unable to reproduce these. Tested on 2019.4.30f1, 2020.3.25f1 and 2021.2.1f1. The Karman Vortex scene works well on all 3 of them regardless of the backend used.

Which Unity version are you using? If it's 2022.1.0b4, keep in mind that beta Unity releases are not officially supported. Beta releases are intended for testing purposes only, as they're often riddled with bugs.

Also a note about the "setting the velocity of a kinematic rigidbody" warning: there's nothing wrong with that, it will have no effect since the inertia tensor and the mass of a kinematic body are infinite for all intents and purposes. Unity recently added this warning to the velocity property setters, but it can safely be ignored. See Unity's documentation:


Unity 2021:
https://docs.unity3d.com/2021.2/Document...ocity.html

Unity 2022:
https://docs.unity3d.com/2022.2/Document...ocity.html

You can see that in 2022 they've added a line at the very end of the documentation page:

Additionally, setting the linear velocity of a kinematic rigidbody is not allowed and will have no effect.

Setting the velocity of a kinematic rigidbody has never had any effect (it is in fact ignored), the only thing that has changed in 2022 is that they've added a warning to the console.