A strange bug in UE5 physics?

Development Programming & Scripting
1

I’m currently creating a physics-based behavioral component.
The created component works fine with UE4.27.

However, when I upgraded to UE5 and checked the behavior, it freezes for a moment when I move on a slope.

When I checked the state of the Rigidbody, I was able to confirm that it was in a sleeping state.

Writing a process to make the Rigidbody wake did not change the result.

In 4.27, such a phenomenon does not occur and it occurs in 5.0, so I thought that it may be a tapirus of the Chaos engine.

You guys have strange physics-related behavior in UE 5.0

Also, I can’t find the AsyncPhysicsTick documentation and I can’t find a way to access the physical thread.

From the above, I will continue to work with 4.27 until Chaos stabilizes.

Also, since I’m from Unity, I’d like to know if there is an equivalent to Fixed Update.

2

I will post a video

3

Hi, I have the same problem but I didn’t found a good solution, so far there is a temporary fix of using p.Chaos.Solver.SleepEnabled 0

3 Likes
4

It seems that there are other people who are encountering the same problem.

I have the same post on the Unreal Engine bug forum

Apparently this issue will be resolved in UE5.1.

I’m also worried that there is no specific documentation for Async Tick Physics.

My way of moving is not CMC with built-in engine
Because it’s my own physical motion controller

Physical glitches are fatal

Maybe in the physical thread automatically when Add Force is done
Is simulation being done?

5

I was also looking into this, and the only thing I found was advice to check chaos vehicle movement component and study how they did it there. From my understanding you don’t really need manager class as they are simulating all vehicles there and I don’t think you need it.

6

I also checked the Chaos vehicle movement component and checked the code
It was like adapting the input to the physical thread part

I didn’t know anything else,
Perhaps the physics simulation part that applies force
I think it will be done automatically

It still existed on the official website
I’m curious that the “Async Tick Physics” page has been removed.
Probably something has changed.

In UE 5.0.2, the physical behavior is slightly stable and steady.
It’s improving, but it’s still a long way off.

7

Physics Tick Function() has been added to UE5.1.
This will make physics-based content even better.
I believe

something like the image below

ue5.1_new_function
ue5.1_new_function1114×944 63.3 KB

1 Like
8

p.Chaos.Solver.SleepEnabled 0 solved problem for me too in UE5.1
I have very slow, idle, animation on skeletal mesh and PhysicalAnimation component. The body is bouncing time to time even in Physical Asset preview (yeh, i know about constrains, damping, mass, mass offset, substepping, etc). Nothing helps. Even wake up rigid bodies node or apply force.
But this console command (wich you can add in DefaultEngine.ini file in your project folder under [ConsoleVariables]) solves the problem.