Physics constraint component behaves unexpectedly on actors in always-loaded sub-levels

Development World Creation
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1

Following on from this answers thread:

I have got physics constraint components working as expected for actors placed at arbitrary angles by integrating the following master commit into our local engine:

https://github.com/EpicGames/UnrealEngine/commit/7e4fd0faef1cdf2a6885730a900127ad05cd93ab

Now everything works great and I can rotate + scale dumpsters into a level and it all works as expected. The lids flap around within the angular constraints I have defined.

However, if I try and move a dumpster into an always-loaded sub-level, the constraint doesn’t initialize properly again. I took a look through the master branch to see if there was a related fix, but nothing showed up.

Here’s a video showing the dumpster blueprint setup (3 static meshes + 2 physics constraints) and demonstrating the dumpsters working in the main level, and not working in the sub-level:

2

Hi sds-,

I was able to reproduce what you are seeing and I have entered it as JIRA UE-6186 in out tracking software. Our developers will be looking into it further.

As for a workaround, I don’t have one for you right now. It only happens in an Always Loaded level. If the level is streamed in instead it works correctly. It’s very strange behavior.

Cheers,

TJ

3

Is there an update on this issue? My team has run into a similar issue. When actors using the Physics Constraint Component are in the persistent level they behave fine (see the box on the right in the attached image), but when in a sub level the pivot and swing behaviors act bizarrely (see the box on the left).

Any update would be tremendously helpful!

83885-ue4hingeissue.png

4

Hi Theodus,

This has been fixed internally but will not be included in the 4.11 build, so you will see it in a future update.

5

As of 4.12.1 this isn’t fixed. Do you think it will make it in a later version of 4.12? Is there a possible work around yet? Sorry to ask so many questions but physics constraints are effectively useless right now.

6

Hi sandford87, the workaround we used is to simply place the objects in the main level rather than in a sublevel. Not a pretty solution (especially for organisation and reusability), but at some point we had to ship our game. I assure you this wasn’t the dirtiest hack we made, haha.

7

Hi sanford57,

The JIRA I mentioned above was fixed in 4.12. I just tested this in 4.12.2 but it is working properly on my end. Here is what I did:

  • Created a BP actor

  • Add 2 StaticMesh components & a PhysicsConstraint

  • Set the constraint to constrain both StaticMesh components

  • Added this actor the the Persistent Level and another to a newly created ‘Always Loaded’ level

  • PIE

Can you try that in a new blank project and see if the issue still happens for you?

If not, what are the exact steps you are using?

8

Change " ‘Always Loaded’ level" to “load streaming level” in blueprint". Some of the constraints will work, some of them not. In standalone is always worse.