Physics Constraint broke in 4.8.2

Development World Creation
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1

Hello,
I recently updated the project from 4.7.6 to 4.8.2 and the physics constraint don’t seem to work any more.

I’m using a constraint with linear velocity drive to act as a spring, holding a platform from falling. It worked fine in 4.7.6, however after upgrading the platforms falls with no sign of ever slowing down - same settings, same everything.

I tried to fiddle with the parameters but I just can’t seem to be able to make the constraint work. It shows the blue like attaching the two bodies but it just doesn’t constrain anything.

Please help, it’s rather important I get this bug fixed.

Thank you,

2

Hi AdrianLazar,

I’m not getting your results. Could you also post some screenshots or a small test project that shows exactly how you have the constraint setup? Specifically any drive settings.

3

Hi TJ,
Thank you for the fast response. Here’s a screenshots with the setup:

As I was saying, no changes were made from 4.7.6 to 4.8.2, however now the platform falls without stopping.
Worked fine before reacting to the player stepping on them (https://vimeo.com/130640471)

Thanks you,

4

I was able to reproduce this on my end as well. I’m not sure of the cause, the 4.8 release notes doesn’t list anything that should have caused this. I believe it has something to do with only using 1 component to constrain to, which has always worked up until now.

I’ve created JIRA UE-19017 and the developers will be investigating it further. We will post back here with updates as we have them.

Cheers,

TJ

5

Great, thank you.
Following your tip about the constraint not working if only one components is used I managed to find a workaround.

First I tried to use a Scene component to attach the platform to and that didn’t worked.
Then I tried using the default cube and it worked fine, however if I disabled the cube collision (needed so the player doesn’t get stuck) the platform will fall again. So the solution was to keep the cube collision on but set the preset to trigger.

To recap, setting Component Name 1 does the following:

  • Left blank worked in 4.7.6 but doesn’t work in 4.8.2
  • Using a scene component doesn’t work
  • Using a cube with Collision Off doesn’t work
  • Using a cube with Collision On: Block All Dynamic - WORKS
  • Using a cube with Collision On: Trigger - WORKS

Hope it helps,

6

Hi Adrian,

The JIRA was marked in our system as Major and it has already been fixed internally. You will see this working properly again in a future update.

Thanks,

TJ