Physics " start awake " option don't work in unreal 4.8

Hi,

I hope you can help me to understand why the option " start awake " isn’t working properly in 4.8. Maybe a new bug.

So I have an skeletal mesh with physics simulation enabled, and start awake option disabled.
In 4.7 the object stay stationary until there is a collision with player or projectile, and in 4.8 the object fall on the ground when I press the play button.

I try to put my object in the air in order to be sure to avoid collision with other object, but it still happen.
Please Could you help for this issue.

Thanks in advance

Hi Fourche13,

Thank you for the report, but I’ve not been able to reproduce this on my end.

I’ve used three separate objects for my test:

  • Skeletal Mesh (Engine folder “HeroTPP”)
  • Cube Static mesh (Modes Panel, basic cube)
  • Destructible Cube (right click on the cube in the content browser > create DM)

I set each of these to use Simulate Physics with Start Awake disabled. I then used my player character to bump into them to “Wake” them and this worked as I would expect.

I also used assets that were already in the engine folder when testing as this gives us a base to work from.

Are you using the final 4.8 release from the luancher/binary version or are you using a source build? Also, can you double check that your version CL is 2579680.

Let me know.

Tim

Hi thanks for your prompt response,

Yes I’m using the 4.8 release( from the launcher ), not the source build, the version is 2579680.

Otherwise, I’m still using older fbx exporter, v 2012.2 or 2013.3, I can’t use fbx 2014 / 2015 export.
I’m working on 3dsmax.

I also tested other skeletal mesh who worked, the third person skeletal mesh.

But the asset I’m testing actually doesn’t work at all since the new 4.8. I tried to :

  • export again
  • import again ( multiple time )
  • add a root dummy node
  • re skin the mesh
  • I Tried to create a simple cylinder on 3dsmax with 3 bones, export it and I got the same problem.

Nothing seems to work. I start to have no idea of the problem. I guess the problem come from export, or import or from my rig/skin setup maybe ( which is really simple ).

I give you a link to the fbx and max file in case you notice something wrong.
https://www.dropbox.com/sh/ddebda8aqm9v2qy/AABqkXsuffsH3MS3OfSHT_7Ua?dl=0

Thanks Fourche13,

I was able to reproduce this. I think the one I tested with initially did not actually have a physics asset setup for it, but regardless I can confirm this is happening with any skeletal meshes imported or otherwise in 4.8. This also affects destructible meshes.

We have a ticket in for the destructible meshes already with UE-16943, so I’m looking to append this to include skeletal meshes. Once we have a fix in for this I’ll post back and let you know the status.

Thank you!

Tim

thanks a lot for your help

Hi, do you have any news about this ticket UE-16943 ? because the " start awake " option on skeletal mesh physics still doesn’t work in 4.10

Hi,

This was fixed with 4.9. I’ve just tested this with 4.10 with a Destructible Cube and a Skeletal Mesh (the Third Person Template Mannequin) with no issue.

Can you test these assets on your end and see if you see the same. This can rule out any issue with any other content, since I’m not able to reproduce the issue any longer.

Thank you!

I’ve tested, the character of the third template work well . So I did some other test, in order to find the issue and I found why in some case the physics asset don’t respond well to the function " start awake ".

So for the other people who have this issue, if the asset have less than 5 body in the physics asset. the start awake function " disabled "have no effect.

So in order to test this, I created a cylinder with 5 bones and with one body for each bone, with start awake disabled : It works well !!
Then I created a cylinder with 4 bones and still one body for each bones with start awake disabled : it don’t work, the object fall to the ground.

So Tim, I hope this issue can be fixed or I’ll need to add 2 useless bones for my skeletal mesh. ( my object have 3 bones ).

Thanks for the added details. I’ve entered a ticket for this now with UE-24224.

Once there is any update to the ticket I will post back here.

Thank you!

Tim

This has recently been fixed and will be included in 4.12. Unfortunately it missed the cut off to make it into 4.11.

Thank you!