Physics in 4.8 very different to 4.7 - reason?

Could someone from Epic explain in more detail what was changed in the physics.
In the project settings there is now PCM, share async etc, and also in the rigid body details tab is async as an option now
Obviously some major changes were done beyond what is mentioned in the release notes.
Are you trying to multi-thread PhysX 3.3 with UE4.8?

All my projects that I worked on for 4 months now since 4.6 are not working anymore because constraint linear limits are ignored and attached bodies shift, even though linear limits are locked. Also forces are largely different and physics are overall more jittery.
These observations are from straight conversions to 4.8 and the last version was 4.7.4.
Everything worked fine in 4.6 and 4.7 and with the new physics changes in 4.8, my work of 4 months is suddenly unusable.

Hi MaZi1,

I’ve setup a simple scene in with two sets of simulated actors.

I have a row that is nothing but Destructible Meshes of different shapes (cube, cylinder, and sphere) that will destroy on impact and are set to simulate physics. The next row is using the same meshes, except they are simple static meshes that are set to simulate physics.

In both 4.7 and 4.8 I’m seeing the exact same simulation with no noticeable difference in the end result.

I’ve also tried setting up some basic constraints, but I’m not seeing anything here on my end as well. This could be just that I’m not matching some of the settings or method you’ve used to do so. Can you provide an example of one of your setup for your constraint issue and I’ll set it up in 4.7 and 4.8 to see what’s going on on my end?

Thank you!