Physics substep callbacks run on main thread

Development Programming & Scripting C++
1

I was under the impression that physics substep callbacks run on a separate thread.

However, in both 4.18 and 4.19 it appears they run on the main game thread.

Is there something special you need to do to enable it to run on separate thread?

2

Which callbacks exactly?

3

When you register for a custom callback during each substep e.g.

GetBodyInstance()->AddCustomPhysics(OnCalculateCustomPhysics);

4

I believe they reverted to single threaded physics a few engine versions ago. I don’t recall exactly when, or what the reasons were.