ReceiveActorBeginOverlap called twice

[Ian_Proulx]

I have a ReceiveActorBeginOverlap method to handle portal teleporting. If I set the OtherActor’s rotation and location, my ReceiveActorBeginOverlap method gets called twice in a row (with exactly the same this pointer and OtherActor pointer). However, if I only change the OtherActor’s rotation and don’t move him, the method correctly gets called only once. And yes, I’m moving the OtherActor sufficiently far away that he isn’t legitimately triggering another overlap. This is totally baffling. I’ve been on this for days now and can’t figure it out.

[anonymous_user_f6530a3e1 (anonymous_user_f6530a3e)]

I know that the physics system has substepping, and last time I read about it all of the collisions and events were stored in a queue and were processed on the next tick. That may be causing some of what you are seeing. It would be interesting to know if you are getting and EndOverlap in between the two BeginOverlaps, in which case it’s probably the substepping.

Here’s a quote:

Another technical detail to be aware of is the way collision callbacks behave while sub-stepping. UE4 runs the physics sub-stepping in a separate physics thread, allowing the game thread to continue doing work. In order to get the best performance we delay the collision callbacks until the final sub-step is done. This means that you can get several callbacks for the same collision. For example, if A collides with B and bounces off, you may get a callback for A and B overlapping AND a callback for A and B no longer overlapping in the same frame. Internally all callbacks are pushed into a queue and so callbacks from sub-step 1 will be processed before callbacks from sub-step 2.

I think it’s in the documentation somewhere, as well as here : Physics Sub-Stepping - Announcements - Epic Developer Community Forums