Hello,
I have found what I believe is a pretty serious bug in UE4.10 engine code that results in the PhysX simulate time randomly being locked to 60fps after a map travel, regardless of the actual game fps. This results in chaos in online multiplayer games as seen here, as the server + client will have wildly different physics simulation rates: Obliteracers - OBLITERATE YOUR FRIENDS ★ Obliteracers Early Look (Obliteracers Gameplay) - YouTube
In PhysScene.cpp, there is a static bool bInitializeConsoleVariable inside FPhysScene::FPhysScene(). It is statically set to true, and is used to set FrameTimeSmoothingFactor[PST_Sync] and FrameTimeSmoothingFactor[PST_Async]. After these are set, it becomes false. Obviously this is a problem, as the next time we run through FPhysScene construction (eg. on a map travel), FrameTimeSmoothingFactor[PST_Sync] and FrameTimeSmoothingFactor[PST_Async] are not set appropriately. Later on they’re clamped between 0 and 1. When 0, the frame time will just use the delta time as is. When 1, InitialAverageFrameRate is always used, which is 0.01666 (1/60), which is why the simulation becomes locked at 60fps sometimes.
My quick fix was to comment out the line: bInitializeConsoleVariable = false;
Cheers,
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