Physics (Bullet) Client-side prediction

[Snowcrash5]

@;546912

Yes, you have to dig into the FPhysicsSubstepTasks.h / .cpp to do that.

Create an input-history of your local client, save there Velocity / Transform and Input-Data of the player every substep with the local timestep.
You fill out the same structure on the server, let that replicate back to the client, who then calculates based on ping, when this package should have been applied if there would have been no ping. You then initially apply the the Server-Data to your pawn, rewind in the input-history to that time and replay Ping milliseconds via the PhysicsSubstepper by adding additional DeltaTime. Also, replicate input state at this point, if need be.
For example, vehicles don’t accelerate to 100% throttle instantly, but the throttle increases while the W key is being hold. To make the replay as precise as possible, these values also have to be replayed. In fact, you need to recalculate everything your physics relay on.

One major letdown is that this technique also fast-forwards other physics actors. You have to cheat a bit to get around that, but it’s now all working for me. 300ms ping with no lag and no input latency

This is amazing, thank you, but I might be missing something, because I don’t see any source file in the engine that’s called FPhysicsSubstepTasks :S

EDIT: Never mind, found it, its called PhysSubstepTasks.h / .cpp