Networking model

I've been reading up on how Valve's Source engine handles network play, and I've come up with an outline for how I want this to work in Project Mod.

The key feature is a deliberate addition of input latency, sacrificing some snappiness for a smoother appearance on the client. Clients sample the local player's controls and send them to the server at the world's step rate (200 Hz at the moment, one step per 5 ms), but tagged for a future step. Source defaults to 100 ms. The server operates in the future, collecting controls packets, simulating the world, and sending periodic bunched updates to all clients.

When network latency is less than (input latency - update interval) and no packets are dropped, every client will already have the current world state stored in a buffer when it's time to refresh the screen. This means no prediction, no extrapolation, and zero jittering for ping up to 80 ms, at the cost of a consistent input latency of 100 ms. This delay could of course be adjusted for connections with higher or lower average latency, or even disabled for a local single player game.

I'll post more as I attempt to implement it.