Multiplayer Game Synchronization

Question

I\'ve a server/client architecture implemented, where all state changes are sent to the function, validated and broadcasted to all clients connected. This works rather well, but

Answer 1

There will never be a way to guarantee perfect synchronisation across multiple viewpoints in real time - the laws of physics make it impossible. If the sun exploded now, how could you guarantee that observers on Alpha Centauri see the supernova at the same time as we would on Earth? Information takes time to travel.

Therefore, your choices are to either model everything accurately with latency that may differ from viewer to viewer (which is what you have currently), or model them inaccurately without latency and broadly synchronised across viewers (which is where prediction/dead reckoning/extrapolation come in). Slower games like real time strategy tends to go the first route, faster games go the second route.

In particular, you should never assume that the time it takes to travel will be constant. This means that merely sending start and stop messages to move entities will never suffice under either model. You need to send periodic updates of the actual state (typically several times a second for faster games) so that the recipient can correct error in its predictions and interpolations.