I will provide some recommendation, this not at all is a whole reply nor the one reply, however it might offer you some meals for thought.
Bear with me as I clarify this, as a result of though we’re utilizing two completely different community fashions, the concepts (actually, enter and synchronisation) aren’t that completely different between the 2 approaches.
Authoritative simulation and timing: Turns
I am growing a hybrid RPG/RTS utilizing the P2P lockstep community mannequin. There isn’t a authoritative server on this community design sample. Nonetheless, given all the required inputs from different shoppers, the output on every shopper is deterministic and definitive throughout all shoppers (with strict use of integer arithmetic in simulation calcs). Even in an authoritative client-server setup, we try for this degree of synchronisation, though the server typically has to situation authoritative corrections to implement this.
It is clear in P2P lockstep — as a result of it’s serverless, very strict and leaves completely no room for discrepancies between shoppers — that there’s just one right simulation end result, per body, although it isn’t coming from any designated server, it’s nonetheless the equal of your server’s authoritative view of the world. That is the true state of the simulation.
However, to implement extrapolation, then from an MVC perspective, that might be a very view(render)-side choice, and this has nothing to do with the true state of the simulation. It’s only a nice phantasm which will or might not be correct. To derive this phantasm, we’ll want a document of a number of gamestates to combine over, with a purpose to arrive at our greatest attainable guess of what the present place and orientation of the opponent’s entity might be.
In my challenge, processing of the simulation works on a turns system (very similar to Age of Empires). Turns execute at 10fps (effectively, ticks per second, or tps), whereas rendering occurs at 60fps. Turns (10tps) are what take participant inputs (learn that once more).
Render frames (60fps) then merely do interpolation between the states produced by every of these turns (10tps), utilizing the flip state simply calculated and the earlier flip state calculated, which we preserve obtainable. (You might retailer three or extra turns states to combine over, for extra correct predictions.)
Thus, you’ll retailer a historical past of turns (or gamestates related to turns) to derive your extrapolations from.
I imagine (???) Quake networking used one thing related, i.e. an idea of turns which act as a vital foundation for timing and processing. I could possibly be improper. All shoppers ought to pay attention to which flip is at the moment in progress (whether or not by way of one another, or as knowledgeable by a server).
Sending & Making use of Inputs
No matter whether or not you are utilizing a client-server or P2P-lockstep method, you have to be sending nothing greater than (1) booleans of whether or not or not the important thing / button was pressed, or (2) quantities by which mouse or analog stick was moved in every axis. On foundation of that uncooked enter solely, you’ll be able to carry out the identical logic throughout all shoppers and the server, or nevertheless your topology works.
If these inputs are, body after body, utilized as deltas to the final recognized gamestate, throughout all shoppers (in my case of P2P lockstep) and all such gamestates stay in sync flip after flip, then all gamestates ought to proceed to stay in sync, indefinitely.
And the packets by which these inputs are despatched, is marked with a novel flip quantity in addition to the sending shopper’s ID. On this approach, we are able to simply allocate to the right flip & shopper on arrival.
Prototyping community programming fashions and ideas, simply
The best strategy to start understanding these issues, is to have the ability to experiment on them inside the confines of your dev system. In case you a easy dummy shopper server setup effectively (abstractly), utilizing simply asynchronous programming, you’ll be able to later plug in lower-level community layer assist (RUDP, TCP sockets, and even greater degree libraries). I counsel modelling the system inside a single app or inside a shopper app so you’ll be able to instantiate a number of occasions towards the identical server working in your dev system. I bought a prototype working and syncing between shoppers inside just a few days.
This consists of nothing greater than asynchronous programming, based mostly on the ideas of packet loss and packet delay. I am positive there are different ideas concerned, or finer distinctions to be made (equivalent to community congestion, as an example) however for my functions these have helped enormously in getting a working, synced prototype going with out touching any true networking code to date.
