I wanted to know when it comes to using UDP in a game for real-time movement,
if I should build an ack layer on top of it.
My game uses an 8-directional movement system. And right now I'm sending keypresses/keyreleases. It works completely fine with UDP, but I'm running it locally.
Eventually when players try sending data to my server via my external IP, there are most likely going to be datagrams dropped. So I was thinking of building an ack layer over top of it, which works like this:
My player would send a movement datagram, saying that he moved to the left.
The server may/may not receive this. If it does receive this, the server will then send back an acknowledgement. If the client does not receive this after a certain amount of time (I set an alarm which is equal to double the ping), then we assume the datagram was dropped and we send the exact same data (move left) to the server and the process repeats until we have an acknowledgement.
The same system is implemented on the server in which the server would then send the move packet back to the client to allow it to move, and wait for an acknowledgement. If it doesn't get one, it re-transmits.
So now it comes to my two questions:
1) Is this a fairly efficient system for an acknowledgement system over-top of UDP messages that are required to be sent/received? When it comes to things like movement and actions in real-time in which dropped messages can have an effect on the game/
2) Is this system really necessary? In other words, do I really need to worry about datagrams being dropped?
I've heard that in reality, it really doesn't happen that often, but when you've got a ton of real-time movement data being transmitted back and forth, one would think it would happen.
The thing is, the way my movement system works is, the server is in control of the movement. The client simply sends a keypress/keyrelease and doesn't move the player until the server sends back a movement datagram. I mention this because, if a datagram gets dropped and I don't have any sort of re-transmit system in place, there would be times when the player would press the movement keys and not even move anywhere because a datagram got dropped.
This can be very annoying, and I know games such as Halo use this system (waiting for the server to tell us to move rather than the clients moving on their own).
And games like that, you hardly ever have times where you would press the movement keys and nothing would happen. Most likely because they have some sort of UDP-ack-reliable system implemented overtop of UDP.
So is it worth it to implement an ack system for things like UDP movement? Or should I not even worry about it? I'm not exactly sure on average, how often a datagram is dropped, and if it would heavily interfere with gameplay?
