I'm working on a game in c++. I've got all the connection stuff set up, client, server, etc., and it runs rather nicely.

Now, I need to know how to best not only coordinate player positions, but when to send what packets as well. So far, I tween player positions when the x,y,z coordinate is close enough, and do a hard set when it's far away. The player data is sent every several milliseconds. Should I be sending key presses to animate the players better? (My game has gravity) What if somebody forges packets and is able to warp to the other side of the map? I need a way to prevent this.

My game also involves bullets, and guns. (It's kind of a FPS) I'd like to make my game fast , so I'd like to avoid sqrt(x*x + y*y + z*z) for every bullet, every update. Is there any other way to get around this? I currently keep track of inventory, so packet forging on bullets wont be an issue. (I'm kind of paranoid of this due to the fact that other games have failed miserably from client side programming and cheaters)

Some general pointers or websites would be great.

Thanks.

Are your clients connecting only to one another (Peer-2-Peer)?

I'm not sure how far along you are with the packet sending but a good system to include is a simple debug slider that lets you alter how frequently the "base" update packets are sent (your player positions, etc). This makes it easy to observe how correct your game looks as you add more network traffic - ideally you want to find the lowest frequency of sending data that still looks good. It's possible you may want to have immediate sending of packets with crucial data in them (firing a rocket, end of a game round, etc).

I apologize for the long delay.. I actually got distracted working on my game

@Kazzahdrane No, it's not peer2peer, I believe server-client works better in my situation. I currently send packets every 500ms, and it seems to work ok. I'm not sure if this is fast or slow compared to the industry standard.

@hplus0603 What exactly do you mean by baseline? I have my data wrapped up for keypresses, but I'm not exactly sure what to do. Do i send a packet every time a key is pressed, or do I simply update every 500ms or so?

@ApochPIQ Thank you, I'm rather new here.

@Sappharos I've always tried to follow Never Trust the Client. Sometimes I feel as though I'm a bit paranoid. For example, can the client ignore packets? I currently implement a strike system. If someone were to use cheatengine (It's scary stuff for developers) to hack their inventory, and the player tries to use that item, they are dealt a strike. After 5 strikes, the server gives end of stream and disconnects the player. Is that okay?

Also, that algorithm is exellent.. I cant believe I didn't think of that.

[color="#1C2837"]

When clients do something they shouldn't, log it, and discard their input.

Then, patrol the logs periodically. You can even write tools to help with this. If you see a particular client doing suspicious stuff consistently, then you can think about taking action. Until then, the best policy is to just ignore things that shouldn't be done. That way, people can't tell the difference between sending garbage to the server (which should do nothing) and sending legitimate but "illegal" input to the server (which, if they knew it was legit but illegal, could tell them how to further exploit your system). [color="#1C2837"][/quote]

[color="#1c2837"]Sort of like Darwinian Evolution...
[color="#1C2837"]That's what I do essentially. Maybe after x number of strikes the server should start making warnings to the admin.
[color="#1C2837"]Should I consider basic packet encryption, such as XOR?