iPad multiplayer Game Synchronization

Question

I'm developing a little 1-4 multiplayer jump & run for the iPad and have a problem regarding the synchronization. The game uses the Game-Center p2p Connection to connect the devices.

Now my problem is,

• what data should i send?

  -> I have enemies, moving platforms, destructible blocks and Items.

• when should I send the data?

Here are my first approaches to sync the PCs (playable characters):

1)

• send position (x,y) every frame --> physics and character don't interact, the character is set to the transmitted position

Problem:

• lots of data to send

• the PC lags sporadicly

2)

• send user input whenever it changes --> physics and character interact, only the opponents button actions are simulated

Problem:

• the latency is not always the same, e.g. the time one button is pressed is not exactly the same on all devices. This means one PC runs longer/shorter on one device.

So what is the best approach to sync a little p2p jump & run game?

Thanks in advance. I appreciate your help.

Answer 1

what data should i send?

Send everything that you would need to know in order to perform the neccesary game logic. Send new locations of enemies, updated health info, etc.

when should I send the data? Very frequently. You'll want fresh data when you update the screen so that the game appears to be very smooth. Ideally around 30 times per second. Some of the less important data may be able to be sent using the Unreliable method to cut down on network traffic.