How can I synchronize ocean waves over the network?

Question

I've been performing a little bit of research in my spare time on ways to increase the interactivity of environments in a networked game or simulation.

One of my areas of research is fluid-dynamics and whether it would be possible to synchronize it over the network. I believe the short answer to that is - Yes of course you can. But there will obviously be trade-offs as there are with any network synchronization problem.

I was recently playing Battlefield 4 and a number of their maps have playable ocean areas with fully functional waves large enough to obscure entire boats during gameplay. It seems to work quite well as well.

My assumption here is that the ocean simulation is completely offline and each client performs synchronization with the server during initialization. This would allow all clients to run the exact same ocean simulation that appears to be dynamic but is in fact the same offline simulation every time.

Interaction with the ocean simulation appears to be only superficial with local splash/wave depression. I assume that is entirely local to the client and not synchronized.

My question here is:

Would the above be an appropriate way to synchronize fluid simulation over a networked game? If not, what would you suggest?

Answer 1

Have you considered generating the waves from a 3d pearl noise generator? That way you can find the height of each wave using just a simple function call with time and exact position, as long as you synch the time across all machines the result should be synchronized waves. Now you only need to send updates whenever one of the waves interacts with something else (well if you do it right you don't even have to do that only when a player interacts with the waves).

So basically use a 3d noise map to generate your waves from and then tread the physics simulair to how you would treat the map (you don't pass the map every frame do you?)

Answer 2

You don't sync the simulation at all. Only the results.

Or in other words: Those waves wouldn't be synced over network (only start/intensity and such). Only things moved by the waves (players, vehicles, etc.) are synced as usual.

The waves themselves are calculated by the clients on their own with details/accuracy based on local settings.

You can't really sync the whole simulation (with all details/elements/nodes) as that would require you to transfer/sync lots and lots of data. If you only have to simulate the surface, consider it being a net or mesh of points.