Bullet on the cloud?

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paulg
Posts: 2
Joined: Mon Mar 12, 2012 4:17 pm

Bullet on the cloud?

Post by paulg »

There are a few cloud services which create a virtual machine for computing needs.
The top one that I can tell is Amazons : http://aws.amazon.com/ (check out ec2 service).

It's free for a whole year which is great!
Anyway, thought I would ask about advice & your ideas?
I am thinking about running a game on the cloud, the physics being done on the cloud and sending the object positions to each client computer.

Any advice?
Karrok
Posts: 65
Joined: Fri May 13, 2011 1:11 pm

Re: Bullet on the cloud?

Post by Karrok »

Use dead-reckoning to limit network traffic between the server and client :)
paulg
Posts: 2
Joined: Mon Mar 12, 2012 4:17 pm

Re: Bullet on the cloud?

Post by paulg »

That is a good idea, was thinking the same. Am also thinking if I dont, then once i have created a client app, any changes I make to the game I wont need to update the client.
But then won't be able to have as many players, or it will cost more to run.

Cheers.
note173
Posts: 16
Joined: Wed Jan 25, 2012 6:32 pm

Re: Bullet on the cloud?

Post by note173 »

Let's see. In an ideal case there will be a 100ms lag at best. It is a very noticeable delay, so you will probably want to implement some extrapolation which can be good in only one case: using the same physical engine as server does.
So it would be in the end the same technique the most multiplayer games have: local physics plus corrections from server.
Karrok
Posts: 65
Joined: Fri May 13, 2011 1:11 pm

Re: Bullet on the cloud?

Post by Karrok »

the whole premise of dead-reckoning is that the client only gets position (1st grade), direction+ velocity (2nd grade) or direction + acceleration(3rd grade).

On the server you run the actual physics engine + a copy of the client.
Starting a simulation the objects are at the same positions.

Something happens to the object and it gets a new position. We then check (locally still) if the delta between the position of that object as known in the physics engine is above a certain error threshold in the client simulation. If this is the case the server sends out an update packet to all clients (including its local client).

Now 2nd and 3rd grade will have fewer updates than 1st grade (obviously) but this is just a simple example.
But you certainly don't run a separate physics engine for each client.
note173
Posts: 16
Joined: Wed Jan 25, 2012 6:32 pm

Re: Bullet on the cloud?

Post by note173 »

It works well in FPSs' without simulated rigid bodies. With the "real" physics, however, even 100ms lag would make user notice how his boxes are penetrating a floor.
With some big random network lags the game would be totally unplayable.
When using a local physics simulation even occasional 10 seconds delay can be unnoticeable.
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