Re: create a network game, where to begin ?

On 18 mai, 06:11, "Jim Langston" <tazmas...@xxxxxxxxxxxxxx> wrote:
<timor.su...@xxxxxxxxx> wrote in message

news:1179340725.032443.117080@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx



Hi all,

I'm a developper that knows some things about software programming,
but nothing about game programming.

I would like to know concept of network game programming. books,
articles, ... are welcome

For example, let me know if it's the good strategy :

I would like to create a 2 players game, very simple for beginning.
The purpose is to establish the network engine.

What i want to do, on a screen, 2 players (2 sprites), and each player
can move his sprite, and each player can see his player and the other
one too.

So, what i've done :
- a server that broadcast the message to the others players (in my
case, to the only one other player)
- 2 clients that :
- can move a sprite when moving pad and send position to the
serveur
- can listen to the server, receving the position and display the
other sprite at the position

I've try something like this, but I encounter a lot of slowness .

My question is : is this the good philosophy ?
I try to send data trough network (wifi capability), but despite the
very little amount of data sended, the game is too slow.
How can real game do with sending many many data during a game ?

Thanks for your answers.

Basically, that's how it works. A client sends a message to the server
saying, "I'm moving to X,Y,Z". The server checks and makes sure it's a
legal move, if so sends the information to all (see note) clients in the
area that player A moved to X,Y,Z.

Now, with internet lag the way it is, this can take some time.A ping time to
a game server under 100ms is considered good (for some games). Lower is
better of course. So, client A sends message which takes 100ms (1/10
second) to reach the server. The server confirms the move and sends to the
client(s) the move. Which takes 100ms to reach them. This is 2/10 of a
second or 1/5 of a second. With this type of movment a player will seem to
jump from place to place.

What a lot of games do is some type of prediction or timing. For a 3D game
it may be more like client A sends to server I'm moving toward X,Y,Z.
Server checks the speed of the character. Sends to clients, Player A moving
to X,Y,Z at speed so and so. It may give some timing information (or not).
Now, at this points the clients can figure out where player A will be
between the 1/5 jumps. It starts at X1,Y1,Z1 going to X2,Y2,Z2 which will
take 1 second to get there (or whatever). It can then predict where that
client will be at any given time, and show them there.

This can be seen in some games when you see another player move across the
screen, then run back to a previous postion. What actually happened was the
client said they were running toward X,Y,Z, the server sent messages saying
they were running, then somewhere a lag spike happened. Maybe player A's
computer lagged and had sent the message to stop running, the the server
didnt' get it for a second or two. Or the server to your client lagged out
and your client never received the message they stopped running. Eventually
the server sends the message that player A is actually at X3,Y3,Z3 and your
client says, hmm, I see them way over here, better move them back.

You can usually never have each client know exactly where other
characters/mobs are at any given millisecond, but you can make it appear as
if the client actually does know.

Try a google link for
prediction game server client
and look at the results.http://www.google.com/search?hl=en&q=prediction+game+server+client
The first hit seems interesting although I didn't read it. Its titled
"Latency Compensating Methods in Client/Server In-game Protocol Design and
Optimization"http://www.resourcecode.de/stuff/clientsideprediction.pdf

thanks all for your answers ... it's seems to be more difficult than
want i thought.
In fact, i'm almost sure that i'm saturate the network by sending the
position each time it changes, that means, during the time i'm holding
the arrow key, my sprite is moving, and each moves send a position.
To go from pos (1,1) to pos (100, 1), i'm sending 50 positions (moves
increments position by 2).
Should i limit the number of positions ? Should i send the positions
only at a certain date ? (for example each 500 ms ?)

thanks for your help

.

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