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I'm wondering what's the best way to to implement the networking model for a game like agar.io - I'm assuming it's an authoritative server, but I'm wondering about:

  1. Does every player "owns" his position, and sends it to the server, or does every player merely sends his input and everything is fully authoritative on the server?
  2. How does it decide what data to send to which player? I'm assuming that for every player I would have to iterate on all players in the server and check if they are currently (or soon to be) visible, and if so begin sending data on them
  3. Where do the actual collisions happen, and how to handle lag?

I'm well aware of the ways to handle this in an FPS game (player prediction, rewind replay, lag compensation, etc) - but it's usually done on a much smaller scale, and I assume a simpler solution is good enough for a casual game like that with thousands of concurrent players.

Ron
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1 Answers1

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the model in agario is shown by 2 things:

  1. You can see other players eating the same dots, so that shows the players are receiving the positions of all players (probably around 5 times a second) and then the dots appearing and disappearing are handled client side. If the dots weren't handled client side that would cost huge bandwidth. That also means that you receive a message containing positions of all dots on startup, which makes sense because not all the dots are there in the beginning
  2. The inputs from players to server are sent as opposed to positions, because otherwise it would be extremely hackable. The logic for collisions are then handled on the server

If the other player's inputs were broadcasted (instead of positions) from the server to the clients after the server got them small differences would build up like the butterfly effect and cause chaos

I'm pretty sure the inputs are only sent 5 times per second because there's a problem with websockets that causes packets sent more than 5 times per second to be clumped together

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hydrix
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