5 ms·

If you can figure out a way to only send inputs for each player instead of their full state, it should significantly reduce network traffic and lag for each pla

If you can figure out a way to only send inputs for each player instead of their full state, it should significantly reduce network traffic and lag for each player-- right now it's sending ~1KB/frame!

airhead969 5y ago
Operational transformations (OTs).
- kgwxd 5y ago
  I don't see "game" mentioned in the wiki at all. Is that something typically used for games or do they tend to use something else?
  - sib301 5y ago
    Collaborative text editing is what it’s traditionally used for.
    - airhead969 5y ago
      It can also be used to mutate hard game state (I wouldn't try it with dynamic, interpolated values like object position, angle, acceleration, or velocity.) There are many other methods, some are more precise and compressible than others: Trailing State Synchronization https://www.cs.ubc.ca/~krasic/cpsc538a/summaries/38/ https://www.cs.ubc.ca/~krasic/cpsc538a/summaries/38/ Basic ideas https://www.gafferongames.com/post/state_synchronization/ https://www.gafferongames.com/post/state_synchronization/ https://engineering.monstar-lab.com/2021/02/09/Game-server-Synchronization https://engineering.monstar-lab.com/2021/02/09/Game-server-S... https://www.gabrielgambetta.com/client-side-prediction-server-reconciliation.html https://www.gabrielgambetta.com/client-side-prediction-serve...
rtkwe 5y ago
You'd have to resync fairly often to avoid desync especially for Joust where positioning during fighting is pretty important.
- Scaevolus 5y ago
  Desync is possible with UDP protocols, where a dropped packet would mean lost inputs, but this uses websockets, which are reliable TCP connections, so just the list of inputs combined with a deterministic engine is sufficient.
  - rtkwe 5y ago
    They can arrive out of order so you still have to deal with rewinding an re'simulating' the whole sequence of moves since the skipped packet then dealing with resolving the client vs server when they disagree.
    - armatav 5y ago
      The TCP connection is never closed with websockets.
      - rtkwe 5y ago
        That doesn't change that TCP packets can arrive out of order does it? (It's been a while since my college networking class and it's not something I come into contact with in my job)
jasonkester 5y ago
Yeah, 700b for 20 players, and normally at least somebody does something every tick, so that will go out 30 times per second. It still only works out to 24kbps, so you might not need to upgrade the modem you had back when the original was in the arcades. I tried only sending updates every 3rd tick, but even there I could notice the difference. You're right that it'd be worth experimenting with sending keystrokes instead, and backing off the full resync to once/second or so.

airhead969 5y ago

Operational transformations (OTs).

kgwxd 5y ago
I don't see "game" mentioned in the wiki at all. Is that something typically used for games or do they tend to use something else?
- sib301 5y ago
  Collaborative text editing is what it’s traditionally used for.
  - airhead969 5y ago
    It can also be used to mutate hard game state (I wouldn't try it with dynamic, interpolated values like object position, angle, acceleration, or velocity.) There are many other methods, some are more precise and compressible than others: Trailing State Synchronization https://www.cs.ubc.ca/~krasic/cpsc538a/summaries/38/ https://www.cs.ubc.ca/~krasic/cpsc538a/summaries/38/ Basic ideas https://www.gafferongames.com/post/state_synchronization/ https://www.gafferongames.com/post/state_synchronization/ https://engineering.monstar-lab.com/2021/02/09/Game-server-Synchronization https://engineering.monstar-lab.com/2021/02/09/Game-server-S... https://www.gabrielgambetta.com/client-side-prediction-server-reconciliation.html https://www.gabrielgambetta.com/client-side-prediction-serve...

rtkwe 5y ago

You'd have to resync fairly often to avoid desync especially for Joust where positioning during fighting is pretty important.

Scaevolus 5y ago
Desync is possible with UDP protocols, where a dropped packet would mean lost inputs, but this uses websockets, which are reliable TCP connections, so just the list of inputs combined with a deterministic engine is sufficient.
- rtkwe 5y ago
  They can arrive out of order so you still have to deal with rewinding an re'simulating' the whole sequence of moves since the skipped packet then dealing with resolving the client vs server when they disagree.
  - armatav 5y ago
    The TCP connection is never closed with websockets.
    - rtkwe 5y ago
      That doesn't change that TCP packets can arrive out of order does it? (It's been a while since my college networking class and it's not something I come into contact with in my job)

jasonkester 5y ago

Yeah, 700b for 20 players, and normally at least somebody does something every tick, so that will go out 30 times per second. It still only works out to 24kbps, so you might not need to upgrade the modem you had back when the original was in the arcades. I tried only sending updates every 3rd tick, but even there I could notice the difference. You're right that it'd be worth experimenting with sending keystrokes instead, and backing off the full resync to once/second or so.