FSCKING LAG

A lightning talk on multiplayer networking that we gave at /dev/world/2015.

Transcript

1. View Slide

2. FSCKING LAG
   

   View Slide

3. Video Games!
   

   View Slide

4. Multi-player video
   games!
   

   View Slide

5. Server
   

   View Slide

6. Server
   Client Client Client
   

   View Slide

7. Server
   Client Client Client
   

   View Slide

8. Server
   Client
   

   View Slide

9. Server
   Client
   “I just killed player 1”
   

   View Slide

10. Server
    Client
    “I just killed player 1”
    “ok”
    

    View Slide

11. Server
    Client
    “I just killed player 1”
    “ok”
    BAD
    

    View Slide

12. Server
    Client
    “I pressed
    these buttons”
    “This is where
    things are”
    

    View Slide

13. Server
    Client
    “I pressed
    these buttons”
    “This is where
    things are”
    BETTER
    

    View Slide

14. PROBLEM
    

    View Slide

15. 1 2
    Lag = 1 second Lag = 0.1 seconds
    

    View Slide

16. 1
    2
    Shoots!
    Runs!
    FROM PLAYER 1’S PERSPECTIVE:
    

    View Slide

17. Server
    Player 1 Player 2
    

    View Slide

18. Server
    Player 1 Player 2
    “I’m shooting!”
    (1 second ago)
    

    View Slide

19. Server
    Player 1 Player 2
    “I’m shooting!”
    (1 second ago)
    “I’m running around
    the corner!”
    (0.1 second ago)
    

    View Slide

20. Server
    Player 1 has shot, and
    Player 2 is around the corner.
    Player 1’s shot missed.
    

    View Slide

21. Server
    Player 1 Player 2
    “Player 2 is now
    around the corner.
    Player 1 shot, but
    missed.”
    

    View Slide

22. Counter-Strike
    

    View Slide

23. Server
    Player 1 shot, and at the
    time, they were aiming at
    Player 2. Their should would
    have hit.
    

    View Slide

24. Server
    Player 1 Player 2
    “Player 1 shot
    Player 2.”
    

    View Slide

25. Server
    Player 1 Player 2
    “Player 1 shot
    Player 2.”
    “Oh, and Player
    2 still ran
    around the
    corner. lol.”
    

    View Slide

26. Server
    Player 1 Player 2
    “Player 1 shot
    Player 2.”
    “Oh, and Player
    2 still ran
    around the
    corner. lol.”
    wtf
    

    View Slide

27. Age of Empires
    

    View Slide

28. 1500 Archers on a 28.8:
    Network Programming
    in Age of Empires and
    Beyond
    Mark Terrano, Paul Bettner
    

    View Slide

29. PROBLEM:
    1500 archers
    Each one has a position
    Each one is moving
    

    View Slide

30. Each position is
    about 4 bytes each
    

    View Slide

31. 4 bytes ✕ 1500 =
    6000 bytes
    

    View Slide

32. 6000 bytes ✕ 30
    frames/sec
    = 175 kB/s
    

    View Slide

33. SOLUTION:
    

    View Slide

34. DON’T SYNC STATE
    

    View Slide

35. SYNC PLAYER INTENT
    

    View Slide

36. Client
    Client
    Client
    

    View Slide

37. Client
    Client
    Client
    “I told my
    archers to move.”
    

    View Slide

38. Client
    Client
    Client
    “I told my
    archers to move.”
    “I told a villager to
    gather wood.”
    

    View Slide

39. Client
    Client
    Client
    Wait for everyone to finish this frame….
    

    View Slide

40. Client
    Client
    Client
    Archers are moving, and the
    villager is gathering wood.
    

    View Slide

41. NOT PERFECT
    

    View Slide

42. RUNS AT THE
    SLOWEST PLAYER
    

    View Slide

43. DESYNCS
    

    View Slide

44. @thesecretlab
    rocketboxgame.tumblr.com
    

    View Slide