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Projectiles with Client Prediction

Discussion in 'Netcode for GameObjects' started by LazyDog_Rich, May 15, 2023.

  1. LazyDog_Rich

    LazyDog_Rich

    Joined:
    Apr 27, 2014
    Posts:
    70
    Hi all!

    I am making a game that uses netcode + relay. And I've implemented client prediciton and server reconciliation, and everything seems to works fine on movement.

    Now I am trying to implement projectiles, and the problem I am facing is, if server aims and hit the client, the client will lose life. But from the client point of view, he wasn't hit at all, because is a bit ahead.

    What would be the best approach for projectiles along client prediction?

    I have this small test set up. If you are the server you are seeing the "real" positions of everyone. If you are a client you are using client prediction, and there's a gray shadow of yourself that shows you were you are acording to the server:
    https://rich4444.github.io/onlinetest2/
     
    LazyDog_Rich, May 15, 2023
    #1

  2. CodeSmile

    CodeSmile

    Joined:
    Apr 10, 2014
    Posts:
    4,108
    You also need to implement server-side rollback to simulate a client event at the time the client issued the event, with all the game state rolled back to the client's timestamp. Basically you want to determine whether a shot was a hit at some time in the past with the simulation state at that point in time.

    Fish-Net has this implemented if I remember correctly, you may want to look through the codebase to get an understanding how this works. For Netcode it's on the Roadmap.
     
    CodeSmile, May 15, 2023
    #2

  3. LazyDog_Rich

    LazyDog_Rich

    Joined:
    Apr 27, 2014
    Posts:
    70
    I already have server reconciliation, when there's a mismatch, I rollback the client to the mismatch momento, fix it, and replay all the inputs. Is that what you mean?

    What is fish-net? Could you provide me some link to take a look? Sorry I am so lost, this is my first attemp at doind a multiplayer game
     
    LazyDog_Rich, May 15, 2023
    #3

  4. NoelStephens_Unity

    NoelStephens_Unity

    Unity Technologies

    Joined:
    Feb 12, 2022
    Posts:
    50
    LazyDog_Rich,

    If I understand your dilemma, you have client prediction with owner/client authoritative NetworkTransforms but you have server authoritative projectiles that visually seem to be out of sync on the client side relative to the client's player object and thus when a server detects a hit, for the client being hit, the visual of the projectile does not look accurate (i.e. doesn't look like the client's player was hit)?

    I have two possible ways to help with the visual alignment issue, but first want to confirm that this is the issue you are having.
     
    NoelStephens_Unity, May 15, 2023
    #4

  5. LazyDog_Rich

    LazyDog_Rich

    Joined:
    Apr 27, 2014
    Posts:
    70
    Yes that's exactly the problem I'm facing! I have been trying different approach but nothing seems to work :(
     
    LazyDog_Rich, May 16, 2023
    #5

  6. CodeSmile

    CodeSmile

    Joined:
    Apr 10, 2014
    Posts:
    4,108
    CodeSmile, May 16, 2023
    #6

  7. LazyDog_Rich

    LazyDog_Rich

    Joined:
    Apr 27, 2014
    Posts:
    70
    Oh I see, I'll take a look at it thanks! But I hope @NoelStephens_Unity can give me some help so I can make it work with netcode!
     
    LazyDog_Rich, May 17, 2023
    #7