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Question How to use Actions correctly in multiplayer games ?

Discussion in 'Netcode for GameObjects' started by edin97, Sep 17, 2022.

  1. edin97


    Aug 9, 2021
    I'm having trouble using Actions for my multiplayer game.

    I have a shop, on item purchased I want to invoke a unity Action so my other classes can do their job on item purchased. Before confirming the purchase, I ask the server if the player has enough money, since Rpc's always return void, I'm using a bool NetworkVariable (HasPlayerEnoughMoney) , which the server sets to true if the player has enough money. If the player has enough money, I send an Action OnItemPurchased. Issue is : I subscribe to this HasPlayerEnoughMoney.OnValueChanged and OnItemPurchased with every player. So for some reason when the host buys an item, it deducts money from other players too. (clients buying doesn't take money from server) BUT, replacing the OnItemPurchased Action invoke by simple functions calls, works. no issues.

    Here are the simple methods : Both scripts are on a player -> if we have 2 players, each script will be read 4 times here (owner+copy on both sides.)
    Code (CSharp):
    2.     private void OnEnable()
    3.     {
    4. // HasPlayerEnoughMoney is the bool NetworkVariable which the server sets to true if player has enough money
    5.         playerMoneyHandler.HasPlayerEnoughMoney.OnValueChanged += AllowPurchase;
    6.     }
    7.     private void OnDisable()
    8.     {
    9.         playerMoneyHandler.HasPlayerEnoughMoney.OnValueChanged -= AllowPurchase;
    10.     }
    11.     private void AllowPurchase(bool oldValue, bool newValue)
    12.     {
    13.         if (!IsOwner) { return; }
    14.         // IF ENOUGH MONEY TO BUY
    15.         if (newValue)
    16.         {
    17.             // THIS IS THE ISSUE : all players access this section ?? and call action on their side ?
    18.             ActionsPlayer.OnItemPurchased?.Invoke(lastCollectibleConsidered); // ISSUE
    20.             // SIMPLE FUNCTION CALLS : SOLUTION
    21.             //playerMoneyHandler.AddMoney(-lastCollectibleConsidered.CollectibleValue);
    22.             //playerMagickHandling.AddMojosRecievedOnCollecting(lastCollectibleConsidered);
    23.             //playerInventoryManager.AddCollectibleInInventory(lastCollectibleConsidered);
    24.             //playerAbilitiesHandler.AddCollectedScroll(lastCollectibleConsidered);
    25.         }
    26.         else
    27.         {
    28.             if (Debug.isDebugBuild) { print("NOT ENOUGH MONEY : "); }
    29.         }
    30.     }
    32. // INPUT : left mouse click -> confirm buy  
    33. private void PlayerWantsToConfirmBuy(InputAction.CallbackContext callbackContext)
    34.     {
    36.         if (IsOwner) playerMoneyHandler.HasPlayerEnoughMoneyToBuy(lastCollectibleConsidered.CollectibleValue);
    37.     }
    this is for example one of the methods that subscribes to OnItemPurchased :
    Code (CSharp):
    2.     private void OnEnable()
    3.     {
    4.         Money.OnValueChanged += OnMoneyChanged;
    5.         ActionsPlayer.OnItemPurchased+= PayCollectibleValue;
    6.     }
    8.     private void OnDisable()
    9.     {
    10.         Money.OnValueChanged -= OnMoneyChanged;
    11.         ActionsPlayer.OnItemPurchased-= PayCollectibleValue;
    13.     private void AddMoney_Network(float amount)
    14.     {
    15.         if (Money.Value + amount <= 0.0f) { Money.Value = 0.0f; }
    16.         else { Money.Value += amount; }
    17.     }
    19.     public void AddMoney(float amount)
    20.     {
    21.         if (IsServer)
    22.         {
    23.             AddMoney_Network(amount);
    24.         }
    25.         else
    26.         {
    27.            if (IsOwner) ManageMoneyOnServerRpc(amount, 1);
    28.         }
    29.     }
    30.     private void PayCollectibleValue(CollectibleScriptableObject collectible)
    31.     {
    32.         AddMoney(-collectible.CollectibleValue);
    33.     }
    34.     }
    Can someone tell me what I'm doing wrong here please ? I would prefer using actions so I don't have to make my methods public. Also I don't understand how the action is been called from 2 different players since I use an input to ask the server if the player has enough money. Input should be read only on the owner player since the copy doesn't recieve inputs ? Thanks in advance.
  2. SamuelBellomoUnity


    Unity Technologies

    Sep 24, 2020
    Is this a client hosted game or a dedicated game server? Cause you usually don't want to have monetization controlled by a client, that'd be exposed to cheating super easily. You'd want a service for this or use a DGS.
    If on DGS, netvars are replicated by default to all clients. so a netvar change server side will get replicated to all clients. you'd either want to change your read permissions on the netvar or use a client RPC. For a transitory event like this, I'd use a client RPC (see this page you don't need state tracking over multiple frames for this.
    REDACT3D_ and CreativeChris like this.