How do I get a client side health bar to update? Netcode for gameobjects

Question

I am working on a multiplayer prototype and am trying to get health bars working. It's working on server side and health is working and subtracting from client side with a network variable, however I cannot get the slider to update properly.

   private void OnTriggerEnter(Collider other)
{
    if (IsServer)
    {
            if (other.GetComponent<PlayerNetworkHealth>() != null)
                other.GetComponent<PlayerNetworkHealth>().DepleteHealthClientRpc(damage);
    }         
}

  [ClientRpc]
public void DepleteHealthClientRpc(int value)
{
    if (!IsServer) return;

    health.Value -= value;


    healthBar.value = health.Value;

    if (health.Value <= 0)
        Debug.Log("Dead");

}

Any info would be appreciated. Im at a loss.

Answer 1

In Mirror (and thus in Unity Networking) you can annotate simple types with SyncVar and let the library handle the syncing. In addition you can define a hook that should be executed, when the value changes. Mirror Unity (The documentation is better in Mirror for this)

[SyncVar(hook = nameof(SetHealth))]
int playerHealth = 100;

void SetHealth(int oldValue, int newValue) {
   healthBar.value = newValue;
   if (newValue <= 0)
       Debug.Log("Dead");
}

However if you are sure that the value is getting updated correctly on the client,

  if (!IsServer) return; 

does not make much sense clientside. It will simply exit your setter and can't update your slider that way.

When you are new to networking, make sure that the test device is never in host (or server) mode when you want to test client code. Since host mode is both client and server in one, it can (and will) hide a lot of mistakes you can make like not actually syncing variables. But because you are both, you can always see the correct server value.