Test-Multiplayer/Assets/Scripts/Chat/Player.cs

using UnityEngine;
using Mirror;

// Networked player. This is the authority object used to run Commands.
public class Player : NetworkBehaviour
{
    [SyncVar(hook = nameof(OnNameChanged))]
    public string playerName;

    [Header("Name Tag")]
    [Tooltip("Optional prefab for the name tag. If empty a simple 3D TextMesh will be created.")]
    [SerializeField] private GameObject nameTagPrefab;
    [SerializeField] private float nameTagHeight = 0.2f;

    // runtime instance of the name tag
    private GameObject nameTagInstance;
    private TextMesh nameTagTextMesh;

    public override void OnStartServer()
    {
        playerName = (string)connectionToClient.authenticationData;
    }

    public override void OnStartClient()
    {
        base.OnStartClient();
        CreateNameTag();
        // initialize text from current syncvar value
        UpdateNameTagText(playerName);
    }

    public override void OnStartLocalPlayer()
    {
        // initialize local UI
        var ui = FindFirstObjectByType<ChatUI>();
        if (ui != null)
        {
            ui.Initialize(this);
            ChatUI.localPlayerName = playerName;
        }

        // request history from server
        if (isLocalPlayer)
            CmdRequestHistory();
    }

    public override void OnStopClient()
    {
        base.OnStopClient();
        if (nameTagInstance != null)
        {
            Destroy(nameTagInstance);
            nameTagInstance = null;
            nameTagTextMesh = null;
        }
    }

    void OnNameChanged(string oldName, string newName)
    {
        if (isLocalPlayer)
            ChatUI.localPlayerName = newName;

        UpdateNameTagText(newName);
    }

    // Called by the local ChatUI to send a message
    public void SendChatToServer(string message)
    {
        if (!isLocalPlayer) return;
        if (string.IsNullOrWhiteSpace(message)) return;
        CmdSendChat(message);
    }

    // Runs on server: store message and broadcast to all clients
    [Command]
    private void CmdSendChat(string message)
    {
        var manager = NetworkManager.singleton as ChatNetworkManager;
        manager?.AddServerMessage($"{playerName}: {message}");

        RpcReceiveChat(playerName, message);
    }

    // Runs on all clients: update local ChatUI
    [ClientRpc]
    private void RpcReceiveChat(string senderName, string message)
    {
        var ui = FindFirstObjectByType<ChatUI>();
        if (ui == null) return;

        var prettyMessage = senderName == ChatUI.localPlayerName ?
            $"<color=red>{senderName}:</color> {message}" :
            $"<color=blue>{senderName}:</color> {message}";

        ui.AddMessage(prettyMessage);
    }

    // Request history from server; server will reply with TargetReceiveHistory
    [Command]
    private void CmdRequestHistory()
    {
        var manager = NetworkManager.singleton as ChatNetworkManager;
        if (manager == null) return;

        var history = manager.GetHistory();
        TargetReceiveHistory(connectionToClient, history);
    }

    // Sent only to the requesting client
    [TargetRpc]
    private void TargetReceiveHistory(NetworkConnection target, string[] history)
    {
        var ui = FindFirstObjectByType<ChatUI>();
        if (ui == null) return;

        ui.SetHistory(history);
    }

    // Create a simple world-space name tag. If a prefab is assigned it will be instantiated instead.
    private void CreateNameTag()
    {
        if (nameTagInstance != null) return;

        if (nameTagPrefab != null)
        {
            nameTagInstance = Instantiate(nameTagPrefab, transform);
            nameTagInstance.transform.localPosition = new Vector3(0f, nameTagHeight, 0f);
            nameTagInstance.transform.localRotation = Quaternion.identity;
            // try to find either a TextMesh or legacy TextMesh in the prefab
            nameTagTextMesh = nameTagInstance.GetComponentInChildren<TextMesh>();
        }
        else
        {
            // create a simple 3D text (TextMesh) so no extra UI package is required
            nameTagInstance = new GameObject("NameTag");
            nameTagInstance.transform.SetParent(transform, false);
            nameTagInstance.transform.localPosition = new Vector3(0f, nameTagHeight, 0f);

            nameTagTextMesh = nameTagInstance.AddComponent<TextMesh>();
            nameTagTextMesh.alignment = TextAlignment.Center;
            nameTagTextMesh.anchor = TextAnchor.MiddleCenter;
            nameTagTextMesh.fontSize = 48;
            nameTagTextMesh.characterSize = 0.025f;
            nameTagTextMesh.color = Color.white;
        }
    }

    // Updates the name text if the name tag exists
    private void UpdateNameTagText(string name)
    {
        if (nameTagTextMesh != null)
        {
            nameTagTextMesh.text = string.IsNullOrEmpty(name) ? "Player" : name;
        }
    }

    // Keep the name tag facing the camera so it's readable
    private void LateUpdate()
    {
        if (nameTagInstance == null) return;

        Camera cam = Camera.main;
        if (cam == null) return;

        // billboard: rotate the name tag to face the camera
        Vector3 dir = nameTagInstance.transform.position - cam.transform.position;
        dir.y = 0f; // optional: keep upright
        if (dir.sqrMagnitude > 0.0001f)
            nameTagInstance.transform.rotation = Quaternion.LookRotation(dir);
    }
}