LogGui, Unity log on screen, Screen Log.

LogGui.cs

using System.Collections.Generic;
using UnityEngine;

namespace Plugins.FanhlCores.Tools
{
    public class LogGui : MonoBehaviour
    {
        private const int MaxChars = 10000;

        private static LogGui sInstance;

        private readonly Queue<string> logQueue = new();
        private string log;

        void Awake()
        {
            if (sInstance == null)
            {
                sInstance = this;
                DontDestroyOnLoad(gameObject);
            }
            else
            {
                Destroy(gameObject);
                return;
            }
        }

        void Start()
        {
            Debug.Log("LogGui start.");
        }

        void OnEnable()
        {
            Application.logMessageReceived += HandleLog;
        }

        void OnDisable()
        {
            Application.logMessageReceived -= HandleLog;
        }

        void HandleLog(string logString, string stackTrace, LogType type)
        {
            logQueue.Enqueue("\n [" + type + "] : " + logString);
            if (type == LogType.Exception)
                logQueue.Enqueue("\n" + stackTrace);
        }

        void Update()
        {
            while (logQueue.Count > 0)
                log = logQueue.Dequeue() + log;
            if (log.Length > MaxChars)
                log = log.Substring(0, MaxChars);
        }

        void OnGUI()
        {
            GUILayout.Label(log);
        }
    }
}