DebugPanel.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class DebugPanel : MonoBehaviour
{
    private static DebugPanel i;
    private void Awake()
    {
        i = this;
    }

    private struct Message
    {
        public string name;
        public string value;
    }

    private int msgCount = 0;
    private Message[] messages = new Message[256];

    public static void SetMessage(string name, object value)
    {
        i.setmsg(name, value.ToString());
    }

    public static void SetMessage(string name, string value)
    {
        i.setmsg(name, value);
    }

    private void setmsg(string name, string value)
    {
        if (!enabled)
            return;
        messages[msgCount].name = name;
        messages[msgCount].value = value;
        msgCount++;
    }

    private void OnGUI()
    {
        Event e = Event.current;
        

        int width = 200;
        int lineHeight = 20;
        Rect root = new Rect(20, 20, width, lineHeight * (msgCount + 2));

        GUI.Box(root, "");
        GUILayout.BeginArea(root);
        GUILayout.Label("Debug Panel");

        for (int i = 0; i < msgCount; i++)
        {
            GUILayout.BeginHorizontal();
            GUILayout.Label(messages[i].name);
            GUILayout.Label(messages[i].value);
            GUILayout.EndHorizontal();
        }

        GUILayout.EndArea();

        if(e.type == EventType.Repaint)
            msgCount = 0;

    }
}