PortalSO.cs

using System;
using System.Linq;
using Game;
using UnityEditor;
using UnityEngine;

namespace SceneManagement
{
    [CreateAssetMenu(fileName = "New Portal", menuName = "RPG/Portal")]
    [Serializable]
    public class PortalSo : ScriptableObject
    {
        [SerializeField] private SceneReference sceneToLoad;
        [SerializeField, HideInInspector] private PortalSo portalData;

        public SceneReference SceneToLoad
        {
            get => sceneToLoad;
            set => sceneToLoad = value;
        }

        public PortalSo PortalData
        {
            get => portalData;
            set => portalData = value;
        }
    }

#if UNITY_EDITOR
    [CustomEditor(typeof(PortalSo))]
    public class PortalSoEditor : Editor
    {
        private PortalSo portalSo;
        private PortalSo[] portalSos;
        private int selectedIndex;
        private string[] portalNames;

        private void OnEnable()
        {
            portalSo = target as PortalSo;

            if (portalSo is null)
                return;

            portalSos = Utilities.GetAllInstances<PortalSo>();

            portalNames = new string[portalSos.Length];
            selectedIndex = portalSos.ToList().IndexOf(portalSo.PortalData);

            for (int i = 0; i < portalSos.Length; i++)
                portalNames[i] = portalSos[i].name;
        }

        public override void OnInspectorGUI()
        {
            base.OnInspectorGUI();
            selectedIndex = EditorGUILayout.Popup(new GUIContent("Portal Data"), selectedIndex, portalNames);
            portalSo.PortalData = portalSos[selectedIndex];

            EditorUtility.SetDirty(target);
        }
    }
#endif
}