Portal.cs

using System.Collections;
using UnityEngine;
using UnityEngine.AI;
using UnityEngine.SceneManagement;
using Sirenix.OdinInspector;

namespace RPG.SceneManagement
{
    public class Portal : MonoBehaviour
    {
        enum DestinationIdentifier
        {
            A, B, C, D, E, F, G, H, I, J, K, L, M,
            N, O, P, Q, R, S, T, U, V, W, X, Y, Z
        }

        // Variables
        [BoxGroup("Portal Info")]
        [GUIColor(1f, 0.3f, 0.3f)]
        [SerializeField] int sceneToLoad = -1;
        [BoxGroup("Portal Info")]
        [GUIColor(0.3f, 0.3f, 1f)]
        [SerializeField] Transform spawnPoint;
        [BoxGroup("Portal Info")]
        [GUIColor(0.3f, 01f, 0.3f)]
        [SerializeField] DestinationIdentifier destination;
        [BoxGroup("Portal Info")]
        [GUIColor(0.3f, 0.3f, 0.3f)]
        [Range(0f, 10f)]
        [SerializeField] float fadeOutTime = 1f;
        [BoxGroup("Portal Info")]
        [GUIColor(1f, 0.3f, 1f)]
        [Range(0f, 10f)]
        [SerializeField] float fadeInTime = 2f;
        [BoxGroup("Portal Info")]
        [GUIColor(0f, 1f, 0.3f)]
        [Range(0f, 10f)]
        [SerializeField] float fadeWaitTime = 0.5f;

        void OnTriggerEnter(Collider other)
        {
            if(other.tag == "Player")
            {
                StartCoroutine(Transition());
            }
        }

        private IEnumerator Transition()
        {

            if(sceneToLoad < 0)
            {
                Debug.LogError("Scene to load not set.");
                yield break;
            }

            DontDestroyOnLoad(gameObject);

            Fader fader = FindObjectOfType<Fader>();

            yield return fader.FadeOut(fadeOutTime);

            SavingWrapper wrapper = FindObjectOfType<SavingWrapper>();
            wrapper.Save();

            yield return SceneManager.LoadSceneAsync(sceneToLoad);

            wrapper.Load();

            Portal otherPortal = GetOtherPortal();
            UpdatePlayer(otherPortal);

            yield return new WaitForSeconds(fadeWaitTime);
            yield return fader.FadeIn(fadeInTime);

            Destroy(gameObject);
        }

        private void UpdatePlayer(Portal otherPortal)
        {
            GameObject player = GameObject.FindWithTag("Player");
            player.GetComponent<NavMeshAgent>().Warp(otherPortal.spawnPoint.position);
            player.transform.rotation = otherPortal.spawnPoint.rotation;
        }

        private Portal GetOtherPortal()
        {
            foreach(Portal portal in FindObjectsOfType<Portal>())
            {
                if(portal == this) { continue; }
                if(portal.destination != destination) { continue; }

                return portal;
            }

            return null;
        }
    }
}