クソ雑に使えるオブジェクトプール

GameObjectPool.cs

using System.Collections.Generic;
using UnityEngine;

namespace FriendSea
{
	public static class GameObjectPool
	{
		static Dictionary<GameObject, GameObject> instance2prefab = new Dictionary<GameObject, GameObject>();
		static Dictionary<GameObject, Stack<GameObject>> prefab2pool = new Dictionary<GameObject, Stack<GameObject>>();

		public static GameObject Instantiate(GameObject original, Vector3 position, Quaternion rotation, Transform parent = null)
		{
			if (!prefab2pool.ContainsKey(original))
				prefab2pool.Add(original, new Stack<GameObject>());

			if (prefab2pool[original].Count <= 0)
			{
				var instance = GameObject.Instantiate<GameObject>(original, position, rotation, parent);
				instance2prefab.Add(instance, original);
				return instance;
			}
			else
			{
				var instance = prefab2pool[original].Pop();
				instance.transform.parent = parent;
				instance.transform.SetPositionAndRotation(position, rotation);
				instance.SetActive(true);
				return instance;
			}
		}

		public static void Destroy(GameObject gameObject)
		{
			gameObject.SetActive(false);
			prefab2pool[instance2prefab[gameObject]].Push(gameObject);
		}

		public static void ClearAll()
		{
			foreach (var pool in prefab2pool.Values)
				foreach (var obj in pool)
					if (obj != null)
						GameObject.Destroy(obj);
			prefab2pool.Clear();
			instance2prefab.Clear();
		}

		[RuntimeInitializeOnLoadMethod]
		static void RegisterClear() =>
			UnityEngine.SceneManagement.SceneManager.sceneUnloaded += _ => ClearAll();
	}
}