【Unity】オブジェクトプーリングでオブジェクト節約術

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

public class ObjectPool : MonoBehaviour {
    private List<GameObject> _poolObjList;
    private GameObject _poolObj;

    // オブジェクトプールを作成
    public void CreatePool(GameObject obj, int maxCount){
        _poolObj = obj;
        _poolObjList = new List<GameObject>();
        for (int i = 0; i < maxCount; i++) {
            var newObj = CreateNewObject();
            newObj.SetActive(false);
            _poolObjList.Add(newObj);
        }
    }

    public GameObject GetObject(){
        // 使用中でないものを探して返す
        foreach (var obj in _poolObjList) {
            if (obj.activeSelf == false) {
                obj.SetActive(true);
                return obj;
            }
        }

        // 全て使用中だったら新しく作って返す
        var newObj = CreateNewObject();
        newObj.SetActive(true);
        _poolObjList.Add(newObj);

        return newObj;
    }

    private GameObject CreateNewObject(){
        var newObj = Instantiate(_poolObj);
        newObj.name = _poolObj.name + (_poolObjList.Count + 1);

        return newObj;
    }

}

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

[RequireComponent(typeof(ObjectPool))]
public class BulletCreator : MonoBehaviour {

    [SerializeField] private GameObject _bulletPrefab;
    private const int BULLET_MAX = 50;
    private int _state = 0;
    private float _originDirection = 0.0f;
    private bool _isReverse = false;
    private ObjectPool _pool;

    private void Awake () {
        _pool = GetComponent<ObjectPool>();
        _pool.CreatePool(_bulletPrefab, BULLET_MAX);
    }

    // Update is called once per frame
    void Update () {
        if (_state % 30 == 0) {
            var way = 16; // 16方向
            for (int i = 0; i < way; i++) {
                var bullet = _pool.GetObject();
                if (bullet != null) {
                    bullet.GetComponent<Bullet>().Initialize(_originDirection + i * (360.0f / way), _isReverse);
                }
            }
            // 発射のたびに10度ずつ回転し、弾の回転方向を反転
            _originDirection = (_originDirection + 10) % 360;
            _isReverse = !_isReverse;
        }
        _state++;
    }
}

using UnityEngine;
using System.Collections;

public class Bullet : MonoBehaviour {

    private float _speed = 4.0f;
    private float _direction;
    private bool _isReverse;
    private Rigidbody2D _rigidBody;

    public void Initialize(float direction, bool isReverse){
        _direction = direction;
        _isReverse = isReverse;
        _rigidBody = GetComponent<Rigidbody2D>();

        if (_isReverse) {
            GetComponent<SpriteRenderer>().color = new Color(1.0f, 0.3f, 0.3f); // 赤っぽい色
        } else {
            GetComponent<SpriteRenderer>().color = Color.white;
        }

        SetDirection();
    }

    public void Update(){
        if (_isReverse) {
            _direction = (_direction - 1) % 360;
        } else {
            _direction = (_direction + 1) % 360;
        }
        SetDirection();
    }

    public void OnBecameInvisible(){
        gameObject.SetActive(false);
        ResetPosition();
    }

    private void SetDirection(){
        Vector2 v;
        v.x = Mathf.Cos(Mathf.Deg2Rad * _direction) * _speed;
        v.y = Mathf.Sin(Mathf.Deg2Rad * _direction) * _speed;

        _rigidBody.velocity = v;
    }

    private void ResetPosition(){
        _rigidBody.velocity = Vector2.zero;
        transform.localPosition = Vector3.zero;
    }
}