📜POOL MANAGER CLASS

Breakdown of Pool Manager Class

SCRIPT DETAILS

Pool Manager Class should be a singleton for easy accessibility

GOAL

The goal of the Pool Manager Class is to manage pools of gameobjects the program will need to recycle through

FEATURES

The Pool Manager Class should have methods that can handle the following features:

1. Ability to pre-generate a list of bullet prefabs ---> Create a pool of bullet prefabs ---> Dynamically grow list as needed

2. Return requested bullets when triggered to

FULL SCRIPT

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

public class PoolManager : MonoBehaviour
{

    private static PoolManager _instance;
    public static PoolManager Instance
    {
        get
        {
            if (_instance == null)
                Debug.LogError("The PoolManager is NULL.");

            return _instance;
        }
    }

    private void Awake()
    {
        _instance = this;
    }

    [SerializeField]
    private GameObject _bulletContainer;
    [SerializeField]
    private GameObject _bulletPrefab;
    [SerializeField]
    private List<GameObject> _bulletPool;
    
    void Start()
    {
        GenerateBullets(2);
    }

  
    private List<GameObject> GenerateBullets(int ammountOfBullets)
    {
        for(int i=0; i < ammountOfBullets; i++)
        {
            GameObject bullet = Instantiate(_bulletPrefab);
            bullet.transform.parent = _bulletContainer.transform;
            bullet.SetActive(false);
            _bulletPool.Add(bullet);
        }
        
        return _bulletPool;
    }

    public GameObject RequestBullet()
    {
        foreach(var bullet in _bulletPool)
        {
            if(bullet.activeInHierarchy == false)
            {
                bullet.SetActive(true);
                return bullet;
            }
        }
        GameObject newBullet = Instantiate(_bulletPrefab);
        newBullet.transform.parent = _bulletContainer.transform;
        _bulletPool.Add(newBullet);
        
        return newBullet;
    }
}

SCRIPT BREAKDOWN

SINGLETON

private static PoolManager _instance;
public static PoolManager Instance
{
    get
    {
        if (_instance == null)
            Debug.LogError("The PoolManager is Null");

        return _instance;
    }
}

private void Awake()
{
    _instance = this;
}

VARIABLES

[SerializeField]
private GameObject _bulletContainer;
[SerializeField]
private GameObject _bulletPrefab;
[SerializeField]
private List<GameObject> _bulletPool;

_bulletContainer --> Empty parent container for unity hierarchy organization

_bulletPrefab --> Bullet prefab reference

_bulletPool --> List of bullet objects in our pool

Start()

private void Start()
{
    _bulletPool = GenerateBullets(10);
}

• LINE 3 --> Triggers the GenerateBullets() method to create a pool of 10 bullets upon the start of the program

GenerateBullets(int amountOfBullets)

GOALS --> Create a pool of bullet prefabs

List<GameObject> GenerateBullets(int amountOfBullets)
{
    for (int i = 0; i < amountOfBullets; i++)
    {
        GameObject bullet = Instantiate(_bulletPrefab);
        bullet.transform.parent = _bulletContainer.transform;
        bullet.SetActive(false);
        _bulletPool.Add(bullet);
    }
    return _bulletPool;
}

• LINE 1 --> Return type method that generates the bullet pool

  • LINE 3 --> For loop that runs for each bullet prefab that is generated

    • LINE 5 --> Each generated bullet is a copy of the bullet prefab

    • LINE 6 --> Each bullet is placed within the bullet container to keep the hierarchy organized

    • LINE 7 --> Each bullet is set to inactive until needed

  • LINE 8 --> Each bullet is added to the bullet Pool list

  • LINE 10 --> Once list is generated, it is returned to the program

RequestBullet()

GOAL --> Return requested bullets when triggered to & Dynamically Grow List as Needed

public GameObject RequestBullet()
{
    foreach (var bullet in _bulletPool)
    {
        if (bullet.activeInHierarchy == false)
        {
            bullet.SetActive(true);
            return bullet;
        }
    }
    GameObject newBullet = Instantiate(_bulletPrefab);
    newBullet.transform.parent = _bulletContainer.transform;
    _bulletPool.Add(newBullet);
   
     return newBullet;
}

• LINE 1 --> PUBLIC method to return requested Bullet GameObjects

  • LINE 3 --> Foreach loop that runs to make sure there is an inactive bullet prefab within the bulletPool

    • LINE 5 --> If statement that runs if a bullet prefab is found inactive

      • LINE 7 --> Sets bullet prefab active

      • LINE 8 --> Returns bullet Prefab | breaks out of method

  The following code runs IF the program finds all bullet prefabs active

  • LINE 11 --> Instantiates a new bullet prefab

  • LINE 12 --> Places newly instantiated bullet within the bullet container for hierarchy organization

  • LINE 13 --> Adds newly instantiated bullet prefab to the pool

  • LINE 15 --> Returns newly instantiated bullet

NOTES

ActiveInHierarchy vs ActiveSelf

Within line 5 of the RequestBullet() Method, we notice that within the if statement there is a snippet of code that states bullet.activeInHierarchy.

activeInHierarchy returns a bool value determined by if a gameObject is active within the scene

--> Only returns true if BOTH the gameObject and ALL it's parent objects are active

activeSelf returns the local active state of the gameobject

--> GameObject may be inactive because a parent is not active, even if it returns true