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How to set Object pooling correctly in 2D game?

I have a couple of problems with object pooling in Unity with my 2D game, cannon balls don't want to stop when there is a collision with the wall, and 1 of them bursts shoot and the other 9 shoot together connected with each other, my cannon is static object on scene. Can someone help or give me some hint about it.
Here is my code, 3 scripts:
ObjectPooling.cs
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class ObjectPooling : MonoBehaviour
{
public static ObjectPooling instance;
[SerializeField] public GameObject objectToPool;
private List<GameObject> cannonBalls = new List<GameObject>();
private int numberOfObjects = 20;
private void Awake()
{
instance = this;
}
// Start is called before the first frame update
void Start()
{
for (int i = 0; i < numberOfObjects; i++)
{
GameObject gameObject = Instantiate(objectToPool);
gameObject.SetActive(false);
cannonBalls.Add(gameObject);
}
}
// Update is called once per frame
void Update()
{
}
public GameObject GetCannonBallObject()
{
for (int i = 0; i < cannonBalls.Count; i++)
{
if (!cannonBalls[i].activeInHierarchy)
{
return cannonBalls[i];
}
}
return null;
}
}
Cannon.cs
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Cannon : MonoBehaviour
{
[SerializeField] private Rigidbody2D rb;
[SerializeField] private GameObject cannonBall;
[SerializeField] private Transform cannonBallPosition;
void Start()
{
}
private void Update()
{
Fire();
}
private void Fire()
{
cannonBall = ObjectPooling.instance.GetCannonBallObject();
if(cannonBall != null)
{
cannonBall.transform.position = cannonBallPosition.position;
cannonBall.SetActive(true);
}
}
}
CannonBall.cs
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class CannonBall : MonoBehaviour
{
private float speed = 10f;
[SerializeField] private Rigidbody2D rb;
// Start is called before the first frame update
void Start()
{
}
// Update is called once per frame
void Update()
{
rb.velocity = Vector2.left * speed;
}
private void OnCollisionEnter2D(Collision2D collision)
{
if (collision.gameObject.CompareTag("FloorAndWall"))
{
// Destroy(this.gameObject);
gameObject.SetActive(false);
}
}
}

Why is you cannonball static? Have your tried not having it marked as static? Also, this problem has nothing to do with object pooling. Make sure that when your objects are enabled, all the components are active. Finally, when working with rigidbodies, you should handle them inside FixedUpdate(), and not inside Update().

Sound not playing on last hit

I have a problem which is that my hurt sound doesn't play on last hit. On other hits it works very well. I think that its because of the gameObject getting destroyed. I have tried it by putting the script to my bullet and changing the tag. Also the Debug.Log works perfectly on last hit. I hope that somebody could help me.
Anyway, here's my code:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
public class HealthSystem : MonoBehaviour
{
public AudioSource source;
public AudioClip clip;
public Image healthBar;
public float healthAmount = 100;
public GameObject bullet;
void Start()
{
}
private void Update()
{
if(healthAmount <= 0)
{
Destroy(gameObject);
}
}
public void TakeDamage(float Damage)
{
source.PlayOneShot(clip);
healthAmount -= Damage;
healthBar.fillAmount = healthAmount / 100;
}
public void Healing(float healPoints)
{
healthAmount += healPoints;
healthAmount = Mathf.Clamp(healthAmount, 0, 100);
healthBar.fillAmount = healthAmount / 100;
}
private void OnTriggerEnter2D(Collider2D collision)
{
if (collision.CompareTag("Bullet"))
{
if (!source.isPlaying)
{
Debug.Log("i have are played");
TakeDamage(20);
}
}
}
}

Exactly as you said: Because your game object is getting destroyed with last bullet, the AudioSource is getting destroyed with it and it cannot play whole sound. What is the workaround? There are 2, you can either:
Spawn new GameObject just to play the sound and destroy it right after
Hide/disable the object (as if it is destroyed), play the sound and once sample is played, destroy it

Destroyed Bullet Won't Make Clones and Shoot After around 3 seconds

I made a script that shoots a bullet and destroys it after 3 seconds, however it destroys the original bullet after it is shot which makes unity unable to make copies of it to shoot another bullet, An okay solution might be to make a copy of the bullet and shoot the copy however I do not know how to do that.
This is the script for the gun
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class GunShootingScript : MonoBehaviour
{
public ParticleSystem MuzzleFlash;
public float damage = 10f;
public float range = 100f;
public GameObject bulletPrefab;
public float bulletLife = 3f;
public Camera playerCamera;
private void Update()
{
if(Input.GetKeyDown(KeyCode.Mouse0))
{
Destroy(bulletPrefab, bulletLife);
Shoot();
}
}
void Shoot()
{
MuzzleFlash.Play();
Instantiate(bulletPrefab, playerCamera.transform.position, playerCamera.transform.rotation);
RaycastHit hit;
if(Physics.Raycast(playerCamera.transform.position, playerCamera.transform.forward, out hit, range))
{
TakeDamage target = hit.transform.GetComponent<TakeDamage>();
if(target != null)
{
target.GiveDamage(damage);
}
}
}
}
This is the script for the bullet.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Shot : MonoBehaviour
{
// Start is called before the first frame update
public float speed = 3000f;
void Update()
{
transform.position += transform.forward * speed * Time.deltaTime;
}
}

From what I see, you destroy the bulletPrefab but you never actually assign an object for it. You can have a separate GameObject and do that when instantiating inside the Shoot method. Try this:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class GunShootingScript : MonoBehaviour
{
public ParticleSystem MuzzleFlash;
public float damage = 10f;
public float range = 100f;
public GameObject bulletPrefab;
public float bulletLife = 3f;
private GameObject bulletShot // This is what I added
public Camera playerCamera;
private void Update()
{
if(Input.GetKeyDown(KeyCode.Mouse0))
{
Destroy(bulletShot); // Removed the timer from here
Shoot();
}
}
void Shoot()
{
MuzzleFlash.Play();
bulletShot = Instantiate(bulletPrefab, playerCamera.transform.position, playerCamera.transform.rotation); // Assigned the bullet to the separate GameObject
RaycastHit hit;
if(Physics.Raycast(playerCamera.transform.position, playerCamera.transform.forward, out hit, range))
{
TakeDamage target = hit.transform.GetComponent<TakeDamage>();
if(target != null)
{
target.GiveDamage(damage);
}
}
}
}
That way, when you try to destroy it, there will actually be something to destroy. However, this will create a new issue. The previously instantiated object will be destroyed instantly when you shoot again. You can fix that by creating a list and adding the bullets there. However, that is NOT efficient. And since you are going to start all over, I suggest you go for an Object Pool. What is that? Glad you asked!
There is a very good video by Jason Weimann on YouTube about object pooling. You might want to give it a go, it is old but definitely not outdated.
https://www.youtube.com/watch?v=uxm4a0QnQ9E

You might need to keep a reference to the shot bullet, to be able to destroy with a coroutine after 3 seconds, it later on like this:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class GunShootingScript : MonoBehaviour
{
public ParticleSystem MuzzleFlash;
public float damage = 10f;
public float range = 100f;
public GameObject bulletPrefab;
public float bulletLife = 3f;
private Queue<GameObject> myQ = new Queue<GameObject>(); //queue to keep track of the shot bullet and handle the delayed destroy
private IEnumerator coroutine;
void Start() {
coroutine = DelayedDestroy(3f);
}
public Camera playerCamera;
private void Update()
{
if(Input.GetKeyDown(KeyCode.Mouse0))
{
//Destroy(bulletPrefab, bulletLife); Commented to avoid immediate destruction
Shoot();
}
}
void Shoot()
{
MuzzleFlash.Play();
myQ.Enqueue(Instantiate(bulletPrefab, playerCamera.transform.position, playerCamera.transform.rotation));
RaycastHit hit;
if(Physics.Raycast(playerCamera.transform.position, playerCamera.transform.forward, out hit, range))
{
TakeDamage target = hit.transform.GetComponent<TakeDamage>();
if(target != null)
{
target.GiveDamage(damage);
}
}
StartCoroutine(coroutine);
}
private IEnumerator DelayedDestroy(float waitTime) {
yield return new WaitForSeconds(waitTime);
GameObject nullcheck = myQ.Dequeue();
if (nullcheck != null) { //in case the queue is empty
Destroy(nullcheck );
}
}
}
Did not debug that, it is to give you the idea. You can check the Queue data structure and coroutines.
Check pooling to achieve what you are making even better :)

Having problems with "OnCollisionEnter2D" in Unity2D

I'm using this code:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
public class CollisionPlayer : MonoBehaviour
{
public bool alreadyDied = false;
public GameObject player;
public float timeDeath;
public ParticleSystem particles;
public GameObject explosionGO;
private SpriteRenderer sr;
private BoxCollider2D bc;
private PlayerController walkScript;
void Start()
{
sr = GetComponent<SpriteRenderer>();
bc = GetComponent<BoxCollider2D>();
walkScript = GetComponent<PlayerController>();
}
void OnCollisionEnter2D (Collision2D collide)
{
if (collide.gameObject.CompareTag("Dead"))
{
Instantiate(particles, player.transform.position, Quaternion.identity);
Instantiate(explosionGO, player.transform.position, Quaternion.identity);
CinemachineShake.Instance.ShakeCamera(30f, .1f);
alreadyDied = true;
}
}
void Update()
{
if(alreadyDied == true)
{
timeDeath -= Time.deltaTime;
sr.enabled = false;
bc.enabled = false;
walkScript.enabled = false;
}
if(timeDeath <= 0)
{
SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
}
}
}
This is the bullet's code:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class LeftBulletScript : MonoBehaviour
{
// Start is called before the first frame update
public float speed;
public float destructionLeftTime;
public ParticleSystem particles;
private GameObject thisGameObject;
void Start()
{
thisGameObject = this.gameObject;
Destroy(gameObject, destructionLeftTime);
}
void Update()
{
transform.Translate(Vector2.left * speed * Time.deltaTime);
if(destructionLeftTime > 0.05f)
{
destructionLeftTime -= Time.deltaTime;
}
else
{
Instantiate(particles, thisGameObject.transform.position, Quaternion.identity);
}
}
}
This code should spawn some particles and a sound effect when the player gets hit by something with tag "Dead". But that does not happen. I have a box collider 2D on both the bullet (that should kill me) and the player. My Rigidbody2D is dynamic on the player with z freezed. The bullet does not have a rigidbody. I made sure that the bullet actually has the tag "Dead", spelled the exact same way as the way I wrote on the script. The weirdest thing is that I used this code on another game and nothing changed (just the name of a script). Both the player and the bullet are on the same layer. Anyone could tell me what could have happened?

How can I change the rate of fire when shooting automatic?

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Shooting : MonoBehaviour
{
[SerializeField]
private Transform[] firePoints;
[SerializeField]
private Rigidbody projectilePrefab;
[SerializeField]
private float launchForce = 700f;
[SerializeField]
private Animator anim;
[SerializeField]
private bool automaticFire = false;
private void Start()
{
anim.SetBool("Shooting", true);
}
public void Update()
{
if (Input.GetButtonDown("Fire1") && automaticFire == false)
{
if (anim.GetBool("Shooting") == true)
{
anim.Play("SHOOTING");
LaunchProjectile();
}
}
if(automaticFire == true)
{
anim.Play("SHOOTING");
LaunchProjectile();
}
}
private void LaunchProjectile()
{
foreach (var firePoint in firePoints)
{
Rigidbody projectileInstance = Instantiate(
projectilePrefab,
firePoint.position,
firePoint.rotation);
projectileInstance.AddForce(new Vector3(0,0,1) * launchForce);
projectileInstance.gameObject.AddComponent<BulletDestruction>().Init();
}
}
}
If it's automatic :
if(automaticFire == true)
{
anim.Play("SHOOTING");
LaunchProjectile();
}
It's shooting nonstop but it looks like one long bullet.
If for example I want it to shoot nonstop but only one bullet each time ? Or shooting many bullets but with some space between them ?
On each bullet I'm adding this destruction script :
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class BulletDestruction : MonoBehaviour
{
// Start is called before the first frame update
public void Init()
{
StartCoroutine(DestroyBullet());
}
IEnumerator DestroyBullet()
{
yield return new WaitForSeconds(0.2f);
Destroy(gameObject);
}
}
But that's also a problem. If I'm setting the destruction delay to be 0.2 the bullets shoot distance is very short but if I will set the delay time for example to 5 the bullets will be shoot to a longer distance but then again there will be a lot of bullets at the same time.
What is the logic on the destruction and the automatic mode ? And how should I do it in the script/s ?

You can try this:
float attackRate = 100;
float timer = 0;
public void Update()
{
timer -= Time.deltaTime;
if(automaticFire && timer <=0)
{
Shoot();
timer = 1/ attackRate;
}
}