Particle system not destroying.

Questions & Answers
1

I got an problem with particle system. I’m instantiating one everytime ball hits an brick, and after it’s done it should be removed automaticly, but these just won’t get destroyed.

Script doesnt give out any errors or warnings, but particle system(clone)'s just won’t get destroyed.

Here’s the whole script:

using UnityEngine;
using System.Collections;

public class BrickScript : MonoBehaviour {
	
	static int numBricks = 0;
	public int pointValue = 1;
	public int currentLvl = 0;
	public int hitPoints = 1;
	public int powerUpChance = 3;
	
	public Transform particlesPrefab;
	
	public GameObject[] powerUpPrefabs;
	
	public AudioClip[] hitaudio;
	
	// Use this for initialization
	void Start () {
		numBricks++;
	}
	
	// Update is called once per frame
	void Update () {
	if ( currentLvl == 4) {
			Application.LoadLevel("GameOver");
		}

	}
	
	void OnCollisionEnter ( Collision col ) {
		hitPoints--;
		if ( hitPoints <= 0 ) {
			Die();
		}
		if (col.gameObject.tag == "Ball")
			Debug.Log ("Particles!");
	    GameObject go = Instantiate(particlesPrefab, transform.position, Quaternion.identity) as GameObject;
		Destroy (go, 2.5f);
	}
	
	void Die() {
	Destroy ( gameObject );
		BallScript ball1Script= GameObject.FindGameObjectWithTag ("Ball").GetComponent<BallScript>();
		PaddleScript paddleScript= GameObject.Find ("Paddle").GetComponent<PaddleScript>();
		paddleScript.AddPoint(pointValue * (int)ball1Script.curspeed);
		
		numBricks--;
		
		Debug.Log (numBricks);
		
		if ( Random.Range(0, powerUpChance) == 0 ) {
		Instantiate( powerUpPrefabs[ Random.Range(0, powerUpPrefabs.Length) ] , transform.position, Quaternion.identity );
		 }
		
		if ( numBricks <= 0 ) {
			//Load Next Level
		Application.LoadLevel(currentLvl+1);
		if(currentLvl == 1){
		GJAPIHelper.Trophies.ShowTrophyUnlockNotification (4086);
		}
		if(currentLvl == 2){
		GJAPIHelper.Trophies.ShowTrophyUnlockNotification (4087);
		}
		}
	}
}

And here’s just the part that SHOULD be removing that.

void OnCollisionEnter ( Collision col ) {
		hitPoints--;
		if ( hitPoints <= 0 ) {
			Die();
		}
		if (col.gameObject.tag == "Ball")
			Debug.Log ("Particles!");
	    GameObject go = Instantiate(particlesPrefab, transform.position, Quaternion.identity) as GameObject;
		Destroy (go, 2.5f);
	}

Why it isnt getting destroyed?

4

I have the following script attached to the particle system prefab, and it works fine:

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

public class HitEmitterScript : MonoBehaviour {
	private float timeLeft;

	public void Awake() {
		ParticleSystem system = GetComponent<ParticleSystem>();
		timeLeft = system.startLifetime;
	}

	public void Update() {
		timeLeft -= Time.deltaTime;
		if (timeLeft <= 0) {
			GameObject.Destroy(gameObject);
		}
	}
}

Note that the lifetime is set to be the particle’s starting life, but you could make it a constant 2.5 seconds.

2

Particle systems don’t self destroy. It’s a problem that a lot of people have. A better option would be to not instantiate the particle system every time but rather instantiate it once at the start, move it to where it needs to be (such as a collision point) and use

[Particle System].Play()

This way it removes needless instantiation and the need for it to be destroyed as you’ll be using it over and over. Better performance too.

3

The code (Instantiate then timed 2.5-sec Destroy) looks fine. I’m wondering if the bricks always have 1 hit point, so always die right away. I think the 2.5-sec Destroy is really a hidden coroutine attached to the brick. So a dead brick can’t destroy the explosion.

Try giving the bricks 2-HP to test (should destroy the puff on first hit.) If that’s the problem, maybe move the OnCollisionEnter into the ball script. Or just move the explosion spawn there.

---- answer #2 -----

From that last test (not printing the name after a spawn,) go is clearly broken.
You’re getting a null reference for go, which means the destroy command is destroying nothing. Specifically, Instantiate is spawning just fine. But the as GameObject conversion doesn’t work, so just gives you a null (just tried it.)

Fix#1: redeclare particlePrefab (up top) as a GameObject (it’s a Transform now)

Alternate fix#2:

Leave particlePrefab as a Transform, but change spawn code to:

Transform go = Instantiate(...) as Transform;
Destroy(go.gameObject, 2.5f);

Either way, the GameObject’s or Transforms all have to match.