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Object Pool object reference is null?
Hey. So I'm new to the whole Unity thing and basically for a college assignment I have to assign a design pattern to my final year project. Since I'm doing a game in Unity I need to apply it to this. I was going to apply it to different spells that you can select to shoot different objects.
So I followed a YouTube tutorial on how to create a ObjectPool and I thought everything was going okay, however when I start the game, upon clicking, nothing emits, and I also get an error at the bottom saying "Object reference was not set to an instance of an object".
I created a prefab with a sphere in it. I created 2 scripts, 1 called Object Pool, the other called Projectile. My Camera has its own script called FirstPersonController that is used for movement. In the ObjectPool script I detect if the user has pushed down the mouse button, then I call the ActivatedProjectile method.
EDIT
I get 2 types of error. The first appears only once at the start of the code:
ArgumentException: The thing you want to instantiate is null. UnityEngine.Object.CheckNullArgument (System.Object arg, System.String message) (at C:/BuildAgent/work/d3d49558e4d408f4/artifacts/EditorGenerated/UnityEngineObject.cs:104) UnityEngine.Object.Instantiate (UnityEngine.Object original) (at C:/BuildAgent/work/d3d49558e4d408f4/artifacts/EditorGenerated/UnityEngineObject.cs:90) ObjectPool.InstantiateProjectiles () (at Assets/Scripts/ObjectPool.cs:28) ObjectPool.Start () (at Assets/Scripts/ObjectPool.cs:12)
The other appears multiple times as follows:
NullReferenceException: Object reference not set to an instance of an object ObjectPool.ActivateProjectile () (at Assets/Scripts/ObjectPool.cs:37) ObjectPool.Update () (at Assets/Scripts/ObjectPool.cs:20)
Here is the code I have for ObjectPool class.
using UnityEngine;
using System.Collections;
public class ObjectPool : MonoBehaviour {
GameObject[] projectiles = null;
public int numberOfProjectilesToCreate = 0;
// Use this for initialization
void Start () {
projectiles = new GameObject[numberOfProjectilesToCreate];
InstantiateProjectiles ();
}
// Update is called once per frame
void Update ()
{
if(Input.GetMouseButton(0))
{
ActivateProjectile();
}
}
private void InstantiateProjectiles()
{
for (int i = 0; i < numberOfProjectilesToCreate; i++)
{
projectiles[i] = Instantiate(Resources.Load("Prefabs/prefab_projectile")) as GameObject;
projectiles[i].SetActive(false);
}
}
private void ActivateProjectile()
{
for (int i = 0; i < numberOfProjectilesToCreate; i++)
{
if(projectiles[i].activeSelf == false)
{
projectiles[i].SetActive(true);
projectiles[i].GetComponent<Projectile>().Activated();
}
}
}
}
Anybody have any ideas on what I'm doing wrong?
It would help if you gave us the line number of the exception.
What line is generating the null? Are you sure your Instantiate() is succeeding? Not your error, but it would be best to only do the Resources.Load() once in Start().
@stevethorne So sorry I completely forgot ha. I get errors on lines 12, 20 and 37 I believe. I updated the OP with the full error messages.
@robertbu I updated the OP with the full error codes, my bad. I'm not too sure what is working and whats not, as I said I'm very new to the unity work flow. Ah okay I will change that now thanks
Answer by flaviusxvii · Dec 11, 2013 at 10:09 PM
For Resources.Load("Prefabs/prefab_projectile") you need to have the folder "Prefabs" inside a folder named "Resources".
Ah I'm an idiot I had an Asset folder but didn't have them inside a Resource folder. Thanks man :)
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