GameObject won't change after updating it with a Method (object reference not set)

Question

Unity newb here :)

I have a button which calls this function which basicly sets a prefab to instantiate.

  public void setTurret()
{
    towerNode.setTurretType(turret)
    Debug.Log("selected shop turret:" + turret.name);
}

My Tower_Node class handles the actual instantiate

 public class Tower_Node : MonoBehaviour
    {
        private GameObject turret;

               public void setTurretType(TowerType _turret) 
                   {
                        turret= _turret.prefab;
                    }



               private void OnMouseDown()
               {             
                Instantiate(turret,GetBuildPosition(),Quaternion.identity);
               }
    ...}

EDIT: What I also tried

      public class Tower_Node : MonoBehaviour
        {
            private TowerType turret;

                   public void setTurretType(TowerType _turret) 
                       {
                            turret = _turret;
                    }



               private void OnMouseDown()
               {             
                Instantiate(turret.prefab,GetBuildPosition(),Quaternion.identity);
               }
    ...}

EDIT: This is how the references in the inspector look. The shop script is the script with the setTurret() method

--

Setting the turret with the setTurretType method works. If i check it with Debug.Log() i get the right TowerType but outside of the function the gameobject is still =null and when i try to instantiate it gives me an NullReferenceException (because Gameobject is null obviously)

What am i missing here?

Thank you for your answers.

Is it possible you have multiple instances of Tower_Node but you do not use setTurretType on all of them? — derHugo
– derHugo, Commented May 20, 2020 at 15:05
My Tower_Node is a prefab, which exists multiple times in my scene. setTurretType should update all of them since its a prefab right? — Shieky2000
– Shieky2000, Commented May 21, 2020 at 13:08

vasmos · Accepted Answer · 2020-05-19 20:31:14Z

0

switch OnMouseDown() for

if (Input.GetMouseButtonDown(0))

in your update loop

just make sure that turret.prefab is a prefab

Instantiate(turret.prefab, GetBuildPosition(),Quaternion.identity);

answered May 19, 2020 at 20:31

vasmos

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1 Comment

Shieky2000 Over a year ago

This did not work, and yes im sure that the prefab is a prefab!

Kuruchy · Accepted Answer · 2020-05-19 21:36:34Z

0

I would say that if your TowerType class has a GameObject var named prefab, you should either assign the prefab to the prefab, or assign the turret to the _turret and the access the prefab.

Either this:

public void setTurretType(TowerType _turret) {
    turret = _turret;
    hoverTurret = _turret.hoverPrefab;  
}

private void OnMouseDown()
{
    Instantiate(turret.prefab, GetBuildPosition(),Quaternion.identity);
}

or

public void setTurretType(TowerType _turret) {
    turret.prefab = _turret.prefab;
    hoverTurret = _turret.hoverPrefab;  
}

private void OnMouseDown()
{
    Instantiate(turret.prefab, GetBuildPosition(),Quaternion.identity);
}

should work.

Edit: You could set the turret while instiantiating:

public void setTurretType(TowerType _turret) {
    turret.prefab = _turret.prefab;
    hoverTurret = _turret.hoverPrefab;  
}

private void OnMouseDown()
{
    turret = Instantiate(turret.prefab, GetBuildPosition(),Quaternion.identity);
}

edited May 19, 2020 at 21:36

answered May 19, 2020 at 20:48

Kuruchy

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5 Comments

Shieky2000 Over a year ago

Yes my TowerType class have a public GameObject prefab. I tried both, but unfortunaly this did not work, the object still won't update

Kuruchy Over a year ago

Are you setting the prefab to null somewhere in your code?

Shieky2000 Over a year ago

No, im not thats the only piece of code which modifies that

Shieky2000 Over a year ago

Sadly this also did not work, even when i set the var to [SerializeField] this does not work, but i can see in the inspector how the actual prefab is swapped. I really dont get why its null

Kuruchy Over a year ago

Then I would say you need to provide more information with your other classes...

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