need help with C# component reference

Question

I have several copies of a box prefab that has the following components: "BoxColider2D", "RigidBody2D", "Sprite Renderer" & a custom C# script called "BoxDestruction".

I also have a "Danger Zone" object which has a BoxCollider2D with isTrigger enabled. I want to destroy boxes that are inside the "Danger Zone" trigger at random intervals (when the destroyBox bool is true).

I am using the following code on the "Dander Zone" trigger to try and call the public DestroyBox() function in the "BoxDestrction" script of the box which is inside the trigger. I am getting a NullReferenceException: Object reference not set to an instance of an object, but i cannot tell why? i thought that starting from "other" would give me the instance of the object i am after?

 void OnTriggerStay2D (Collider2D other)
 {
     if(other.tag == "Destructible")
     {
         if(destroyBox)
             other.gameObject.GetComponent<BoxDestruction>().DestroyBox(); 
     }
 }

Can anyone tell me what i am doing wrong when trying to reference this? i would really appreciate an explanation, as i can't see where i am going wrong...

Thanks in advance!

Answer 1

Answer by Burla · May 03, 2014 at 02:39 PM

Assuming that the DestroyBox takes a GameObject parameter you could do it this way.

Declare the BoxDestruction variable at the top of your script.

 BoxDestruction boxDestruction;

Make the reference in the Start function.

 void Start() {
      boxDestruction = GetComponent<BoxDestruction>();
 }

Now call the function.

 void OnTriggerStay2D (Collider2D other)
 {
     if(other.tag == "Destructible")
     {
        if(destroyBox)
          boxDestruction.DestroyBox(other.gameObject); 
     }
 }

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