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Question by Regalith · Feb 14, 2014 at 04:28 PM · c#gameobjectinstantiateclone

Instantiating a GameObject from scene that changes

So I'm currently trying to instantiate a game object in a scene every few seconds, and that object is constantly changing. I tried linking it as a public variable to the script, but I keep getting null reference exceptions. any idea why this code is unable to spawn the GameObject wall?

 using UnityEngine;
 using System.Collections;
 
 public class BPMController : MonoBehaviour {
     
     public int bpm;
     public GameObject wall;
     public GameObject floor;
     bool wait = false;
     int spawnCounter = 0;
     public int spawnInterval = 4;
 
     //find the wall in the scene
     void Start () {
         wall = GameObject.FindGameObjectWithTag("wall");
     }
 
     void Update () {
 
         //if coroutine isnt running start it
         if (!wait) 
         {
             wait = true;
             StartCoroutine(waitCoRoutine());
         }
         //if interval count is reached, spawn wall
         if(spawnCounter >= spawnInterval)
         {
             spawnWall();
             spawnCounter = 0;
         }
     }
 
     //coroutine to wait a set time and increment counter
     IEnumerator waitCoRoutine(){
         yield return new WaitForSeconds(bpm/60);
         spawnCounter++;
         wait = false;
     }
 
     void spawnWall(){
         //create cloneObject to manipulate
         GameObject wallClone = null;
         //instantiate wallCone as a clone of wall
         wallClone = Instantiate (wall, wall.transform.position, wallClone.transform.rotation) as GameObject;
         //set wallcone as a child of floor;
         wallClone.transform.parent = floor.transform;
     }
 }
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Answer by RudyTheDev · Feb 14, 2014 at 05:44 PM

In the line

 wallClone = Instantiate (wall, wall.transform.position, wallClone.transform.rotation) as GameObject;

you have wallClone.transform.rotation before you have wallClone assigned. I'm guessing this is where your null exception happens, since you didn't specify the exact line.

If it's not, then either your public GameObject wall; is getting destroyed at some point or your wall = GameObject.FindGameObjectWithTag("wall"); has failed to find it to begin with.

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avatar image Regalith · Feb 14, 2014 at 09:43 PM 0
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your my hero. I coded this at 4am last night and somehow never noticed it said wallClone in the instantiate. thanks for that

avatar image RudyTheDev · Feb 14, 2014 at 10:28 PM 0
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