Order of instantiated objects in hierachy

Question

I made a test script that looks like this:

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

public class TestScript : MonoBehaviour {

 public bool Test = true;
 public bool _Test;

 public GameObject TestObject;
 public Transform _TestObject;

 public GameObject[] TestArray;

 void Start()
 {

 }


 void Update()
 {

     if (_Test != Test)
     {
         _Test = Test;
         Debug.Log("Changed");

         TestArray = GameObject.FindGameObjectsWithTag("clone");

         foreach (GameObject Clone in TestArray)
         {
             Destroy(Clone);
             Debug.Log("Destroyed");
         }

         for (int i = 0; i < 4; i++)
         {
             Debug.Log(i);
             Instantiate(TestObject, _TestObject);
             TestObject.tag = "clone";
             TestObject.name = "Clone" + i;
         }
     }
 }

}

As you see I am instantiating an object and giving it a name for ease, but when I look in the hierachy it looks like this: Clone3, clone0, clone1, clone 2

And I want it to look like this: clone 0, clone1, clone2, clone3

I've tried setting the sibling index to the i variable but it gives the same result. Can someone explain to me why this is happening and tell me how I can fix it. (Also when I first start the game it doesn't instantiate anything only after I change the variable ones it does.)

Answer 1

This code:

 Instantiate(TestObject, _TestObject);
 TestObject.tag = "clone";
 TestObject.name = "Clone" + i;

does not what you think it does. "TestObject" is your prefab. You actually clone your prefab and afterwards you modify your prefab. Note that you do not modify your already cloned object.

Just assume the for loop has already run once. That means the last thing you did to your prefab was naming it "clone3". Next time you run your loop it means your first object you instantiate will get the name clone3. Now you rename your prefab to "clone0". So the next loop iteration (i==1) you instantiate the prefab again but this time with the name "clone0". Again after you cloned it you change the prefab's name to "clone1". So you get the following names in order:

 clone3
 clone0
 clone1
 clone2

After the loop your prefab will be called again clone3.

The Instantiate method actually returns the cloned object which you completely ignore. You essentially have two options:

rename your prefab before you clone it
leave the prefab alone and rename the actual instance you just created.

I would highly recommend the second option. The first one, when tested in the editor, will actually modify your prefab asset permanently. So you should do:

 TestObject.tag = "clone";
 for (int i = 0; i < 4; i++)
 {
     GameObject clone = Instantiate(TestObject, _TestObject);
     clone.name = "Clone" + i;
 }

Note that I moved the tag setting out of the loop and actually modifed the prefab before we clone it. While this can be done I would highly recommend that you get rid of it completely and just set the tag on your prefab in the inspector.

Answer 2

Answer by Horothenic · Jan 04, 2020 at 08:19 PM

I dont know why but maybe this thing gives you an incorrect order.

TestArray = GameObject.FindGameObjectsWithTag("clone");

Try this:

 List<GameObject>testList = new List<GameObject>();
 foreach(Transform t in myParentObject)
     testList.Add(t.gameObject);

Just specify the parent object, that should give you the bjects in the correct order.

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jayvle · Jan 04, 2020 at 11:22 PM 0

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I tried it, but it still is giving me a wrong order. Can you maybe tell me why the very first time nothing happens and only after i change the test bool the clones spawn?

Stobros1 jayvle · Feb 13 at 01:56 PM 0

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@jayvle, try this one. Make sure you put this after the for/foreach loop.

 testList[0].transform.SetAsLastSibling();

Before I tried this code, I also had a similar problem while I was working on my level select screen where the last instantiated clone is the first sibling and not the last as we wanted to be. After I added this code after the for loop that instantiates my object on the scene, I was surprised it worked wonders that it now placed that last clone where it belongs.

Answer 3

Answer by nikunjsth5 · Mar 21 at 04:02 PM

@Bunny83 Your way worked. I have literally wasted my weekend over this issue, thanks man!

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Order of instantiated objects in hierachy

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