[XR Interaction Toolkit][AR] Limit placable objects to 1

Dear Community,

does anybody know if there is any way to limit the AR Objects to 1 with the interaction toolkit? Would be very important to me to know that.

Thanks in advance
Danex

 

I actually found a (very cruel) way to do it with the toolkit.
Just add the following script to the PlacementInteractableObject and after placing the first time, you will not be able to place one again till u set the prefab new.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.XR.Interaction.Toolkit.AR;
5.  
6. public class LimitPlaceableObjectsToOne : MonoBehaviour
7. {
8.     private ARPlacementInteractable placementInteractable;
9.     // Start is called before the first frame update
10.     void Start()
11.     {
12.         placementInteractable = this.GetComponent<ARPlacementInteractable>();
13.         ARObjectPlacedEvent aRObjectPlacedEvent = placementInteractable.onObjectPlaced;
14.         aRObjectPlacedEvent.AddListener(ObjectPlaced);
15.     }
16.  
17.  
18.     private void ObjectPlaced(ARPlacementInteractable p, GameObject q)
19.     {
20.         placementInteractable.placementPrefab = null;
21.     }
22. }
23.  

Greets Danex

Update:
To Fix the Bug below you ned to add the following line to the PlacementInteractable code of the toolkit simply after the raycast:

Code (CSharp):

1.  
2. if(placementPrefab == null)
3.                     return;
4.  

 

Actually if you want to place a prefab and the placement prefab is set to null - the toolkit breaks. I hope somebody has an solution for this....^^

 

Hi, any updates about this problem ?

 

Unfortunately no. Until there will be a fix, I scripted another simple but drastic solution, without modifying any of the XR-Toolkit Scripts. I'm not proud of it, but it works for now ^^.

If a prefab was spawned first time, everytime a new one is spawned, I simply destroy its parent, which is the trackable anchor ("PlacementAnchor"). I made this modification to d4n3x script

Code (CSharp):

1.     public class LimitPlaceableObjectsToOne : MonoBehaviour
2.     {
3.         protected ARPlacementInteractable _placementInteractable;
4.         protected bool _oneSpawned = false;
5.  
6.         protected virtual void OnEnable()
7.         {
8.             if (!_placementInteractable)
9.                 _placementInteractable = GetComponent<ARPlacementInteractable>();
10.  
11.             _placementInteractable.onObjectPlaced.AddListener(ObjectPlaced);
12.         }
13.  
14.         protected virtual void OnDisable()
15.         {
16.             _placementInteractable.onObjectPlaced.RemoveAllListeners();
17.         }
18.  
19.         protected virtual void ObjectPlaced(ARPlacementInteractable p, GameObject q)
20.         {
21.             if (_oneSpawned)
22.             {
23.                 Destroy(q.transform.parent.gameObject);
24.             }
25.  
26.             _oneSpawned = true;
27.         }
28.     }

 

Hi, only a simple question, where I must put LimitPlaceableObjectsToOne script?

tanks

 

Because of the

_placementInteractable = GetComponent<ARPlacementInteractable>();

expression, the LimitPlaceableObjectsToOne component has to be located on the same GameObject as the ARPlacementInteractable component.

You could also set the _placementInteractable public and simply drag and drop the ARPlacementInteractable component into that field, in the Unity Editor.

 

I love this! But I also hate this, it is soo ugly! I'm using AR Foundation 5.0 and I get a warning that 'onObjectPlaced' is deprecated and use' objectPlaced' instead. Here's an updated script to work with 5.0:

Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.XR.Interaction.Toolkit.AR;
3.  
4.  
5. public class LimitPlacedObjectsToOne : MonoBehaviour
6. {
7.  
8.         protected ARPlacementInteractable _placementInteractable;
9.         protected bool _oneSpawned = false;
10.  
11.         protected virtual void OnEnable()
12.         {
13.             if (!_placementInteractable)
14.                 _placementInteractable = GetComponent<ARPlacementInteractable>();
15.  
16.             _placementInteractable.objectPlaced.AddListener(ObjectPlaced);
17.         }
18.  
19.         protected virtual void OnDisable()
20.         {
21.             _placementInteractable.objectPlaced.RemoveAllListeners();
22.         }
23.  
24.         protected virtual void ObjectPlaced(ARObjectPlacementEventArgs args)
25.         {
26.             if (_oneSpawned)
27.             {
28.                 Destroy(args.placementObject);
29.             }
30.             _oneSpawned = true;
31.         }
32.  
33. }
34.  

@Matt_D_work or anyone at Unity, is there a more elegant fix for this? It seems an odd choice to assume folks want to place unlimited copies of an object in an AR scene. Maybe expose a maxObjects created int option?