Nrthugu

I'm working on an AR app that tracks planes with ARCore and makes me choose from a series of different models that I can then instantiate on the plane. After the model is instatiated on the scene I used the free asset Lean Touch by Carlos Wilkes to interact with it using gestures. Using the scripts from this asset I'm also trying to make a circle appear under the model when it is selected, but while it works perfectly appling components on a cube directly in the scene, I can't make it work when I apply the components via script.

This is my scene. It shows how I set up the components on my cube.

LeanSelectable is a script from the asset that is used to define which objects can be selected. LeanSelectableCircle is my script, it extends LeanSelectableBehavior, an abtract class from the asset specifically made to make handling selectable actions easier. My script finds the circle, child of the cube, and overide the functions OnSelect and OnDeselect of the abstract class. In the method OnSelect it activate the circle, making it visible when the object is selected. In the method OnDeselect it deactivate the circle, hiding it when the object is not selected. As I said this combination of components works fine on the cube in the scene: if I select the cube the circle appears, if I deselect the cube the circle disappears.

This is the abstract class:

public abstract class LeanSelectableBehaviour : MonoBehaviour

    {

        [System.NonSerialized]

        private LeanSelectable selectable;



        public LeanSelectable Selectable

        {

            get

            {

                if (selectable == null)

                {

                    UpdateSelectable();

                }



                return selectable;

            }

        }



        protected virtual void OnEnable()

        {

            UpdateSelectable();



            // Hook LeanSelectable events

            selectable.OnSelect.AddListener(OnSelect);

            selectable.OnSelectUp.AddListener(OnSelectUp);

            selectable.OnDeselect.AddListener(OnDeselect);

        }



        protected virtual void OnDisable()

        {

            UpdateSelectable();



            // Unhook LeanSelectable events

            selectable.OnSelect.RemoveListener(OnSelect);

            selectable.OnSelectUp.RemoveListener(OnSelectUp);

            selectable.OnDeselect.RemoveListener(OnDeselect);

        }



        // Called when selection begins (finger = the finger that selected this)

        protected virtual void OnSelect(LeanFinger finger)

        {

        }



        // Called when the selecting finger goes up (finger = the finger that selected this)

        protected virtual void OnSelectUp(LeanFinger finger)

        {

        }



        // Called when this is deselected, if OnSelectUp hasn't been called yet, it will get called first

        protected virtual void OnDeselect()

        {

        }



        private void UpdateSelectable()

        {

            if (selectable == null)

            {

                selectable = GetComponentInParent<LeanSelectable>();



                if (selectable == null)

                {

                    Debug.LogError("This GameObject or one of its parents must have the LeanSelectable component.", this);

                }

            }

        }

    }

This is my class:

public class LeanSelectableCircle : LeanSelectableBehaviour

    {

        GameObject circle;



        protected virtual void Awake()

        {

            circle = this.gameObject.transform.GetChild(1).gameObject;

            Debug.Log(circle.ToString());

        }



        protected override void OnSelect(LeanFinger finger)

        {

            circle.SetActive(true);

            Debug.Log("Oggetto selezionato");

        }



        protected override void OnDeselect()

        {

            circle.SetActive(false);

            Debug.Log("Oggetto deselezionato");

        }

    }

Lastly I have an ARController class that handles all AR related stuff, including the placing of the model on the plane (the model is instantiated in another class, but it's not relevant here). After the model is scaled, placed in position and made child of the anchor, it instantiate the circle and set it to false to make it hidden. Then I add all the required components to make the touch gestures work with LeanTouch asset. And then I set the model active.

This is the method that handles this part, and that is called during the Update() function in the ARController.

public void _InteractWithARScene()

    {

        Touch touch;

        if (Input.touchCount < 1 || (touch = Input.GetTouch(0)).phase != TouchPhase.Began) // If the player has not touched the screen, we are done with this update.

        {

            return;

        }

        _SpawnARObject();

    }



    public void _SpawnARObject()

    {

        Touch touch;

        touch = Input.GetTouch(0);



        TrackableHit hit;

        TrackableHitFlags raycastFilter = TrackableHitFlags.PlaneWithinPolygon | TrackableHitFlags.FeaturePointWithSurfaceNormal; // Raycast against the location the player touched to search for planes.



        if (!EventSystem.current.IsPointerOverGameObject(touch.fingerId)) //Evita di istanziare oggetti se il touch non è sopra un elemento dell'UI

        {

            if (Frame.Raycast(touch.position.x, touch.position.y, raycastFilter, out hit))

            {

                // Use hit pose and camera pose to check if hittest is from the back of the plane, if it is, no need to create the anchor.

                if ((hit.Trackable is DetectedPlane) && Vector3.Dot(FirstPersonCamera.transform.position - hit.Pose.position, hit.Pose.rotation * Vector3.up) < 0)

                {

                    Debug.Log("Hit at back of the current DetectedPlane");

                }

                else

                {

                    //Choose the Andy model for the Trackable that got hit.

                    GameObject modelObject = assetBundleSytem.transform.GetChild(0).gameObject;

                    //GameObject modelObject = GameObject.FindWithTag("NEW");

                    if (modelObject != null) Debug.Log("Model foud");





                    //Scale model

                    GameObject scaledObject = scalingCube.Scale(modelObject);

                    scaledObject.transform.SetPositionAndRotation(hit.Pose.position, hit.Pose.rotation);

                    scaledObject.tag = "AR";



                    // Compensate for the hitPose rotation facing away from the raycast (i.e. camera).

                    scaledObject.transform.Rotate(0, k_ModelRotation, 0, Space.Self);



                    // Create an anchor to allow ARCore to track the hitpoint as understanding of the physical world evolves.

                    var anchor = hit.Trackable.CreateAnchor(hit.Pose);



                    // Make Andy model a child of the anchor.

                    scaledObject.transform.parent = anchor.transform;



                    //Instantiate the circle that tells when the object is selected

                    GameObject circle = Instantiate(selectionCircle, scaledObject.transform, true) as GameObject;

                    circle.transform.SetPositionAndRotation(scaledObject.transform.position, circle.transform.rotation);

                    circle.SetActive(false);



                    //Add a MeshCollider Componet to the object mesh

                    GameObject modelObjectMesh = scaledObject.transform.GetChild(0).gameObject;

                    modelObjectMesh.AddComponent<MeshCollider>();



                    //Implement LeanTouch

                    scaledObject.AddComponent<LeanSelectable>();

                    scaledObject.AddComponent<LeanSelectableCircle>();



                    //Set the object to active

                    scaledObject.SetActive(true);

                }

            }

        }

    }

When it tries to add the component LeanSelectableCircle to the medel, the OnEnable() function of LeanSelectableBehaviour is called and it returns this error:

NullReferenceException: Object reference not set to an instance of an
object Lean.Touch.LeanSelectableBehaviour.OnEnable () (at

Assets/LeanTouch/Examples/Scripts/LeanSelectableBehaviour.cs:29) UnityEngine.GameObject:AddComponent() ARController:_SpawnARObject()
(at Assets/Scripts/ARController.cs:117)
ARController:_InteractWithARScene() (at
Assets/Scripts/ARController.cs:64) ARController:Update() (at
Assets/Scripts/ARController.cs:38)

This is my scene after i placed the model on the plane. It shows all the components on the model.
The odd thing is that if I deactivate the model and then reactivate it in the inspector while the scene is playing, then it works fine!

I can't for the life of me understand what I'm doing wrong, so any help will be appreciated, thanks!

Ps. Please forgive me any imprecision, I'm a beginner programmer and english is not my mothertongue!