HitTest prints AR Entity name even when I am not tapping on it

Question

My Experience.rcproject has animations that can be triggered by tap action. Two cylinders are named “Button 1” and “Button 2” and have Collide turned on.

I am using Async method to load Experience.Map scene and addAnchor method to add mapAnchor to ARView in a ViewController.

I tried to run HitTest on the scene to see if the app reacts properly.

Nonetheless, the HitTest result prints the entity name of a button even when I am not tapping on it but area near it.

class augmentedReality: UIViewController {

    @IBOutlet weak var arView: ARView!

    @IBAction func onTap(_ sender: UITapGestureRecognizer) {
        let tapLocation = sender.location(in: arView)
        // Get the entity at the location we've tapped, if one exists
        if let button = arView.entity(at: tapLocation) {
            // For testing purposes, print the name of the tapped entity
            print(button.name)
        }
    }
}

Below is my attempt to add the AR scene and tap gesture recogniser to arView.

class augmentedReality: UIViewController {

    arView.scene.addAnchor(mapAnchor)
    mapAnchor.notifications.hideAll.post()
    mapAnchor.notifications.mapStart.post()

    self.arView.isUserInteractionEnabled = true
    let tapGesture = UITapGestureRecognizer(target: self, action: #selector(onTap))
    self.arView.addGestureRecognizer(tapGesture)
}

Question 1

How can I achieve the goal of only having the entity name of a button printed when I am really tapping on it instead of close to it?

Question 2

Do I actually need to turn Collide on to have both buttons able to be detected in the HitTest?

Question 3

There’s an installGestures method. There’s no online tutorials or discussions about this at the moment. I tried but I am confused by (Entity & HasCollision). How can this method be implemented?

Andy Jazz · Answer 1 · 2020-01-22T19:36:52.117

To implement a robust Hit-Testing in RealityKit, all you need is the following code:

import RealityKit

class ViewController: UIViewController {

    @IBOutlet var arView: ARView!
    let scene = try! Experience.loadScene()

    @IBAction func onTap(_ sender: UITapGestureRecognizer) {

        let tapLocation: CGPoint = sender.location(in: arView)
        let result: [CollisionCastHit] = arView.hitTest(tapLocation)

        guard let hitTest: CollisionCastHit = result.first
        else { return }

        let entity: Entity = hitTest.entity
        print(entity.name)
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        scene.steelBox!.scale = [2,2,2]
        scene.steelCylinder!.scale = [2,2,2]

        scene.steelBox!.name = "BOX"
        scene.steelCylinder!.name = "CYLINDER"

        arView.scene.anchors.append(scene)
    }
}

When you tap on entities in ARView a Debug Area prints "BOX" or "CYLINDER". And if you tap anything but entities, a Debug Area prints just "Ground Plane".

If you need to implement a Ray-Casting read this post, please.

P.S.

In case you run this app on macOS Simulator, it prints just Ground Plane instead of BOX and CYLINDER. So you need to run this app on iPhone.

HitTest prints AR Entity name even when I am not tapping on it

1 Answers1

Linked