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

问题

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?

回答1:

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".