How can I move a ModelEntity along the Y-axis using gesture?

Question

Following this documentation, I have not understood if there is an easy way to move a ModelEntity along the Y-axis. The reason I expected this is that in ARQuickLook this functionality works together with the .scale and .rotate functions, also listed in the Apple documentation.

If there is any easy/similar way to install these gestures, please let me know.

Answer 1

In RealityKit 2.0, unlike ARQuickLook, only a single touch drag gesture is implemented to move a model (double-finger gesture for vertical drag isn't implemented at the moment). With a single-finger gesture you can move entity along its anchoring plane – as a rule it's XZ plane, so there's no Y-axis drag.

public static let translation: ARView.EntityGestures

Despite this, you have the option to additionally implement 2D UIGestureRecognizer.

(The same way you can implement a two-finger pan gesture (also known as levitation gesture) like in AR Quick Look apps)

import UIKit
import RealityKit

class ViewController: UIViewController {    
    @IBOutlet var arView: ARView!
    var box: ModelEntity? = nil

    override func viewDidLoad() {
        super.viewDidLoad()    

        box = ModelEntity(mesh: .generateBox(size: 0.05))
        box!.generateCollisionShapes(recursive: true)
        arView.installGestures([.all], for: box! as (Entity & HasCollision))

        let anchor = AnchorEntity(world: [0, 0,-0.2])
        anchor.addChild(box!)
        arView.scene.anchors.append(anchor)
        
        for swipe in [UISwipeGestureRecognizer.Direction.up,
                      UISwipeGestureRecognizer.Direction.down] {

            let sw = UISwipeGestureRecognizer(target: self,
                                       action: #selector(dragUpAndDown))
            sw.direction = swipe
            arView.addGestureRecognizer(sw)
        }
    }       
    @objc func dragUpAndDown(recognizer: UISwipeGestureRecognizer) {
        if recognizer.direction == .up {
            box!.position.y += 0.01
        }
        if recognizer.direction == .down {
            box!.position.y -= 0.01
        }
    }
}

P. S.

Also, this post will show you how raycasting works in conjunction with RealityKit gestures.