How to use trackedRaycast(_:updateHandler:) method in ARKit?

Question

Repeats a ray-cast query over time to notify you of updated surfaces in the physical environment.

How to use this func in ARKit?

func trackedRaycast(_ query: ARRaycastQuery, 
              updateHandler: @escaping ([ARRaycastResult]) -> Void) -> ARTrackedRaycast?

Answer 1

Apple Developer documentation says the following about trackedRaycast():

trackedRaycast(_:updateHandler:) instance method repeats a ray-cast query over time to notify you of updated surfaces in the physical environment. A tracked ray cast wraps a ray-cast query that the ARSession calls repeatedly, each time invoking your update handler to provide you with new results. When you're ready to stop a tracked ray cast, call stopTracking().

So, here's a code snippet that you can use in your project:

import RealityKit
import ARKit

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

let raycastQuery: ARRaycastQuery = .init(origin: [0,0,0],
                                      direction: [7,7,7],
                                       allowing: .estimatedPlane,
                                      alignment: .horizontal)

let repeatRaycast = self.arView.session.trackedRaycast(raycastQuery) { results in

    // Update Handler's content
    guard let result: ARRaycastResult = results.first
    else { return }

    let anchor = AnchorEntity(world: result.worldTransform)
    anchor.addChild(self.scene)

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

Then you can stop tracking:

repeatRaycast?.stopTracking()