How do I use a RealityKit ARView with ARImageTrackingConfiguration? - arkit

Question

Can I see an example using a RealityKit ARView with ARImageTrackingConfiguration including the ARSessionDelegate delegate methods?

Answer 1

Here is an example of a RealityKit ARView using ARImageTrackingConfiguration and the ARSessionDelegate delegate methods. I didn't see a complete example of exactly this on Stack Overflow so thought I would ask/answer it myself.
import ARKit
import RealityKit
class ViewController: UIViewController, ARSessionDelegate {
#IBOutlet var arView: ARView!
override func viewDidLoad() {
super.viewDidLoad()
// There must be a set of reference images in project's assets
guard let referenceImages = ARReferenceImage.referenceImages(inGroupNamed: "AR Resources", bundle: nil) else { fatalError("Missing expected asset catalog resources.") }
// Set ARView delegate so we can define delegate methods in this controller
arView.session.delegate = self
// Forgo automatic configuration to do it manually instead
arView.automaticallyConfigureSession = false
// Show statistics if desired
arView.debugOptions = [.showStatistics]
// Disable any unneeded rendering options
arView.renderOptions = [.disableCameraGrain, .disableHDR, .disableMotionBlur, .disableDepthOfField, .disableFaceOcclusions, .disablePersonOcclusion, .disableGroundingShadows, .disableAREnvironmentLighting]
// Instantiate configuration object
let configuration = ARImageTrackingConfiguration()
// Both trackingImages and maximumNumberOfTrackedImages are required
// This example assumes there is only one reference image named "target"
configuration.maximumNumberOfTrackedImages = 1
configuration.trackingImages = referenceImages
// Note that this config option is different than in world tracking, where it is
// configuration.detectionImages
// Run an ARView session with the defined configuration object
arView.session.run(configuration)
}
func session(_ session: ARSession, didAdd anchors: [ARAnchor]) {
// This example assumes only one reference image of interest
// A for-in loop could work for more targets
// Ensure the first anchor in the list of added anchors can be downcast to an ARImageAnchor
guard let imageAnchor = anchors[0] as? ARImageAnchor else { return }
// If the added anchor is named "target", do something with it
if let imageName = imageAnchor.name, imageName == "target" {
// An example of something to do: Attach a ball marker to the added reference image.
// Create an AnchorEntity, create a virtual object, add object to AnchorEntity
let refImageAnchor = AnchorEntity(anchor: imageAnchor)
let refImageMarker = generateBallMarker(radius: 0.02, color: .systemPink)
refImageMarker.position.y = 0.04
refImageAnchor.addChild(refImageMarker)
// Add new AnchorEntity and its children to ARView's scene's anchor collection
arView.scene.addAnchor(refImageAnchor)
// There is now RealityKit content anchored to the target reference image!
}
}
func session(_ session: ARSession, didUpdate anchors: [ARAnchor]) {
guard let imageAnchor = anchors[0] as? ARImageAnchor else { return }
// Assuming only one reference image. A for-in loop could work for more targets
if let imageName = imageAnchor.name, imageName == "target" {
// If anything needs to be done as the ref image anchor is updated frame-to-frame, do it here
// E.g., to check if the reference image is still being tracked:
// (https://developer.apple.com/documentation/arkit/artrackable/2928210-istracked)
if imageAnchor.isTracked {
print("\(imageName) is tracked and has a valid transform")
} else {
print("The anchor for \(imageName) is not guaranteed to match the movement of its corresponding real-world feature, even if it remains in the visible scene.")
}
}
}
// Convenience method to create colored spheres
func generateBallMarker(radius: Float, color: UIColor) -> ModelEntity {
let ball = ModelEntity(mesh: .generateSphere(radius: radius), materials: [SimpleMaterial(color: color, isMetallic: false)])
return ball
}
}