AR objects not anchoring or sizing correctly in RealityKit - swift

Question

I have an AR scene with two objects, one brown cow and one black one. They're both supposed to be displayed in the scene, distanced a little apart. I originally only had the brown cow, which was just a little bit too big. I changed something, which I can't remember, and now my scene is from the inside of the cow, and I can't exit the cow's corpse. It seems like it moves around when I do. I think the issue is because of a positive number for the [minimum bounds]but I'm not entirely sure. I've set the z axis for the cow as well.How can I make the cow a little bit smaller and about 5-7 yards away from me at spawn?
import UIKit
import RealityKit
import ARKit
class ViewController: UIViewController {
#IBOutlet var arView: ARView!
override func viewDidLoad() {
super.viewDidLoad()
arView.session.delegate = self
showModel()
overlayCoachingView()
setupARView()
arView.addGestureRecognizer(UITapGestureRecognizer(target: self, action:
#selector(handleTap(recognizer:))))
}
func showModel(){
let anchorEntity = AnchorEntity(plane: .horizontal, minimumBounds:[0.7, 0.7])
let entity = try! Entity.loadModel(named: "COW_ANIMATIONS")
entity.setParent(anchorEntity)
arView.scene.addAnchor(anchorEntity)
}
func overlayCoachingView () {
let coachingView = ARCoachingOverlayView(frame: CGRect(x: 0, y: 0, width:
arView.frame.width, height: arView.frame.height))
coachingView.session = arView.session
coachingView.activatesAutomatically = true
coachingView.goal = .horizontalPlane
view.addSubview(coachingView)
}
// Load the "Box" scene from the "Experience" Reality File
// let boxAnchor = try! Experience.loadBox()
// Add the box anchor to the scene
//arView.scene.anchors.append(boxAnchor)
func setupARView(){
arView.automaticallyConfigureSession = false
let configuration = ARWorldTrackingConfiguration()
configuration.planeDetection = [.horizontal, .vertical]
configuration.environmentTexturing = .automatic
arView.session.run(configuration)
}
//object placement
#objc
func handleTap(recognizer: UITapGestureRecognizer){
let location = recognizer.location(in:arView)
let results = arView.raycast(from: location, allowing: .estimatedPlane, alignment: .horizontal)
if let firstResult = results.first {
let anchor = ARAnchor(name: "COW_ANIMATIONS", transform: firstResult.worldTransform)
arView.session.add(anchor: anchor)
} else {
print("Object placement failed - couldn't find surface.")
//cow animations
let robot = try! ModelEntity.load(named: "COW_ANIMATIONS")
let anchor = AnchorEntity()
anchor.children.append(robot)
arView.scene.anchors.append(anchor)
robot.playAnimation(robot.availableAnimations[0].repeat(duration: .infinity),
transitionDuration: 0.5,
startsPaused: false)
//start cow animation
let brownCow = try! ModelEntity.load(named: "COW_ANIMATIONS")
let blackCow = try! ModelEntity.load(named: "Cow")
brownCow.position.x = -1.0
blackCow.position.x = 1.0
brownCow.setParent(anchor)
blackCow.setParent(anchor)
arView.scene.anchors.append(anchor)
let cowAnimationResource = brownCow.availableAnimations[0]
let horseAnimationResource = blackCow.availableAnimations[0]
brownCow.playAnimation(cowAnimationResource.repeat(duration: .infinity),
transitionDuration: 1.25,
startsPaused: false)
blackCow.playAnimation(horseAnimationResource.repeat(duration: .infinity),
transitionDuration: 0.75,
startsPaused: false)
//end cow animations
func placeObject(named entityName: String, for anchor: ARAnchor) {
let entity = try! ModelEntity.loadModel(named: entityName)
entity.generateCollisionShapes(recursive: true)
arView.installGestures([.rotation, .translation], for: entity)
let anchorEntity = AnchorEntity(anchor: anchor)
anchorEntity.addChild(entity)
arView.scene.addAnchor(anchorEntity)
}
}
extension ViewController: ARSessionDelegate {
func session( session: ARSession, didAdd anchors: [ARAnchor]) {
for anchor in anchors {
if let anchorName = anchor.name, anchorName == "COW_ANIMATIONS" {
placeObject(named: anchorName, for: anchor)
} }
}
}

Answer 1

First step
In RealityKit, if a model was tethered with its personal anchor (the case when one anchor holds just one model), you have two ways to scale it:
cowEntity.scale = [0.7, 0.7, 0.7]
// or
cowAnchor.scale = SIMD3<Float>([1, 1, 1] * 0.7)
and you have minimum two ways to position cow model along any axis (for instance along Z axis):
cowEntity.position = SIMD3<Float>(0, 0,-2)
// or
cowAnchor.position.z = -2.0
So, as you see, when you transform cowAnchor, all its children get this transformation as well.
Second step
You need to appropriately place a model's pivot point in 3D authoring app. At the moment RealityKit doesn't have a tool to fix pivot's position as you can do in SceneKit using simdPivot instance property.