I'm starting my journey in developing an immersive app for VisionOS. I've been making steady progress, but I've encountered a specific challenge that I haven't been able to resolve.
I created two ModelEntity objects — a sphere and a cube — and added a DragGesture to the cube. When I drag the cube over the sphere, the two collide correctly, and the collision is logged in the console. So far, everything works as expected.
However, when I try to anchor the cube to my hand, the collision stops working. It's as if the cube loses its ability to detect collisions once it's anchored.
Any guidance or clarification on this behavior would be greatly appreciated.
// ImmersiveView.swift
// estudos_vision
//
// Created by Lailan Rogerio Rodrigues Matos on 15/05/25.
//
import SwiftUI
import RealityKit
import RealityKitContent
struct ImmersiveView: View {
@Environment(AppModel.self) var appModel
@State private var session: SpatialTrackingSession?
@State private var box = ModelEntity()
@State private var subs: [EventSubscription] = []
@State private var ballEntity: Entity?
var body: some View {
RealityView { content in
// Load initial content from the RealityKit scene.
if let immersiveContentEntity = try? await Entity(named: "Immersive", in: realityKitContentBundle) {
content.add(immersiveContentEntity)
}
// Create and run a spatial tracking session.
let session = SpatialTrackingSession()
let configuration = SpatialTrackingSession.Configuration(tracking: [.hand])
_ = await session.run(configuration)
self.session = session
// Create a red box.
let boxMesh = MeshResource.generateBox(size: 0.2)
let material = SimpleMaterial(color: .red, isMetallic: false)
box = ModelEntity(mesh: boxMesh, materials: [material])
box.position.y += 0.15 // Position the box slightly above the origin.
// Configure the box for user interaction and physics.
box.components.set(InputTargetComponent(allowedInputTypes: .indirect)) // Make it interactive.
box.generateCollisionShapes(recursive: false) // Generate collision shapes for physics.
box.components.set(PhysicsBodyComponent( // Add physics behavior.
massProperties: .default,
material: .default,
mode: .kinematic // Use kinematic mode so it can be moved by user interaction.
))
box.components.set(GroundingShadowComponent(castsShadow: true)) // Add a shadow.
//content.add(box) //commented out to add to hand anchor
// Create a left hand anchor and add the box as a child.
let handAnchor = AnchorEntity(.hand(.left, location: .palm), trackingMode: .continuous)
handAnchor.addChild(box)
content.add(handAnchor) // Add the hand anchor to the scene.
// Create a sphere.
let ball = ModelEntity(mesh: .generateSphere(radius: 0.15))
ball.position = [0.0, 1.5, -1.0] // Initial position of the ball.
ball.generateCollisionShapes(recursive: false) // Add collision.
ball.name = "Sphere"
content.add(ball)
ballEntity = ball
// Subscribe to collision events between the box and other entities.
let event = content.subscribe(to: CollisionEvents.Began.self, on: box) { ce in
print("Collision between \(ce.entityA.name) and \(ce.entityB.name) occurred")
//ce.entityA.removeFromParent() // removes the colliding object
//ce.entityB.removeFromParent()
}
Task {
subs.append(event)
}
}
// Add a drag gesture to the box, allowing the user to move it.
.gesture(
DragGesture()
.targetedToEntity(box) // Target the drag gesture to the box.
.onChanged({ value in
// Update the position of the box based on the drag gesture.
box.position = value.convert(value.location3D, from: .local, to: box.parent!)
})
)
}
}
#Preview(immersionStyle: .full) {
ImmersiveView()
.environment(AppModel())
}
