Discuss spatial computing on Apple platforms and how to design and build an entirely new universe of apps and games for Apple Vision Pro.

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Playing USDZ animation at last known location of reference object
Hi there I'm using Reality Composer Pro to anchor virtual content to a .referenceobject. However by moving the referenceobject quickly, it causes tracking to stop. (I know this is a limitation so im trying to make it a feature) IS there a way to play a USDZ animation at the last known location, after detecting that reference object is no longer being tracked? is it possible to set this up in Reality Composer pro? Nearly everything is set up in Reality Composer pro with my immersive.scene just anchoring virtual content to the Reference object in the RCP Scene, so my immersive view just does this - if let immersiveContentEntity = try? await Entity(named: "Immersive", in: realityKitContentBundle) { content.add(immersiveContentEntity) & this .onAppear { appModel.immersiveSpaceState = .open } .onDisappear { appModel.immersiveSpaceState = .closed } I have tried Using SpatialTracking & WorldTrackProvider, but I'm still quite new to Swift and coding in general so im unsure how to implement in conjunction with my RCP scene and if this is actually the right way to do it. Apologies for my lack of knowledge.
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Apr ’25
Playing USDZ animation at last known location of reference object
Hi there I'm using Reality Composer Pro to anchor virtual content to a .referenceobject. However moving the referenceobject quickly causes tracking to stop. (I know this is a limitation and I am trying to embrace it as a feature) Is there a way to play a USDZ animation at the last known location, after detecting that the reference object is no longer tracked? is it possible to set this up in Reality Composer pro? I'm trying to get the USDZ to play before the Virtual Content disappears (due to reference object not being located). So that it smooths out the vanishing of the content. Nearly everything is set up in Reality Composer pro with my immersive.scene just adding virtual content to the reference object which anchors it in the RCP Scene, so my immersive view just does this - if let immersiveContentEntity = try? await Entity(named: "Immersive", in: realityKitContentBundle) { content.add(immersiveContentEntity) & this .onAppear { appModel.immersiveSpaceState = .open } .onDisappear { appModel.immersiveSpaceState = .closed } I have tried Using SpatialTracking & WorldTrackingProvider, but I'm still quite new to Swift and coding in general so im unsure how to implement in conjunction with my RCP scene and/or if this is the right way to go about it. Also I have implemented this at the beginning of object tracking. All I had to do was add a onAppear behavior to the object to play a USDZ and that works. Doing it for disappearing (due to loss of reference object) seems to be a lot harder.
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Apr ’25
Cannot reassign worldTracking / planeDetection providers in my PlacementManager when switching environments
Environment Xcode: 16.2 VisionOS SDK 2.4 Swift 6.1 Targets: Apple Vision Pro (immersive space) Frameworks: ARKit, RealityKit, SwiftUI What I’m Trying to Do I have a view-model class PlacementManager that holds two AR providers: private var worldTracking: WorldTrackingProvider private var planeDetection: PlaneDetectionProvider I want to dynamically replace these providers in a setEnvironment(_:) method (so I can save/clear a JSON scene and restart ARKit). What’s Happening If I declare them as : private let worldTracking = WorldTrackingProvider() private let planeDetection = PlaneDetectionProvider() I get compile-errors when I later do: self.worldTracking = newWorldTracking // Cannot assign to property: 'worldTracking' is a 'let' constant If I change them to un-initialized vars: private var worldTracking: WorldTrackingProvider private var planeDetection: PlaneDetectionProvider then in my init() I get: self used in property access 'worldTracking' before all stored properties are initialized Code snipet @Observable final class PlacementManager : ObservableObject { private var worldTracking: WorldTrackingProvider private var planeDetection: PlaneDetectionProvider // … other props … @MainActor init() { // error: self.worldTracking used before init… planeAnchorHandler = PlaneAnchorHandler(rootEntity: root) persistenceManager = PersistenceManager( worldTracking: worldTracking, rootEntity: root ) // … } @MainActor func setEnvironment(env: Environnement) async { let newWorldTracking = WorldTrackingProvider() let newPlaneDetection = PlaneDetectionProvider() try await appState!.arkitSession.run( [ newWorldTracking, newPlaneDetection ] ) self.worldTracking = newWorldTracking self.planeDetection = newPlaneDetection // … } } What I’ve Tried Giving them default values at declaration (= WorldTrackingProvider()) Initializing them at the top of init() before any use Passing the new providers into arkitSession.run(...) My Question What is the recommended Swift-style pattern to declare and reassign these ARKit provider properties so that: They’re fully initialized before use in init(), and I can swap them out later in setEnvironment(...) without compiler errors? Any pointers (or links to forum threads / docs) would be greatly appreciated!
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137
May ’25
RoomPlan - The delegate of ARSession is retaining x ARFrames
Hi, I'm encountering an issue in our app that uses RoomPlan and ARsession for scanning. After prolonged use—especially under heavy load from both the scanning process and other unrelated app operations—the iPhone becomes very hot, and the following warning begins to appear more frequently: "ARSession <0x107559680>: The delegate of ARSession is retaining 11 ARFrames. The camera will stop delivering camera images if the delegate keeps holding on to too many ARFrames. This could be a threading or memory management issue in the delegate and should be fixed." I was able to reproduce this behavior using Apple’s RoomPlanExampleApp, with only one change: I introduced a CPU-intensive workload at the end of the startSession() function: DispatchQueue.global().asyncAfter(deadline: .now() + 5) { for i in 0..<4 { var value = 10_000 DispatchQueue.global().async { while true { value *= 10_000 value /= 10_000 value ^= 10_000 value = 10_000 } } } } I suspect this is some RoomPlan API problem that's why a filed an feedback: 17441091
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May ’25
RealityKit System update and timing
Hi, I'm playing now with hand tracking. I want to get position of hand inside a system update function. I was not sure if transform I'm getting from hand attached AnchorEntity (with trackingMode: .predicted) would give same results as handAnchors(at:) from hand tracking provider, so I started to read them both and compare. For handAnchors i tried using context.scene.timebase.sourceTimebase!.sourceClock!.time.seconds and CACurrentMediaTime() as timestamp source. They seem to use exactly same clock, so that doesn't matter, but: for some reason update handler is always called twice with same context.deltaTime, but first time the query finds 0 entities, second time it finds them all. The query is the standard EntityQuery(where: .has(MyComponent.self)) and in update (matching: Self.query, updatingSystemWhen: .rendering). Here's part of logs: System update called, entity count: 0, dt: 0.01000458374619484, absTime: 4654.222593541 System update called, entity count: 11, dt: 0.01000458374619484, absTime: 4654.22262525 System update called, entity count: 0, dt: 0.009999999776482582, absTime: 4654.249390875 System update called, entity count: 11, dt: 0.009999999776482582, absTime: 4654.249425 accounting for the double update calling I started to calculate time delta of absolute time between calls and they're most of the time much bigger, or much smaller than advertised by system's context.deltaTime, only sometimes they kind of match, for example: system: (dt: 0.01000458374619484) scene : (dt: 0.021419291667371) (absTime: 4654.222628125001) and the very next call system: (dt: 0.010009 166784584522) scene : (dt: 0.0013097083328830195) (absTime: 4654.223937833334) but sometimes system: (dt: 0.009999999776482582) scene : (dt: 0.009 112249999816413) (absTime: 4654.351299 166668) Shouldn't those be more or less equal, or am I missing something? In the end it seems that getting hand position from AnchorEntity and with handAnchors(at:) gives kind of same results, but at different time points, so I'd love to understand what's the correct way to use them and why time flows differently :). --Edit-- P.S. Had to put spaces everywhere in logs between "9" and "1", otherwise post was blocked due to "sensitive content" :D
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May ’25
Can not remove final World Anchor
I’ve been having some issues removing anchors. I can add anchors with no issue. They will be there the next time I run the scene. I can also get updates when ARKit sends them. I can remove anchors, but not all the time. The method I’m using is to call removeAnchor() on the data provider. worldTracking.removeAnchor(forID: uuid) // Yes, I have also tried `removeAnchor(_ worldAnchor: WorldAnchor)` This works if there are more than one anchor in a scene. When I’m down to one remaining anchor, I can remove it. It seems to succeed (does not raise an error) but the next time I run the scene the removed anchor is back. This only happens when there is only one remaining anchor. do { // This always run, but it doesn't seem to "save" the removal when there is only one anchor left. try await worldTracking.removeAnchor(forID: uuid) } catch { // I have never seen this block fire! print("Failed to remove world anchor \(uuid) with error: \(error).") } I posted a video on my website if you want to see it happening. https://stepinto.vision/labs/lab-051-issues-with-world-tracking/ Here is the full code. Can you see if I’m doing something wrong? Is this a bug? struct Lab051: View { @State var session = ARKitSession() @State var worldTracking = WorldTrackingProvider() @State var worldAnchorEntities: [UUID: Entity] = [:] @State var placement = Entity() @State var subject : ModelEntity = { let subject = ModelEntity( mesh: .generateSphere(radius: 0.06), materials: [SimpleMaterial(color: .stepRed, isMetallic: false)]) subject.setPosition([0, 0, 0], relativeTo: nil) let collision = CollisionComponent(shapes: [.generateSphere(radius: 0.06)]) let input = InputTargetComponent() subject.components.set([collision, input]) return subject }() var body: some View { RealityView { content in guard let scene = try? await Entity(named: "WorldTracking", in: realityKitContentBundle) else { return } content.add(scene) if let placementEntity = scene.findEntity(named: "PlacementPreview") { placement = placementEntity } } update: { content in for (_, entity) in worldAnchorEntities { if !content.entities.contains(entity) { content.add(entity) } } } .modifier(DragGestureImproved()) .gesture(tapGesture) .task { try! await setupAndRunWorldTracking() } } var tapGesture: some Gesture { TapGesture() .targetedToAnyEntity() .onEnded { value in if value.entity.name == "PlacementPreview" { // If we tapped the placement preview cube, create an anchor Task { let anchor = WorldAnchor(originFromAnchorTransform: value.entity.transformMatrix(relativeTo: nil)) try await worldTracking.addAnchor(anchor) } } else { Task { // Get the UUID we stored on the entity let uuid = UUID(uuidString: value.entity.name) ?? UUID() do { try await worldTracking.removeAnchor(forID: uuid) } catch { print("Failed to remove world anchor \(uuid) with error: \(error).") } } } } } func setupAndRunWorldTracking() async throws { if WorldTrackingProvider.isSupported { do { try await session.run([worldTracking]) for await update in worldTracking.anchorUpdates { switch update.event { case .added: let subjectClone = subject.clone(recursive: true) subjectClone.isEnabled = true subjectClone.name = update.anchor.id.uuidString subjectClone.transform = Transform(matrix: update.anchor.originFromAnchorTransform) worldAnchorEntities[update.anchor.id] = subjectClone print("🟢 Anchor added \(update.anchor.id)") case .updated: guard let entity = worldAnchorEntities[update.anchor.id] else { print("No entity found to update for anchor \(update.anchor.id)") return } entity.transform = Transform(matrix: update.anchor.originFromAnchorTransform) print("🔵 Anchor updated \(update.anchor.id)") case .removed: worldAnchorEntities[update.anchor.id]?.removeFromParent() worldAnchorEntities.removeValue(forKey: update.anchor.id) print("🔴 Anchor removed \(update.anchor.id)") if let remainingAnchors = await worldTracking.allAnchors { print("Remaining Anchors: \(remainingAnchors.count)") } } } } catch { print("ARKit session error \(error)") } } } }
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May ’25
How to Achieve Realistic Colors and Textures in LiDAR Scanning with Swift
Hello, I'm developing a LiDAR-based scanning app using Swift, where I can successfully perform scans and export the results as .obj files. My goal is to have the scan's colors and textures closely resemble real-world visuals as captured by the camera, similar to the results shown in this repository. In the referenced repository, the result is demonstrated with a single screenshot, but I want to display the textures and colors throughout the entire scanning process, not just at the final result. To clarify, I'm not focused on scanning individual objects but rather larger environments like rooms, houses, or outdoor spaces such as streets. Here’s what I’m aiming for: Realistic colors and textures that match what the camera sees during the scan. Continuous texture rendering during the scanning process, not just in the final exported model. Could anyone share guidance, sample code, or point me to relevant documentation to achieve this? Any help would be greatly appreciated! Thank you!
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May ’25
Vision Pro stucks on "Retrieving configuration"
Hi, after upgrading to 2.4.1 (from 1.0) my vision stucks on "Retrieving configuration" screen. Apple Store didn't support my case since it has been sold in USA and the product isn't still present in italian market. I don't have dev strap, how can I manage the issue? Thank you
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May ’25
Is `ParticleEmitterComponent` implemented for `RealityKit` on iOS?
Hi there, I was looking to add a particle emitter to my augmented reality app I'm developing using RealityKit. I'm targeting iOS. I noticed in the documentation for the ParticleEmitterComponent that it looks like iOS 18.0+ is supported, but when I try to use the ParticleEmitterComponent in my code in XCode, I get an error that it isn't found. Furthermore, this StackOverflow post seems to indicate that particle systems are not available for iOS. Would it be possible to get clarification on this?
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150
May ’25
How to implement the semi-transparent overlay effect in Immersive View?
I noticed that when I drag the menu window in an Immersive View, the entities behind it becomes semi-transparent, and the boundary between virtual and real-world objects is very pronounced. May I ask how does VisionOS implement this effect? Is there any API or technique I can use in my own code to enable the same semi-transparent overlay - even when I am not dragging the menu window?
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May ’25
Is it Possible to Place a 3D Model at the Exact Position of a QR Code in AR with ARKit ?
I'm working on an iOS app using ARKit and RealityKit where I scan QR codes and want to place 3D models at the exact position of the QR code in the real world. Is it possible to accurately place a 3D model at the exact position of a QR code in AR using ARKit and RealityKit? Specifically, I want the model to appear at the precise location where the QR code is detected, rather than just somewhere in the AR space. If this is possible, could you point me in the right direction or recommend the best approach to achieve this? Thank you for your help!
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May ’25
The folding and unfolding effect of the NBA sand table
Seeing this magical sand table, the unfolding and folding effects are similar to spreading out cards, which is very interesting. But I don't know how to achieve it. I want to see if there are any ways to achieve this effect and give some ideas. May I ask if this effect can be achieved under the existing API
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May ’25
Lidar sensor does not work on some Iphone 13 Pro
I am experience problem with three iPhone 13 Pro. They are reporting the lowest quality for all points in the depthmap from the Lidar sensor. The readings I get are unusable. If it was just one phone I would consider it a faulty sensor, but in this case it is three phones that gives the same result. I have other iPhone 13 Pro that works as expected. Have any else experienced a similar behavior? I am using iOS 18.4.1 https://developer.apple.com/documentation/avfoundation/avdepthdata/depthdataquality
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May ’25
Launching a timeline on a specific model via notification
Hello! I’m familiar with the discussion on “Sending messages to the scene”, and I’ve successfully used that code. However, I have several instances of the same model in my scene. Is it possible to make only one specific model respond to a notification? For example, can I pass something like RealityKit.NotificationTrigger.SourceEntity in userInfo or use another method to target just one instance?
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May ’25
RealityRenderer's Perspective Camera's FOV
Hi, I have been using RealityRenderer to render scenes in MacOS as spatial videos and view it in Vision Pro and it is awesome. I understand that it uses PerspectiveCamera to render. I wanted to know what is the default FOV for this camera and how much can we push it? I want to ideally render a scene with 180 degrees of fov. Thanks
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May ’25