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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Parent is changed during gesture interaction producing incorrect relative translation values.
I'm having trouble re-setting the position of a child entity during app re-load even though it appears that I am correctly obtaining and persisting the correct translation values after a drag gesture. The problem exists when I drag a child element to a new location (persist those new values) then reload the app to force re-positioning from persisted translation values. I notice that the parent relationship changes during interaction (tap or drag) which can be seen in the debug statements. I'm wondering if this is related to the problem, or, if the parent change is normal during re-rendering and is un-related to my problem. My thought process is since we care about relative translation values when persisting, if the parent relationship is changed just before persistence, then, are we persisting and setting the wrong values? Project Link: Private STEPS TO REPRODUCE Run the app. Drag the pre-loaded stage down the Y axis so that the floor of the stage is more visible to your eye (in order to better visualize the problem). Tap the button in the timeline to create a new project. Drag the only visible element from the left panel onto the timeline (element is labeled f_works_entity_1). There should now be a green 3d model added to the stage. Drag this green element to a new location (be careful to hover over the green element so that you don't inadvertently drag the stage). Re-run the app to see that the green element is offset to a new location, not the last dragged location. To reset and try again, delete the project canvas next to the project name (trash button) then restart the app. Areas of concern: RealityKitView is the only file you may need. Line 119 is where we create new child entities Lines 185-219 is where we persist and apply persisted values. You can also search FIXME in the file to see areas of concern. Tip: I have a tap gesture on each entity that produces a debug statement with info about the entity and its parent including IDs.
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502
Nov ’24
Rendering bug when layering transparent textures front and back
If I put an alpha image texture on a model created in Blender and run it on RCP or visionOS, the rendering between the front and back due to alpha will result in an unintended rendering. Details are below. I expor ted a USDC file of a Blender-created cylindrical object wit h a PNG (wit h alpha) texture applied to t he inside, and t hen impor ted it into Reality Composer Pro. When multiple objects t hat make extensive use of transparent textures are placed in front of and behind each ot her, t he following behaviors were obser ved in t he transparent areas ・The transparent areas do not become transparent ・The transparent areas become transparent toget her wit h t he image behind t hem the order of t he images becomes incorrect Best regards.
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704
Nov ’24
Physics
Given my limited knowledge of physics, I would appreciate it if individuals with a solid understanding of the subject could provide insights into this matter. I have added a physical component to a entity in Reality Composer Pro, but I am seeking guidance on how to achieve the following: Make an object float in the air (with a slight downward motion reminiscent of the moon’s surface) Enable the object to move at a slow pace Implement a strong rebound force I would be grateful if you could provide appropriate values for these parameters. Thank you for your assistance.
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609
Sep ’24
Regarding real-time object tracking and real-time image recognition
We used real-time object tracking, and with enterprise permissions, we can improve the smoothness to 30Hz, but there are still noticeable delays. On one hand, we want to know why this delay occurs; is it due to performance considerations? Because we found that the delay in hand tracking is actually very low. On the other hand, we consider that it may be due to the complexity of 3D objects, so I considered using image tracking. However, we found that there are even more serious delays in image tracking and QR code tracking. We hope to optimize it. Currently, the frame rate for recognizing images for tracking seems to be one frame per second, and we hope to increase it because object recognition and tracking can be very smooth on other Apple platforms, such as iOS. Additionally, can we appropriately consider interfaces for depth recognition to obtain depth data? We want to know what accuracy vision can achieve in measuring the physical world, as well as the accuracy in rendering on the screen. We wonder if this is related to hardware devices like radar. Also, what accuracy can we achieve in tracking the movement distance of objects?
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450
Nov ’24
Obect Capture App getting rejected for not supporting non Pro Models
Hi, I created an app using iOS Object Capture API which works only on Lidar enabled phones. It's a limitation of the Api provided by apple itself. I Submitted an app for Review , but It is getting rejected (Twice) saying it doesnt work on non pro models. Even though I explained that capturing Needs Lidar and supported only in PRO models, It still gets rejected after testing in Non Pro models. is there a way out?
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326
Feb ’25
Reality kit Entities Appearing to Lag in a Full or Progressive Style Immersive Space When Opened with Environment Turned On
PLATFORM AND VERSION Vision OS Development environment: Xcode 16.2, macOS 15.2 Run-time configuration: visionOS 2.3 (On Real Device, Not simulator) Please someone confirm I'm not crazy and this issue is actually out of my control. Spent hours trying to fix my app and running profiles because thought it was an issue related to my apps performance. Finally considered chance it was issue with API itself and made sample app to isolate problem, and it still existed in it. The issue is when a model entity moves around in a full space that was launched when the system environment immersion was turned up before opening it, the entities looks very choppy as they move around. If you take off the headset while still in the space, and put it back on, this fixes it and then they move smoothly as they should. In addition, you can also leave the space, and then turn the system environment immersion all the way down before launching the full space again, this will also make the entity moves smoothly as it should. If you launch a mixed immersion style instead of a full immersion style, this issue never arrises. The issue only arrises if you launch the space with either a full style, or progressive style, while the system immersion level is turned on. STEPS TO REPRODUCE https://github.com/nathan-707/ChoppyEntitySample Open my test project, its a small, modified vision os project template that shows it clearly. otherwise: create immersive space with either full or progressive immersion style. setup a entity in kinematic mode, apply a velocity to it to make it pass over your head when the space appears. if you opened the space while the Apple Vision Pros system environment was turned up, the entity will look choppy. if you take the headset off while in the same space, and put it back on, it will fix the issue and it will look smooth. alternatively if you open the space with the system immersion environment all the way down, you will also not run into the issue. Again, issue also does not happen if space launched is in mixed style.
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522
Jan ’25
ShaderGraphMaterial with Occlusion Surface Output fails to load on iOS and macOS
A ShaderGraphMaterial with an Occlusion Surface Output generated with RealityComposer 2 fails to load on iOS 18 and macOS 15 with the following error: RealityFoundation.ShaderGraphMaterial.LoadError.invalidTypeFound (https://developer.apple.com/documentation/realitykit/shadergraphmaterial/loaderror/invalidtypefound) This happens with both https://developer.apple.com/documentation/shadergraph/realitykit/occlusion-surface-(realitykit) and https://developer.apple.com/documentation/shadergraph/realitykit/shadow-receiving-occlusion-surface-(realitykit) RealityView { content in do { let bgEntity = ModelEntity(mesh: .generateCone(height: 0.5, radius: 0.1), materials: [SimpleMaterial(color: .red, isMetallic: true)]) bgEntity.position.z = -0.2 content.add(bgEntity) let occlusionMaterial = try await ShaderGraphMaterial(named: "/Root/OcclusionMaterial", from: "OcclusionMaterial") let testEntity = ModelEntity(mesh: .generateSphere(radius: 0.4), materials: [occlusionMaterial]) content.add(testEntity) content.cameraTarget = testEntity } catch { print("Shader Graph Load Error:") dump(error) } } .realityViewCameraControls(.orbit) .edgesIgnoringSafeArea(.all) Feedback ID: FB15081296
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703
Jan ’25
RealityKit Rotation Origin
I am trying to rotate topEntity around the origin point of shapeEntity, but have not found a way to do so. topEntity is an entity group that also contains shapeEntity, so I cannot set topEntity as a child of shapeEntity. From Blender I set the correct origin of topEntity, but when I import the usd model into Reality Composer Pro it does not save the origin point and there is no way to set the origin in Reality Composer Pro. DragGesture() .targetedToEntity(where: .has(CustomComponent.self)) .onChanged({ value in let rotation = -Float(value.translation.height) let clampedRotation = min(max(rotation, 0), 45) if value.entity.name == "grab"{ if let topEntity = selectedEntity.findEntity(named: "top"), let shapeEntity = selectedEntity.findEntity(named: "Shape_1"){ topEntity.transform.rotation = simd_quatf( angle: clampedRotation * .pi / 180, axis: SIMD3(x: 0, y: 0, z: 1) ) } } })
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399
Nov ’24
Translation API availability on visionOS
Hi, One of the great features introduced in WWDC24 is the Translation API. But unfortunately it's currently unavailable on visionOS. My question is, does Apple have any plan to support it on visionOS as well? If so, what's the ETA for this feature? I would really like to see it on visionOS, otherwise I'll have to pay Google to use their translation API.
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598
Oct ’24
Game controller issues in visionOS
Hi, I'm building a windowed game in visionOS which requires a gamepad. And I'm using a PS5 controller for this case. However, I found a few problems: When looking at the window close button, and press X in the gamepad, the window will be closed. This can happen accidentally when the user is playing. When press the PS button(the home button), I want my app to handle it, e.g. take the user to the title screen. But visionOS will always capture this input and opens the home screen(App Library). How to avoid these 2 issues? Or in general, how to make the gamepad input only available to my app but not the visionOS system?
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632
Nov ’24
I want to know the update principle of the `RealityView`.
Here is the code snippets. struct RealityViewTestView: View { @State private var texts: [String] = [] var body: some View { RealityView { content, attachments in } update: { content, attachments in for text in texts { if let textEntity = attachments.entity(for: text) { textEntity.position.x = Float.random(in: -0.1...0.1) content.add(textEntity) } } } attachments: { ForEach(texts, id: \.self) { text in Attachment(id: text) { Text(text) .padding() .glassBackgroundEffect() } } } .toolbar { ToolbarItem { Button("Add") { texts.append(String(UUID().uuidString.prefix(6))) } } ToolbarItem { Button("Remove") { texts.remove(at: Int.random(in: 0..<texts.count)) } } } } } struct RealityViewTestView: View { @State private var texts: [String] = [] @State private var entities: [Entity] = [] var body: some View { RealityView { content, attachments in } update: { content, attachments in // for text in texts { // if let textEntity = attachments.entity(for: text) { // textEntity.position.x = Float.random(in: -0.1...0.1) // content.add(textEntity) // } // } for entity in entities { content.add(entity) } } attachments: { ForEach(texts, id: \.self) { text in Attachment(id: text) { Text(text) .padding() .glassBackgroundEffect() } } } .toolbar { ToolbarItem { Button("Add") { //texts.append(String(UUID().uuidString.prefix(6))) let m = ModelEntity(mesh: .generateSphere(radius: 0.1), materials: [SimpleMaterial(color: .white, isMetallic: false)]) m.position.x = Float.random(in: -0.2...0.2) entities.append(m) } } ToolbarItem { Button("Remove") { //texts.remove(at: Int.random(in: 0..<texts.count)) entities.removeLast() } } } } } About the first code snippet, when I remove an element from the texts, why content can automatically remove the corresponding entity? And about the second code snippet, content do not automatically remove the corresponding entity. I am very curious.
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412
Jan ’25
How to use `unproject(_:from:to:ontoPlane:)` of Content of RealityView
When using ARView of RealityKit, I can code like this let results = arView.raycast(from: point, allowing: .estimatedPlane, alignment: .any) to get the 3D position of where I tap on the plane. In iOS 18, we can use RealityView and I found that unproject(_:from:to:ontoPlane:) may implement the same function, but I don't know how to set the ontoPlane parameter. Can someone help me with some code snippets?
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580
Nov ’24
Need to get The VisonOS Player's Camera forward vector on runtime
How can I access the player’s camera vector in VisionOS, specifically using RealityKit? In Unity and other game engines, there’s often an API like "Camera.main.transform.forward for this purpose. " I’ve found the head anchor but haven’t identified a way to obtain the forward vector in RealityKit. Is there a related API for this? Any guidance would be greatly appreciated. Thanks!
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670
Nov ’24
DeactivatedEntities in scene not found with entity.findEntity(named:)?
I have a rkasset package, from which I load my scene. In the scene, I'm using entity.findEntity(named:"..") to find entities to activate/deactivate. When I have entities deactivated in the *.usda, they are not found with this method. Further inspection shows that the deactivated entities seem not to be compiled into the build. Is there anything I can set that prevents skipping the build for these deactivated entities?
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353
Oct ’24