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Simulate and render 3D content for use in your augmented reality apps using RealityKit.

RealityKit Documentation

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RealityKit and USDZ: Winding Order Issue with Negatively Scaled Meshes
Hi all, I've encountered a potential issue with how the winding order of geometry is handled when their transformations involve negative scaling. I created a simple test asset, a single triangle, to demonstrate this. The triangle's vertices are defined in a counter-clockwise ("right-handed") winding order, and its transform has a negative scale on the X-axis. According to the OpenUSD specification, this negative determinant in the transformation matrix should effectively reverse the winding order of the geometry: However, any given gprim's local-to-world transformation can flip its effective orientation, when it contains an odd number of negative scales. This condition can be reliably detected using the (Jacobian) determinant of the local-to-world transform: if the determinant is less than zero, then the gprim's orientation has been flipped, and therefore one must apply the opposite handedness rule when computing its surface normals (or just flip the computed normals) for the purposes of hidden surface detection and lighting calculations. When I view the asset in tools like Blender or Preview on macOS, it behaves as expected. The triangle's effective orientation is flipped to CW. However, when the same asset is viewed in Reality Composer Pro or with QuickLook on iOS, its effective orientation remains CCW. In other words, the triangle faces the opposite direction. My questions for the community and Apple are: Is this behavior in RealityKit a known issue? If this is a known issue, is there official guidance for DCC tools on how to export USDZ assets to ensure they appear correctly in the Apple ecosystem? Any insights or recommendations would be greatly appreciated.
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1k
Nov ’25
Moving from SceneKit - fog missing
I am rewriting an unfinished SceneKit project as RealityKit (NonAR). As far as I can see, RealityKit is missing basic fog functionality? Fog was simple & easy to implement in SCeneKit (fogStartDistance / fogEndDistance / fogDensityExponent / fogColor). Are there any plans to implement something like this in RealityKit? Are there any simple workarounds?
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610
Aug ’25
Multiply exr lightmap in Reality Composer Pro Shader Graph
I’m trying to use EXR lightmaps to overlay baked lighting on top of a base texture in the RCP Shader Graph. When I multiply an EXR image set to Image(float) with an 8-bit base texture, the output becomes Image(float). I can’t connect that to the BaseColor input on the UnlitSurface node, since it only accepts Color3f. I expected to be able to use a Convert node between the Multiply node and the BaseColor input, but when I do that, the result becomes black and white instead of the expected outcome: the EXR multiplied with the base texture using a baseline value of 1, where values below 1 in the EXR would darken the base texture and values above 1 would brighten it. Is there any documentation on how to properly overlay a 32-bit EXR lightmap in the RCP Shader Graph, or is the black-and-white output from the Convert node a bug?
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1.1k
Jan ’26
Skybox for iOS/swiftUI not working
I have tried every combination of suggestions to get a skybox to appear. Using swiftUI, realityKit and iOS. Non immersive environment. Does anyone have code that works to display a skybox. When i use a do/catch loop i get environmentResource not found. I have checked the syntax, ensured the folder is referencing the target, used the same name for the folder as the file, the file is a .hdr (i assume this is supported), i have moved the file folder to the top level - no change.
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614
Dec ’25
RealityKit animation with bindTarget: .opacity doesn't work
I want to fade objects in and out, and while setting an entity's OpacityComponent works, animating it doesn't seem to do anything. In the following code the second sphere should fade out, but it keeps its initial opacity. On the other hand, the animation that changes its transform works. What am I doing wrong? class ViewController: NSViewController { override func loadView() { let arView = ARView(frame: NSScreen.main!.frame) let anchor = AnchorEntity(.world(transform: matrix_identity_float4x4)) arView.scene.addAnchor(anchor) let sphere = ModelEntity(mesh: .generateSphere(radius: 0.5)) anchor.addChild(sphere) sphere.components.set(OpacityComponent(opacity: 0.1)) let sphere2 = ModelEntity(mesh: .generateSphere(radius: 0.5)) sphere2.position = .init(x: 0.2, y: 0, z: 0) anchor.addChild(sphere2) sphere2.components.set(OpacityComponent(opacity: 0.1)) sphere.playAnimation(try! AnimationResource.makeActionAnimation(for: FromToByAction(to: 0, timing: .linear), duration: 1, bindTarget: .opacity)) sphere.playAnimation(try! AnimationResource.makeActionAnimation(for: FromToByAction(to: Transform(translation: SIMD3(x: 0.1, y: 0, z: 0)), timing: .linear), duration: 1, bindTarget: .transform)) view = arView } }
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1w
Anchor an Reality scene on an image anchor
Developing a prototype Vision Pro app and would like to render a 3D scene made from Reality Composer Pro on an image anchor in a RealityView. But I have no luck so far to make it work and need some guidance to move on. I got the image file stored in the assets like below: And from below is the source codes: import SwiftUI import RealityKit import RealityKitContent struct AnchorView: View { @State var imageEntity: Entity = { let anchorEntity = AnchorEntity(.image(group: "AR Resources", name: "reanchor")) return anchorEntity }() var body: some View { RealityView { content in do { // Add the initial RealityKit content if let scene = try? await Entity(named: "Scene", in: realityKitContentBundle) { imageEntity.addChild(scene) content.add(imageEntity) } } catch { print("Error occurs when adding reality view content: \(error)") } } } }
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1.3k
Sep ’25
Reality Composer Pro 2.0 shader graphs can't be loaded on visionOS 1
Using Reality Composer Pro 2.0, I created a simple shader graph that displays a texture on an unlit surface: On visionOS 2 beta, I can successfully use ShaderGraphMaterial(named:from:in:) to load that shader graph material and assign it to a model entity. However, on visionOS 1.2 and earlier, either in Simulator or on the device, ShaderGraphMaterial(named:from:in:) fails and I see the following logged to the console: If, using Reality Composer Pro 1.0, I experimentally open the same project and delete and recreate exactly the same nodes above, then ShaderGraphMaterial(named:from:in:) works as expected on visionOS 1.2. Is it a known issue that Reality Composer 2 can't be used with visionOS 1? Is this intentional behavior? I've submitted feedback as FB14828873, including a sample project and repro steps. If possible, I would appreciate guidance from an Apple engineer, like "This is a known issue for [list of node types]" or "Reality Composer Pro 2 is not supported for visionOS 1 development, please refer to [documentation]" or "We recommend [workaround]." Thank you.
7
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1.6k
May ’25
ModelEntity(named:in:) fails to load USD file from RealityKitContent bundle with misleading error?
My experience has been that ModelEntity(named:in:) can be used to load a USD file with a simple structure consisting of entities and model entities, and, critically, it will flatten the entity hierarchy down to a single ModelEntity, presumably reducing the number of draw calls. However, can anyone verify that the following is true? If ModelEntity(named:in:) is used to load a USD file from a RealityKit content bundle, it may fail when the USD file contains more complex data, such as shader graph material definitions, or perhaps for some other reason. I am not sure. AND the error that ModelEntity(named:in:) throws in this case is Cannot load RealityKitContent entity: Failed to find resource with name "<name>" in bundle which would literally suggest that the file does not exist, instead of what I assume the error actually is, which is "the file exists but its entity hierarchy could not be flattened to a single ModelEntity" ? Is that an accurate description of the known behavior of ModelEntity:named:in:)? I understand that I could use Entity(named:in:) instead, without the flattening feature. My question is really more about the seemingly misleading error message. Thank you for any clarification you can provide.
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213
May ’25
RealityKit VideoMaterial renders pink on iOS 18
our app is live, and it appears that since the ios 18 update - the VideoMaterial renders pink / purple color instead of the video (picture attached). the audio is rendered properly. we found that it occurs on old devices: iPhone 11 & iPhone SE 2020. I've found this thread of Andy Jazz on stackoverflow: Steps to Reproduce: Create a plane for the video screen. Apply a VideoMaterial using AVPlayerItem. Anchor the model entity to an ARImageAnchor. Expected Outcome: The video should play as a material on the plane in RealityKit. Actual Outcome: On iOS 18, the plane appears pink, indicating the VideoMaterial isn’t applied. What I’ve Tried: -Verified the video URL is correct. -Checked that the AVPlayerItem and VideoMaterial are initialised correctly. -Ensured the AVPlayer is playing the video. I also tried different formats (mov / mp4 / m4v), and verifying that the video's status is readyToPlay. any suggestions?
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223
Jun ’25
Can spatial scene function be used outside of the Photo App?
I'm new here so I don't know what's this function belongs to which topic... Sorry about that! I watched the WWDC stream and I am really interested in this function, I'm wondering if this function could be used in my apps. I looked up the document but I find it only support visionOS(i'm not sure about that, but I saw the demo is base on the visionOS)
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274
Jun ’25
'tangents' was deprecated in visionOS 2.0: Use cp_drawable_compute_projection instead
I'm using a class with tangents to render on RealityKit for VisionOS but in Vision26 it cause a crash on App and there not documentation how implement cp_drawable_compute_projection I have tried a few options but without success. Could you help me to implement it ? The part of code is: return drawable.views.map { view in let userViewpointMatrix = (simdDeviceAnchor * view.transform).inverse let projectionMatrix = ProjectiveTransform3D( leftTangent: Double(view.tangents[0]), rightTangent: Double(view.tangents[1]), topTangent: Double(view.tangents[2]), bottomTangent: Double(view.tangents[3]), nearZ: Double(drawable.depthRange.y), farZ: Double(drawable.depthRange.x), reverseZ: true ) let screenSize = SIMD2(x: Int(view.textureMap.viewport.width), y: Int(view.textureMap.viewport.height)) return ModelRendererViewportDescriptor(viewport: view.textureMap.viewport, projectionMatrix: .init(projectionMatrix), viewMatrix: userViewpointMatrix * translationMatrix * rotationMatrix * scalingMatrix * commonUpCalibration, screenSize: screenSize) }
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164
Jun ’25
How to load a USDZ inside of a Reality Composer Pro package as ModelEntity in RealityKit ?
I need a MeshResource from ModelEntity to generate a box collider, but ModelEntity fails to load USDZ files from the Reality Composer Pro (RCP) bundle. This code works for loading an Entity: // Successfully loads as generic Entity previewEntity = try await Entity(named: fileName, in: realityKitContentBundle) But this fails when trying to load as ModelEntity: // Fails to load as ModelEntity modelEntity = try await ModelEntity(named: fileName, in: realityKitContentBundle) I found this thread mentioning: "You'll likely go from USDZ to Entity which contains a MeshResource when you load/init the USDZ file." But it doesn't explain ​how to actually extract the MeshResource. Could anyone advise: How to properly load USDZ files as ModelEntity from RCP bundles? How to extract MeshResource from a successfully loaded Entity? Alternative approaches to generate box colliders if direct extraction isn't possible? Sample code for extraction or workarounds would be greatly appreciated!
1
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277
Jun ’25
ShaderGraphMaterial.getParameter(handle:) always return nil, is this expected behavior?
I've loaded a ShaderGraphMaterial from a RealityKit content bundle and I'm attempting to access the initial values of its parameters using getParameter(handle:), but this method appears to always return nil: let shaderGraphMaterial = try await ShaderGraphMaterial(named: "MyMaterial", from: "MyFile") let namedParameterValue = shaderGraphMaterial.getParameter(name: "myParameter") // This prints the value of the `myParameter` parameter, as expected. print("namedParameterValue = \(namedParameterValue)") let handle = ShaderGraphMaterial.parameterHandle(name: "myParameter") let handleParameterValue = shaderGraphMaterial.getParameter(handle: handle) // Expected behavior: prints the value of the `myParameter` parameter, as above. // Observed behavior: prints `nil`. print("handleParameterValue = \(handleParameterValue)") Is this expected behavior? Based on the documentation at https://developer.apple.com/documentation/realitykit/shadergraphmaterial/getparameter(handle:) I'd expect getParameter(handle:) to return the value of the parameter, just as getParameter(name:) does. I've tested this on iOS 18.5 and iOS 26.0 beta 2. Assuming this getParameter(handle:) works as designed, is the following ShaderGraphMaterial extension an appropriate workaround, or can you recommend a better approach? Thank you. public extension ShaderGraphMaterial { /// Reassigns the values of all named material parameters using the handle-based API. /// /// This works around an issue where, at least as of RealityKit 26.0 beta 2 and /// earlier, `getParameter(handle:)` will always return `nil` when used to read the /// initial value of a shader graph material parameter read using /// `ShaderGraphMaterial(named:from:in:)`, whereas `getParameter(name:)` will work /// as expected. private mutating func copyNamedParametersToHandles() { for parameterName in self.parameterNames { if let value = self.getParameter(name: parameterName) { let handle = ShaderGraphMaterial.parameterHandle(name: parameterName) do { try self.setParameter(handle: handle, value: value) } catch { assertionFailure("Cannot set parameter value") } } } } }
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522
Jun ’25
Why Large-Scale Model Scenes Cause Real Device Crashes
Is there any limitation in Vision Pro when loading scenes with large-scale models? ​Test Case: Asset: Composite USDA file containing ​10 individual models​ (total triangles count: ~4.2M) Simulator: Loads and renders correctly Real Device: Loads asset successfully but ​ failure during rendering phase: Environment abruptly dims System spontaneously reboots How can we resolve this issue? Below are excerpted logs preceding the crash: <<<< FigAudioSession(AV) >>>> audioSessionAVAudioSession_CopyMXSessionProperty signalled err=-19224 (kFigAudioSessionError_UnsupportedOperation) (getMXSessionProperty unsupported) at FigAudioSession_AVAudioSession.m:606 Attempted to add ornament: <MRUIPlatterOrnament: 0x10a658f00; _isInternal: YES; _displaceWindowChrome: NO; _canCaptureUI: NO; _isBeingRemoved: NO; contentAnchorPoint3D: "{0.5, 0.5, 0}"; position: <MRUIPlatterOrnamentRelativePosition: 0x105b68e70; anchorPoint: {0.5, 0.5, 1}>; rotation: "{{0, 0, 0}, 0}"; opacity: 1.000000; canFollowUser: YES; effectiveOffset: "{0, 0, 0}"; presentingViewController: 0x0; billboardingBehavior: 0x0; scalingBehavior: 0x0; relativeToParent: NO; nonHeritableDepthDisplacement: 0.000000; order: 0.000000; _window._determinedSize: {0, 0}; _window: (null)> to nil or non-supporting UIScene: <UIWindowScene: 0x10a8a0000; role: UISceneSessionRoleImmersiveSpaceApplication; persistentIdentifier: test.test:SFBSystemService-BA3A21A3-D1AB-42E2-8AF0-AE0AB83BE528; activationState: UISceneActivationStateUnattached>. No action taken. Failed to set dependencies on asset 2823930584475958382 because NetworkAssetManager does not have an asset entity for that id. apply fence tx failed (client=0x98490e18) [0x10000003 (ipc/send) invalid destination port] Failed to commit transaction (client=0xa86516e2) [0x10000003 (ipc/send) invalid destination port]
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253
Jul ’25