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.
RealityKit
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In the CanyonCrosser example project, some RealityKit systems are implemented as classes while others are structs. What’s the reason for using different types?
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?
Topic:
Graphics & Games
SubTopic:
RealityKit
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?
Topic:
Graphics & Games
SubTopic:
RealityKit
Tags:
RealityKit
Reality Composer Pro
Shader Graph Editor
Is there any support pr plans for support for for raytraced reflections in RealityKit on the Vision Pro M5? I cannot find any documentation regarding this topic.
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.
Hi, I'm trying to set the displayScale environment value for a RealityView, so it renders at 2x instead of 3x on the iPhone, but it seems to have no effect.
.environment(\.displayScale, 2.0)
Is this expected behavior, or a bug?
The reason I want it to render at 2x and not at the default 3x is for game optimization and performance.
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
}
}
I'm working on an application for viewing AMF models on macOS, using RealityKit. AMF supports several different ways to color models, including per-vertex color (where the color of a triangle is interpolated from vertex to vertex) as well as per-face color (where the color of the triangle is the same across the entire face).
I'm trying to figure out how to support those color models using a RealityKit mesh. Apple's documentation (https://developer.apple.com/documentation/realitykit/modifying-realitykit-rendering-using-custom-materials) talks about per-vertex colors, but I haven't found a way to create a mesh that includes per-vertex colors, other than use a texture map (which might be the correct solution).
Can someone give me some pointers?
As part of the WWDC25 Keynote, a technology was announced that can present 2D images as 3D spatial scenes. This announcement is supported by a Press Release.
...developers can use the Spatial Scene API to make their app experience even more immersive. Zillow is taking advantage of the API for their Zillow Immersive app, allowing users to see images of homes and apartments with the rich depth and dimension that spatial scenes offer.
The feature also appears in the Photos App on iOS 26 Developer Beta 1. Tapping "Spatial Scene" on any photo opens a view of that photo with a parallax effect. I've searched the WWDC sessions and new documentation and have come up short. Reaching out here for help.
Is there any documentation for Spatial Scene API? Or any guidance on how to implement the spatial scene in iOS?
What is the recommended way to attach SwiftUI views to RealityKit entities on macOS, iOS, etc?
All the APIs seem to be visionOS only:
https://developer.apple.com/documentation/realitykit/realityviewattachments
https://developer.apple.com/documentation/realitykit/viewattachmentcomponent
https://developer.apple.com/documentation/realitykit/presentationcomponent
https://developer.apple.com/documentation/realitykit/imagepresentationcomponent
My only idea is to do it "manually" with a ZStack and RealityView somehow?
I submitted this as a feedback since it seemed like an oversight: FB18034856.
We're using RealityKit to create a science education AR app for iOS, iPadOS, and visionOS.
In the WWDC25 session video "Bring your SceneKit project to RealityKit" https://developer.apple.com/videos/play/wwdc2025/288 at 8:15, it's explained that when using RealityKit, RealityView should be used in all cases, whereas in the past, SceneKit required SCNView, SceneView, or ARSCNView, depending on an app's requirements.
Because the initial development of our app on iOS predates iOS 18's RealityView, our app currently uses ARView to render RealityKit AR content on iOS and iPadOS.
Is it recommended that we migrate to RealityView, or can we safely continue using our existing ARView implementation? We'd prefer to avoid unnecessary development cost.
If migrating from ARView to RealityView is recommended, what specific benefits should we expect from this transition?
Thank you.
In SceneKit, when creating an .scn file from a rigged model, the framework created an SCNNode for each bone/joint, so you could add and remove child nodes directly to and from joints, and like any other SCNNode, you could access world position and world orientation for each joint. The analog would be for joints to be accessible as child entities of a ModelEntity in RealityKit. I am unable to proceed with migrating my project from SceneKit because of this, as there does not seem to be a way to even access the true world position of a joint with the current jointNames/jointTransforms paradigm.
The translation information from the given transforms is insufficient to determine the location of a joint at any given time, and other approaches like creating a GeometricPin for the given joint name and attaching it to another entity do not seem to work. So conveniently being able to attach an item to the hand of a rigged model was trivial in SceneKit and now feels impossible in RealityKit.
I am not the first person to notice this, and am feeling demoralized about proceeding with RealityKit with such a critical piece of functionality blocked
https://stackoverflow.com/questions/76726241/how-do-i-attach-an-entity-to-a-skeletons-joint-in-realitykit
Will this be addressed in some way?
The following code using the new GestureComponent demonstrates inconsistency. The tap gesture prints output, but the drag gesture does not.
I already checked this post, which points to this seemingly outdated sample code
I assume that example is deprecated in favour of the now built in version of GestureComponent.
Nonetheless, there are no compiler warnings or errors, it just fails silently.
TapGesture, LongPressGesture, MagnifyGesture, RotateGesture all work, so this feels like an oversight.
RealityView { content in
let testEntity = ModelEntity(mesh: .generateBox(size: .init(x: 1, y: 1, z: 1)))
testEntity.position = SIMD3<Float>(0,0,-1)
testEntity.components.set(InputTargetComponent())
testEntity.components.set(CollisionComponent(
shapes: [.generateBox(size: .init(x: 1, y: 1, z: 1))]
))
let testGesture = TapGesture()
.onEnded { value in
print("Tapped")
}
testEntity.components.set(GestureComponent(testGesture))
let dragGesture = DragGesture()
.onEnded { value in
print("Dragged")
}
testEntity.components.set(GestureComponent(dragGesture))
content.add(testEntity)
}
Hi all,
I’m running into an issue when trying to reconstruct a 3D model using PhotogrammetrySession on macOS from a set of images captured via the iOS Object Capture sample app, specifically in Area mode.
When I attempt to create the model from these images (using the raw Images/ folder exported directly from the capture session), I get the following errors:
ERROR cv3dapi.pg: Internal error codes (2): 4011 4012
WARN cv3dapi.pg: Internal warning codes (1): 4507
Output error with code = -15
requestError: CoreOC.PhotogrammetrySession.Error.processError
I use the "Images" directory directly exported from Object Capture with my iphone 12 pro max (has lidar) set to "area mode" in the object capture app
here is an example heic image metadata from the sequence.
heif-info Images/00044.869568833.HEIC
MIME type: image/heic
main brand: heic
compatible brands: mif1, MiHE, MiPr, miaf, MiHB, heic
image: 3024x4032 (id=49), primary
tiles: 6x8, tile size: 512x512
colorspace: YCbCr, 4:2:0
bit depth: 8
thumbnail: 240x320
color profile: nclx
alpha channel: no
depth channel: yes
size: 192x256
bits per pixel: 8
z-near: 1.173828
z-far: 2.552734
d-min: undefined
d-max: undefined
representation: uniform Z
metadata:
Exif: 960 bytes
uri /tag:apple.com,2023:ObjectCapture#CameraTrackingState: 4 bytes
uri /tag:apple.com,2023:ObjectCapture#CameraCalibrationData: 1015 bytes
uri /tag:apple.com,2023:ObjectCapture#ObjectTransform: 48 bytes
uri /tag:apple.com,2023:ObjectCapture#ObjectBoundingBox: 48 bytes
uri /tag:apple.com,2023:ObjectCapture#RawFeaturePoints: 832 bytes
uri /tag:apple.com,2023:ObjectCapture#PointCloudData: 23984 bytes
uri /tag:apple.com,2023:ObjectCapture#BundleVersion: 5 bytes
uri /tag:apple.com,2023:ObjectCapture#SegmentID: 4 bytes
uri /tag:apple.com,2024:ObjectCapture#SessionUUID: 36 bytes
uri /tag:apple.com,2024:ObjectCapture#CaptureMode: 4 bytes
uri /tag:apple.com,2023:ObjectCapture#Feedback: 4 bytes
uri /tag:apple.com,2023:ObjectCapture#WideToDepthCameraTransform: 48 bytes
uri /tag:apple.com,2023:ObjectCapture#TemporalDepthPointClouds: 864026 bytes
transformations:
angle (ccw): 270
region annotations:
none
properties:
camera intrinsic matrix:
focal length: 2813.695557; 2813.695557
principal point: 1522.338502; 2002.843018
skew: 0.000000
camera extrinsic matrix:
rotation matrix:
-0.695 0.344 -0.632
0.007 -0.875 -0.483
-0.719 -0.340 0.606
Questions:
• What do internal error codes 4011 and 4012 refer to?
• Is there something specific about Area mode captures that require preprocessing before they’re compatible with PhotogrammetrySession?
• Has anyone successfully reconstructed a model from an Area mode session using the stock Apple tools?
NOTE: I can provide the folder of images for debugging if that would help!
A bit of background on what our app is doing:
We have a RealityKit ARView session running.
During this period we place objects in RealityKit.
At some point user can "take photo" and we use session.captureHighResolutionFrame to capture a frame.
We then use captured frame and frame.camera.projectPoint to project my objects back to 2D
Issue we found is that on devices that have iOS26, first photo user takes and the first frame received from session.captureHighResolutionFrame gives incorrect CGPoint for frame.camera.projectPoint. If user takes the second photo with the same camera phostion, second frame received from session.captureHighResolutionFrame gives correct CGPoint for frame.camera.projectPoint
I notices some difference between first and subsequent frames that i believe is corresponding with the issue. Yaw value of camera (frame.camera.eulerAngles.y) on first frame is not correct ( inconsistent with any subsequent frame)
I also created a small example app and i followed Building an Immersive Experience with RealityKit example to create it. The issue exists in this app for iOS26, while iOS18.* has consistent values between first and subsequent captured frames.
Note:
The yaw value seems to differ more if we start session in portrait but take photo in landscape.
Example result for 3 captured frames:
Frame captured with yaw: 1.4855177402496338
Frame captured with yaw: -0.08803760260343552
Frame captured with yaw: -0.08179682493209839
Example code:
class CustomARView: ARView, ARSessionDelegate {
required init(frame: CGRect) { super.init(frame: frame) }
required init?(coder decoder: NSCoder) { fatalError("init(coder:) has not been implemented")}
func setup() {
let singleTap = UITapGestureRecognizer(target: self, action: #selector(handleTap))
addGestureRecognizer(singleTap)
}
@objc
func handleTap(_ gestureRecognizer: UIGestureRecognizer) {
Task {
do {
let frame = try await session.captureHighResolutionFrame()
print("Frame captured with yaw: \(Double(frame.camera.eulerAngles.y))")
} catch { }
}
}
}
struct CustomARViewUIViewRepresentable: UIViewRepresentable {
func makeUIView(context: Context) -> some UIView {
let arView = CustomARView(frame: .zero)
arView.setup()
return arView
}
func updateUIView(_ uiView: UIViewType, context: Context) { }
}
struct ContentView: View {
var body: some View {
CustomARViewUIViewRepresentable()
.frame(maxWidth: .infinity, maxHeight: .infinity)
.ignoresSafeArea()
}
}
Hi everyone,
I'm developing an ARKit app using RealityKit and encountering an issue where a video displayed on a 3D plane shows up as a pink screen instead of the actual video content.
Here's a simplified version of my setup:
func createVideoScreen(video: AVPlayerItem, canvasWidth: Float, canvasHeight: Float, aspectRatio: Float, fitsWidth: Bool = true) -> ModelEntity {
let width = (fitsWidth) ? canvasWidth : canvasHeight * aspectRatio
let height = (fitsWidth) ? canvasWidth * (1/aspectRatio) : canvasHeight
let screenPlane = MeshResource.generatePlane(width: width, depth: height)
let videoMaterial: Material = createVideoMaterial(videoItem: video)
let videoScreenModel = ModelEntity(mesh: screenPlane, materials: [videoMaterial])
return videoScreenModel
}
func createVideoMaterial(videoItem: AVPlayerItem) -> VideoMaterial {
let player = AVPlayer(playerItem: videoItem)
let videoMaterial = VideoMaterial(avPlayer: player)
player.play()
return videoMaterial
}
Despite following the standard process, the video plane renders pink. Has anyone encountered this before, or does anyone know what might be causing it?
Thanks in advance!
Hi everyone,
I’m running into an issue with RealityKit when trying to animate BlendShapes (ShapeKeys) while a skeletal animation is playing. The model is a rigged character in .usdz format with both predefined skeletal animations and BlendShapes (exported from Blender).
The problem: when I play any animation using entity.playAnimation(...), the BlendShapes stop responding. Calling setBlendShapes(...) still logs that weights are being updated, but the visual changes are not visible.
The exact same blend shape animation works perfectly when no animation is playing.
In SceneKit the same model works as expected: shape keys get animated during animation playback. But not in realitykit
Still, as soon as an animation starts, the shape keys don’t animate anymore.
Here’s the test project on GitHub that demonstrates the issue clearly:
https://github.com/IAMTHEBURT/RealityKitWitnBlendShapesSample
The goal is to play facial expressions (like blinking or talking) while a body animation (like waving) is playing.
Is this a known limitation in RealityKit? Or is there a recommended way to combine skeletal animations with real-time BlendShape updates?
Thanks in advance for any insights.
Is there any standard way of efficiently showing a MTLTexture on a RealityKit Entity?
I can't find anything proper on how to , for example, generate a LowLevelTexture out of a MTLTexture. Closest match was this two year old thread.
In the old SceneKit app, we would just do
guard let material = someNode.geometry?.materials.first else { return }
material.diffuse.contents = mtlTexture
Our flow is as follows (for visualizing the currently detected object):
Camera-Stream -> CoreML Segmentation -> Send the relevant part of the MLShapedArray-Tensor to a MTLComputeShader that returns a MTLTexture -> Show the resulting texture on a 3D object to the user
Hi! I watched the WWDC25 session "Bring your SceneKit project to RealityKit" which seemed like a great resource for those of us transitioning from the now-deprecated SceneKit framework. The session mentioned that the full sample code for the project would be available to download, but I haven't been able to find it in the Code section of the video page or in the Sample Code Library.
Has the sample code been released yet? Having the project code would make it much easier to follow along with the RealityKit changes shown in the video. Thanks again for the great session.