Is the pseudocode below thread-safe? Imagine that the Main thread sets the CAMetalLayer's drawableSize to a new size meanwhile the rendering thread is in the middle of rendering into an existing MTLDrawable which does still have the old size. Is the change of metalLayer.drawableSize thread-safe in the sense that I can present an old MTLDrawable which has a different resolution than the current value of metalLayer.drawableSize? I assume that setting the drawableSize property informs Metal that the next MTLDrawable offered by the CAMetalLayer should have the new size, right? Is it valid to assume that "metalLayer.drawableSize = newSize" and "metalLayer.nextDrawable()" are internally synchronized, so it cannot happen that metalLayer.nextDrawable() would produce e.g. a MTLDrawable with the old width but with the new height (or a completely invalid resolution due to potential race conditions)? func onWindowResized(newSize: CGSize) { // Called on the Main thread metalLayer.drawableSize = newSize } func onVsync(drawable: MTLDrawable) { // Called on a background rendering thread renderer.renderInto(drawable: drawable) }

We set the CVDisplayLink on macOS to 0 or 120, and get the following. This then clamps maximum refresh to 60Hz on the 120Hz ProMotion display on a MBP M2 Max laptop. How is this not fixed in 4 macOS releases? CoreVideo: currentVBLDelta returned 200000 for display 1 -- ignoring unreasonable value CoreVideo: [0x7fe2fb816020] Bad CurrentVBLDelta for display 1 is zero. defaulting to 60Hz.

Hi everyone, I'm currently working on a Swift Playgrounds project where I need to incorporate a Metal shader file. However, when I tried to include my shader file (PincushionShader.metal), I encountered the following error: Is it possible to use Metal shader files within Swift Playgrounds, it is really important for my swift student challenge scene? If not, are there any workarounds or recommended approaches for testing Metal shaders in a similar environment? Any guidance or suggestions would be greatly appreciated!

Hello. I migrated yesterday two machines from OS15 to OS26 (same Ram; M1Max chip). On the first one, a MBP, everything is allright, and my old Metal projects can compile and run, even with MacOS12 as a destination. On the second computer (MacStudio) I got a compile "error: cannot execute tool 'metal' due to missing Metal Toolchain; use: xcodebuild -downloadComponent MetalToolchain". I spent hours on many forums and tried all proposed solutions and still get the same error. Any idea? Thanks

The maximumExtendedDynamicRangeColorComponentValue should provide some value between 1.0 and maximumPotentialExtendedDynamicRangeColorComponentValue depending on the available EDR headroom if there is any content on-screen that uses EDR. This works fine in most scenarios but in macOS 26 Tahoe (including in 26.2) this seemingly breaks down when a third party external display is in HDR mode and the Mac goes to sleep and wakes up. After wake only a value of 1.0 is provided by the third party external display's NSScreen object, no matter what (although when the SDR peak brightness is being changed using the brightness slider, didChangeScreenParametersNotification is firing and the system should provide a proper updated headroom value). This makes dynamic tone-mapping that adapts to actual screen brightness impossible. Everything works fine in Sequoia. In Tahoe the user needs to turn off HDR, then go through a sleep/wake cycle and turn HDR back on to have this fixed, which is obviously not a sustainable workaround.

I have a model that uses a video material as the surface shader and I need to also use a geometry modifier on the material. This seemed like it would be promising (adapted from https://developer.apple.com/wwdc21/10075 ~5m 50s). // Did the setup for the video and AVPlayer eventually leading me to let videoMaterial = VideoMaterial(avPlayer: avPlayer) // Assign the material to the entity entity.model!.materials = [videoMaterial] // The part shown in WWDC: Set up the library and geometry modifier before, so now try to map the new custom material to the video material entity.model!.materials = entity.model!.materials.map { baseMaterial in       try! CustomMaterial(from: baseMaterial, geometryModifier: geometryModifier)     } But, I get the following error Thread 1: Fatal error: 'try!' expression unexpectedly raised an error: RealityFoundation.CustomMaterialError.defaultSurfaceShaderForMaterialNotFound How can I apply a geometry modifier to a VideoMaterial? Or, if I can't do that, is there an easy way to route the AVPlayer video data into the baseColor of CustomMaterial?

Hi all, I'm encountering an issue with Metal raytracing on my M5 MacBook Pro regarding Instance Acceleration Structure (IAS). Intersection tests suddenly stop working after a certain point in the sampling loop. Situation I implemented an offline GPU path tracer that runs the same kernel multiple times per pixel (sampleCount) using metal::raytracing. Intersection tests are performed using an IAS. Since this is an offline path tracer, geometries inside the IAS never changes across samples (no transforms or updates). As sampleCount increases, there comes a point where the number of intersections drops to zero, and remains zero for all subsequent samples. Here's a code sketch: let sampleCount: UInt16 = 1024 for sampleIndex: UInt16 in 0..<sampleCount { // ... do { let commandBuffer = commandQueue.makeCommandBuffer() // Dispatch the intersection kernel. await commandBuffer.completed() } do { let commandBuffer = commandQueue.makeCommandBuffer() // Use the intersection test results from the previous command buffer. await commandBuffer.completed() } // ... } kernel void intersectAlongRay( const metal::uint32_t threadIndex [[thread_position_in_grid]], // ... const metal::raytracing::instance_acceleration_structure accelerationStructure [[buffer(2)]], // ... ) { // ... const auto result = intersector.intersect(ray, accelerationStructure); switch (result.type) { case metal::raytracing::intersection_type::triangle: { // Write intersection result to device buffers. break; } default: break; } Observations Encoding both the intersection kernel and the subsequent result usage in the same command buffer does not resolve the problem. Switching from IAS to Primitive Acceleration Structure (PAS) fixes the problem. Rebuilding the IAS for each sample also resolves the issue. Intersections produce inconsistent results even though the IAS and rays are identical — Image 1 shows a hit, while Image 2 shows a miss. Questions Am I misusing IAS in some way ? Could this be a Metal bug ? Any guidance or confirmation would be greatly appreciated.

I work on a Qt/QML app that uses Esri Maps SDK for Qt and that is deployed to both Windows and iPads. With a recent iPad OS upgrade to 26.1, many iPad users are reporting the application freezing after panning and/or identifying features in the map. It runs fine for our Windows users. I was able to reproduce this and grabbed the following error messages when the freeze happens: IOGPUMetalError: Caused GPU Address Fault Error (0000000b:kIOGPUCommandBufferCallbackErrorPageFault) IOGPUMetalError: Invalid Resource (00000009:kIOGPUCommandBufferCallbackErrorInvalidResource) Environment: Qt 6.5.4 (Qt for iOS) Esri Maps SDK for Qt 200.3 iPadOS 26.1 Because it appears to be a Metal error, I tried using OpenGL (Qt offers a way to easily set hte target graphics api): QQuickWindow::setGraphicsApi(QSGRendererInterface::GraphicsApi::OpenGL) Which worked! No more freezing. But I'm seeing many posts that OpenGL has been deprecated by Apple. I've seen posts that Apple deprecated OpenGL ES. But it seems to still be available with iPadOS 26.1. If so, will this fix (above) just cause problems with a future iPadOS update? Any other suggestions to address this issue? Upgrading our version of Qt + Esri SDK to the latest version is not an option for us. We are in the process to upgrade the full application, but it is a year or two out. So, we just need a fix to buy us some time for now. Appreciate any thoughts/insights....

View Layout Add the following views in a view controller: Label View A, with a subview of the same size: MTKView A View B, with a subview of the same size: MTKView B Refresh Rates of Each View The label view refreshes at 60fps (driven by CADisplayLink). MTKView A and B refresh at 15fps. MTKView Implementation Details The corresponding CAMetalLayer's maximumDrawableCount is set to 2, changed to double buffering. The scheduling mechanism is modified; drawing is not driven by the internal loop but is done manually. The draw call is triggered immediately upon receiving a frame. self.metalView.enableSetNeedsDisplay = NO; self.metalView.paused = YES; A new high-priority queue is created for drawing, instead of handling it on the main queue. MTKView Latency Tracking The GPU completion time T1 is observed through the addCompletedHandler callback of the CommandBuffer. The presentation time T2 of the frame is observed through the addPresentedHandler callback of the currentDrawable in MTKView. Testing shows that T2 - T1 > 16.6ms (the Vsync period at 60Hz). This means that after the GPU rendering in MTLView is finished, the frame is not actually displayed at the next Vsync instruction but only at the Vsync instruction after that. I believe there is an extra 16.6ms of latency here, which I want to eliminate by adjusting the rendering mechanism. Observation from Instruments From Instruments, the Surface presentation aligns with the above test results. After the Metal encoder finishes, the Surface in Display switches only after the next-next Vsync instruction. See the image in the link for details. Questions According to a beginner's understanding, after MTKView's GPU rendering is finished, the next Vsync instruction should officially display (make it visible). However, this is not what is observed. Does the subview MTKView need to wait for another Vsync cycle to be drawn to the actual display buffer? The label updates its text at 60fps, so the entire interface should be displayed at 60fps. Is the content of MTKView not synchronized when the display happens? Explanation of the Reasoning Behind Some MTKView Code Details Changing from the default triple buffering to double buffering helps reduce the latency introduced by rendering. Not using MTKView's own scheduling mechanism but using manual triggering of the draw method is because MTKView's own scheduling mechanism is driven by CADisplayLink. Therefore, if a frame falls within a Vsync window, it needs to wait for the next Vsync window to trigger the draw operation, which introduces waiting latency.

I was encountering visual artifacts in my Unity game only on iOS devices and wanted to use the Metal Debugger to diagnose it. However, it seems to only capture static noise which is not helpful as shown below For reference, this is a frame of the visual artifact and also the location where I asked Metal to capture the frame Am I missing any settings in Unity/Xcode?

I am running some experiments with WebGPU using the wgpu crate in rust. I have some Buffers already allocated in the GPU. Is it possible to use those already existing buffers directly as inputs to a predict call in CoreML? I want to prevent gpu to cpu download time as much as possible. Or are there any other ways to do something like this. Is this only possible using the latest Tensor object which came out with Metal 4 ?

Also submitted as feedback (ID: FB20612561). Tensorflow-metal fails on tensorflow versions above 2.18.1, but works fine on tensorflow 2.18.1 In a new python 3.12 virtual environment: pip install tensorflow pip install tensor flow-metal python -c "import tensorflow as tf" Prints error: Traceback (most recent call last): File "", line 1, in File "/Users//pt/venv/lib/python3.12/site-packages/tensorflow/init.py", line 438, in _ll.load_library(_plugin_dir) File "/Users//pt/venv/lib/python3.12/site-packages/tensorflow/python/framework/load_library.py", line 151, in load_library py_tf.TF_LoadLibrary(lib) tensorflow.python.framework.errors_impl.NotFoundError: dlopen(/Users//pt/venv/lib/python3.12/site-packages/tensorflow-plugins/libmetal_plugin.dylib, 0x0006): Library not loaded: @rpath/_pywrap_tensorflow_internal.so Referenced from: <8B62586B-B082-3113-93AB-FD766A9960AE> /Users//pt/venv/lib/python3.12/site-packages/tensorflow-plugins/libmetal_plugin.dylib Reason: tried: '/Users//pt/venv/lib/python3.12/site-packages/tensorflow-plugins/../_solib_darwin_arm64/_U@local_Uconfig_Utf_S_S_C_Upywrap_Utensorflow_Uinternal___Uexternal_Slocal_Uconfig_Utf/_pywrap_tensorflow_internal.so' (no such file), '/Users//pt/venv/lib/python3.12/site-packages/tensorflow-plugins/../_solib_darwin_arm64/_U@local_Uconfig_Utf_S_S_C_Upywrap_Utensorflow_Uinternal___Uexternal_Slocal_Uconfig_Utf/_pywrap_tensorflow_internal.so' (no such file), '/opt/homebrew/lib/_pywrap_tensorflow_internal.so' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/opt/homebrew/lib/_pywrap_tensorflow_internal.so' (no such file)

Hello, I am currently working on a research project under ENINCA Consulting, focused on advanced diagnostic tools for pseudorandom number generators (structural metrics, multi-seed stability, cross-architecture reproducibility, and complementary indicators to TestU01). To validate this diagnostic framework, I prototyped a small non-linear 64-bit PRNG (not as a goal in itself, but simply as a vehicle to test the methodology). During these evaluations, I observed something interesting on Apple Silicon (Mac M1): • bit-exact reproducibility between M1 ARM CPU and M1 Metal GPU, • full BigCrush pass on both CPU and Metal backends, • excellent p-values, • stable behaviour across multiple seeds and runs. This was not the intended objective, the goal was mainly to validate the diagnostic concepts, but these results raised some questions about deterministic compute behaviour in Metal. My question: Is there any official guidance on achieving (or expecting) deterministic RNG or compute behaviour across CPU ↔ Metal GPU on Apple Silicon? More specifically: • Are deterministic compute kernels expected or guaranteed on Metal for scientific workloads? • Are there recommended patterns or best practices to ensure reproducibility across GPU generations (M1 → M2 → M3 → M4)? • Are there known Metal features that can introduce non-determinism? I am not sharing the internal recurrence (this work is proprietary), but I can discuss the high-level diagnostic observations if helpful. Thank you for any insight, very interested in how the Metal engineering team views deterministic compute patterns on Apple Silicon. Pascal ENINCA Consulting

Environment Versions ・macOS15.6.1 ・visionOS26.0.1 ・Xcode16.1 or 26.0.1 ・unity6000.2.9f1 ・Apple.core3.2.0 ・Apple.PHASE1.2.7 ・polyspatial2.4.2 With the above environment, after installing Apple.PHASE into unity and building to a visionOS device, Audio is available and distance attention works, but Early Reflection and Late Reverb produce no audible change even when checked and their parameters are adjusted. What is required to make Early Reflection and Late Reverb take effect on a visionOS device build? action taken ・created a SoundEvent. ・in composer, created a Sampler and a SpatialMixer; attached an AudioClip to the Sampler; enabled Direct Path, Early Reflection, and Late Reverb on the SpatialMixer. ・attached a PHASE Source to the object to be played, attached the created SoundEvent to it, and set non-zero values for Early Reflection and Late Reverb. ・attached a PHASE Listener to the mainCamera and set the ReverbPreset to a value other than None. ・in project settings > Audio, set Spatializer plugin to PHASE Spatializer. ・from there, build for visionOS.

Unable to open mach-O at path: /AppleInternal/Library/BuildRoots/4~B5FIugA1pgyNPFl0-ZGG8fewoBL0-6a_xWhpzsk/Library/Caches/com.apple.xbs/Binaries/RenderBox/install/TempContent/Root/System/Library/PrivateFrameworks/RenderBox.framework/Versions/A/Resources/default.metallib Error:2 This happens only on macOS Sequoia - not on macOS Tahoe. I have got a noticeable amount of lag in the animations of my App where this Warning arises I've tried to isolate the respective animations from the main thread too - still getting the same issue with the lag Is it possible to resolve it, as I want backwards compatibility with my app for the users

Hi, I'm currently using Metal Performance Shaders Graph (MPSGraphExecutable) to run neural network inference operations as part of a metal rendering pipeline. I also tried to profile the usage of neural engine when running inference using MPSGraphExecutable but the graph shows no sign of neural engine usage. However, when I used the coreML model inspection tool in xcode and run performance report, it was able to use ANE. Does MPSGraphExecutable automatically utilize the Apple Neural Engine (ANE) when running inference operations, or does it only execute on GPU? My model (Core ML Package) was converted from a pytouch model using coremltools with ML program type and support iOS17.0+. Any insights or documentation references would be greatly appreciated!

Hi there, We’re encountering this error in all of our builds when using the latest Xcode and macOS: The Metal Toolchain was not installed and could not compile the Metal source files. Download the Metal Toolchain from Xcode > Settings > Components and try again. In short, all builds are failing. I’ve tried fixing this by installing Metal and applying other solutions, but none of them worked reliably. Is there a way to ensure that the Metal Toolchain is installed on the CI machine?

Summary After updating to visionOS 26, we’ve encountered severe transparency rendering issues in RealityKit that did not exist in visionOS 2.6 and earlier. These regressions affect applications that dynamically control scene opacity (via OpacityComponent). Our app renders ultra-realistic apartment environments in real time, where users can walk or teleport inside 3D spaces. When the user moves above a speed threshold, we apply a global transparency effect to prevent physical collisions with real-world objects. Everything worked perfectly in visionOS 2.6 — the problems appeared only after upgrading to 26. Scene Setup Overview The environment consists of multiple USDZ models (e.g., architecture, rooms, furniture). We manage LODs manually for performance (e.g., walls and floors always visible in full-res, while rooms swap between low/high-res versions based on user position and field of view). Transparency is achieved using OpacityComponent, applied dynamically when the user moves. Some meshes (e.g., portals to skyboxes, glass windows) use alpha materials We also use OcclusionMaterials to prevent things to be seen through walls when scene is transparent Observed Behavior by Scenario (I can share a video showing the results of each scenario if needed.) Scenario 1 — Severe Flickering (Root Opacity) Setup: OpacityComponent applied to the root entity NO ModelSortGroupComponent used Symptoms: Strong flickering when transparency is active Triangles within the same mesh render at inconsistent opacity levels Appears as if per-triangle alpha sorting is broken Workaround: Moving the OpacityComponent from the root to each individual USDZ entity removes the per-triangle flicker Pros: No conflicts with portals or alpha materials Scenario 2 — Partially Stable, But Alpha Conflicts Setup: OpacityComponent applied per USDZ entity ModelSortGroupComponent(planarUIAlwaysBehind) applied to portal meshes Other entities have NO ModelSortGroupComponent Symptoms: Frequent alpha blending conflicts: Transparent surfaces behind other transparent surfaces flicker or disappear Example: Wine glasses behind glass doors — sometimes neither is rendered, or only one Even opaque meshes behind glass flicker due to depth buffer confusion Alpha materials sometimes render portals or the real world behind them, ignoring other geometry entirely Analysis: Appears related to internal changes in alpha sorting or depth pre-pass behavior introduced in visionOS 26 Pros: Most stable setup so far Cons: Still unreliable when OpacityComponent is active Scenario 3 — Layer Separation Attempt (Regression) Setup: Same as Scenario 2, but: Entities with alpha materials moved to separate USDZs Explicit ModelSortGroupComponent order set (alpha surfaces rendered last) Symptoms: Transparent surfaces behind other transparent surfaces flicker or disappear Depth is completely broken when there's a large transparent surface Alpha materials sometimes render portals or the real world behind them, ignoring other geometry entirely Workaround Attempt: Re-ordering and further separating models did not solve it Pros: None — this setup makes transparency unusable Conclusion There appears to be a regression in RealityKit’s handling of transparency and sorting in visionOS 26, particularly when: OpacityComponent is applied dynamically, and Scenes rely on multiple overlapping transparent materials. These issues did not exist prior to 26, and the same project (no code changes) behaves correctly on previous versions. Request We’d appreciate any insight or confirmation from Apple engineers regarding: Whether alpha sorting or opacity blending behavior changed in visionOS 26 If there are new recommended practices for combining OpacityComponent with transparent materials If a bug report already exists for this regression Thanks in advance!

Hello, Question re: iOS RealityView postProcess. I've got a working postProcess kernel and I'd like to add some depth-based effects to it. Theoretically I should be able to just do: encoder.setTexture(context.sourceDepthTexture, index: 1) and then in the kernel: texture2d<float, access::read> depthIn [[texture(1)]] ... outTexture.write(depthIn.read(gid), gid); And I consistently see all black rendered to the view. The postProcess shader works, so that's not the issue. It just seems to not be receiving actual depth information. (If I set a breakpoint at the encoder setTexture step, I can see preview the color texture of the scene, but the context's depthTexture looks like all NaN / blank.) I've looked at all the WWDC samples, but they include ARView for all the depth sample code, which has a different set of configuration options than RealityView. So far I haven't seen anywhere to explicitly tell RealityView "include the depth information". So I'm not sure if I'm missing something there. It appears that there is indeed a depth texture being passed, but it looks blank. Is there a working example somewhere that we can reference?

Fundamentally, my questions are: is there a known transform I can apply onto a given (pixel) position (passed into a Metal Fragment Function) to correctly sample a texture provided by the main cameras + processed by a Vision request. If so, what is it? If not, how can I accurately sample my masks? My goal is to highlight people in a Vision Pro app using Compositor Services. To start, I asynchronously receive camera frames for the main left and right cameras. This is the breakdown of the specific CameraVideoFormat I pass along to the CameraFrameProvider: minFrameDuration: 0.03 maxFrameDuration: 0.033333335 frameSize: (1920.0, 1080.0) pixelFormat: 875704422 cameraType: main cameraPositions: [left, right] cameraRectification: mono From each camera frame sample, I extract the left and right buffers (CVReadOnlyPixelBuffer.withUnsafebuffer ==> CVPixelBuffer). I asynchronously process the extracted buffers by performing a VNGeneratePersonSegmentationRequest on both of them: // NOTE: This block of code and all following code blocks contain simplified representations of my code for clarity's sake. var request = VNGeneratePersonSegmentationRequest() request.qualityLevel = .balanced request.outputPixelFormat = kCVPixelFormatType_OneComponent8 ... let lHandler = VNSequenceRequestHandler() let rHandler = VNSequenceRequestHandler() ... func processBuffers() async { try lHandler.perform([request], on: lBuffer) guard let lMask = request.results?.first?.pixelBuffer else {...} try rHandler.perform([request], on: rBuffer) guard let rMask = request.results?.first?.pixelBuffer else {...} appModel.latestPersonMasks = (lMask, rMask) } I store the two resulting CVPixelBuffers in my appModel. For both of these buffers aka grayscale masks: width (in pixels) = 512 height (in pixels) = 384 byters per row = 512 plane count = 0 pixel format type = 1278226488 I am using Compositor Services to render my content in Immersive Space. My implementation of Compositor Services is based off of the same code from Interacting with virtual content blended with passthrough. Within the Shaders.metal, the tint's Fragment Shader is now passed the grayscale masks (converted from CVPixelBuffer to MTLTexture via CVMetalTextureCacheCreateTextureFromImage() at the beginning of the main render pipeline). fragment float4 tintFragmentShader( TintInOut in [[stage_in]], ushort amp_id [[amplification_id]], texture2d<uint> leftMask [[texture(0)]], texture2d<uint> rightMask [[texture(1)]] ) { if (in.color.a <= 0.0) { discard_fragment(); } float2 uv; if (amp_id == 0) { // LEFT uv = ??????????????????????; } else { // RIGHT uv = ??????????????????????; } constexpr sampler linearSampler (mip_filter::linear, mag_filter::linear, min_filter::linear); // Sample the PersonSegmentation grayscale mask float maskValue = 0.0; if (amp_id == 0) { // LEFT if (leftMask.get_width() > 0) { maskValue = rightMask.sample(linearSampler, uv).r; } } else { // RIGHT if (rightMask.get_width() > 0) { maskValue = rightMask.sample(linearSampler, uv).r; } } if (maskValue > 250) { return (1.0, 1.0, 1.0, 0.5) } return in.color; } I need to correctly sample the masks for a given fragment. The LayerRenderer.Layout is set to .layered. From Developer Documentation. A layout that specifies each view’s content as a slice of a single texture. Using the Metal debugger, I know that the final render target texture for each view / eye is 1888 x 1792 pixels, giving an aspect ratio of 59:56. The initial CVPixelBuffer provided by the main left and right cameras is 1920x1080 (16:9). The grayscale CVPixelBuffer returned by the VNPersonSegmentationRequest is 512x384 (4:3). All of these aspect ratios are different. My questions come down to: is there a known transform I can apply onto a given (pixel) position to correctly sample a texture provided by the main cameras + processed by a Vision request. If so, what is it? If not, how can I accurately sample my masks? Within the tint's Vertex Shader, after applying the modelViewProjectionMatrix, I have tried every version I have been able to find that takes the pixel space position (= vertices[vertexID].position.xy) and the viewport size (1888x1792) to compute the correct clip space position (maybe = pixel space position.xy / (viewport size * 0.5)???) of the grayscale masks but nothing has worked. The "highlight" of the person segmentations is off: scaled a little too big, offset little to far up and off to the side.