MetalKit

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Render graphics in a standard Metal view, load textures from many sources, and work efficiently with models provided by Model I/O using MetalKit.

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GPTK 3 and D3DMetal issue with Modern Pipeline Creation
Death Stranding 2: On the Beach (v1.0.48.0, Steam) crashes during rendering initialization when running through CrossOver 26 with D3DMetal 3.0 on an Apple M2 Max Mac Studio running macOS Sequoia. The game successfully initializes Streamline, NVAPI, DLSS (Result::eOk), DLSSG (Result::eOk), Reflex, and XeSS — all subsystems report success. The crash occurs immediately after, during rendering pipeline creation, before the game reaches NXStorage initialization or window creation. Minidump analysis confirms the crash is an access violation (0xc0000005) at DS2.exe+0x67233d, writing to address 0x0. RAX=0x0 (null pointer being dereferenced), R12=0xFFFFFFFFFFFFFFFF (error/invalid handle return). The game appears to call a D3D12 API — likely CheckFeatureSupport or a pipeline state creation function — that D3DMetal acknowledges as supported but returns null or invalid data for. The game trusts the response and dereferences the null pointer. Two other Nixxes titles using the same engine and D3DMetal setup run without issue: Spider-Man 2 (~50 FPS) and Horizon Zero Dawn Remastered (~34 FPS). DS2 uses newer technology versions (DLSS 4, FSR 4, XeSS 2) and a newer DirectX 12 Agility SDK, which likely queries D3D12 features that D3DMetal does not yet fully implement. The crash also reproduces when D3DMetal reports as AMD vendor (1002) instead of NVIDIA (10de), crashing at the same executable offset, confirming it is a D3D12 feature reporting gap in D3DMetal rather than a vendor-specific issue. How To Reproduce Install Crossover 26+ on MacOS 26.4 Install Steam and download Death Stranding 2 Run Death Stranding 2 and check logs after crash in Documents\DEATH STRANDING 2 ON THE BEACH Feedback Requests FB22285513 — Game Porting Toolkit 3 issue with Modern Pipeline Creation
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2d
RealityKit fill the background environment
I am new to RealityKit and Metal and I am building a RealityKit app that renders a procedural LowLevelMesh road. But the left and right side of the road is a complete green terrain mesh object and it doesn't look great. What I want is to add some rocks, tall trees and dence bushes (or weed) to make it look like the player is in the woods. But when I add many of those objects then the performance drains. What is the best approach to fill background empty spaces in the scene?
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Metal Shader inside Swift Package not found?
Hello everyone! I am trying to wrap a ViewModifier inside a Swift Package that bundles a metal shader file to be used in the modifier. Everything works as expected in the Preview, in the Simulator and on a real device for iOS. It also works in Preview and in the Simulator for tvOS but not on a real AppleTV. I have tried this on a 4th generation Apple TV running tvOS 26.3 using Xcode 26.2.0. Xcode logs the following: The metallib is processed and exists in the bundle. Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Contents of Package.swift: import PackageDescription let package = Package( name: "Test", platforms: [ .iOS(.v17), .tvOS(.v17) ], products: [ .library( name: "Test", targets: [ "Test" ] ) ], targets: [ .target( name: "Test", resources: [ .process("Shaders") ] ), .testTarget( name: "TestTests", dependencies: [ "Test" ] ) ] ) Content of my metal file: #include <metal_stdlib> using namespace metal; [[ stitchable ]] float2 complexWave(float2 position, float time, float2 size, float speed, float strength, float frequency) { float2 normalizedPosition = position / size; float moveAmount = time * speed; position.x += sin((normalizedPosition.x + moveAmount) * frequency) * strength; position.y += cos((normalizedPosition.y + moveAmount) * frequency) * strength; return position; } And my ViewModifier: import MetalKit import SwiftUI extension ShaderFunction { static let complexWave: ShaderFunction = { ShaderFunction( library: .bundle(.module), name: "complexWave" ) }() } extension Shader { static func complexWave(arguments: [Shader.Argument]) -> Shader { Shader(function: .complexWave, arguments: arguments) } } struct WaveModifier: ViewModifier { let start: Date = .now func body(content: Content) -> some View { TimelineView(.animation) { context in let delta = context.date.timeIntervalSince(start) content .visualEffect { view, proxy in view.distortionEffect( .complexWave( arguments: [ .float(delta), .float2(proxy.size), .float(0.5), .float(8), .float(10) ] ), maxSampleOffset: .zero ) } } .onAppear { let paths = Bundle.module.paths(forResourcesOfType: "metallib", inDirectory: nil) print(paths) } } } extension View { public func wave() -> some View { modifier(WaveModifier()) } } #Preview { Image(systemName: "cart") .wave() } Any help is appreciated.
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Xcode Metal Capture crash when using MTLSamplerState
The sample code just draw a triangle and sample texture. both sample code can draw a correct triangle and sample texture as expected. there are no error message from terminal. Sample code using constexpr Sampler can capture and replay well. Sample code using a argumentTable to bind a MTLSamplerState was crashed when using Metal capture and replay on Xcode. Here are sample codes. Sample Code Test Environment: M1 Pro MacOS 26.3 (25D125) Xcode Version 26.2 (17C52) Feedback ID: FB22031701
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3w
Optimizing HZB Mip-Chain Generation and Bindless Argument Tables in a Custom Metal Engine
Hi everyone, I’ve been developing a custom, end-to-end 3D rendering engine called Crescent from scratch using C++20 and Metal-cpp (targeting macOS and visionOS). My primary goal is to build a zero-bottleneck, GPU-driven pipeline that maximizes the potential of Apple Silicon’s Unified Memory and TBDR architecture. While the fundamental systems are stable, I am looking for architectural feedback from Metal framework engineers regarding specific synchronization and latency challenges. Current Core Implementations: GPU-Driven Instance Culling: High-performance occlusion culling using a Hierarchical Z-Buffer (HZB) approach via Compute Shaders. Clustered Forward Shading: Support for high-count dynamic lights through view-space clustering. Temporal Stability: Custom TAA with history rejection and Motion Blur resolve. Asset Infrastructure: Robust GUID-based scene serialization and a JSON-driven ECS hierarchy. The Architectural Challenge: I am currently seeing slight synchronization overhead when generating the HZB mip-chain. On Apple Silicon, I am evaluating the cost of encoder transitions versus cache-friendly barriers. && m_hzbInitPipeline && m_hzbDownsamplePipeline && !m_hzbMipViews.empty(); if (canBuildHzb) { MTL::ComputeCommandEncoder* hzbInit = commandBuffer->computeCommandEncoder(); hzbInit->setComputePipelineState(m_hzbInitPipeline); hzbInit->setTexture(m_depthTexture, 0); hzbInit->setTexture(m_hzbMipViews[0], 1); if (m_pointClampSampler) { hzbInit->setSamplerState(m_pointClampSampler, 0); } else if (m_linearClampSampler) { hzbInit->setSamplerState(m_linearClampSampler, 0); } const uint32_t hzbWidth = m_hzbMipViews[0]->width(); const uint32_t hzbHeight = m_hzbMipViews[0]->height(); const uint32_t threads = 8; MTL::Size tgSize = MTL::Size(threads, threads, 1); MTL::Size gridSize = MTL::Size((hzbWidth + threads - 1) / threads * threads, (hzbHeight + threads - 1) / threads * threads, 1); hzbInit->dispatchThreads(gridSize, tgSize); hzbInit->endEncoding(); for (size_t mip = 1; mip < m_hzbMipViews.size(); ++mip) { MTL::Texture* src = m_hzbMipViews[mip - 1]; MTL::Texture* dst = m_hzbMipViews[mip]; if (!src || !dst) { continue; } MTL::ComputeCommandEncoder* downEncoder = commandBuffer->computeCommandEncoder(); downEncoder->setComputePipelineState(m_hzbDownsamplePipeline); downEncoder->setTexture(src, 0); downEncoder->setTexture(dst, 1); const uint32_t mipWidth = dst->width(); const uint32_t mipHeight = dst->height(); MTL::Size downGrid = MTL::Size((mipWidth + threads - 1) / threads * threads, (mipHeight + threads - 1) / threads * threads, 1); downEncoder->dispatchThreads(downGrid, tgSize); downEncoder->endEncoding(); } if (m_instanceCullHzbPipeline) { dispatchInstanceCulling(m_instanceCullHzbPipeline, true); } } My Questions: Encoder Synchronization: Would you recommend moving this loop into a single ComputeCommandEncoder using MTLBarrier between dispatches to maintain L2 cache residency, or is the overhead of separate encoders negligible for depth-downsampling on TBDR? visionOS Bindless Latency: For stereo rendering on visionOS, what are the best practices for managing MTL4ArgumentTable updates at 90Hz+? I want to ensure that updating bindless resources for each eye doesn't introduce unnecessary CPU-to-GPU latency. Memory Management: Are there specific hints for Memoryless textures that could be applied to intermediate HZB levels to save bandwidth during this process? I’ve attached a screenshot of a scene rendered with the engine (PBR, SSR, and IBL).
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Feb ’26
RenderBox Framework Warning
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
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Nov ’25
Help Request! How to Render Models with SubMeshes Using Metal 4?
Hi, I'm Beginner with Metal 4 and Model I/O 🥺. I can render simple models with just one mesh, but when I try to render models with SubMeshes, nothing shows up on screen. Can anyone help me figure out how to properly render models with multiple submeshes? I think I'm not iterating through them correctly or maybe missing some buffers setup. Here's what I have so far: https://www.icloud.com.cn/iclouddrive/0a6x_NLwlWy-herPocExZ8g3Q#LoadModel
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Nov ’25
Cannot load .mtlpackage to MTLLibrary
After watching WWDC 2025 session "Combine Metal 4 machine learning and graphics", I have decided to give it a shot to integrate the latest MTL4MachineLearningCommandEncoder to my existing render pipeline. After a lot of trial and errors, I managed to set up the pipeline and have the app compiled. However, I am now stuck on creating a MTLLibrary with .mtlpackage. Here is the code I have to create a MTLLibrary according the WWDC session https://developer.apple.com/videos/play/wwdc2025/262/?time=550: let coreMLFilePath = bundle.path(forResource: "my_model", ofType: "mtlpackage")! let coreMLURL = URL(string: coreMLFilePath)! do { metalDevice.makeLibrary(URL: coreMLURL) } catch { print("error: \(error)") } With the above code, I am getting error: Error Domain=MTLLibraryErrorDomain Code=1 "Invalid metal package" UserInfo={NSLocalizedDescription=Invalid metal package} What is the correct way to create a MTLLibrary with .mtlpackage? Do I see this error because the .mtlpackage I am using is incorrect? How should I go with debugging this? I'd really appreciate if I could get some help on this as I have been stuck with it for some time now. Thanks in advance!
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Nov ’25
Are there complete code examples available for “Combine Metal 4 machine learning and graphics”?
Hello, I recently watched the WWDC2025 session titled “Combine Metal 4 machine learning and graphics” (https://developer.apple.com/videos/play/wwdc2025/262/ ), and I’m very excited about the new Metal 4 features that integrate machine learning with graphics—such as neural ambient occlusion, shader-based ML inference, and the use of MTLTensor and MTL4MachineLearningCommandEncoder. While the session includes helpful code snippets and a compelling debug demo (e.g., the neural ambient occlusion example), the implementation details are not fully shown, and I haven’t been able to find a complete, runnable sample project that demonstrates end-to-end integration of ML and rendering in Metal 4. Would Apple be able to provide a full, working example—such as an Xcode project—that shows how to: Export a model to an .mlpackage, Convert it to an .mtlpackage, Use MTL4MachineLearningCommandEncoder alongside render passes, Or embed small neural networks directly in shaders using Shader ML? Having such a sample would greatly help developers like me adopt these powerful new capabilities correctly and efficiently. Thank you very much for your time and support! Best regards,
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Nov ’25
Showing a MTLTexture on an Entity in RealityKit
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
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1.1k
Sep ’25
[visionOS] How to render side-by-side stereo video?
I want to render a 3d/stereoscopic video in an Apple Vision Pro window using RealityKit/RealityView. The video is a left-right stereo. The straight forward approach would be to spawn a quad, and give it a custom Shader Graph material, which has a CameraIndexSwitch. The CameraIndexSwitch chooses between the right texture vs the left texture. https://i.sstatic.net/XawqjNcg.png The issue I have here is that I have to extract the video frames from my AVSampleBufferVideoRenderer. This should work ok, but not if I'm playing FairPlay content. So, my question is, how to render stereo FairPlay videos in a SwiftUI RealityView?
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Aug ’25
MetalToolchain fail installation xcode 26.0 beta 5, tahoe 26.0
Failed fetching catalog for assetType (com.apple.MobileAsset.MetalToolchain), serverParameters ({ RequestedBuild = 17A5295f; }) Domain: DVTDownloadsUtilitiesErrorDomain Code: -1 User Info: { DVTErrorCreationDateKey = "2025-08-08 07:59:24 +0000"; } Failed fetching catalog for assetType (com.apple.MobileAsset.MetalToolchain), serverParameters ({ RequestedBuild = 17A5295f; }) Domain: DVTDownloadsUtilitiesErrorDomain Code: -1 Download failed due to not being able to find the host. (Catalog download for com.apple.MobileAsset.MetalToolchain) Domain: com.apple.MobileAssetError.Download Code: 59 User Info: { checkConfiguration = 1; } System Information macOS Version 26.0 (Build 25A5327h) Xcode 26.0 (24198.5) (Build 17A5295f) Timestamp: 2025-08-08T08:59:24+01:00
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Aug ’25
打开显示HUD图形后,应用崩溃
hi everyone, 我们发现了一个和Metal相关崩溃。应用中使用了Metal相关的接口,在进行性能测试时,打开了设置-开发者-显示HUD图形。运行应用后,正常展示HUD,但应用很快发生了崩溃,日志主要信息如下: Incident Identifier: 1F093635-2DB8-4B29-9DA5-488A6609277B CrashReporter Key: 233e54398e2a0266d95265cfb96c5a89eb3403fd Hardware Model: iPhone14,3 Process: waimai [16584] Path: /private/var/containers/Bundle/Application/CCCFC0AE-EFB8-4BD8-B674-ED089B776221/waimai.app/waimai Identifier: Version: 61488 (8.53.0) Code Type: ARM-64 Parent Process: ? [1] Date/Time: 2025-06-12 14:41:45.296 +0800 OS Version: iOS 18.0 (22A3354) Report Version: 104 Monitor Type: Mach Exception Exception Type: EXC_BAD_ACCESS (SIGBUS) Exception Codes: KERN_PROTECTION_FAILURE at 0x000000014fffae00 Crashed Thread: 57 Thread 57 Crashed: 0 libMTLHud.dylib esfm_GenerateTriangesForString + 408 1 libMTLHud.dylib esfm_GenerateTriangesForString + 92 2 libMTLHud.dylib Renderer::DrawText(char const*, int, unsigned int) + 204 3 libMTLHud.dylib Overlay::onPresent(id<CAMetalDrawable>) + 1656 4 libMTLHud.dylib CAMetalDrawable_present(void (*)(), objc_object*, objc_selector*) + 72 5 libMTLHud.dylib invocation function for block in void replaceMethod<void>(objc_class*, objc_selector*, void (*)(void (*)(), objc_object*, objc_selector*)) + 56 6 Metal __45-[_MTLCommandBuffer presentDrawable:options:]_block_invoke + 104 7 Metal MTLDispatchListApply + 52 8 Metal -[_MTLCommandBuffer didScheduleWithStartTime:endTime:error:] + 312 9 IOGPU IOGPUNotificationQueueDispatchAvailableCompletionNotifications + 136 10 IOGPU __IOGPUNotificationQueueSetDispatchQueue_block_invoke + 64 11 libdispatch.dylib _dispatch_client_callout4 + 20 12 libdispatch.dylib _dispatch_mach_msg_invoke + 464 13 libdispatch.dylib _dispatch_lane_serial_drain + 368 14 libdispatch.dylib _dispatch_mach_invoke + 456 15 libdispatch.dylib _dispatch_lane_serial_drain + 368 16 libdispatch.dylib _dispatch_lane_invoke + 432 17 libdispatch.dylib _dispatch_lane_serial_drain + 368 18 libdispatch.dylib _dispatch_lane_invoke + 380 19 libdispatch.dylib _dispatch_root_queue_drain_deferred_wlh + 288 20 libdispatch.dylib _dispatch_workloop_worker_thread + 540 21 libsystem_pthread.dylib _pthread_wqthread + 288 我们测试了几个不同的机型,只有iPhone 13 Pro Max会发生崩溃。 Q1:为什么会发生这个崩溃? Q2:相同的逻辑,为什么仅在iPhone 13 Pro Max机型上出现崩溃? 期待您的解答。
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Jul ’25
How to customize shader code for visionos ?
Hello experts, I'm trying to implement a material with custom shader code, but I saw that visionOS doesn't allow you to inject custom Metal functions or use CustomMaterial like iOS/macOS, nor can you directly write Metal Shading Language (.metal) and use it through ShaderGraphMaterial. So my question is, if i want to implement your own shader code, how should i do it?
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515
Jul ’25
VisionOS 26 - threadsPerThreadgroup limit causing crash on device (but not in simulator)
Hi all, I'm running into an issue with an app that previously worked fine on device using visionOS 2.0. After updating to visionOS 26, the same code runs fine in the simulator but crashes on the device with the following error: -[MTLDebugComputeCommandEncoder _validateThreadsPerThreadgroup:]:1330: failed assertion `(threadsPerThreadgroup.width(32) * threadsPerThreadgroup.height(32) * threadsPerThreadgroup.depth(1))(1024) must be <= 832. (kernel threadgroup size limit)` Is there any documented way to check or increase the allowed threadsPerThreadgroup size on Apple Vision Pro? Or any recommended workaround for this regression? Thanks in advance!
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Jun ’25
Creating a voxel mesh and render it using metal within a RealityKit ImmersiveView
Hi everyone, I'm creating an educational App that allows doing computational design in an immersive environment with the Vision Pro. The App is free and can be found here: https://apps.apple.com/us/app/arcade-topology/id6742103633 The problem I have is that the mesh of voxels I currently create use ModelEntity and I recently read that this is horrible for scalability. I already start to see issues when I try to use thousands of voxels. I also read somewhere that I should then take advantage of GPUs and use metal to that end. I was wondering if someone could point me to a tutorial or article that discusses this. In essence, I need to create a 3D voxel mesh, and those voxels have to update their opacity within an iterative loop. Thanks! —Alejandro
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Jun ’25
SCNTechnique clearColor Always Shows sceneBackground When Passes Share Depth Buffer
Problem Description I'm encountering an issue with SCNTechnique where the clearColor setting is being ignored when multiple passes share the same depth buffer. The clear color always appears as the scene background, regardless of what value I set. The minimal project for reproducing the issue: https://www.dropbox.com/scl/fi/30mx06xunh75wgl3t4sbd/SCNTechniqueCustomSymbols.zip?rlkey=yuehjtk7xh2pmdbetv2r8t2lx&st=b9uobpkp&dl=0 Problem Details In my SCNTechnique configuration, I have two passes that need to share the same depth buffer for proper occlusion handling: "passes": [ "box1_pass": [ "draw": "DRAW_SCENE", "includeCategoryMask": 1, "colorStates": [ "clear": true, "clearColor": "0 0 0 0" // Expecting transparent black ], "depthStates": [ "clear": true, "enableWrite": true ], "outputs": [ "depth": "box1_depth", "color": "box1_color" ], ], "box2_pass": [ "draw": "DRAW_SCENE", "includeCategoryMask": 2, "colorStates": [ "clear": true, "clearColor": "0 0 0 0" // Also expecting transparent black ], "depthStates": [ "clear": false, "enableWrite": false ], "outputs": [ "depth": "box1_depth", // Sharing the same depth buffer "color": "box2_color", ], ], "final_quad": [ "draw": "DRAW_QUAD", "metalVertexShader": "myVertexShader", "metalFragmentShader": "myFragmentShader", "inputs": [ "box1_color": "box1_color", "box2_color": "box2_color", ], "outputs": [ "color": "COLOR" ] ] ] And the metal shader used to display box1_color and box2_color with splitting: fragment half4 myFragmentShader(VertexOut in [[stage_in]], texture2d<half, access::sample> box1_color [[texture(0)]], texture2d<half, access::sample> box2_color [[texture(1)]]) { half4 color1 = box1_color.sample(s, in.texcoord); half4 color2 = box2_color.sample(s, in.texcoord); if (in.texcoord.x < 0.5) { return color1; } return color2; }; Expected Behavior Both passes should clear their color targets to transparent black (0, 0, 0, 0) The depth buffer should be shared between passes for proper occlusion Actual Behavior Both box1_color and box2_color targets contain the scene background instead of being cleared to transparent (see attached image) This happens even when I explicitly set clearColor: "0 0 0 0" for both passes Setting scene.background.contents = UIColor.clear makes the clearColor work as expected, but I need to keep the scene background for other purposes What I've Tried Setting different clearColor values - all are ignored when sharing depth buffer Using DRAW_NODE instead of DRAW_SCENE - didn't solve the issue Creating a separate pass to capture the background - the background still appears in the other passes Various combinations of clear flags and render orders Environment iOS/macOS, running with "My Mac (Designed for iPad)" Xcode 16.2 Question Is this a known limitation of SceneKit when passes share a depth buffer? Is there a workaround to achieve truly transparent clear colors while maintaining a shared depth buffer for occlusion testing? The core issue seems to be that SceneKit automatically renders the scene background in every DRAW_SCENE pass when a shared depth buffer is detected, overriding any clearColor settings. Any insights or workarounds would be greatly appreciated. Thank you!
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391
Jun ’25
Any recommended content-aware compression strategy for .ktx textures in Reality Composer Pro?
In my Reality Composer Pro workflow for Vision Pro development, I’m using xcrun realitytool image to pre-compress textures into .ktx format, typically using ASTC block compression. These textures are used for cubemaps and environment assets. I’ve noticed that regardless of the image content—whether it’s a highly detailed photo or a completely black image—once compressed with the same ASTC block size (e.g., ASTC_8x8), the resulting .ktx file size is nearly identical. There appears to be no content-aware logic that adapts the compression ratio to the actual texture complexity. In contrast, Unreal Engine behaves differently: even when all cubemap faces are imported at the same resolution as DDS textures, the engine performs content-aware compression during packaging: Low-complexity images are compressed more aggressively The final packaged file size varies based on content complexity Since Reality Composer Pro requires textures to be pre-compressed as .ktx, there’s no opportunity for runtime optimization or per-image compression adjustment. Just wondering: is there any recommended way to implement content-aware compression for .ktx textures in Reality Composer Pro? Or any best practices to optimize .ktx sizes based on image complexity? Thanks!
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199
Jun ’25
Any recommended content-aware compression strategy for .ktx textures in Reality Composer Pro?
In my Reality Composer Pro workflow for Vision Pro development, I’m using xcrun realitytool image to pre-compress textures into .ktx format, typically using ASTC block compression. These textures are used for cubemaps and environment assets. I’ve noticed that regardless of the image content—whether it’s a highly detailed photo or a completely black image—once compressed with the same ASTC block size (e.g., ASTC_8x8), the resulting .ktx file size is nearly identical. There appears to be no content-aware logic that adapts the compression ratio to the actual texture complexity. In contrast, Unreal Engine behaves differently: even when all cubemap faces are imported at the same resolution as DDS textures, the engine performs content-aware compression during packaging: Low-complexity images are compressed more aggressively The final packaged file size varies based on content complexity Since Reality Composer Pro requires textures to be pre-compressed as .ktx, there’s no opportunity for runtime optimization or per-image compression adjustment. Just wondering: is there any recommended way to implement content-aware compression for .ktx textures in Reality Composer Pro? Or any best practices to optimize .ktx sizes based on image complexity? Thanks!
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199
May ’25
GPTK 3 and D3DMetal issue with Modern Pipeline Creation
Death Stranding 2: On the Beach (v1.0.48.0, Steam) crashes during rendering initialization when running through CrossOver 26 with D3DMetal 3.0 on an Apple M2 Max Mac Studio running macOS Sequoia. The game successfully initializes Streamline, NVAPI, DLSS (Result::eOk), DLSSG (Result::eOk), Reflex, and XeSS — all subsystems report success. The crash occurs immediately after, during rendering pipeline creation, before the game reaches NXStorage initialization or window creation. Minidump analysis confirms the crash is an access violation (0xc0000005) at DS2.exe+0x67233d, writing to address 0x0. RAX=0x0 (null pointer being dereferenced), R12=0xFFFFFFFFFFFFFFFF (error/invalid handle return). The game appears to call a D3D12 API — likely CheckFeatureSupport or a pipeline state creation function — that D3DMetal acknowledges as supported but returns null or invalid data for. The game trusts the response and dereferences the null pointer. Two other Nixxes titles using the same engine and D3DMetal setup run without issue: Spider-Man 2 (~50 FPS) and Horizon Zero Dawn Remastered (~34 FPS). DS2 uses newer technology versions (DLSS 4, FSR 4, XeSS 2) and a newer DirectX 12 Agility SDK, which likely queries D3D12 features that D3DMetal does not yet fully implement. The crash also reproduces when D3DMetal reports as AMD vendor (1002) instead of NVIDIA (10de), crashing at the same executable offset, confirming it is a D3D12 feature reporting gap in D3DMetal rather than a vendor-specific issue. How To Reproduce Install Crossover 26+ on MacOS 26.4 Install Steam and download Death Stranding 2 Run Death Stranding 2 and check logs after crash in Documents\DEATH STRANDING 2 ON THE BEACH Feedback Requests FB22285513 — Game Porting Toolkit 3 issue with Modern Pipeline Creation
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385
Activity
2d
RealityKit fill the background environment
I am new to RealityKit and Metal and I am building a RealityKit app that renders a procedural LowLevelMesh road. But the left and right side of the road is a complete green terrain mesh object and it doesn't look great. What I want is to add some rocks, tall trees and dence bushes (or weed) to make it look like the player is in the woods. But when I add many of those objects then the performance drains. What is the best approach to fill background empty spaces in the scene?
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131
Activity
3d
Metal Shader inside Swift Package not found?
Hello everyone! I am trying to wrap a ViewModifier inside a Swift Package that bundles a metal shader file to be used in the modifier. Everything works as expected in the Preview, in the Simulator and on a real device for iOS. It also works in Preview and in the Simulator for tvOS but not on a real AppleTV. I have tried this on a 4th generation Apple TV running tvOS 26.3 using Xcode 26.2.0. Xcode logs the following: The metallib is processed and exists in the bundle. Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Compiler failed to build request precondition failure: pipeline error: custom_effect-fg2a5cia7fmha4: error: unresolved visible function reference: custom_fn Reason: visible function not loaded Contents of Package.swift: import PackageDescription let package = Package( name: "Test", platforms: [ .iOS(.v17), .tvOS(.v17) ], products: [ .library( name: "Test", targets: [ "Test" ] ) ], targets: [ .target( name: "Test", resources: [ .process("Shaders") ] ), .testTarget( name: "TestTests", dependencies: [ "Test" ] ) ] ) Content of my metal file: #include <metal_stdlib> using namespace metal; [[ stitchable ]] float2 complexWave(float2 position, float time, float2 size, float speed, float strength, float frequency) { float2 normalizedPosition = position / size; float moveAmount = time * speed; position.x += sin((normalizedPosition.x + moveAmount) * frequency) * strength; position.y += cos((normalizedPosition.y + moveAmount) * frequency) * strength; return position; } And my ViewModifier: import MetalKit import SwiftUI extension ShaderFunction { static let complexWave: ShaderFunction = { ShaderFunction( library: .bundle(.module), name: "complexWave" ) }() } extension Shader { static func complexWave(arguments: [Shader.Argument]) -> Shader { Shader(function: .complexWave, arguments: arguments) } } struct WaveModifier: ViewModifier { let start: Date = .now func body(content: Content) -> some View { TimelineView(.animation) { context in let delta = context.date.timeIntervalSince(start) content .visualEffect { view, proxy in view.distortionEffect( .complexWave( arguments: [ .float(delta), .float2(proxy.size), .float(0.5), .float(8), .float(10) ] ), maxSampleOffset: .zero ) } } .onAppear { let paths = Bundle.module.paths(forResourcesOfType: "metallib", inDirectory: nil) print(paths) } } } extension View { public func wave() -> some View { modifier(WaveModifier()) } } #Preview { Image(systemName: "cart") .wave() } Any help is appreciated.
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Activity
2w
Xcode Metal Capture crash when using MTLSamplerState
The sample code just draw a triangle and sample texture. both sample code can draw a correct triangle and sample texture as expected. there are no error message from terminal. Sample code using constexpr Sampler can capture and replay well. Sample code using a argumentTable to bind a MTLSamplerState was crashed when using Metal capture and replay on Xcode. Here are sample codes. Sample Code Test Environment: M1 Pro MacOS 26.3 (25D125) Xcode Version 26.2 (17C52) Feedback ID: FB22031701
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Activity
3w
Optimizing HZB Mip-Chain Generation and Bindless Argument Tables in a Custom Metal Engine
Hi everyone, I’ve been developing a custom, end-to-end 3D rendering engine called Crescent from scratch using C++20 and Metal-cpp (targeting macOS and visionOS). My primary goal is to build a zero-bottleneck, GPU-driven pipeline that maximizes the potential of Apple Silicon’s Unified Memory and TBDR architecture. While the fundamental systems are stable, I am looking for architectural feedback from Metal framework engineers regarding specific synchronization and latency challenges. Current Core Implementations: GPU-Driven Instance Culling: High-performance occlusion culling using a Hierarchical Z-Buffer (HZB) approach via Compute Shaders. Clustered Forward Shading: Support for high-count dynamic lights through view-space clustering. Temporal Stability: Custom TAA with history rejection and Motion Blur resolve. Asset Infrastructure: Robust GUID-based scene serialization and a JSON-driven ECS hierarchy. The Architectural Challenge: I am currently seeing slight synchronization overhead when generating the HZB mip-chain. On Apple Silicon, I am evaluating the cost of encoder transitions versus cache-friendly barriers. && m_hzbInitPipeline && m_hzbDownsamplePipeline && !m_hzbMipViews.empty(); if (canBuildHzb) { MTL::ComputeCommandEncoder* hzbInit = commandBuffer->computeCommandEncoder(); hzbInit->setComputePipelineState(m_hzbInitPipeline); hzbInit->setTexture(m_depthTexture, 0); hzbInit->setTexture(m_hzbMipViews[0], 1); if (m_pointClampSampler) { hzbInit->setSamplerState(m_pointClampSampler, 0); } else if (m_linearClampSampler) { hzbInit->setSamplerState(m_linearClampSampler, 0); } const uint32_t hzbWidth = m_hzbMipViews[0]->width(); const uint32_t hzbHeight = m_hzbMipViews[0]->height(); const uint32_t threads = 8; MTL::Size tgSize = MTL::Size(threads, threads, 1); MTL::Size gridSize = MTL::Size((hzbWidth + threads - 1) / threads * threads, (hzbHeight + threads - 1) / threads * threads, 1); hzbInit->dispatchThreads(gridSize, tgSize); hzbInit->endEncoding(); for (size_t mip = 1; mip < m_hzbMipViews.size(); ++mip) { MTL::Texture* src = m_hzbMipViews[mip - 1]; MTL::Texture* dst = m_hzbMipViews[mip]; if (!src || !dst) { continue; } MTL::ComputeCommandEncoder* downEncoder = commandBuffer->computeCommandEncoder(); downEncoder->setComputePipelineState(m_hzbDownsamplePipeline); downEncoder->setTexture(src, 0); downEncoder->setTexture(dst, 1); const uint32_t mipWidth = dst->width(); const uint32_t mipHeight = dst->height(); MTL::Size downGrid = MTL::Size((mipWidth + threads - 1) / threads * threads, (mipHeight + threads - 1) / threads * threads, 1); downEncoder->dispatchThreads(downGrid, tgSize); downEncoder->endEncoding(); } if (m_instanceCullHzbPipeline) { dispatchInstanceCulling(m_instanceCullHzbPipeline, true); } } My Questions: Encoder Synchronization: Would you recommend moving this loop into a single ComputeCommandEncoder using MTLBarrier between dispatches to maintain L2 cache residency, or is the overhead of separate encoders negligible for depth-downsampling on TBDR? visionOS Bindless Latency: For stereo rendering on visionOS, what are the best practices for managing MTL4ArgumentTable updates at 90Hz+? I want to ensure that updating bindless resources for each eye doesn't introduce unnecessary CPU-to-GPU latency. Memory Management: Are there specific hints for Memoryless textures that could be applied to intermediate HZB levels to save bandwidth during this process? I’ve attached a screenshot of a scene rendered with the engine (PBR, SSR, and IBL).
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Activity
Feb ’26
RenderBox Framework Warning
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
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Activity
Nov ’25
Help Request! How to Render Models with SubMeshes Using Metal 4?
Hi, I'm Beginner with Metal 4 and Model I/O 🥺. I can render simple models with just one mesh, but when I try to render models with SubMeshes, nothing shows up on screen. Can anyone help me figure out how to properly render models with multiple submeshes? I think I'm not iterating through them correctly or maybe missing some buffers setup. Here's what I have so far: https://www.icloud.com.cn/iclouddrive/0a6x_NLwlWy-herPocExZ8g3Q#LoadModel
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Activity
Nov ’25
Cannot load .mtlpackage to MTLLibrary
After watching WWDC 2025 session "Combine Metal 4 machine learning and graphics", I have decided to give it a shot to integrate the latest MTL4MachineLearningCommandEncoder to my existing render pipeline. After a lot of trial and errors, I managed to set up the pipeline and have the app compiled. However, I am now stuck on creating a MTLLibrary with .mtlpackage. Here is the code I have to create a MTLLibrary according the WWDC session https://developer.apple.com/videos/play/wwdc2025/262/?time=550: let coreMLFilePath = bundle.path(forResource: "my_model", ofType: "mtlpackage")! let coreMLURL = URL(string: coreMLFilePath)! do { metalDevice.makeLibrary(URL: coreMLURL) } catch { print("error: \(error)") } With the above code, I am getting error: Error Domain=MTLLibraryErrorDomain Code=1 "Invalid metal package" UserInfo={NSLocalizedDescription=Invalid metal package} What is the correct way to create a MTLLibrary with .mtlpackage? Do I see this error because the .mtlpackage I am using is incorrect? How should I go with debugging this? I'd really appreciate if I could get some help on this as I have been stuck with it for some time now. Thanks in advance!
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Activity
Nov ’25
Are there complete code examples available for “Combine Metal 4 machine learning and graphics”?
Hello, I recently watched the WWDC2025 session titled “Combine Metal 4 machine learning and graphics” (https://developer.apple.com/videos/play/wwdc2025/262/ ), and I’m very excited about the new Metal 4 features that integrate machine learning with graphics—such as neural ambient occlusion, shader-based ML inference, and the use of MTLTensor and MTL4MachineLearningCommandEncoder. While the session includes helpful code snippets and a compelling debug demo (e.g., the neural ambient occlusion example), the implementation details are not fully shown, and I haven’t been able to find a complete, runnable sample project that demonstrates end-to-end integration of ML and rendering in Metal 4. Would Apple be able to provide a full, working example—such as an Xcode project—that shows how to: Export a model to an .mlpackage, Convert it to an .mtlpackage, Use MTL4MachineLearningCommandEncoder alongside render passes, Or embed small neural networks directly in shaders using Shader ML? Having such a sample would greatly help developers like me adopt these powerful new capabilities correctly and efficiently. Thank you very much for your time and support! Best regards,
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975
Activity
Nov ’25
Showing a MTLTexture on an Entity in RealityKit
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
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Activity
Sep ’25
[visionOS] How to render side-by-side stereo video?
I want to render a 3d/stereoscopic video in an Apple Vision Pro window using RealityKit/RealityView. The video is a left-right stereo. The straight forward approach would be to spawn a quad, and give it a custom Shader Graph material, which has a CameraIndexSwitch. The CameraIndexSwitch chooses between the right texture vs the left texture. https://i.sstatic.net/XawqjNcg.png The issue I have here is that I have to extract the video frames from my AVSampleBufferVideoRenderer. This should work ok, but not if I'm playing FairPlay content. So, my question is, how to render stereo FairPlay videos in a SwiftUI RealityView?
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Activity
Aug ’25
MetalToolchain fail installation xcode 26.0 beta 5, tahoe 26.0
Failed fetching catalog for assetType (com.apple.MobileAsset.MetalToolchain), serverParameters ({ RequestedBuild = 17A5295f; }) Domain: DVTDownloadsUtilitiesErrorDomain Code: -1 User Info: { DVTErrorCreationDateKey = "2025-08-08 07:59:24 +0000"; } Failed fetching catalog for assetType (com.apple.MobileAsset.MetalToolchain), serverParameters ({ RequestedBuild = 17A5295f; }) Domain: DVTDownloadsUtilitiesErrorDomain Code: -1 Download failed due to not being able to find the host. (Catalog download for com.apple.MobileAsset.MetalToolchain) Domain: com.apple.MobileAssetError.Download Code: 59 User Info: { checkConfiguration = 1; } System Information macOS Version 26.0 (Build 25A5327h) Xcode 26.0 (24198.5) (Build 17A5295f) Timestamp: 2025-08-08T08:59:24+01:00
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Activity
Aug ’25
打开显示HUD图形后,应用崩溃
hi everyone, 我们发现了一个和Metal相关崩溃。应用中使用了Metal相关的接口,在进行性能测试时,打开了设置-开发者-显示HUD图形。运行应用后,正常展示HUD,但应用很快发生了崩溃,日志主要信息如下: Incident Identifier: 1F093635-2DB8-4B29-9DA5-488A6609277B CrashReporter Key: 233e54398e2a0266d95265cfb96c5a89eb3403fd Hardware Model: iPhone14,3 Process: waimai [16584] Path: /private/var/containers/Bundle/Application/CCCFC0AE-EFB8-4BD8-B674-ED089B776221/waimai.app/waimai Identifier: Version: 61488 (8.53.0) Code Type: ARM-64 Parent Process: ? [1] Date/Time: 2025-06-12 14:41:45.296 +0800 OS Version: iOS 18.0 (22A3354) Report Version: 104 Monitor Type: Mach Exception Exception Type: EXC_BAD_ACCESS (SIGBUS) Exception Codes: KERN_PROTECTION_FAILURE at 0x000000014fffae00 Crashed Thread: 57 Thread 57 Crashed: 0 libMTLHud.dylib esfm_GenerateTriangesForString + 408 1 libMTLHud.dylib esfm_GenerateTriangesForString + 92 2 libMTLHud.dylib Renderer::DrawText(char const*, int, unsigned int) + 204 3 libMTLHud.dylib Overlay::onPresent(id<CAMetalDrawable>) + 1656 4 libMTLHud.dylib CAMetalDrawable_present(void (*)(), objc_object*, objc_selector*) + 72 5 libMTLHud.dylib invocation function for block in void replaceMethod<void>(objc_class*, objc_selector*, void (*)(void (*)(), objc_object*, objc_selector*)) + 56 6 Metal __45-[_MTLCommandBuffer presentDrawable:options:]_block_invoke + 104 7 Metal MTLDispatchListApply + 52 8 Metal -[_MTLCommandBuffer didScheduleWithStartTime:endTime:error:] + 312 9 IOGPU IOGPUNotificationQueueDispatchAvailableCompletionNotifications + 136 10 IOGPU __IOGPUNotificationQueueSetDispatchQueue_block_invoke + 64 11 libdispatch.dylib _dispatch_client_callout4 + 20 12 libdispatch.dylib _dispatch_mach_msg_invoke + 464 13 libdispatch.dylib _dispatch_lane_serial_drain + 368 14 libdispatch.dylib _dispatch_mach_invoke + 456 15 libdispatch.dylib _dispatch_lane_serial_drain + 368 16 libdispatch.dylib _dispatch_lane_invoke + 432 17 libdispatch.dylib _dispatch_lane_serial_drain + 368 18 libdispatch.dylib _dispatch_lane_invoke + 380 19 libdispatch.dylib _dispatch_root_queue_drain_deferred_wlh + 288 20 libdispatch.dylib _dispatch_workloop_worker_thread + 540 21 libsystem_pthread.dylib _pthread_wqthread + 288 我们测试了几个不同的机型,只有iPhone 13 Pro Max会发生崩溃。 Q1:为什么会发生这个崩溃? Q2:相同的逻辑,为什么仅在iPhone 13 Pro Max机型上出现崩溃? 期待您的解答。
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Activity
Jul ’25
How to customize shader code for visionos ?
Hello experts, I'm trying to implement a material with custom shader code, but I saw that visionOS doesn't allow you to inject custom Metal functions or use CustomMaterial like iOS/macOS, nor can you directly write Metal Shading Language (.metal) and use it through ShaderGraphMaterial. So my question is, if i want to implement your own shader code, how should i do it?
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Activity
Jul ’25
VisionOS 26 - threadsPerThreadgroup limit causing crash on device (but not in simulator)
Hi all, I'm running into an issue with an app that previously worked fine on device using visionOS 2.0. After updating to visionOS 26, the same code runs fine in the simulator but crashes on the device with the following error: -[MTLDebugComputeCommandEncoder _validateThreadsPerThreadgroup:]:1330: failed assertion `(threadsPerThreadgroup.width(32) * threadsPerThreadgroup.height(32) * threadsPerThreadgroup.depth(1))(1024) must be <= 832. (kernel threadgroup size limit)` Is there any documented way to check or increase the allowed threadsPerThreadgroup size on Apple Vision Pro? Or any recommended workaround for this regression? Thanks in advance!
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Activity
Jun ’25
Regarding Smoothing in Spectrogram using Metal
Hey, I need to know how to use texture mapping for rendering a spectrogram in metal. As I need smoothens the spectrogram. In my current project I am using vertex based approach which results in blocky behaviour between each quad. I need to smooth across each qaud so that It will smoothly gradient over.
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Activity
Jun ’25
Creating a voxel mesh and render it using metal within a RealityKit ImmersiveView
Hi everyone, I'm creating an educational App that allows doing computational design in an immersive environment with the Vision Pro. The App is free and can be found here: https://apps.apple.com/us/app/arcade-topology/id6742103633 The problem I have is that the mesh of voxels I currently create use ModelEntity and I recently read that this is horrible for scalability. I already start to see issues when I try to use thousands of voxels. I also read somewhere that I should then take advantage of GPUs and use metal to that end. I was wondering if someone could point me to a tutorial or article that discusses this. In essence, I need to create a 3D voxel mesh, and those voxels have to update their opacity within an iterative loop. Thanks! —Alejandro
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152
Activity
Jun ’25
SCNTechnique clearColor Always Shows sceneBackground When Passes Share Depth Buffer
Problem Description I'm encountering an issue with SCNTechnique where the clearColor setting is being ignored when multiple passes share the same depth buffer. The clear color always appears as the scene background, regardless of what value I set. The minimal project for reproducing the issue: https://www.dropbox.com/scl/fi/30mx06xunh75wgl3t4sbd/SCNTechniqueCustomSymbols.zip?rlkey=yuehjtk7xh2pmdbetv2r8t2lx&st=b9uobpkp&dl=0 Problem Details In my SCNTechnique configuration, I have two passes that need to share the same depth buffer for proper occlusion handling: "passes": [ "box1_pass": [ "draw": "DRAW_SCENE", "includeCategoryMask": 1, "colorStates": [ "clear": true, "clearColor": "0 0 0 0" // Expecting transparent black ], "depthStates": [ "clear": true, "enableWrite": true ], "outputs": [ "depth": "box1_depth", "color": "box1_color" ], ], "box2_pass": [ "draw": "DRAW_SCENE", "includeCategoryMask": 2, "colorStates": [ "clear": true, "clearColor": "0 0 0 0" // Also expecting transparent black ], "depthStates": [ "clear": false, "enableWrite": false ], "outputs": [ "depth": "box1_depth", // Sharing the same depth buffer "color": "box2_color", ], ], "final_quad": [ "draw": "DRAW_QUAD", "metalVertexShader": "myVertexShader", "metalFragmentShader": "myFragmentShader", "inputs": [ "box1_color": "box1_color", "box2_color": "box2_color", ], "outputs": [ "color": "COLOR" ] ] ] And the metal shader used to display box1_color and box2_color with splitting: fragment half4 myFragmentShader(VertexOut in [[stage_in]], texture2d<half, access::sample> box1_color [[texture(0)]], texture2d<half, access::sample> box2_color [[texture(1)]]) { half4 color1 = box1_color.sample(s, in.texcoord); half4 color2 = box2_color.sample(s, in.texcoord); if (in.texcoord.x < 0.5) { return color1; } return color2; }; Expected Behavior Both passes should clear their color targets to transparent black (0, 0, 0, 0) The depth buffer should be shared between passes for proper occlusion Actual Behavior Both box1_color and box2_color targets contain the scene background instead of being cleared to transparent (see attached image) This happens even when I explicitly set clearColor: "0 0 0 0" for both passes Setting scene.background.contents = UIColor.clear makes the clearColor work as expected, but I need to keep the scene background for other purposes What I've Tried Setting different clearColor values - all are ignored when sharing depth buffer Using DRAW_NODE instead of DRAW_SCENE - didn't solve the issue Creating a separate pass to capture the background - the background still appears in the other passes Various combinations of clear flags and render orders Environment iOS/macOS, running with "My Mac (Designed for iPad)" Xcode 16.2 Question Is this a known limitation of SceneKit when passes share a depth buffer? Is there a workaround to achieve truly transparent clear colors while maintaining a shared depth buffer for occlusion testing? The core issue seems to be that SceneKit automatically renders the scene background in every DRAW_SCENE pass when a shared depth buffer is detected, overriding any clearColor settings. Any insights or workarounds would be greatly appreciated. Thank you!
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Activity
Jun ’25
Any recommended content-aware compression strategy for .ktx textures in Reality Composer Pro?
In my Reality Composer Pro workflow for Vision Pro development, I’m using xcrun realitytool image to pre-compress textures into .ktx format, typically using ASTC block compression. These textures are used for cubemaps and environment assets. I’ve noticed that regardless of the image content—whether it’s a highly detailed photo or a completely black image—once compressed with the same ASTC block size (e.g., ASTC_8x8), the resulting .ktx file size is nearly identical. There appears to be no content-aware logic that adapts the compression ratio to the actual texture complexity. In contrast, Unreal Engine behaves differently: even when all cubemap faces are imported at the same resolution as DDS textures, the engine performs content-aware compression during packaging: Low-complexity images are compressed more aggressively The final packaged file size varies based on content complexity Since Reality Composer Pro requires textures to be pre-compressed as .ktx, there’s no opportunity for runtime optimization or per-image compression adjustment. Just wondering: is there any recommended way to implement content-aware compression for .ktx textures in Reality Composer Pro? Or any best practices to optimize .ktx sizes based on image complexity? Thanks!
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199
Activity
Jun ’25
Any recommended content-aware compression strategy for .ktx textures in Reality Composer Pro?
In my Reality Composer Pro workflow for Vision Pro development, I’m using xcrun realitytool image to pre-compress textures into .ktx format, typically using ASTC block compression. These textures are used for cubemaps and environment assets. I’ve noticed that regardless of the image content—whether it’s a highly detailed photo or a completely black image—once compressed with the same ASTC block size (e.g., ASTC_8x8), the resulting .ktx file size is nearly identical. There appears to be no content-aware logic that adapts the compression ratio to the actual texture complexity. In contrast, Unreal Engine behaves differently: even when all cubemap faces are imported at the same resolution as DDS textures, the engine performs content-aware compression during packaging: Low-complexity images are compressed more aggressively The final packaged file size varies based on content complexity Since Reality Composer Pro requires textures to be pre-compressed as .ktx, there’s no opportunity for runtime optimization or per-image compression adjustment. Just wondering: is there any recommended way to implement content-aware compression for .ktx textures in Reality Composer Pro? Or any best practices to optimize .ktx sizes based on image complexity? Thanks!
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199
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May ’25