I am working on a project for macOS where I am taking an AVCaptureSession's CVPixelBuffer and I need to convert it into a MTLTexture for rendering. On macOS the pixel format is 2vuy, there does not seem to be a clear format conversion while converting to a metal texture. I have been able to convert it to a texture but the color space seems to be off as it is rendering distorted colors with a double image. I believe 2vuy is a single pane color space and I have tried to account for that, but I am unaware of what is off. I have attached The CVPixelBuffer and The distorted MTLTexture along with a laundry list of errors. On iOS my conversions are fine, it is only the macOS 2vuy pixel format that seems to have issues. My code for the conversion is also attached. If there are any suggestions or guidance on how to properly convert a 2vuy CVPixelBuffer to a MTLTexture I would greatly appreciate it. Many Thanks Conversion_Logs.txt ConversionCode.swift

I am working on a project for macOS where I am taking an AVCaptureSession's CVPixelBuffer and I need to convert it into a MTLTexture for rendering. On macOS the pixel format is 2vuy, there does not seem to be a clear format conversion while converting to a metal texture. I have been able to convert it to a texture but the color space seems to be off as it is rendering distorted colors with a double image. I believe 2vuy is a single pane color space and I have tried to account for that, but I am unaware of what is off. I have attached The CVPixelBuffer and The distorted MTLTexture along with a laundry list of errors. On iOS my conversions are fine, it is only the macOS 2vuy pixel format that seems to have issues. My code for the conversion is also attached. If there are any suggestions or guidance on how to properly convert a 2vuy CVPixelBuffer to a MTLTexture I would greatly appreciate it. Many Thanks Conversion_Logs.txt ConversionCode.swift

Hello! I have a question about how thread groups work with tile shading. When running "traditional" compute, I get to choose both thread group size and the grid size. However, when using tile shading kernel I only have dispatchThreadsPerTile method - this controls how many threads will be ran in each tile. So far so good, but what about thread groups? The examples in video "Tile Shading on A11" seem to suggest that there will be only one thread group per tile. In the video, [[thread_index_in_threadgroup]] is called "local_id" and it is used to access the image block. I assume this is the default configuration. So when one does the following: Creates MTLRenderPassDescriptor with tileWidth set to W and tileHeight set to H Fires up the tile shading kernel using dispatchThreadsPerTile with MTLSize size = { W, H, 1 } I understand that the result is 1-to-1 mapping between the tile "pixels" and kernel threads. Now, what I would like to do is to have more than one thread group there. I want this for performance reasons: I have a certain compute kernel which I know executes very well with small thread group size. In fact, { 32, 1, 1 } seems to be the fastest. My understanding is that even if I set tile size to 16x16, and so I am executing 256 threads there, there will only be one SIMD group active in a thread group. Meaning that this SIMD group has to execute 8 times over the tile. Is it possible somehow? Or perhaps the limitations of the API are pointing at the limitations of hardware itself, and if I want to execute with SIMD group sized thread groups I have to use "traditional" compute encoder? Will be grateful for help. Michał

I have this drawing app that I have been working on for the past few years when I have free time. I recently rebuilt the app in Metal to build out other brushes and improve performance, need to render 10000s of lines in realtime. I’m running into this issue trying to create a uniform opacity per path. I have a solution but do not love it - as this is a realtime app and the solution could have some bottlenecks. If I just generate a triangle strip from touch points and do my best to smooth, resample, and handle miters I will always get some overlaps. See: To create a uniform opacity I render to an offscreen texture with blending disabled. I then pre-multiply the color and draw that texture to a composite texture with blending on (I do this per path). This works but gets tricky when you introduce a textured brush, the edges of the texture in the frag shader cut out the line. Pasted Graphic 1.png Solution: I discard below a threshold fragment float4 fragment_line(VertexOut in [[stage_in]], texture2d<float> texture [[ texture(0) ]]) { constexpr sampler s(coord::normalized, address::mirrored_repeat, filter::linear); float2 texCoord = in.texCoord; float4 texColor = texture.sample(s, texCoord); if (texColor.a < 0.01) discard_fragment(); // may be slow (from what I read) return in.color * texColor; } Better but still not perfect. Question: I'm looking for better ways to create a uniform opacity per path. I tried .max blending but that will cause no blending of other paths. Any tips, ideas, much appreciated. If this is too detailed of a question just achieve.

I am develop visionOS app. I am now very interested in Metal and Compositor Services, but I have not explored them in depth. I know that Metal has a higher degree of control freedom. I am wondering if using Compositor Services will have fewer functions than RealityKit in AR technology (such as scene reconstruction and understanding, hover effect, etc.).

In this video, tile fragment shading is recommended for image processing. In this example, the unpack function takes two arguments, one of which is RasterizerData. As I understand it, this is the data passed to us from the previous stage (Vertex) of the graphics pipeline. However, the properties of MTLTileRenderPipelineDescriptor do not include an option for specifying a Vertex function. Therefore, in this render pass, a mix of commands is used: first, a draw command is executed to obtain UV coordinates, and then threads are dispatched. My question is: without using a draw command, only dispatch, how can I get pixel coordinates in the fragment tile function? For the kernel tile function, everything is clear. typedef struct { float4 OPTexture [[ color(0) ]]; float4 IntermediateTex [[ color(1) ]]; } FragmentIO; fragment FragmentIO Unpack(RasterizerData in [[ stage_in ]], texture2d<float, access::sample> srcImageTexture [[texture(0)]]) { FragmentIO out; //... // Run necessary per-pixel operations out.OPTexture = // assign computed value; out.IntermediateTex = // assign computed value; return out; }

When I toggle a panel like navigationsidebar, I get a message in the console. I guess it's not a big issue, but is there a way to fix this message? because it appears in every project. Unable to open mach-O at path: /AppleInternal/Library/BuildRoots/d187757d-b9a3-11ef-83e5-aabfac210453/Library/Caches/com.apple.xbs/Binaries/RenderBox/install/TempContent/Root/System/Library/PrivateFrameworks/RenderBox.framework/Versions/A/Resources/default.metallib Error:2

I am trying to achieve an animated gradient effect that changes values over time based on the current seconds. I am also using AVPlayer and AVMutableVideoComposition along with custom instruction and class to generate the effect. I didn't want to load any video file, but rather generate a custom video with my own set of instructions. I used Metal Compute shaders to generate the effects and make the video to be 20 seconds. However, when I run the code, I get a frozen player with the gradient applied, but when I try to play the video, I get this warning in the console :- Visual isTranslatable: NO; reason: observation failure: noObservations Here is the screenshot :- My entire code :- import AVFoundation import Metal class GradientVideoCompositorTest: NSObject, AVVideoCompositing { var sourcePixelBufferAttributes: [String: Any]? = [ kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA ] var requiredPixelBufferAttributesForRenderContext: [String: Any] = [ kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA ] private var renderContext: AVVideoCompositionRenderContext? private var metalDevice: MTLDevice! private var metalCommandQueue: MTLCommandQueue! private var metalLibrary: MTLLibrary! private var metalPipeline: MTLComputePipelineState! override init() { super.init() setupMetal() } func setupMetal() { guard let device = MTLCreateSystemDefaultDevice(), let queue = device.makeCommandQueue(), let library = try? device.makeDefaultLibrary(), let function = library.makeFunction(name: "gradientShader") else { fatalError("Metal setup failed") } self.metalDevice = device self.metalCommandQueue = queue self.metalLibrary = library self.metalPipeline = try? device.makeComputePipelineState(function: function) } func renderContextChanged(_ newRenderContext: AVVideoCompositionRenderContext) { renderContext = newRenderContext } func startRequest(_ request: AVAsynchronousVideoCompositionRequest) { guard let outputPixelBuffer = renderContext?.newPixelBuffer(), let metalTexture = createMetalTexture(from: outputPixelBuffer) else { request.finish(with: NSError(domain: "com.example.gradient", code: -1, userInfo: nil)) return } var time = Float(request.compositionTime.seconds) renderGradient(to: metalTexture, time: time) request.finish(withComposedVideoFrame: outputPixelBuffer) } private func createMetalTexture(from pixelBuffer: CVPixelBuffer) -> MTLTexture? { var texture: MTLTexture? let width = CVPixelBufferGetWidth(pixelBuffer) let height = CVPixelBufferGetHeight(pixelBuffer) let textureDescriptor = MTLTextureDescriptor.texture2DDescriptor( pixelFormat: .bgra8Unorm, width: width, height: height, mipmapped: false ) textureDescriptor.usage = [.shaderWrite, .shaderRead] CVPixelBufferLockBaseAddress(pixelBuffer, .readOnly) if let textureCache = createTextureCache(), let cvTexture = createCVMetalTexture(from: pixelBuffer, cache: textureCache) { texture = CVMetalTextureGetTexture(cvTexture) } CVPixelBufferUnlockBaseAddress(pixelBuffer, .readOnly) return texture } private func renderGradient(to texture: MTLTexture, time: Float) { guard let commandBuffer = metalCommandQueue.makeCommandBuffer(), let commandEncoder = commandBuffer.makeComputeCommandEncoder() else { return } commandEncoder.setComputePipelineState(metalPipeline) commandEncoder.setTexture(texture, index: 0) var mutableTime = time commandEncoder.setBytes(&mutableTime, length: MemoryLayout<Float>.size, index: 0) let threadsPerGroup = MTLSize(width: 16, height: 16, depth: 1) let threadGroups = MTLSize( width: (texture.width + 15) / 16, height: (texture.height + 15) / 16, depth: 1 ) commandEncoder.dispatchThreadgroups(threadGroups, threadsPerThreadgroup: threadsPerGroup) commandEncoder.endEncoding() commandBuffer.commit() } private func createTextureCache() -> CVMetalTextureCache? { var cache: CVMetalTextureCache? CVMetalTextureCacheCreate(kCFAllocatorDefault, nil, metalDevice, nil, &cache) return cache } private func createCVMetalTexture(from pixelBuffer: CVPixelBuffer, cache: CVMetalTextureCache) -> CVMetalTexture? { var cvTexture: CVMetalTexture? let width = CVPixelBufferGetWidth(pixelBuffer) let height = CVPixelBufferGetHeight(pixelBuffer) CVMetalTextureCacheCreateTextureFromImage( kCFAllocatorDefault, cache, pixelBuffer, nil, .bgra8Unorm, width, height, 0, &cvTexture ) return cvTexture } } class GradientCompositionInstructionTest: NSObject, AVVideoCompositionInstructionProtocol { var timeRange: CMTimeRange var enablePostProcessing: Bool = true var containsTweening: Bool = true var requiredSourceTrackIDs: [NSValue]? = nil var passthroughTrackID: CMPersistentTrackID = kCMPersistentTrackID_Invalid init(timeRange: CMTimeRange) { self.timeRange = timeRange } } func createGradientVideoComposition(duration: CMTime, size: CGSize) -> AVMutableVideoComposition { let composition = AVMutableComposition() let instruction = GradientCompositionInstructionTest(timeRange: CMTimeRange(start: .zero, duration: duration)) let videoComposition = AVMutableVideoComposition() videoComposition.customVideoCompositorClass = GradientVideoCompositorTest.self videoComposition.renderSize = size videoComposition.frameDuration = CMTime(value: 1, timescale: 30) // 30 FPS videoComposition.instructions = [instruction] return videoComposition } #include <metal_stdlib> using namespace metal; kernel void gradientShader(texture2d<float, access::write> output [[texture(0)]], constant float &time [[buffer(0)]], uint2 id [[thread_position_in_grid]]) { float2 uv = float2(id) / float2(output.get_width(), output.get_height()); // Animated colors based on time float3 color1 = float3(sin(time) * 0.8 + 0.1, 0.6, 1.0); float3 color2 = float3(0.12, 0.99, cos(time) * 0.9 + 0.3); // Linear interpolation for gradient float3 gradientColor = mix(color1, color2, uv.y); output.write(float4(gradientColor, 1.0), id); }

Hello! I'm currently porting a videogame console emulator to iOS and I'm trying to make the renderer (tested on MacOS) work on iOS as well. The emulator core is written in C++ and uses metal-cpp for rendering, whereas the iOS frontend is written in Swift with SwiftUI. I have an Objective-C++ bridging header for bridging the Swift and C++ sides. On the Swift side, I create an MTKView. Inside the MTKView delegate, I run the emulator for 1 video frame and pass it the view's backing layer for it to render the final output image with. The emulator runs and returns, but when it returns I get a crash in Swift land (callstack attached below), inside objc_release, which indicates I'm doing something wrong with memory management. My bridging interface (ios_driver.h): #pragma once #include <Foundation/Foundation.h> #include <QuartzCore/QuartzCore.h> void iosCreateEmulator(); void iosRunFrame(CAMetalLayer* layer); Bridge implementation (ios_driver.mm): #import <Foundation/Foundation.h> extern "C" { #include "ios_driver.h" } <...> #define IOS_EXPORT extern "C" __attribute__((visibility("default"))) std::unique_ptr<Emulator> emulator = nullptr; IOS_EXPORT void iosCreateEmulator() { ... } // Runs 1 video frame of the emulator and IOS_EXPORT void iosRunFrame(CAMetalLayer* layer) { void* layerBridged = (__bridge void*)layer; // Pass the CAMetalLayer to the emulator emulator->getRenderer()->setMTKLayer(layerBridged); // Runs the emulator for 1 frame and renders the output image using our layer emulator->runFrame(); } My MTKView delegate: class Renderer: NSObject, MTKViewDelegate { var parent: ContentView var device: MTLDevice! init(_ parent: ContentView) { self.parent = parent if let device = MTLCreateSystemDefaultDevice() { self.device = device } super.init() } func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) {} func draw(in view: MTKView) { var metalLayer = view.layer as! CAMetalLayer // Run the emulator for 1 frame & display the output image iosRunFrame(metalLayer) } } Finally, the emulator's render function that interacts with the layer: void RendererMTL::setMTKLayer(void* layer) { metalLayer = (CA::MetalLayer*)layer; } void RendererMTL::display() { CA::MetalDrawable* drawable = metalLayer->nextDrawable(); if (!drawable) { return; } MTL::Texture* texture = drawable->texture(); <rest of rendering follows here using the drawable & its texture> } This is the Swift callstack at the time of the crash: To my understanding, I shouldn't be violating ARC rules as my bridging header uses CAMetalLayer* instead of void* and Swift will automatically account for ARC when passing CoreFoundation objects to Objective-C. However I don't have any other idea as to what might be causing this. I've been trying to debug this code for a couple of days without much success. If you need more info, the emulator code is also on Github Metal renderer: https://github.com/wheremyfoodat/Panda3DS/blob/ios/src/core/renderer_mtl/renderer_mtl.cpp#L58-L68 Bridge implementation: https://github.com/wheremyfoodat/Panda3DS/blob/ios/src/ios_driver.mm Bridging header: https://github.com/wheremyfoodat/Panda3DS/blob/ios/include/ios_driver.h Any help is more than appreciated. Thank you for your time in advance.

I notice some metal-cpp classes have static funtion like static URL* fileURLWithPath(const class String* pPath); static class ComputePassDescriptor* computePassDescriptor(); static class AccelerationStructurePassDescriptor* accelerationStructurePassDescriptor(); which return a new object. these classes also provide 'alloc' and 'init' function to create object by default. for object created by 'alloc' and 'init', I use something like NS::Shaderd_Ptr or call release directly to free memory. Because 'alloc' and 'init' not explicit call on these static function. I wonder how to correctly free object created by these static function? did they managed by autorelease pool?

After following the instructions here: https://developer.apple.com/metal/cpp/ I attempted building my project and Xcode presented several errors. In essence it's complaining about some redeclarations in the Metal-CPP headers. NSBundle.hpp and NSError.hpp are included in the metal-cpp/foundation directory from the metal-cpp download. Any help in getting these issues resolved is appreciated. Thanks!

I am trying to learn Metal development on my MacBook Pro M1 Pro (Sequoia 15.3.1) on Xcode Playground, but when I write these two lines of code: import Metal let device = MTLCreateSystemDefaultDevice()! I get the error The LLDB RPC server has crashed. Any ideas as to what I can do to solve this? I have rebooted the machine and reinstalled Xcode...

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSBundle allFrameworks]: unrecognized selector sent to instance NS::Bundle* Bundle = NS::Bundle::mainBundle(); Bundle->allFrameworks(); call to allFrameworks() and allBundles() will throw exception, but other functions work well.

On an iOS 18 phone, I use AVCaptureSession to capture HDR with x420 format. The output CMSampleBuffer is HLG colorspace, the propagated attachments contain kCVImageBufferAmbientViewingEnvironmentKey and kCVImageBufferSceneIlluminationKey. Now I use CAMetalLayer to render the CVPixelBuffer to the screen, but the brightness is brighter than AVSampleBufferDisplayLayer. Here is my code. - (void)_updateColorSpaceIfNeed:(CVPixelBufferRef)pixelBuffer { CAMetalLayer *layer = (CAMetalLayer *)_mtkView.layer; if (![layer isKindOfClass:CAMetalLayer.class]) return; layer.wantsExtendedDynamicRangeContent = YES; CFDataRef ambientViewingEnvironment = (CFDataRef)CVBufferCopyAttachment(pixelBuffer, kCVImageBufferAmbientViewingEnvironmentKey, NULL); NSData *data = (__bridge NSData *)ambientViewingEnvironment; if (ambientViewingEnvironment) CFRelease(ambientViewingEnvironment); CAEDRMetadata *metadata = [CAEDRMetadata HLGMetadataWithAmbientViewingEnvironment:data]; // CAEDRMetadata *metadata = [CAEDRMetadata HLGMetadata]; layer.EDRMetadata = metadata; layer.pixelFormat = MTLPixelFormatRGBA16Float; CGColorSpaceRef colorspace = CGColorSpaceCreateWithName(kCGColorSpaceITUR_2100_HLG); layer.colorspace = colorspace; if (colorspace) CGColorSpaceRelease(colorspace); } Why does the CAEDRMetadata class have "HLGMetadataWithAmbientViewingEnvironment:" and "HLGMetadata" methods, but does not provide the "HLGMetadataWithAmbientViewingEnvironment:sceneIllumination" method? I want to know how kCVImageBufferAmbientViewingEnvironmentKey and kCVImageBufferSceneIlluminationKey affect tone mapping. Is there any documentation I can refer to?

My app is running Compute Shaders that use non-uniform thread groups. When I run the app in the debugger with a simulator target the app crashes on encoder.dispatchThreads and the error message is: Dispatch Threads with Non-Uniform Threadgroup Size is not supported on this device. Previously the log output states that: Metal Shader Validation is unsupported for Simulator. However: When I stop the debugger and just run the app in the simulator without the debugger attached, the app just runs fine and does not crash. The SwiftUI Preview that also triggers the Compute Shader when preparing data also just runs fine without a crash. I can run and debug on a real device no problem - I just don't have all sizes available. Is there anything I need to check in my lldb/simulator configuration? It obviously does work, just the debugger cannot really deal with it? Any input would be nice as this really slows my down as I have to be extremely careful when debugging on the simulator.

Hello ladies and gentlemen, I'm writing a simple renderer on the main actor using Metal and Swift 6. I am at the stage now where I want to create a render pipeline state using asynchronous API: @MainActor class Renderer { let opaqueMeshRPS: MTLRenderPipelineState init(/*...*/) async throws { let descriptor = MTLRenderPipelineDescriptor() // ... opaqueMeshRPS = try await device.makeRenderPipelineState(descriptor: descriptor) } } I get a compilation error if try to use the asynchronous version of the makeRenderPipelineState method: Non-sendable type 'any MTLRenderPipelineState' returned by implicitly asynchronous call to nonisolated function cannot cross actor boundary Which is understandable, since MTLRenderPipelineState is not Sendable. But it looks like no matter where or how I try to access this method, I just can't do it - you have this API, but you can't use it, you can only use the synchronous versions. Am I missing something or is Metal just not usable with Swift 6 right now?

I’m working on a Vision Pro app using Metal and need to implement multi-pass rendering. Specifically, I want to render intermediate results to a texture, then use that texture in a second pass for post-processing before presenting the final output. What’s the best approach in visionOS? Should I use multiple render passes in a single command buffer or separate command buffers? Any insights on efficiently handling this in RealityKit or Metal? Thanks!

Hi, Apple’s documentation on Order-Independent Transparency (OIT) describes an approach using image blocks, where an array of size 4 is allocated per fragment to store depth and color in a tile shading compute pass. However, when increasing the scene’s depth complexity by adding more overlapping quads, the OIT implementation fails due to the fixed array size. Is there a way to dynamically allocate storage for fragments based on actual depth complexity encountered during rasterization, rather than using a fixed-size array? Specifically, can an adaptive array of fragments be maintained and sorted by depth, where the size grows as needed instead of being limited to 4 entries? Any insights or alternative approaches would be greatly appreciated. Thank you!

Hello guys, I have a question regarding the submission requirements. My app uses ARKit and requires Metal files for shaders, which are not supported by Swift Playgrounds. Therefore, I developed my app using Xcode. (swift playgrounds returning error for metal file) Since my app relies on a real device for proper functionality, I would like to know if, under these circumstances, the scene build is performed by Xcode. If the build were instead done by Swift Playgrounds, my scene would not function correctly. I'm asking that because of this note Thank you for your time and assistance.

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!