Hi, I can capture a frame on the Apple TV, but when I try to profile the capture for GPU timing information, I got "Abort Trap 6" error and with following error in the report: Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Triggered by Thread: 7 Application Specific Information: abort() called Last Exception Backtrace: 0 CoreFoundation 0x18c0a99d0 __exceptionPreprocess + 160 1 libobjc.A.dylib 0x18b596d24 objc_exception_throw + 71 2 CoreFoundation 0x18bfa7308 -[__NSArrayM insertObject:atIndex:] + 1239 3 MTLReplayController 0x101f5d148 DYMTLReplayFrameProfiler_loadAnalysis + 1140 4 MTLReplayController 0x101e97f90 GTMTLReplayClient_collectGPUShaderTimelineData + 224 5 MTLReplayController 0x101e81794 __30-[GTMTLReplayService profile:]_block_invoke_4 + 288 6 Foundation 0x18eb6072c __NSOPERATION_IS_INVOKING_MAIN__ + 11 7 Foundation 0x18eb5cc1c -[NSOperation start] + 623 8 Foundation 0x18eb60edc __NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 11 9 Foundation 0x18eb60bc4 __NSOQSchedule_f + 167 10 libdispatch.dylib 0x18b8d6a84 _dispatch_block_async_invoke2 + 103 11 libdispatch.dylib 0x18b8c9420 _dispatch_client_callout + 15 12 libdispatch.dylib 0x18b8cc5d0 _dispatch_continuation_pop + 531 13 libdispatch.dylib 0x18b8cbcd4 _dispatch_async_redirect_invoke + 635 14 libdispatch.dylib 0x18b8d9224 _dispatch_root_queue_drain + 335 15 libdispatch.dylib 0x18b8d9a08 _dispatch_worker_thread2 + 163 16 libsystem_pthread.dylib 0x18b6e652c _pthread_wqthread + 223 17 libsystem_pthread.dylib 0x18b6ed8d0 start_wqthread + 7 It's Xcode 16.0 + Apply TV 4K (4th Gen) tvOS 18, does anyone know what's the cause of this error and is there any solution for it? Thank you very much, Kai

Given I do not understand much at all about how to write shaders I do not understand the math associated with page-curl effects I am trying to: implement a page-curl shader for use on SwiftUI views. I've lifted a shader from HIROKI IKEUCHI that I believe they lifted from a non-metal shader resource online, and I'm trying to digest it. One thing I want to do is to paint the "underside" of the view with a given color and maintain the transparency of rounded corners when they are flipped over. So, if an underside pixel is "clear" then I want to sample the pixel at that position on the original layer instead of the "curl effect" pixel. There are two comments in the shader below where I check the alpha, and underside flags, and paint the color red as a debug test. The shader gives this result: The outside of those rounded corners is appropriately red and the white border pixels are detected as "not-clear". But the "inner" portion of the border is... mistakingly red? I don't get it. Any help would be appreciated. I feel tapped out and I don't have any IRL resources I can ask. // // PageCurl.metal // ShaderDemo3 // // Created by HIROKI IKEUCHI on 2023/10/17. // #include <metal_stdlib> #include <SwiftUI/SwiftUI_Metal.h> using namespace metal; #define pi float(3.14159265359) #define blue half4(0.0, 0.0, 1.0, 1.0) #define red half4(1.0, 0.0, 0.0, 1.0) #define radius float(0.4) // そのピクセルの色を返す [[ stitchable ]] half4 pageCurl ( float2 _position, SwiftUI::Layer layer, float4 bounds, float2 _clickedPoint, float2 _mouseCursor ) { half4 undersideColor = half4(0.5, 0.5, 1.0, 1.0); float2 originalPosition = _position; // y座標の補正 float2 position = float2(_position.x, bounds.w - _position.y); float2 clickedPoint = float2(_clickedPoint.x, bounds.w - _clickedPoint.y); float2 mouseCursor = float2(_mouseCursor.x, bounds.w - _mouseCursor.y); float aspect = bounds.z / bounds.w; float2 uv = position * float2(aspect, 1.) / bounds.zw; float2 mouse = mouseCursor.xy * float2(aspect, 1.) / bounds.zw; float2 mouseDir = normalize(abs(clickedPoint.xy) - mouseCursor.xy); float2 origin = clamp(mouse - mouseDir * mouse.x / mouseDir.x, 0., 1.); float mouseDist = clamp(length(mouse - origin) + (aspect - (abs(clickedPoint.x) / bounds.z) * aspect) / mouseDir.x, 0., aspect / mouseDir.x); if (mouseDir.x < 0.) { mouseDist = distance(mouse, origin); } float proj = dot(uv - origin, mouseDir); float dist = proj - mouseDist; float2 linePoint = uv - dist * mouseDir; half4 pixel = layer.sample(position); if (dist > radius) { pixel = half4(0.0, 0.0, 0.0, 0.0); // background behind curling layer (note: 0.0 opacity) pixel.rgb *= pow(clamp(dist - radius, 0., 1.) * 1.5, .2); } else if (dist >= 0.0) { // THIS PORTION HANDLES THE CURL SHADED PORTION OF THE RESULT // map to cylinder point float theta = asin(dist / radius); float2 p2 = linePoint + mouseDir * (pi - theta) * radius; float2 p1 = linePoint + mouseDir * theta * radius; bool underside = (p2.x <= aspect && p2.y <= 1. && p2.x > 0. && p2.y > 0.); uv = underside ? p2 : p1; uv = float2(uv.x, 1.0 - uv.y); // invert y pixel = layer.sample(uv * float2(1. / aspect, 1.) * float2(bounds[2], bounds[3])); // ME<---- if (underside && pixel.a == 0.0) { //<---- PIXEL.A IS 0.0 WHYYYYY pixel = red; } // Commented out while debugging alpha issues // if (underside && pixel.a == 0.0) { // pixel = layer.sample(originalPosition); // } else if (underside) { // pixel = undersideColor; // underside // } // Shadow the pixel being returned pixel.rgb *= pow(clamp((radius - dist) / radius, 0., 1.), .2); } else { // THIS PORTION HANDLES THE NON-CURL-SHADED PORTION OF THE SAMPLING. float2 p = linePoint + mouseDir * (abs(dist) + pi * radius); bool underside = (p.x <= aspect && p.y <= 1. && p.x > 0. && p.y > 0.); uv = underside ? p : uv; uv = float2(uv.x, 1.0 - uv.y); // invert y pixel = layer.sample(uv * float2(1. / aspect, 1.) * float2(bounds[2], bounds[3])); // ME if (underside && pixel.a == 0.0) { //<---- PIXEL.A IS 0.0 WHYYYYY pixel = red; } // Commented out while debugging alpha issues // if (underside && pixel.a == 0.0) { // // If the new underside pixel is clear, we should sample the original image's pixel. // pixel = layer.sample(originalPosition); // } else if (underside) { // pixel = undersideColor; // } } return pixel; }

Hey guys, is it possible to implement mirror like reflections like in this project: https://developer.apple.com/documentation/metal/metal_sample_code_library/rendering_reflections_in_real_time_using_ray_tracing for visionOS? Or is the hardware not prepared for Metal Raytracing? Thanks in advance

Is there anywhere that the format of error/warning/other? messages that are generated by the Metal compiler are documented?

I've been working with ARKit and Metal on the Vision Pro, but I've encountered a slight flickering issue with the mesh rendered using Metal. The flickering tends to occur around the edges of objects or on pixels with high color contrast, and it becomes more noticeable as the distance increases. Is there any way to resolve this issue?

First I get this ar_world_tracking_provider_query_device_anchor_at_timestamp <0x302b9c0a0>: The device_anchor can only be queried when the world tracking provider is running. This seemed to all break with the auto-update to 2.0.1. Simulator runs the code fine. I seem to see an infinite stall here frameLayer.endUpdate() // Pace frames by waiting for the optimal prediction time. try await LayerRenderer.Clock().sleep(until: timing.optimalInputTime, tolerance: nil) // Start submitting the updated frame. frameLayer.startSubmission() <-

Hi everyone, I encountered a very strange shader bug that seems related to Metal only (not OpenGL). You can find the full description of the issue on the Babylon.js forums here: https://forum.babylonjs.com/t/strange-shader-related-issue-on-macos-with-safari-and-chrome-not-firefox/54289 (sorry, I couldn't post a clickable link here as this seems to be blocked here). I have a workaround to fix the issue (as described in the link above), but this really looks like an issue in Metal itself. Let me know if you need more details or explanations.

I am looking to implement CAMetalDisplayLink on a separate thread on a macOS application. I am basing my implementation on the following example project: Achieving Smooth Frame Rates with Metal Display Link This project allows you to configure whether a separate thread is used for rendering by setting RENDER_ON_MAIN_THREAD in GameConfig to 0. However, when I set it to use a separate thread nothing is rendered. Stepping through the code shows that a separate thread is created, but a CAMetalDisplayLinkUpdate is never received. Does anyone know why this does not work?

Hi, A user sent us a crash report that indicates an error occurring just after loading the default Metal library of our app. Application Specific Information: Crashing on exception: *** -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array The report pointed me to these (simplified) lines of codes in the library setup: _vertexFunctions = [[NSMutableArray alloc] init]; _fragmentFunctions = [[NSMutableArray alloc] init]; id<MTLLibrary> library = [device newDefaultLibrary]; 2 vertex shaders and 5 fragment shaders are then loaded and stored in these two arrays using this method: -(BOOL) addShaderNamed:(NSString *)name library:(id<MTLLibrary>)library isFragment:(BOOL)isFragment { id shader = [library newFunctionWithName:name]; if (!shader) { ALOG(@"Error : Unable to find the shader named : “%@”", name); return NO; } [(isFragment ? _fragmentFunctions : _vertexFunctions) addObject:shader]; return YES; } As you can see, the arrays are not filled if the method fails... however, a few lines later, they are used without checking if they are really filled, and that causes the crash... But this coding error doesn't explain why no shader of a certain type (or both types) have been added to the array, meaning: why -newFunctionWithName: returned nil for all given names (since the implied array appears completely empty)? Clue This error has only be detected once by a user running the app on macOS 10.13 with a NVIDIA Web Driver instead of the default macOS graphic driver. Moreover, it wasn't possible to reproduce the problem on the same OS using the native macOS driver. So my question is: is it some known conflicts between NVIDIA drivers and the use of Metal libraries? Or does this case would require some specific options in the Metal implementation? Any help appreciated, thanks!

When generating large arrays of random numbers, NaNs show up. They also show up at the same indices when using the same seed, leading me to believe that this is a bug with MPSMatrixRandom's normally distributed Float32 random number distribution. Happens with both Philox and MTGP32. Is this intentional and how do I work around this? See the original post for a MWE in Swift and Julia: https://github.com/JuliaGPU/Metal.jl/issues/474

I'm experiencing a strange issue where I'm seeing black in a metal drawable where it should be a different color. When I capture the frame and inspect the returned value from the fragment function, it's correct, but the drawable isn't. This screenshot hopefully illustrates the issue. I've not found any references to similar issues. I saw something about some out of bounds or NaN values being dropped to 0 (which would be black), but the debugger doesn't indicate this is happening.

Hi! How to define and call an inline function in Metal? Or simple function that will return some value. Case: inline uint index4D(constant _4D& shape, constant uint& n, constant uint& c, constant uint& h, constant uint& w) { return n * shape.C * shape.H * shape.W + c * shape.H * shape.W + h * shape.W + w; } When I call it in my kernel function I get No matching function for call error. Thx in advance.

Hello, We are experimenting with Metal to accelerate some peculiar numerical computation. Our workloads are relatively small, so the ability to avoid moving data to and from the GPU's memory is very appealing. However, we are observing higher overhead compared to CUDA, which negates the benefits of avoiding data transfer. In our tests using an empty kernel, CUDA completes in 0.001 ms (Intel i7 10700K, RTX 3080), while Metal's waitUntilCompleted takes 0.12 ms (M2 Max). As we do not have prior experience with Metal, we are wondering if we are using the APIs just fine and this timing is expected, or if there is a way to reduce it. Thank you in advance for any comment! test-metal.cpp

I have multiple CAMetalLayers that I render content to and noticed that the graphics overview HUD does not function properly when I have more than one CAMetalLayer. The values reported will be very strange. For example, FPS may report 999 or some large negative value. It the HUD simply not designed to work with multiple CAMetalLayers or MTKViews? When I disable all but one of my CAMetalLayers, the HUD works as expected.

I am building a MacOS desktop app (https://anukari.com) that is using Metal compute to do real-time audio/DSP processing, as I have a problem that is highly parallelizable and too computationally expensive for the CPU. However it seems that the way in which I am using the GPU, even when my app is fully compute-limited, the OS never increases the power/performance state. Because this is a real-time audio synthesis application, it's a huge problem to not be able to take advantage of the full clock speeds that the GPU is capable of, because the app can't keep up with real-time. I discovered this issue while profiling the app using Instrument's Metal tracing (and Game tracing) modes. In the profiling configuration under "Metal Application" there is a drop-down to select the "Performance State." If I run the application under Instruments with Performance State set to Maximum, it runs amazingly well, and all my problems go away. For comparison, when I run the app on its own, outside of Instruments, the expensive GPU computation it's doing takes around 2x as long to complete, meaning that the app performs half as well. I've done a ton of work to micro-optimize my Metal compute code, based on every scrap of information from the WWDC videos, etc. A problem I'm running into is that I think that the more efficient I make my code, the less it signals to the OS that I want high GPU clock speeds! I think part of why the OS is confused is that in most use cases, my computation can be done using only a small number of Metal threadgroups. I'm guessing that the OS heuristics see that only a small fraction of the GPU is saturated and fail to scale up the power/clock state. I'm not sure what to do here; I'm in a bit of a bind. One possibility is that I intentionally schedule busy work -- spin threadgroups just to waste energy and signal to the OS that I need higher clock speeds. This is obviously a really bad idea, but it might work. Is there any other (better) way for my app to signal to the OS that it is doing real-time latency-sensitive computation on the GPU and needs the clock speeds to be scaled up? Note that game mode is not really an option, as my app also runs as an AU plugin inside hosts like Garageband, so it can't be made fullscreen, etc.

I've noticed a major third-party app has the following flag set to 1/true in its Info.plist: CAMetalLayerWantsCompositingDependencies Does anyone know if it’s recognized by Core Animation / Metal, and what it’s supposed to do? It might obviously have zero relationship to the OS, defined by that app and for that app... but since it looks very much like an unofficial/undocumented environment setting, it might be great to know what problem it solves. I happen to have issues related to compositing other CALayers over a CAMetalLayer in my app... so this definitely stood out as interesting. Thank you!

Ever since the release of iOS18, we've been seeing a new crash related to calling jpegData(compressionQuality:). From reports, this isn't crashing during foreground usage of the app, but instead will prompt the user about a background app crash upon foregrounding. The stacks from crash reports show this crash is happening from a variety of callers, but all go through jpegData(compressionQuality:), down through [HDRImageConverter_Metal init] and end up in apthread_mutex_local call when it crashes. Attached is a sample crash report from 18.2(22C5125e), but we've been seeing this since the first iOS18 release. Did something change with around these calls in iOS18 that prohibits their use in the background? crash.txt

I would like to take YCbCr CVPixelBuffers from AVCaptureVideoDataOutput, apply some processing in RGB space, render to an MTKView, and pass to AVAssetWriter for recording. Right now, I'm doing this all manually – deswing the incoming data if necessary, choose the right matrix to convert to RGB, apply processing, etc. I also have to convert back to YCbCr before feeding the frames to AVAssetWriter because encoding performs much better if I do. Is there any efficient, built-in way to achieve the same? I can't use AVCaptureVideoPreviewLayer, since I need to do some further processing before display. I can't use AVCaptureVideoDataOutput's videoSettings to get automatic BGRA conversion because that would lose bit depth for 10 bit video formats (and isn't available on all formats anyway). I see these Accelerate functions, but they seemingly don't use the GPU, nor do they support all the formats and bit depths I'd need. I found reference to some undocumented MTLPixelFormats that seem to do exactly what I want, but I don't want to rely on something like this unless it's explicitly endorsed. This would also incur an RGB/YCbCr conversion on every texture read and write, right? Is there anything I'm missing here?

I want to turn off my ray-tracing conditionally. There's is_null_acceleration_structure but when I don't bind an acceleration structure (or pass nil to setFragmentAccelerationStructure), I get the following API validation error: -[MTLDebugRenderCommandEncoder validateCommonDrawErrors:]:5782: failed assertion `Draw Errors Validation Fragment Function(vol_deferred_lighting): missing instanceAccelerationStructure binding at index 6 for accelerationStructure[0]. I can turn off API validation and it works, but it seems like I should be able to use nil for the acceleration structure w/o triggering a validation error. Seems like a bug, right? I suppose I can work around this by creating a separate pipeline with the ray-tracing disabled via a function constant instead of using is_null_acceleration_structure. (Can we get a ray-tracing tag for questions?)

Hi, wanted to test if possible to use Mesa3D Dozen driver(Vulkan on D3D12 )+D3DMetal 2b3 to get maybe better Vulkan driver on Wine than default MoltenVK.. this will support Vulkan windows apps via using D3D12Metal.. using vulkan_dzn.dll,dzn_icd.x86_64.json,dxil.dll from x64 folder from: https://github.com/pal1000/mesa-dist-win/releases/download/24.3.0-rc1/mesa3d-24.3.0-rc1-release-msvc.7z using simple vulkaninfo app and running like: wine64 vulkaninfo I get error: [D3DMetal:LOG:2A825] Unsupported API: CheckFeatureSupport, unhandled support query 53 also seems D3DMetal Wine integration on Whisky doesn't expose d3d12core.dll and d3d12.dll like new Agility D3D12 dlls or VKD3D, so getting: MESA: error: Failed to retrieve D3D12GetInterface MESA: error: Failed to load DXCore but anyways seems to try to load the driver as: WARNING: dzn is not a conformant Vulkan implementation, testing use only. full log: MESA: error: Failed to retrieve D3D12GetInterface MESA: error: Failed to load DXCore WARNING: dzn is not a conformant Vulkan implementation, testing use only. [D3DMetal:LOG:2A825] Unsupported API: CheckFeatureSupport, unhandled support query 53 00bc:fixme:dcomp:DCompositionCreateDevice 0000000000000000, {c37ea93a-e7aa-450d-b16f-9746cb0407f3}, 000000000011E328. MESA: error: Failed to load DXCore WARNING: dzn is not a conformant Vulkan implementation, testing use only. [D3DMetal:LOG:2A825] Unsupported API: CheckFeatureSupport, unhandled support query 53 00bc:fixme:dcomp:DCompositionCreateDevice 0000000000000000, {c37ea93a-e7aa-450d-b16f-9746cb0407f3}, 000000000011E578. ERROR: [Loader Message] Code 0 : setup_loader_term_phys_devs: Call to 'vkEnumeratePhysicalDevices' in ICD c:\windows\system32\.\vulkan_dzn.dll failed with error code -3 ERROR: [Loader Message] Code 0 : setup_loader_term_phys_devs: Failed to detect any valid GPUs in the current config ERROR at C:\j\msdk0\build\Khronos-Tools\repo\vulkaninfo\vulkaninfo.h:241:vkEnumeratePhysicalDevices failed with ERROR_INITIALIZATION_FAILED