Capturing WebGPU metal trace on MacOS

webgpu_metal_capture.txt

1) Clone and build WebKit

git clone https://github.com/WebKit/WebKit.git WebKit
cd WebKit
Tools/Scripts/build-webkit -cmakeargs="-DENABLE_WEBGPU_BY_DEFAULT=1" --debug


2) Run your app

__XPC_METAL_CAPTURE_ENABLED=1 Tools/Scripts/run-minibrowser --debug --url http://localhost:5000/index.html#/loaders/gsplat

3) While app is running invoke WebGPU capture from a new terminal

notifyutil -p com.apple.WebKit.WebGPU.CaptureFrame

4) File is written to HD, WebKit terminal displays the path.

5) Load the file into xcode (file open) and profit.

For me the output path of the debug info only appeared after interacting with the app in the minibrowser to trigger a frame render.

Yes. You have to click on window / cmd+tab / give it focus somehow to trigger the capture.

Huh, even though I compiled successfully with the full command including -cmakeargs="-DENABLE_WEBGPU_BY_DEFAULT=1", I get "Error: WebGPU is not supported (no navigator.gpu)" when I launch my app with __XPC_METAL_CAPTURE_ENABLED=1 Tools/Scripts/run-minibrowser --debug --url example.com

I'm on Sequoia 15.0.1 and can confirm that WebGPU works normally with the WebGPU feature flag set on the included version of Safari.

Oh, I got it working by finding the flag in the minibrowser menu and enabling it! Onto the next steps

So even though I got it working on macOS 15.0.1 on one computer, on another one with the same OS, I cannot get it to compile properly. I've tried deleting/re-cloning, restarting, it always fails at:

** BUILD FAILED **


The following build commands failed:
	PhaseScriptExecution Run\ Script /Users/brandon/Files/WebKit/WebKitBuild/WebKitLegacy.build/Debug/Generate\ Unified\ Sources.build/Script-5C9D925722D7E849008E9266.sh (in target 'Generate Unified Sources' from project 'WebKitLegacy')
	Building workspace WebKit with scheme Everything up to WebKit + Tools and configuration Debug
(2 failures)

Anyone run into something similar? I've had this computer for over a year, while the one where it worked is basically a fresh install with only Xcode on it.