Bug 315186

Summary: Rerun WebGPU view rendering stopped working in 26.4 (21624.1.16.11.4) & Safari Technology Preview 243
Product: WebKit Reporter: andreas
Component: WebGPUAssignee: Mike Wyrzykowski <mwyrzykowski>
Status: RESOLVED FIXED    
Severity: Normal CC: mwyrzykowski, tzagallo, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Safari 26   
Hardware: Mac (Apple Silicon)   
OS: macOS 26   
Attachments:
Description Flags
disabling-buffer-map-count-checking none

andreas
Reported 2026-05-20 05:01:28 PDT
At Rerun we recently enabled our WebGPU based renderer, unfortunately I didn't note down the exact version, but it worked with the latest version as of March 6th which is when we enabled it by default. Example: https://rerun.io/viewer/version/0.32.0?url=https%3A%2F%2Fapp.rerun.io%2Fversion%2F0.32.1%2Fexamples%2Fanimated_urdf.rrd&renderer=webgpu Instead of the black screen in the middle this should show a mesh - it works fine in Chrome and used to work in earlier Safari versions. I tried a bunch of different ways to isolate the problem, but to no avail: individual views in Rerun render to RGB8Srgb textures and are then later composited with the ui - the composite shader seems to run fine, adding a color there will show up, but the textures for individual views, including textures for outlines, remain the same. I tried experimenting with different formats and things like disabling anti-aliasing but wasn't able to figure out what causes the problem. Any advice on how to perform frame debugging in Safari would be greatly appreciated! Tracking ticket on our side: https://github.com/rerun-io/rerun/issues/12788
Attachments
disabling-buffer-map-count-checking (583.12 KB, image/heic)
2026-05-20 07:52 PDT, Mike Wyrzykowski 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
andreas
Comment 1 2026-05-20 06:03:34 PDT
Looks like the issue happens consistently on iOS as well which allowed us to narrow the version range a bit - Safari 26.3 doesn't have this problem yet!
Radar WebKit Bug Importer
Comment 2 2026-05-20 06:46:19 PDT
<rdar://problem/177523442>
Mike Wyrzykowski
Comment 3 2026-05-20 07:52:45 PDT
Created attachment 479739 [details] disabling-buffer-map-count-checking Oh this is useful, there is a regression in our buffer map counting I think. Disabling it yields the attached image
Mike Wyrzykowski
Comment 4 2026-05-20 08:47:37 PDT
Caused by https://commits.webkit.org/303984@main
Mike Wyrzykowski
Comment 5 2026-05-20 09:02:10 PDT
Pull request: https://github.com/WebKit/WebKit/pull/65295
andreas
Comment 6 2026-05-21 00:32:28 PDT
That was quick, thank you!
EWS
Comment 7 2026-05-22 00:06:51 PDT
Committed 313712@main (69f81c15d795): <https://commits.webkit.org/313712@main> Reviewed commits have been landed. Closing PR #65295 and removing active labels.
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