237230 2022-02-25 15:54:16 -0800 REGRESSION (iOS 15.4 beta) - WebGL race condition between clearing depth buffer and switching framebuffers 2022-06-23 15:44:17 -0700 1 1 1 Unclassified WebKit WebGL Safari 15 iPhone / iPad iOS 15 RESOLVED DUPLICATE 237113 InRadar P2 Normal --- 237113 1 christoph webkit-unassigned bfulgham dino johncunningham kbr kkinnunen kpiddington webkit-bug-importer oldest_to_newest 1846224 0 christoph 2022-02-25 15:54:16 -0800 This is a regression between iOS 15.3.1 and 15.4. As can be see in this demo: https://codepen.io/cmb8/pen/GROXmKp We should see two gears spinning normally, but instead we get visual artifacts that obscure the objects from getting properly rendered. This behavior is caused by calling: context.clear(context.DEPTH_BUFFER_BIT) then immediately calling: context.bindFramebuffer(...) If we add a finish() call between the two calls, the issue does not occur. This problem affects many 8th Wall projects that use three.js, like our sample project here: https://8thwall.8thwall.app/unitcube-threejs/ or more recently, this Super Bowl promotional tie-in from Kia: https://www.kiadogmentedreality.com Disabling "WebGL via Metal" in "Experimental WebKit Features" and relaunching Safari fixes the behavior. Video of expected behavior: https://www.youtube.com/watch?v=SAp_RXDD7_0 Video of unexpected behavior: https://www.youtube.com/watch?v=d8cr-LP40hs 1846226 1 kbr 2022-02-25 15:56:10 -0800 +Kyle and John in case they can help triage this. Wonder whether it was fixed in the most recent ANGLE roll. 1846931 2 kkinnunen 2022-02-28 23:42:37 -0800 Thanks for the report. I think this has the same root cause as bug 237113. In order to workaround, you can try if you can rework the rendering so that it does not need the `autoClear = false`. I.e. use `autoClear = true`. Leaving this in until fix for bug 237113 is testable. 1848438 3 webkit-bug-importer 2022-03-04 15:55:17 -0800 <rdar://problem/89839163> 1856446 4 christoph 2022-03-30 10:29:06 -0700 Now that bug 237113 has been closed, do we have confirmation that the problem described here has also been fixed? 1877946 5 bfulgham 2022-06-23 15:44:17 -0700 *** This bug has been marked as a duplicate of bug 237113 ***