237113 2022-02-23 14:35:21 -0800 REGRESSION (iOS 15.4 beta) - WebGL yields incorrect results when using preserveDrawingBuffer on iOS 15.4 Beta 2022-06-23 15:44:17 -0700 1 1 1 Unclassified WebKit WebGL Safari 15 iPhone / iPad iOS 15 RESOLVED FIXED https://bugs.webkit.org/show_bug.cgi?id=233977 https://bugs.webkit.org/show_bug.cgi?id=237906 InRadar P2 Normal --- 238196 237230 1 christoph kkinnunen avpeery bfulgham dino ews-watchlist gman kbr kkinnunen kondapallykalyan kpiddington mmaxfield mvaligursky rigel webkit-bug-importer oldest_to_newest 1845324 0 christoph 2022-02-23 14:35:21 -0800 This is a regression between iOS 15.3.1 and 15.4. It appears that preserveDrawingBuffer is not taking effect. When we render a three.js scene with: const context = canvas.getContext('webgl', {preserveDrawingBuffer: true}) ... renderer.autoClear = false We expect that each frame is rendered on top of the previous frame, without replacing it. However, as can be see in this demo: https://codepen.io/cmb8/pen/bGYKPrP We should see a check mark getting drawn, but instead, we only see the circle moving across the screen, without leaving a trail. The problem occurs for both 'webgl' and 'webgl2' in the getContext call. Disabling "WebGL via Metal" in "Experimental WebKit Features" and relaunching Safari fixes the behavior. Video of expected behavior: https://youtu.be/4EpijoQe_Kw Video of unexpected behavior: https://youtu.be/YHNgSRgy8ag 1845353 1 webkit-bug-importer 2022-02-23 15:36:06 -0800 <rdar://problem/89382320> 1845429 2 kbr 2022-02-23 16:53:08 -0800 This can actually be reproduced in Safari Technology Preview Release 140 (Safari 15.4, WebKit 17614.1.1.5) on M1 hardware, making it easier to diagnose. I wonder whether the ANGLE roll in Bug 235746 will affect this behavior - somewhat doubt it if this is a WebKit-side change. 1845431 3 kbr 2022-02-23 16:55:45 -0800 Note that this doesn't reproduce in the same version of Safari Technology Preview on Intel hardware. 1845577 4 kkinnunen 2022-02-24 04:28:54 -0800 ANGLE roll in Bug 235746 does not fix this issue. 1845609 5 kkinnunen 2022-02-24 07:49:00 -0800 Bisection initially points to r286645 bug 233977 1845611 6 kkinnunen 2022-02-24 08:11:53 -0800 Scratch that, second initial bisection points to bug 220896 r286603 1845627 7 kkinnunen 2022-02-24 09:09:12 -0800 Bug 235746 fixes https://greggman.com/downloads/examples/webgl/lessons/resources/webgl-preservedrawingbuffer-true.html Does not fix https://codepen.io/cmb8/pen/bGYKPrP 1845748 8 kbr 2022-02-24 14:10:55 -0800 This bug reproduces in Chromium, too, when using the ANGLE/Metal backend on M1 hardware. I used the tools to run a bisect there: ./src/tools/bisect-builds.py -a mac-arm -g 874000 -b 974000 --use-local-cache --verify-range -- --no-first-run --use-cmd-decoder=passthrough --use-angle=metal https://codepen.io/cmb8/pen/bGYKPrP which turned up: You are probably looking for a change made after 901356 (known good), but no later than 901367 (first known bad). CHANGELOG URL: https://chromium.googlesource.com/chromium/src/+log/047f67dec3ae1322e17a408954b12bf0e000a433..5eca15b4748370af38b90b98314d84523af8c6ba containing the ANGLE roll in which Apple's direct-to-Metal translator first began upstreaming last July: https://chromium.googlesource.com/chromium/src/+/3fc5546c60cfc7db7b3cf8c0d0c0ccf16927c850 https://chromium.googlesource.com/angle/angle.git/+log/b7cfbac4f8c5..2a668d9219dd so unfortunately this bug crept in a while ago and there's no fine-grained way to track it down. It probably occurred in this large patch: https://chromium-review.googlesource.com/c/angle/angle/+/2950067 and the reason this is showing up in 15.4 is that contains the ANGLE roll into WebKit from last December, Bug 220896. 1845752 9 kbr 2022-02-24 14:19:44 -0800 Looking through that patch, I doubt this is the problem but perhaps you'd like to try taking out the EXT_multisampled_render_to_texture code path on iOS as well: https://source.chromium.org/chromium/chromium/src/+/main:third_party/angle/src/libANGLE/renderer/metal/DisplayMtl.mm;l=907?q=DisplayMtl.mm 1845891 10 kbr 2022-02-24 20:01:45 -0800 The work-in-progress fix https://chromium-review.googlesource.com/c/angle/angle/+/3465937/ doesn't fix this either on the M1. 1846816 11 kbr 2022-02-28 15:37:21 -0800 This is almost surely a regression in the MTLStoreAction used to resolve the multisampled framebuffer; the multisampled contents have to be preserved after the blit to resolve, unless discarded. Can this be investigated from that standpoint? 1848900 12 kbr 2022-03-07 12:45:03 -0800 A note that there's a fix in review in upstream ANGLE which may fix this: https://chromium-review.googlesource.com/c/angle/angle/+/3506089 1849074 13 kbr 2022-03-07 19:23:49 -0800 gman@'s upstream fix in ANGLE is confirmed to fix this bug: https://chromium-review.googlesource.com/c/angle/angle/+/3506089 1850433 14 454467 kkinnunen 2022-03-11 03:34:44 -0800 Created attachment 454467 Patch 1850434 15 454468 kkinnunen 2022-03-11 03:35:45 -0800 Created attachment 454468 Patch 1850435 16 ews-watchlist 2022-03-11 03:36:53 -0800 Note that there are important steps to take when updating ANGLE. See https://trac.webkit.org/wiki/UpdatingANGLE 1850712 17 454468 mmaxfield 2022-03-12 13:36:30 -0800 Comment on attachment 454468 Patch View in context: https://bugs.webkit.org/attachment.cgi?id=454468&action=review > Source/ThirdParty/ANGLE/ChangeLog:17 > + https://www.khronos.org/registry/webgl/sdk/tests/conformance2/renderbuffers/multisample-draws-between-blits.html Does this patch enable the test somehow? 1850798 18 kkinnunen 2022-03-14 00:50:14 -0700 (In reply to Myles C. Maxfield from comment #17) > Comment on attachment 454468 [details] > Patch > > View in context: > https://bugs.webkit.org/attachment.cgi?id=454468&action=review > > > Source/ThirdParty/ANGLE/ChangeLog:17 > > + https://www.khronos.org/registry/webgl/sdk/tests/conformance2/renderbuffers/multisample-draws-between-blits.html > > Does this patch enable the test somehow? No, tests need to be rolled from the conformance test repo. 1850800 19 ews-feeder 2022-03-14 01:43:12 -0700 Committed r291218 (248373@main): <https://commits.webkit.org/248373@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 454468. 1852401 20 avpeery 2022-03-17 12:03:05 -0700 Hi all, is this fix going to be released in a patch for 15.4? It there a way to test this fix in a beta version? We have a similar problem: https://bugs.webkit.org/show_bug.cgi?id=237918. Thanks! 1852531 21 kpiddington 2022-03-17 15:55:09 -0700 I can confirm that on iOS, (In reply to Anna from Mapbox from comment #20) > Hi all, is this fix going to be released in a patch for 15.4? It there a way > to test this fix in a beta version? We have a similar problem: > https://bugs.webkit.org/show_bug.cgi?id=237918. Thanks! Hi Anna, I can't comment on when this fix will show up on iOS, but I can confirm that on iOS, this patch fixes your Mapbox regression. I'll make sure to mirror this information on your bug report. 1853578 22 kkinnunen 2022-03-22 02:15:56 -0700 *** Bug 237918 has been marked as a duplicate of this bug. *** 1853733 23 avpeery 2022-03-22 10:21:42 -0700 (In reply to Kyle Piddington from comment #21) > I can confirm that on iOS, (In reply to Anna from Mapbox from comment #20) > > Hi all, is this fix going to be released in a patch for 15.4? It there a way > > to test this fix in a beta version? We have a similar problem: > > https://bugs.webkit.org/show_bug.cgi?id=237918. Thanks! > > Hi Anna, > I can't comment on when this fix will show up on iOS, but I can confirm that > on iOS, this patch fixes your Mapbox regression. I'll make sure to mirror > this information on your bug report. Thanks Kyle for digging into this! We were able to do a patch release last week that disables antialiasing for 15.4 Safari to resolve this problem on our end. We found it reproducible in iOS 15.4 devices and M1 Macbooks. 1856047 24 avpeery 2022-03-29 09:39:59 -0700 Hey all, so this issue is also happening for us on M1 Macbooks. We tested the newly released Safari Technology Preview Release 142 (Safari 15.4, WebKit 16614.1.5.16) on an M1 Mac and still see this issue. There isn't an iOS beta out yet to test on iOS. Does/Can this solution also apply to Safari (non iOS)? Thanks! Here's the jsbin example: https://jsbin.com/mojuyosenu/edit?html,css,js,output 1858609 25 dino 2022-04-05 15:03:33 -0700 (In reply to Anna from Mapbox from comment #24) > Hey all, so this issue is also happening for us on M1 Macbooks. We tested > the newly released Safari Technology Preview Release 142 (Safari 15.4, > WebKit 16614.1.5.16) on an M1 Mac and still see this issue. There isn't an > iOS beta out yet to test on iOS. Does/Can this solution also apply to Safari > (non iOS)? Thanks! Here's the jsbin example: > https://jsbin.com/mojuyosenu/edit?html,css,js,output I think it will be in the next Safari Technology Preview. Sorry, it hasn't been updated in a while. 1872157 26 bfulgham 2022-05-26 15:02:18 -0700 This fix shipped with Safari 15.5 (all platforms). 1877947 27 bfulgham 2022-06-23 15:44:17 -0700 *** Bug 237230 has been marked as a duplicate of this bug. *** 454467 2022-03-11 03:34:44 -0800 2022-03-11 03:35:40 -0800 Patch bug-237113-20220311133442.patch text/plain 2015 kkinnunen U3VidmVyc2lvbiBSZXZpc2lvbjogMjkxMTUzCmRpZmYgLS1naXQgYS9Tb3VyY2UvVGhpcmRQYXJ0 eS9BTkdMRS9DaGFuZ2VMb2cgYi9Tb3VyY2UvVGhpcmRQYXJ0eS9BTkdMRS9DaGFuZ2VMb2cKaW5k ZXggYzliZDA0NTVlYmIxMjk1ZWQxOWNlZjI0MzBmZDk1YTZjNGQ2ZDYxZS4uZWIzODdkNGIwNWE4 NWU5MDZmNjM5N2QzNGNkNjAyMjgzNjk2MjAwMiAxMDA2NDQKLS0tIGEvU291cmNlL1RoaXJkUGFy dHkvQU5HTEUvQ2hhbmdlTG9nCisrKyBiL1NvdXJjZS9UaGlyZFBhcnR5L0FOR0xFL0NoYW5nZUxv ZwpAQCAtMSwzICsxLDEzIEBACisyMDIyLTAzLTExICBLaW1tbyBLaW5udW5lbiAgPGtraW5udW5l bkBhcHBsZS5jb20+CisKKyAgICAgICAgUkVHUkVTU0lPTiAoaU9TIDE1LjQgYmV0YSkgLSBXZWJH TCB5aWVsZHMgaW5jb3JyZWN0IHJlc3VsdHMgd2hlbiB1c2luZyBwcmVzZXJ2ZURyYXdpbmdCdWZm 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