RESOLVED CONFIGURATION CHANGED 181007
WebGL canvas with enabled blending and no antialiasing is incorrectly composed with background 
https://bugs.webkit.org/show_bug.cgi?id=181007
Summary WebGL canvas with enabled blending and no antialiasing is incorrectly compose...
Kirill S. Dmitrenko
Reported 2017-12-19 16:00:11 PST
Created attachment 329849 [details] Expected result If threre's a html element with a background underneath the canvas, and blending is enabled in the context, composition for some reason goes "additive". Here's a test page: https://codepen.io/dmikis/full/ZvQPBG/.
Attachments
Expected result (325.37 KB, image/png)
2017-12-19 16:00 PST, Kirill S. Dmitrenko 		no flags
Details
Actual result in Safari 11.0.3 (203.04 KB, image/png)
2017-12-19 16:00 PST, Kirill S. Dmitrenko 		no flags
Details
Code of the test page (3.36 KB, application/zip)
2017-12-19 16:01 PST, Kirill S. Dmitrenko 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Kirill S. Dmitrenko
Comment 1 2017-12-19 16:00:41 PST
Created attachment 329850 [details] Actual result in Safari 11.0.3
Kirill S. Dmitrenko
Comment 2 2017-12-19 16:01:07 PST
Created attachment 329851 [details] Code of the test page
Radar WebKit Bug Importer
Comment 3 2017-12-19 17:21:19 PST
<rdar://problem/36145405>
Kirill S. Dmitrenko
Comment 4 2018-01-09 06:28:45 PST
I forgot to mention that the problem reproduces only on discrete GPUs.
Dean Jackson
Comment 5 2018-01-12 15:23:16 PST
We can reproduce. We've forwarded on to our compositing team.
Kirill S. Dmitrenko
Comment 6 2018-01-31 05:18:39 PST
We've got more complaint from users, and it seems that on some configuration antialiasing doesn't affect the problem (i.e., if antialias is set, rendered result is still "blended" with CSS background). In particular, on macOS 10.11 and 10.13 the problem occurs.
Simon Fraser (smfr)
Comment 7 2018-11-28 13:38:59 PST
The test page no longer works (stv.maps.yandex.net now gives 404 errors).
Simon Fraser (smfr)
Comment 8 2018-11-28 13:49:17 PST
Also, this should have been fixed in macOS Mojave. Can you test and report back?
Gregg Tavares
Comment 9 2019-06-10 23:11:34 PDT
this seems fixed to me. Tested on MacOS 10.14.5 on 2014 MBP and on iOS 12.3.1 iPhoneX Mark as resolved?
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