Bug 218282

Summary: rendering to an offscreen framebuffer alterates canvas display
Product: WebKit Reporter: zebontheweb
Component: WebGLAssignee: Kimmo Kinnunen <kkinnunen>
Status: RESOLVED DUPLICATE    
Severity: Blocker CC: dino, jdarpinian, kbr, kkinnunen, smoley
Priority: P1 Keywords: DoNotImportToRadar
Version: Safari 14   
Hardware: iPhone / iPad   
OS: Other   
Bug Depends on: 218177    
Bug Blocks:    
Attachments:
Description Flags
sample reproducing the pb none

Description zebontheweb 2020-10-28 05:45:12 PDT 
Created attachment 412522 [details]
sample reproducing the pb

See attached sample.

1/ create a canvas
2/ create an webgl context 
3/ clear with black color

4/ create an offscreen framebuffer to render to a texture
5/ clear with black color in a setTimeout callback

Result : the canvas switch to transparent

Expected result : the canvas should remain black

Maybe similar to https://bugs.webkit.org/show_bug.cgi?id=218177 or related bugs
Comment 1 Smoley 2020-10-28 10:54:15 PDT 
I can reproduce this on an iPad running iOS 14 GM, but this appears to be fixed on the iOS 14.2 Beta https://developer.apple.com/news/releases/?id=10132020b

Are you able to reproduce this on the latest beta build as well?
Comment 2 Kenneth Russell 2020-10-28 11:01:33 PDT 
I think this is a duplicate of Bug 218177 which Kimmo just fixed. Kimmo, can you confirm?
Comment 3 zebontheweb 2020-10-28 15:05:49 PDT 
(In reply to Smoley from comment #1)
> I can reproduce this on an iPad running iOS 14 GM, but this appears to be
> fixed on the iOS 14.2 Beta
> https://developer.apple.com/news/releases/?id=10132020b
> 
> Are you able to reproduce this on the latest beta build as well?

I will give it a try on the real scenario failing, give me some time, we have a restricted number of iOS devices. Thanks.
Comment 4 Kimmo Kinnunen 2020-10-29 01:14:58 PDT 
Thanks for the report.
With tip of the tree, the canvas is showing black on screen.
Yes, this should be fixed by the fix in bug 218177.

*** This bug has been marked as a duplicate of bug 218177 ***