Bug 230625

Summary:	fast/mediastream/captureStream/canvas3d.html succeeds on bots surprisingly, as the underlying code is broken
Product:	WebKit	Reporter:	Kimmo Kinnunen <kkinnunen>
Component:	WebRTC	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	ap, webkit-bug-importer, youennf
Priority:	P2	Keywords:	InRadar
Version:	WebKit Local Build
Hardware:	Unspecified
OS:	Unspecified
See Also:	https://bugs.webkit.org/show_bug.cgi?id=230613

Description Kimmo Kinnunen 2021-09-22 06:37:44 PDT

fast/mediastream/captureStream/canvas3d.html does not seem to be part of any test expectation

* The test fails
* I cannot see where the test is not marked as failing (?)
* The underlying code was not fixed

Comment 1 Alexey Proskuryakov 2021-09-22 11:06:55 PDT

It somehow passes on the bots: https://results.webkit.org/?suite=layout-tests&test=fast%2Fmediastream%2FcaptureStream%2Fcanvas3d.html

Comment 2 Radar WebKit Bug Importer 2021-09-29 06:38:20 PDT

<rdar://problem/83668855>

Comment 3 Kimmo Kinnunen 2021-09-29 11:05:58 PDT

So the bug was that due to reading the drawing buffer of webgl, the iosurface would be read as uninitialised.
Uninitialised IOSurfaces appear red.

The test does not test that captured WebGL image is certain pattern. It tests that the captured image is not black. As such, it was fooled by the red.

Eventually the test should be improved to draw some common test pattern (such as subset of the bip-bop image) and then common test pattern verification code should be used to verify that the image was received as intended.