1944678 - OffscreenCanvas with webgl2 flickers after certain DOM changes.

Status: UNCONFIRMED

(Core :: Graphics: CanvasWebGL, defect)

Description

[mrolig+bugzilla]

Attachment: offscreen_flicker.html

Steps to reproduce:

Using WebGL to render to an offscreen canvas and then showing a new transparent element over the canvas.

See attached offscreen_flicker.html for the repro when clicking the overlay toggle button repeatedly (no need for a high frequency toggle).

Actual results:

The offscreen canvas element disappears for an arbitrary amount of time before reappearing, usually for only a frame or two, and sometimes for many seconds.

UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:134.0) Gecko/20100101 Firefox/134.0

This may be related to https://bugzilla.mozilla.org/show_bug.cgi?id=1853207 however, that seems to be for 2d context and may already be fixed.

Expected results:

The canvases should both display throughout the toggling of the overlay, and the grid pattern should never show through the canvases that have opaque pixels at all times.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Graphics: Canvas2D' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[mrolig+bugzilla]

Even if this is hard to fix, we'd like to understand root cause to know how exposed we might be to this bug in our application, it seems likely that only a limited set of operations might trigger the issue.