[Public WebGL] Moving WEBGL_shared_resources to rejected status

James Ritts [email protected]
Fri May 4 21:02:35 PDT 2018


>> On a technical note, you can use glFenceSync in lieu of glFinish to guarantee
data updates are propagated correctly.

Ken, is there a reason fences couldn't be used to synchronize resource
updates between WebGL contexts, as Jeff suggested?


On Wed, May 2, 2018 at 2:11 PM, Jeff Gilbert <[email protected]> wrote:

>
> This is on the roadmap for being fixed.
>
> On Wed, May 2, 2018 at 1:18 PM, Ashley Gullen <[email protected]> wrote:
> >>> Multiple visible canvases can be created with the '2d' rendering
> context,
> >>> and an invisible WebGL-rendered canvas drawn to them using
> >>> CanvasRenderingContext2D.drawImage.
> >>
> >>
> >> Afaik this would be pretty slow as it'll perform a readback to obtain
> >> pixel data to put into the 2D canvas buffer does it not?
> >
> >
> > It appears to be hardware accelerated in Chrome, but it is indeed slow in
> > Firefox and Safari:
> > https://bugzilla.mozilla.org/show_bug.cgi?id=1163426
> > https://bugs.webkit.org/show_bug.cgi?id=177132
> >
> > It's slow enough to not really be useful, as in you probably can't hit 30
> > FPS if you simply draw the webgl canvas every frame. Not much action on
> > either report so far unfortunately.
> >
> > The new imagebitmap context might provide another way, but that's not
> > implemented outside of Chrome yet.
> >
>
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