[Public WebGL] Moving WEBGL_shared_resources to rejected status

Ken Russell [email protected]
Thu May 10 20:15:20 PDT 2018


On Fri, May 4, 2018 at 9:03 PM James Ritts <[email protected]> wrote:

> >> 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?
>

Jeff's right, in ES 3.0 fences can be used instead of glFinish. The fact
remains that this extension would be a large and intrusive change to the
WebGL API and would be difficult to use. We are going to pursue other,
guaranteed ways that applications can quickly render to multiple canvases
from one WebGL context.

-Ken



>
>
> 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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