Re: [Public WebGL] Moving WEBGL_shared_resources to rejected status

[Ashley Gullen <ashley@scirra.com>]

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.