653658 - JavaScript implementation of WebGL MOZ_dom_element_texture extension

Status: RESOLVED WONTFIX

(DevTools :: General, defect, P2)

Description

[Cedric Vivier [:cedricv]]

Implement MOZ_dom_element_texture (#653656) as a JavaScript shim using canvas.drawWindow or similar.

Won't provide awesome performance, but it shouldn't take much time to do and it will validate the extension's semantics, which is a good thing before working on #653657.

Comment 1

[Kevin Dangoor]

This doesn't seem like a Developer Tools bug?

Comment 2

[Cedric Vivier [:cedricv]]

I think this is, I thought one of us at DevTools (Victor?) would implement this.
This is a JavaScript shim that can be implemented by Tilt directly with currently available APIs... when the extension API is agreed upon (canvas.webgl bug #653656)

Not very efficient but this does not require native implementation, which will take longer to write/review/land.
We will then switch to the efficient native implementation (which is definitely a canvas.webgl bug) as soon it lands with no change.

Comment 3

[Rob Campbell [:rc] (:robcee)]

yup. I agree with Cedric that this is something that we can and should do. We are the primary consumers of this shim.

Comment 4

[Cedric Vivier [:cedricv]]

This is a placeholder for the native/optimized implementation of the extension, reusing underlying textures (or FBOs?) when possible.

First we need to all agree on a sane design for #653656, and it does not seem necessary for now as Tilt's framerate seems quite acceptable as it does not do interactive refresh yet afaik (the native implementation will be probably needed for interactive refresh rates - especially on pages using canvas or video heavily).

Additionally it might not make sense to implement this natively before Azure is ready, depending whether or not access to underlying gfx objects is going to significantly change. Benoit?

Comment 5

[Cedric Vivier [:cedricv]]

Please ignore comment #4. It was intended for #653657.

Comment 6

[Cedric Vivier [:cedricv]]

Attachment: First version. Completely untested.

Comment 7

[Cedric Vivier [:cedricv]]

Need to update according to comment #26 over at #653656.

- add readWindowTexCoords, always [0.0,0.0, <stride>, 0.0,1.0, <stride>, 1.0,1.0, <stride>, 1.0,0.0] in the shim
- rename MAX_WINDOW_REGION to MAX_WINDOW_REGIONS (+1!)

Comment 8

[Victor Porof [:vporof][:vp]]

We're getting closer to making our tools update themselves. This would be a great start for Tilt, maybe we can start playing with this again? See also bug 703910.

Comment 9

[Victor Porof [:vporof][:vp]]

Or we could skip this entirely and focus on the actual bug 653656 and bug 653657. I would somewhat prefer the latter, because wasting time on a JavaScript shim that is temporary anyway and doesn't really help much is probably not a good idea.

Cedric, what do you think?

Comment 10

[Cedric Vivier [:cedricv]]

(In reply to Victor Porof from comment #9)
> Or we could skip this entirely and focus on the actual bug 653656 and bug
> 653657. I would somewhat prefer the latter
> Cedric, what do you think?

I think that's reasonable since the proposed API in bug 653656 seems to be in a good shape now (there's still a few issues to answer/validate tho).

Comment 11

[Victor Porof [:vporof][:vp]]

Ok, I'll mark bug 653656 as P2.