625353 - Vertically flipped (upside down) text when using "show image" on a WebGL canvas element

Status: VERIFIED FIXED

(Core :: Graphics: CanvasWebGL, defect)

Description

[Daniel Kirsch]

User-Agent:       Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b9pre) Gecko/20110112 Firefox/4.0b9pre
Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b9pre) Gecko/20110112 Firefox/4.0b9pre

I clicked the "view image" context menu option in the credits of the "flight of the navigator" demo. The image then shows the text vertically flipped.

Reproducible: Always

Steps to Reproduce:
1. Go to the "Flight of the navigator" demo (URL given)
2. Go to the end of the demo (simply click at the end in the timeline in the media player on top)
3. As soon as the credits text appears, select "View image" from the context menu.

Comment 1

[Daniel Kirsch]

Attachment: Screenshot of the flipped text

Comment 2

[Henrik Skupin [:whimboo][⌚️UTC+1]]

David, I assume that is not wanted in the demo, right?

Comment 3

[Boris Zbarsky [:bzbarsky]]

Just loading the page and doing:

  javascript:window.open(document.getElementById("creditCanvas").toDataURL()); void(0)

in the url bar will show the same behavior.  And I see this on Mac too.

Is this canvas using a GL context?  If so, is there a difference between GL and 2d contexts in terms of the y-ordering of the stored bits or something?

Comment 4

[Boris Zbarsky [:bzbarsky]]

Actually, it looks like the context itself is responsible for producing the output stream.

And I see similar upside-down behavior on http://webglsamples.googlecode.com/hg/aquarium/aquarium.html if I do this:

  javascript:window.open(document.getElementById("canvas").toDataURL());
void(0)

So this is a gl context issue.  Something somewhere is flipped and it's not unflipping it....

Requesting blocking, since this is a web-visible correctness bug in gl canvas...

Comment 5

[Chris B.]

I viewed the demo, which is very neat by the way, and it is actually an entire horizontal axis flip, not a vertical flip.

Comment 7

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Attachment: use Render directly=

bah, y-flip annoyances...

Comment 8

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

http://hg.mozilla.org/mozilla-central/rev/46d40c236f3d

Comment 9

[Cameron Dawson [:camd]]

This worked fine on my mac, but on Windows 7 in a VM, it won't even load the demo.
I get an error dialog saying:

Could not initialise WebGL, sorry :-(

In beta 10, it is able to at least load the demo and start.

Reopening as this is a regression.

Comment 10

[Joe Drew (not getting mail)]

We don't support WebGL (or any hardware acceleration) on VMs. Feel free to open a new bug on that, but this bug's fixed.

Comment 11

[Chris B.]

(In reply to comment #9)
> This worked fine on my mac, but on Windows 7 in a VM, it won't even load the
> demo.
> I get an error dialog saying:
> 
> Could not initialise WebGL, sorry :-(
> 
> In beta 10, it is able to at least load the demo and start.
> 
> Reopening as this is a regression.

I am using the current Nightly (2/4/11) on Windows 7 (NOT Virtual Machine) and it is working fine.

Comment 12

[Cameron Dawson [:camd]]

Joe and Chris: thanks.  Sorry for the false alarm...

Comment 13

[Aleksei Perepelkin [:chaos]]

Verified with Mozilla/5.0 (X11; Linux i686; rv:2.0b12pre) Gecko/20110204 Firefox/4.0b12pre
and nvidia drivers 260.19.36.