688112 - WebGL Conformance fails on drawingbuffer-*

Status: RESOLVED DUPLICATE of bug 681791

(Core :: Graphics: CanvasWebGL, defect)

Description

[Kelsey Gilbert [:jgilbert]]

Attachment: Prevents (windows) crashes by clamping the resulting size of resizes.

The drawingbuffer-* tests fail, as we don't properly handle too-large resizes, sometimes leading to crashes.

Comment 1

[Kelsey Gilbert [:jgilbert]]

This doesn't actually fix all the fails, because we're still resizing to sizes above the max viewport size, which is what the tests test against.
On WGL+FBO, this can be fixed by clamping based on the viewport size. I suppose this makes sense, but would we like to keep the option of the larger canvas sizes?

On EGL/ANGLE and WGL+PBuffers, I don't think we can request the max viewport size before creating the PBuffer surface, which gives us the GLContext. To clamp to viewport size, I think we will need to create a PBuffer surface (and associated GLContext) in order to query the max viewport size, then, if we're above this, destroy and recreate the surface at a valid size.

Comment 2

[Kelsey Gilbert [:jgilbert]]

Also, this should probably be fixed on other platforms, but I'm primarily working with windows at the moment.

Comment 3

[Kelsey Gilbert [:jgilbert]]

Attachment: Updates WebGL canvas width/height attibutes to result of creation/resize

On (my) windows7, this now passes on EGL and WGL paths.

Comment 4

[Kelsey Gilbert [:jgilbert]]

Attachment: Attempts to clamp width/height to valid values.

Comment 5

[Kelsey Gilbert [:jgilbert]]

I put together a patch which should help with this. It fixes and guarantees that ResizeOffscreen will not change the GLContext on failure, and it changes the webgl context resize operation to soft-fail if resize fails. That is, we attempt a resize, but if it fails, we just leave it in its previous valid state.

Previously, if webgl context resize failed, we tried to create a new GLContext with the requested dimensions, which is why we are failing this pair of tests: The creation of a too-large context fails, leaving us with no valid context.

I'll upload and pass it by try later today.

Comment 6

[Kelsey Gilbert [:jgilbert]]

This is just an effect, though important, of 681791. Patch posted there.

Comment 7

[Benoit Jacob [:bjacob] (mostly away)]

What should we do with this bug and patch?

Comment 8

[Kelsey Gilbert [:jgilbert]]

It's basically a dupe of bug 681791, so marking it as such.