Created attachment 279863 [details] [review]
Allow setting up quad-buffer stereo output

Add clutter_x11_set_use_stereo_stage() that can be called
before clutter_init() so that the CoglDisplay we create and all
stages created from that CoglDisplay will be created with a
stereo fbconfig.

This is done in clutter-x11 because of the similarity to the
existing clutter_x11_set_use_argb_visual(), and because it's
not clear without other examples whether the need to have
stereo enabled from before clutter_init() is universal or
somethign specific to GLX.

Review of attachment 279863 [details] [review]:

in general, it looks good to me.

::: clutter/x11/clutter-backend-x11.c
@@ +708,3 @@
+   * could just return that display, then it would be more efficient
+   * not to use cogl_renderer_check_onscreen_template(). However, the
+   * backend API requires that we return an CoglDisplay that has not

the backend API does not require much: it's just the way it was written to provide enough overridable steps for every backend.

it's all private anyway, so if you want to change its semantics, it's perfectly fine by me; you just need to ensure that the other backends can use the same semantics.

Patch has been in "accepted-commit_now" status for >200 days now.

Owen, ebassi: Anybody willing to push?

(In reply to André Klapper from comment #3)
> Patch has been in "accepted-commit_now" status for >200 days now.
> 
> Owen, ebassi: Anybody willing to push?

I don't think the needed API landed in Cogl, or that Cogl had a release with the API. I'm also not really enthused by the prospect of bumping the Cogl dependency at the end of the cycle.

I'll defer to Owen for this one.

The Cogl API changes were been sitting in the tree without a release since July.
Robert Bragg has now done a 1.20 release of Cogl with the new API.

Attachment 279863 [details] pushed as c32dc34 - Allow setting up quad-buffer stereo output