Re: 3.8 "feature": Drop or Fix Fallback Mode

[Emmanuele Bassi <ebassi gmail com>]

hi Adam;

On 23 October 2012 18:49, Adam Jackson <ajax redhat com> wrote:
> On 10/22/12 10:55 AM, Vincent Untz wrote:
>
> 4) XDMCP.  At least on my F18 machine gnome-shell does not work in indirect
> GLX contexts.  To a first approximation I think that's more bugs than
> anything fundamentally broken.  However, the remote GLX protocol as
> currently defined doesn't give you anything newer than OpenGL 1.5; it's not
> clear to me whether cogl/clutter will continue to work against so old of a
> GL.  We could also extend XDMCP to allow for the wm/cm to run on the same
> machine as xserver, which would allow mutter to run in a direct GL context;
> the downside there is it would require a firmware update to enable this
> usage model on existing thin clients.  (Wayland remoting is, let's say, an
> open research problem.)

this is a fair assessment.

as far as I'm concerned, Clutter 1.x and Cogl 1.x will still support
the GL fixed pipeline - though any user of the API will have to deal
with the feature and performance implications of doing so (i.e. no
shaders, no offscreen framebuffers, etc.). if something is broken in
that regard, I consider it a bug - and I'd ask users of these
configurations to file issues as such in Bugzilla, as well as possibly
helping us with testing.

for Clutter 2.x, using framebuffer objects and the programmable
pipeline becomes a bit more of a requirement: opacity groups, filters,
etc. are doable client-side, in some cases, but not all. I can degrade
the features, but if I have to chose between dropping indirect GLX and
dropping correct alpha blending and decent performance at the design
phase of the toolkit implementation, then the former gets on the
chopping block.

as a side note, I'd like to point out that most of our accessibility
features in the Shell are implemented using FBOs and GLSL shaders;
which means that on indirect GLX you get a non-accessible shell.

ciao,
 Emmanuele.

--
W: http://www.emmanuelebassi.name
B: http://blogs.gnome.org/ebassi/