Hi,
I read through the entire "Enabling Compiz by default" thread and
decided to send out a braindump/status/roadmap type of writeup, to
explain what we're doing in this area and where we'd like to go:
1) We are working towards being able to enable a compositor by default.
Redirected direct rendering, Xv, Java problems, these are
problems in the drivers and X server and affects all
compositors. To get this done, we need to land a big chunk of
code in the kernel (the DRM memory manager), we need to update
the X server, the 2D drivers and the 3D drivers to take
advantage of the new memory manager. We need to fix Xv.
Hopefully the OpenGL support will broaden to support more
chipsets (nouveaou, avivo). Getting all this to a shippable
state may take years, and in the mean time, the composited
desktop, whether it's compiz, kwin4 or something else will only
be an opt-in tech demo.
2) Once we get there, the default compositor will be compiz.
Some people can't get over on the wobbly windows and spinning
cube, and claim it's over the top or apparently get nauseous.
At the core, compiz is just a very efficient OpenGL redraw loop
with a flexible plugin architecture. Compiz allows burning
windows and spinning cubes, but we ship it in a very toned down
default configuration that looks a lot like good old metacity.
Consider xeyes; like wobbly windows, it's a neat tech demo and
shows off the flexibility of X, but just because nobody runs
xeyes for more that 2 minutes at a time that doesn't mean that X
(or shaped windows) isn't useful.
A valid point about compiz is that it is not yet a great window
manager. Metacity has a few years of head start there, but that
doesn't mean that we can't fix compiz or that it'll be
duplicated effort. For now, our efforts have gone towards
fixing the big underlying shortcomings in the X and OpenGL
stack, which has left compiz with a set of minor (but certainly
annoying) windows manager bugs.
Other spins (Fedora KDE or Fedora XFCE) can set up different
default compositing managers, and they will of course benefit
from the infrastructure work mentioned in 1).
3) Metacity as a compositing manager.
We tried it and decided that the metacity code base was not a
welcoming place for a compositor. When we put down the work in
metacity, the conclusion was to leave this very stable and well
tested code base alone instead of injecting an OpenGL based
compositor. The flip side of this decision is that we can now
do a clean break in compiz and assume throughout the code that
we're an OpenGL based combined compositing and window manager.
4) Compiz configuration tools
desktop-effects is close to what we should ship by default,
perhaps we want to fold it into the new
gnome-appearance-properties capplet as a new tab. At the same
time, we want to allow installation of other compiz
configuration managers for people who like the tweak-ui kind-of
tools.
4) Power consumption and other hand-wavey fud arguments.
Clearly running a 3D screen saver at the full frame rate is
going to burn more battery than the blank screen saver, but
that's not really relevant here. When idling, compiz and
metacity use exactly the same amount of power. There are no
code paths anywhere in the stack that "turn on 3d powerplanes".
My bet is that it's more power consuming to wake up all
applications to redraw their exposed areas under the window
you're dragging than it is for compiz to just recomposite that
out of textures already in video memory.
5) If you don't know what you're talking about, will being excessively
dismissive and assertive make you right?
No.
Kristian
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