If we manually wait for the VBLANK with:
- SGI_video_sync
- Direct usage of the DRM ioctl
Then we should call glFinish() first, or otherwise the swap-buffers
may be delayed by pending drawing and cause a tear.
http://bugzilla.openedhand.com/show_bug.cgi?id=1636
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
This function should only need to be called in exceptional circumstances
since Cogl can normally determine internally when a flush is necessary.
As an optimization Cogl drawing functions may batch up primitives
internally, so if you are trying to use raw GL outside of Cogl you stand a
better chance of being successful if you ask Cogl to flush any batched
geometry before making your state changes.
cogl_flush() ensures that the underlying driver is issued all the commands
necessary to draw the batched primitives. It provides no guarantees about
when the driver will complete the rendering.
This provides no guarantees about the GL state upon returning and to avoid
confusing Cogl you should aim to restore any changes you make before
resuming use of Cogl.
If you are making state changes with the intention of affecting Cogl drawing
primitives you are 100% on your own since you stand a good chance of
conflicting with Cogl internals. For example clutter-gst which currently
uses direct GL calls to bind ARBfp programs will very likely break when Cogl
starts to use ARBfb programs internally for the material API, but for now it
can use cogl_flush() to at least ensure that the ARBfp program isn't applied
to additional primitives.
This does not provide a robust generalized solution supporting safe use of
raw GL, its use is very much discouraged.
Previously the journal was always flushed at the end of
_cogl_rectangles_with_multitexture_coords, (i.e. the end of any
cogl_rectangle* calls) but now we have broadened the potential for batching
geometry. In ideal circumstances we will only flush once per scene.
In summary the journal works like this:
When you use any of the cogl_rectangle* APIs then nothing is emitted to the
GPU at this point, we just log one or more quads into the journal. A
journal entry consists of the quad coordinates, an associated material
reference, and a modelview matrix. Ideally the journal only gets flushed
once at the end of a scene, but in fact there are things to consider that
may cause unwanted flushing, including:
- modifying materials mid-scene
This is because each quad in the journal has an associated material
reference (i.e. not copy), so if you try and modify a material that is
already referenced in the journal we force a flush first)
NOTE: For now this means you should avoid using cogl_set_source_color()
since that currently uses a single shared material. Later we
should change it to use a pool of materials that is recycled
when the journal is flushed.
- modifying any state that isn't currently logged, such as depth, fog and
backface culling enables.
The first thing that happens when flushing, is to upload all the vertex data
associated with the journal into a single VBO.
We then go through a process of splitting up the journal into batches that
have compatible state so they can be emitted to the GPU together. This is
currently broken up into 3 levels so we can stagger the state changes:
1) we break the journal up according to changes in the number of material layers
associated with logged quads. The number of layers in a material determines
the stride of the associated vertices, so we have to update our vertex
array offsets at this level. (i.e. calling gl{Vertex,Color},Pointer etc)
2) we further split batches up according to material compatability. (e.g.
materials with different textures) We flush material state at this level.
3) Finally we split batches up according to modelview changes. At this level
we update the modelview matrix and actually emit the actual draw command.
This commit is largely about putting the initial design in-place; this will be
followed by other changes that take advantage of the extended batching.
This is the another step into abstracting the backend operations
that are currently spread all across the board back into the
backend implementations where they belong.
The GL context creation, for instance, is demanded to the stage
realization which makes it a critical path for every operation
that is GL-context bound. This usually does not make any difference
since we realize the default stage, but at some point we might
start looking into avoiding the default stage realization in order
to make the Clutter startup faster.
It also makes the code maintainable because every part is self
contained and can be reworked with the minimum amount of pain.
The XVisualInfo for GL is created when a stage is being realized.
When embedding Clutter inside another toolkit we might not want to
realize a stage to extract the XVisualInfo, then set the stage
window using a foreign X Window -- which will cause a re-realization.
Instead, we should abstract as much as possible into the X11 backend.
Unfortunately, the XVisualInfo for GL is requested using GLX API; for
this reason we have to create a ClutterBackendX11 method that we
override inside the ClutterBackendGLX implementation.
This also allows us to move a little bit of complexity from out of
the stage realization, which is currently a very delicate and hard
to debug section.
The fix for bug 1138 broke multi-stage support on GLX, causing
X11 to segfault with the following stack trace:
Backtrace:
0: /usr/X11R6/bin/X(xf86SigHandler+0x7e) [0x80c91fe]
1: [0xb7eea400]
2: /usr/lib/xorg/modules/extensions//libglx.so [0xb7ae880c]
3: /usr/lib/xorg/modules/extensions//libglx.so [0xb7aec0d6]
4: /usr/X11R6/bin/X [0x8154c24]
5: /usr/X11R6/bin/X(Dispatch+0x314) [0x808de54]
6: /usr/X11R6/bin/X(main+0x4b5) [0x8074795]
7: /lib/i686/cmov/libc.so.6(__libc_start_main+0xe5) [0xb7c75775]
8: /usr/X11R6/bin/X(FontFileCompleteXLFD+0x21d) [0x8073a81]
which I can only track down to clutter_backend_glx_ensure_current()
being passed a NULL stage -- something that happens when a stage
is not correct realized. That should lead to a glXMakeCurrent(None)
and not to a segmentation fault, though.
Clutter has a set of command line options that are added to every
application by means of clutter_init() or by obtaining the Clutter
GOptionGroup and using g_option_context_parse(). Thus, every Clutter
application will automatically have an --help command line switch
showing the list of options and their description.
At the moment, Clutter does not enable localization of the help,
thus making it less than useful on non-English locales.
This patch enables the machinery to create a localization file and
load it when initializing Clutter, by means of the GLib macros and
locale.h API we already use.
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
Bug 1200 - Crash with invalid DISPLAY
* clutter/clutter-main.c: Use the ClutterBackend wrapper API
instead of directly checking the class structure.
* clutter/glx/clutter-backend-glx.c: Return the correct value
in case of failure.
* clutter/x11/clutter-backend-x11.c: Bail out if XOpenDisplay()
failed.
* clutter/glx/clutter-stage-glx.c:
(clutter_stage_glx_unrealize): Move the shaders release from here...
* clutter/glx/clutter-backend-glx.c:
(clutter_backend_glx_dispose): ... to here. Shaders should be
released when the GL context is being destroyed, and that only
happens when the backend is being disposed, now that we support
multiple stages.
* clutter/clutter-backend.c:
(_clutter_backend_create_stage): Call _clutter_stage_set_window()
ourselves, thus removing yet another action that backends must
implement and might get wrong; also cuts a backend-agnostic piece
of code duplication.
* clutter/eglnative/clutter-backend-egl.c:
(clutter_backend_egl_create_stage): Update the EGL native backend.
* clutter/eglx/clutter-backend-egl.c:
(clutter_backend_egl_create_stage): Update the EGLX backend.
* clutter/fruity/clutter-backend-fruity.c:
(clutter_backend_egl_create_stage): Update the fruity backend
* clutter/glx/clutter-backend-glx.c:
(clutter_backend_glx_create_stage): Update the GLX backend.
* clutter/sdl/clutter-backend-sdl.c:
(clutter_backend_sdl_create_stage): Update the SDL backend.
* HACKING.backends: Update the ::create_stage() description.
Rework the stage wrapper/implementation relation: remove
duplicated code and all the bookkeeping from the backends into
ClutterStage whenever possible, to reduce the amount of work a
backend must do (and possibly get wrong). Thanks to Tommi
Komulainen.
* clutter/clutter-main.c:
(clutter_init_with_args), (clutter_init): Realize the default
stage after creation. The default stage is special, because we
use it in the initialization sequence. This removes the burden
from the backends and reduces the things a backend can get
wrong.
* clutter/clutter-stage.c:
(clutter_stage_show): Make sure to realize the implementation if
it hasn't been realized yet.
(clutter_stage_realize): Set the REALIZED flag and call
clutter_stage_ensure_current() if the implementation was
successfully realized.
(clutter_stage_unrealized): Call clutter_stage_ensure_current()
on unrealize.
* clutter/glx/clutter-backend-glx.c:
(clutter_backend_glx_create_stage): Do not realize the stage anymore
when creating it, and let the normal realization sequence take
place.
(clutter_backend_glx_ensure_context): Trap for X11 errors.
* clutter/glx/clutter-stage-glx.c:
(clutter_stage_glx_realize): Chain up to the X11 implementation
so that we can set up the window state (title, cursor visibility)
when we actually have a X window. Also, do not call
clutter_stage_ensure_current(), and rely on the wrapper to do
it for us. This means we can drop setting the REALIZED flag on
the wrapper.
(clutter_stage_glx_unrealize): Do not call
clutter_stage_ensure_current() ourselves, and rely on the wrapper
to do it for us.
* clutter/x11/clutter-stage-x11.c:
(set_wm_title), (set_cursor_visible): Move the WM title and
cursor visibility code inside their own functions.
(clutter_stage_x11_realize): Set the window title and whether the
cursor is visible or not after realizing the stage.
(clutter_stage_x11_set_cursor_visible),
(clutter_stage_x11_set_title): Call set_wm_title() and
set_cursor_visible().
(clutter_stage_x11_finalize): Free the title string.
* clutter/x11/clutter-stage-x11.h: Save more of the stage state,
so that we can set it even when the stage hasn't been realized
yet.
* clutter/eglnative/clutter-backend-egl.c:
(clutter_backend_egl_create_stage):
* clutter/eglnative/clutter-stage-egl.c:
(clutter_stage_egl_unrealize),
(clutter_stage_egl_realize): Update the eglnative backend.
* clutter/eglx/clutter-backend-egl.c:
(clutter_backend_egl_ensure_context),
(clutter_backend_egl_create_stage):
* clutter/eglx/clutter-stage-egl.c:
(clutter_stage_egl_unrealize),
(clutter_stage_egl_realize): Update the eglx backend.
* clutter/sdl/clutter-backend-sdl.c:
(clutter_backend_sdl_create_stage):
* clutter/sdl/clutter-stage-sdl.c:
(clutter_stage_sdl_realize): Update the sdl backend.
* clutter/fruity/clutter-backend-fruity.c:
(clutter_backend_fruity_create_stage):
* clutter/sdl/clutter-stage-fruity.c:
(clutter_stage_fruity_realize): Update the fruity backend.
* tests/test-multistage.c (on_button_press): Bail out if
clutter_stage_new() returns NULL.
* HACKING.backends: Update backend writing documentation.
Work related to #873;
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-backend-glx.h:
* clutter/x11/clutter-x11-texture-pixmap.c:
* clutter/x11/clutter-x11-texture-pixmap.h:
General cleanup of texture pixmap code, adding;
- Pixmap dimentions and depth now auto probed, read only props.
- More X safety traps
- Add support for optionally tracking damage and automatically
updating texture.
* clutter/glx/clutter-glx-texture-pixmap.c:
* clutter/glx/clutter-glx-texture-pixmap.h:
General cleanup and some safety additions. Needs more work so
'proper' subclass - dependent on new COGL.
* clutter/x11/clutter-backend-x11.c: (clutter_x11_remove_filter):
Invert g_return_if check.
* configure.ac:
Pull in XComposite and XDamage (at least for now)
* tests/Makefile.am:
* tests/test-pixmap.c:
Add a modified test from Johan for above.
* clutter/eglx/clutter-backend-egl.c:
(clutter_backend_egl_ensure_context): Sync up with the GLX
backend.
(clutter_backend_egl_create_stage): Dumb compilation fix.
* clutter/glx/clutter-backend-glx.c:
(clutter_backend_glx_create_stage): Unref the stage if we are
erroring out.
* clutter/clutter-backend.c: Add more debug messages
* clutter/clutter-stage.h:
* clutter/clutter-stage.c:
(clutter_stage_is_default): Add a function to check if the
stage is the default one.
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-stage-glx.c:
* clutter/x11/clutter-stage-x11.c: Keep the stage wrapper
and implementation flags in sync, to ensure that the GL
context is always set.
Bug #864 - Allow instantiating and subclassing of ClutterStage
* clutter/Makefile.am: Add clutter-stage-window.[ch]
* clutter/clutter-stage-manager.c:
(_clutter_stage_manager_remove_stage): Do not warn if removing
a stage we don't manage, as we might be invoked multiple times
during a ClutterState dispose sequence.
* clutter/clutter-actor.c:
* clutter/clutter-backend.[ch]:
* clutter/clutter-main.c:
* clutter/clutter-private.h:
* clutter/clutter-stage.[ch]: Make ClutterStage a proxy actor,
with a private actor implementing the ClutterStageWindow
interface for handling the per-backend realization, painting
and unrealization, plus all the windowing system abstraction.
* clutter/x11/clutter-event-x11.c:
* clutter/x11/clutter-stage-x11.[ch]: Port the X11 backend
to the new backend and stage API and semantics.
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-stage-glx.c: Port the GLX backend to
the new backend and stage API and semantics.
* clutter/eglx/clutter-backend-egl.[ch]:
* clutter/eglx/clutter-stage-egl.[ch]: Port the EGLX backend
to the new backend and stage API and semantics (untested).
* tests/test-multistage.c (on_button_press): Rename
clutter_stage_create_new() to clutter_stage_new().
* clutter/glx/clutter-backend-glx.c:
(clutter_backend_glx_get_features): Assert if we don't have a
GL context here or if it's not matched to a drawable. Asserting
might seem too drastic, but if we don't have a valid GL context
here then Clutter will segfault anyway, and I'll take an assert()
over a hard to read, deep in GLX guts backtrace any day (and
twice on a monday).
* clutter/x11/clutter-backend-x11.c:
(clutter_backend_x11_get_features): No need for a variable here.
* clutter/clutter-backend.c:
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-stage-glx.c:
Allow NULL to be passed to _clutter_backend_ensure_context
which essentially clears GL context. This is hooked into stage
unrealisation. Isn't yet quite bulletproof.
Fixes issues with gtk-embed crasher (thanks to Neil).
* README:
Add notes on new multistage feature.
* clutter/clutter-stage-manager.c:
Dont ref contained stages.
* clutter/clutter-stage.c:
Automatically remove stage from stage manager on finalisation.
Cleans up warnings when a stage is destroyed.
* clutter/clutter-backend.h:
* clutter/glx/clutter-backend-glx.c:
Minor formatting cleanups.
* clutter/glx/clutter-stage-glx.c:
* configure.ac:
* clutter/clutter-version.h.in:
Add a general CLUTTER_STAGE_TYPE define, should be useful for
evntual stage subclassing and creating with g_object_new()
* clutter/Makefile.am:
* clutter/eglx/Makefile.am:
* clutter/eglx/clutter-backend-egl.c:
* clutter/eglx/clutter-backend-egl.h:
* clutter/eglx/clutter-eglx.h:
* clutter/eglx/clutter-event-egl.c:
* clutter/eglx/clutter-stage-egl.c:
* clutter/eglx/clutter-stage-egl.h:
* clutter/glx/Makefile.am:
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-backend-glx.h:
* clutter/glx/clutter-event-glx.c:
* clutter/glx/clutter-glx.h:
* clutter/glx/clutter-stage-glx.c:
* clutter/glx/clutter-stage-glx.h:
* clutter/x11/Makefile.am:
* clutter/x11/clutter-backend-x11-private.h:
* clutter/x11/clutter-backend-x11.c:
* clutter/x11/clutter-backend-x11.h:
* clutter/x11/clutter-event-x11.c:
* clutter/x11/clutter-stage-x11.c:
* clutter/x11/clutter-stage-x11.h:
* clutter/x11/clutter-x11.h:
Create a new X11 backend class of which EGL and GLX 'real' backends
then subclass. Effectively shares all X11 code between both backends
avoids code duplication and brings many missing features to EGL X
backend. Requires some cleanup and testing. (#518)
* clutter/cogl/gles/cogl.c: (cogl_color):
Add define to use color4ub only if configure finds it.
If not fall back to old code.
* configure.ac:
Drop support for vincent checks.
Drop sdles backend.
Specifically check for color4ub call.
* clutter/clutter-actor.c:
* clutter/clutter-event.h:
* clutter/clutter-main.c:
* clutter/clutter-stage.c:
* clutter/clutter-stage.h:
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-backend-glx.h:
* clutter/glx/clutter-event-glx.c:
* clutter/glx/clutter-stage-glx.c:
* clutter/glx/clutter-stage-glx.h:
Add initial support for stage state events.
Fix fullscreening for an already mapped stage.
* tests/test-events.c:
Print out info from the above. Blue button now toggles
fullscreen.
* clutter/clutter-effect.c:
* clutter/clutter-effect.h:
Add a setting for templates to ref or clone underlying
timelines. (As to improve sync issues like those in foofone)
* tests/test-timeline.c:
Also add completed signals.
* clutter/cogl/gles/cogl.c: (cogl_texture_image_2d):
* configure.ac:
Forward port from stable branch. RGB Image fixes gles
and check for lower case libgles_cm.
* clutter/clutter-actor.c:
* clutter/clutter-actor.h:
* clutter/clutter-event.c:
* clutter/clutter-event.h:
* clutter/clutter-main.c:
* clutter/clutter-main.h:
* clutter/clutter-private.h:
* clutter/clutter-stage.c:
* clutter/clutter-stage.h:
* clutter/clutter-types.h:
Initial implementation of actors emmitting event signals (423);
- Actors set_reactive() to receive mouse events.
(call clutter_enable_motion_events() for per action motion events)
- clutter_stage_set_key_focus () to direct key events.
- Events bubble up to parents (ending at stage)
(original source identified by clutter_event_get_source())
TODO:
- enter/leave notifys for actors.
- stage specific events - fullscreen
- grabs
* tests/test-events.c:
Extend a little to use new API
* clutter/cogl/gl/cogl.c:
* clutter/glx/clutter-backend-glx.c:
Move get_proc_address into cogl and out of backend.
(shaders will need it)
* clutter/clutter-group.c: (clutter_group_real_lower):
Fix a minor compile warning.
* TODO:
Sync up.
* clutter/clutter-backend.[ch]: Add clutter_backend_set_resolution()
and clutter_backend_get_resolution(); backends should use the former
to set the resolution of the display when initialising, while actors
should use the latter when sizing themselves depending on the
resolution or the font size.
* clutter/glx/clutter-backend-glx.c: Set the resolution as 96 dpi
as a default and query the X server when opening the display.
* clutter/clutter-entry.c: Drop the hardcoded dpi value and use
clutter_backend_get_resolution() to compute the default size.
* clutter/clutter-feature.h:
Add new stage feature flags and document.
* clutter/eglnative/clutter-backend-egl.c:
* clutter/eglx/clutter-backend-egl.c:
* clutter/sdl/clutter-backend-sdl.c:
Set new feature flags.
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-stage-glx.c:
* clutter/clutter-stage.c:
* clutter/clutter-stage.h:
Add a 'user_resizeable' setting to the backend and implement
for glx backend.
Two small fixes for correctly debugging the deinitialisation
phase of the backend:
* clutter/glx/clutter-backend-glx.c: Remove the event source
after we unref the main stage.
* clutter/glx/clutter-stage-glx.c: Add a mark at the end of the
unrealize call (the perl bindings seem to crash before we reach
this point).
This patch adds a command line switch to make every X call synchronous.
It's only useful for debugging purposes, so it will not be displayed when
calling a Clutter application with --help.
* clutter/cogl/gl/cogl.c: (cogl_check_extension):
Actually populate this func and remove the static alternate
named one. Means GLX actually checks for available extensions.
Other minor tidy ups.
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-backend-glx.h:
Add support for GLX_SGI_swap_control to do vblanking prefering
over glXGetVideoSyncSGI. Should fix issues on Intel chips with
very slow frame rates due to vblank problems.
Thanks to Michel Danzer for tips, see;
http://bugs.freedesktop.org/show_bug.cgi?id=10542
* test/test-actors.c:
Change FPS to 60.
* clutter/clutter-backend.c:
* clutter/clutter-backend.h:
* clutter/glx/clutter-stage-glx.c:
* clutter/glx/clutter-backend-glx.c:
Fix up rendering pipeline removing clutter_backend_XXX_stage_paint
and adding clutter_backend_XXX_redraw instead. Duplicates less
code in backends, avoids clutter_actor_paint() getting called
before stage is set up (viewport wise) and unbreaks things like
picking.
* clutter/clutter-actor.c:
* clutter/clutter-actor.h:
* clutter/clutter-main.c:
* clutter/clutter-private.h:
* clutter/clutter-stage.c: (clutter_stage_get_actor_at_pos):
Redo picking functionality a different way (via color indexing)
as to provide more flexibility, possibly speed and more likely
work with GL/ES (doesn't currently however - not sure why).
* clutter/clutter-group.c:
Add groups own 'pick' method.
* clutter/cogl/cogl.h:
* clutter/cogl/gl/cogl.c:
* clutter/cogl/gles/cogl.c:
Move clipping funtionality into cogl.
* clutter/cogl/gles/cogl-defines.h:
Hack around missing BGR format in GL/ES.
* clutter/egl/clutter-backend-egl.c:
* clutter/egl/clutter-backend-egl.h:
* clutter/egl/clutter-stage-egl.c:
* clutter/sdl/clutter-backend-sdl.c:
* clutter/sdl/clutter-backend-sdl.h:
* clutter/sdl/clutter-event-sdl.c:
* clutter/sdl/clutter-stage-sdl.c:
Update backends to newer API.
Add basic mouse event translation to SDL.
* clutter/clutter-backend.c:
* clutter/clutter-backend.h:
* clutter/clutter-event.c:
* clutter/clutter-main.c:
* clutter/clutter-private.h:
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-backend-glx.h:
* clutter/glx/clutter-event-glx.c:
Rejig backend event code as to simplify a little.
NOTE: This breaks non glx backends.
* tests/Makefile.am:
* tests/test-events.c:
Add a very simple event test.
* tests/test-textures.c: (main):
Add some more sizes to the test.
Add clutter_backend_get_n_screens(), which returns the number of screens
manager by the ClutterBackend, and change clutter_backend_get_screen_number()
to return the screen number of the currently used screen; this is semantically
equivalent to clutter_glx_get_default_screen(), but leaves the door open for
a "screen" abstraction in Clutter, handled by the backend. Update the GLX
and EGL backends to retrieve and set the screen_num and n_screens members of
ClutterBackend using Xlib calls.
Add functions to retrieve some of the properties of the screen used by
the backend, like its dimensions (also physical, in millimeters); the
number of screens. Also add setters and getters for the double click
time (in milliseconds) and distance.
* clutter/clutter-backend.c: Clear the event queue when
disposing the backend object; remove the initialisation
of the backend structure members...
* clutter/glx/clutter-backend-glx.c: ... and keep it here
in the backends where it belongs.
* clutter/clutter-private.h: Remove inclusion of backend-specific
headers; update the main context object; add the declarations for
the event queue functions.
* clutter/clutter-backend.[ch]: Add the abstract ClutterBackend
object, which holds backend-specific settings, the main stage,
and the event queue. Every backend must implement a subclass of
ClutterBackend and ClutterStage.
* clutter/clutter-feature.c: Protect the GLX specific calls
behing #ifdef HAVE_CLUTTER_GLX.
* clutter/clutter-actor.c:
* clutter/clutter-group.c:
* clutter/clutter-clone-texture.c: Include GL/gl.h
* clutter/clutter-event.[ch]: Update public API and implement the
event queue private API; hold a reference on the event objects;
move out the keysym-to-unicode table; add the new event types.
* clutter/clutter-color.h: Include clutter-fixed.h
* clutter/clutter-main.c: Update API; get the main stage
from the backend object; process the event received from the
queue; lock/unlock the main mutex if we have one; move the
initialisation process sooner in the init sequence, in order to
have the backend object when we check for options; call the
backed vfuncs in the pre/post parse hooks.
* clutter/clutter-stage.c: Make ClutterStage and abstract class,
implemented by the backends.
* clutter/clutter/glx/clutter-glx.h:
* clutter/clutter/glx/clutter-backend-glx.[ch]:
* clutter/clutter/glx/clutter-event-glx.c:
* clutter/clutter/glx/clutter-stage-glx.[ch]:
* clutter/clutter/glx/Makefile.am: Add the GLX backend.
* clutter/clutter/egl/clutter-backend-egl.[ch]:
* clutter/clutter/egl/clutter-event-egl.c:
* clutter/clutter/egl/clutter-stage-egl.[ch]:
* clutter/clutter/egl/Makefile.am: Add the stub for a EGL backend.
* examples/*.c: Update for the new API.
