Commit Graph

39 Commits

Author SHA1 Message Date
Sjoerd Simons
cde0eb3e76 Make the default driver selectable at configure time
When building COGL with multiple backends it can be useful to force a
default driver to be selected. For example while for Debian we do want to
build the GL renderer on ARM, GLESv2 is much more suitable as the
default renderer on that platform.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 8a43aa7167b56784f7b50c557391b990861d594f)
2012-09-03 15:51:45 +01:00
Neil Roberts
df77e8565e Don't use eglGetProcAddress to retrieve core functions
According to the EGL spec, eglGetProcAddress should only be used to
retrieve extension functions. It also says that returning non-NULL
does not mean the extension is available so you could interpret this
as saying that the function is allowed to return garbage for core
functions. This seems to happen at least for the Android
implementation of EGL.

To workaround this the winsys's are now passed down a flag to say
whether the function is from the core API. This information is already
in the gl-prototypes headers as the minimum core GL version and as a
pair of flags to specify whether it is available in core GLES1 and
GLES2. If the function is in core the EGL winsys will now avoid using
eglGetProcAddress and always fallback to querying the library directly
with the GModule API.

The GLX winsys is left alone because glXGetProcAddress apparently
supports querying core API and extension functions.

The WGL winsys could ideally be changed because wglGetProcAddress
should also only be used for extension functions but the situation is
slightly different because WGL considers anything from GL > 1.1 to be
an extension so it would need a bit more information to determine
whether to query the function directly from the library.

The SDL winsys is also left alone because it's not as easy to portably
determine which GL library SDL has chosen to load in order to resolve
the symbols directly.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 72089730ad06ccdd38a344279a893965ae68cec1)

  Since we aren't able to break API on the 1.12 branch
  cogl_get_proc_address is still supported but isn't easily able to
  determine whether the given name corresponds to a core symbol or
  not.  For now we just assume the symbol being queried isn't part
  of the core GL api and update the documentation accordingly.
2012-08-06 14:27:45 +01:00
Robert Bragg
498937083e Adds gles2-context renderer constraint
This adds a new renderer constraint enum:
  COGL_RENDERER_CONSTRAINT_SUPPORTS_GLES2_CONTEXT
that can be used by applications to ensure the renderer they connect to
has support for creating a GLES2 context via cogl_gles2_context_new().

The cogl-gles2-context and cogl-gles2-gears examples and the conformance
tests have been updated to use this constraint.

Reviewed-by: Neil Roberts <neil@linux.intel.com>

(cherry picked from commit ed61463d7194354b26624e8014859f0fbfc06a12)
2012-08-06 14:27:43 +01:00
Robert Bragg
54735dec84 Switch use of primitive glib types to c99 equivalents
The coding style has for a long time said to avoid using redundant glib
data types such as gint or gchar etc because we feel that they make the
code look unnecessarily foreign to developers coming from outside of the
Gnome developer community.

Note: When we tried to find the historical rationale for the types we
just found that they were apparently only added for consistent syntax
highlighting which didn't seem that compelling.

Up until now we have been continuing to use some of the platform
specific type such as gint{8,16,32,64} and gsize but this patch switches
us over to using the standard c99 equivalents instead so we can further
ensure that our code looks familiar to the widest range of C developers
who might potentially contribute to Cogl.

So instead of using the gint{8,16,32,64} and guint{8,16,32,64} types this
switches all Cogl code to instead use the int{8,16,32,64}_t and
uint{8,16,32,64}_t c99 types instead.

Instead of gsize we now use size_t

For now we are not going to use the c99 _Bool type and instead we have
introduced a new CoglBool type to use instead of gboolean.

Reviewed-by: Neil Roberts <neil@linux.intel.com>

(cherry picked from commit 5967dad2400d32ca6319cef6cb572e81bf2c15f0)
2012-08-06 14:27:39 +01:00
Robert Bragg
125c31a70b kms: Add mirror support and env var configurability
This adds support for mirroring the display output on two KMS
connectors.

This patch also checks for a number of environment variables that can
influence how KMS is configured. The following variables can be set:

COGL_KMS_MIRROR: If this is set to anything then Cogl will try and setup
two connectors with the same resolution so that onscreen frame buffers
can be mirrored.

COGL_KMS_CONNECTOR0: This can be set to an integer identifier for a
specific KMS connector id to use for the first output.

COGL_KMS_CONNECTOR0_MODE: Can be set to a mode name like "1024x768"
explicitly select what mode should be used for the first output.

If COGL_KMS_MIRROR is set then COGL_KMS_CONNECTOR1 and
COGL_KMS_CONNECTOR1_MODE can optionally be set to specify a connector id
and mode name for the second output.

Reviewed-by: Neil Roberts <neil@linux.intel.com>
2012-04-11 15:44:58 +01:00
Neil Roberts
185630085c Add -Wmissing-declarations to maintainer flags and fix problems
This option to GCC makes it give a warning whenever a global function
is defined without a declaration. This should catch cases were we've
defined a function but forgot to put it in a header. In that case it
is either only used within one file so we should make it static or we
should declare it in a header.

The following changes where made to fix problems:

• Some functions were made static

• cogl-path.h (the one containing the 1.0 API) was split into two
  files, one defining the functions and one defining the enums so that
  cogl-path.c can include the enum and function declarations from the
  2.0 API as well as the function declarations from the 1.0 API.

• cogl2-clip-state has been removed. This only had one experimental
  function called cogl_clip_push_from_path but as this is unstable we
  might as well remove it favour of the equivalent cogl_framebuffer_*
  API.

• The GLX, SDL and WGL winsys's now have a private header to define
  their get_vtable function instead of directly declaring in the C
  file where it is called.

• All places that were calling COGL_OBJECT_DEFINE need to have the
  cogl_is_whatever function declared so these have been added either
  as a public function or in a private header.

• Some files that were not including the header containing their
  function declarations have been fixed to do so.

• Any unused error quark functions have been removed. If we later want
  them we should add them back one by one and add a declaration for
  them in a header.

• _cogl_is_framebuffer has been renamed to cogl_is_framebuffer and
  made a public function with a declaration in cogl-framebuffer.h

• Similarly for CoglOnscreen.

• cogl_vdraw_indexed_attributes is called
  cogl_framebuffer_vdraw_indexed_attributes in the header. The
  definition has been changed to match the header.

• cogl_index_buffer_allocate has been removed. This had no declaration
  and I'm not sure what it's supposed to do.

• CoglJournal has been changed to use the internal CoglObject macro so
  that it won't define an exported cogl_is_journal symbol.

• The _cogl_blah_pointer_from_handle functions have been removed.
  CoglHandle isn't used much anymore anyway and in the few places
  where it is used I think it's safe to just use the implicit cast
  from void* to the right type.

• The test-utils.h header for the conformance tests explicitly
  disables the -Wmissing-declaration option using a pragma because all
  of the tests declare their main function without a header. Any
  mistakes relating to missing declarations aren't really important
  for the tests.

• cogl_quaternion_init_from_quaternion and init_from_matrix have been
  given declarations in cogl-quaternion.h

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2012-03-06 18:45:44 +00:00
Robert Bragg
be237cc2b7 renderer: Adds getters/setters for driver preference
This adds api for explicitly choosing what underlying driver cogl should
use internally for rendering as well as api for querying back what
driver is actually in use.

Reviewed-by: Neil Roberts <neil@linux.intel.com>
2012-02-24 14:42:31 +00:00
Robert Bragg
680f63a48c Remove all internal includes of cogl.h
The cogl.h header is meant to be the public header for including the 1.x
api used by Clutter so we should stop using that as a convenient way to
include all likely prototypes and typedefs. Actually we already do a
good job of listing the specific headers we depend on in each of the .c
files we have so mostly this patch just strip out the redundant
includes for cogl.h with a few fixups where that broke the build.

Reviewed-by: Neil Roberts <neil@linux.intel.com>
2012-02-20 23:12:45 +00:00
Robert Bragg
6b7af18313 renderer: fix s/contraint/constraint/ typo
The recent patch to add an api for explicitly constraining how a
renderer backend is chosen had a typo which this patch fixes.

Reviewed-by: Neil Roberts <neil@linux.intel.com>
2012-02-08 17:00:25 +00:00
Robert Bragg
a8513c1d77 renderer: Adds api to add/remove selection constraints
This allows applications to specify certain constraints that feed into
the process of selecting a CoglRenderer backend. For example
applications might depend on x11 for handling input and so they require
a backend that's also based on x11.
2012-01-16 18:27:19 +00:00
Neil Roberts
181b875a3d xlib: Internally retrieve XEvents
Previously we relied on the application to send all X events through
Cogl using cogl_xlib_renderer_handle_event. This breaks the
abstraction that an application shouldn't need to know what winsys
Cogl is using. Now that we have main loop integreation in Cogl, the
Xlib-based winsys's can report that Cogl needs to block on the file
descriptor of the X connection and it can manually handle the
events.

The event retrieval can be disabled by an application if it calls the
new cogl_xlib_renderer_set_event_retrieval_enabled() function. The
event retrieval will also automatically be disabled if the application
sets a foreign display.

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2012-01-05 13:40:24 +00:00
Robert Bragg
9a82b9d21b build: removes unused variable
Simply removes an unused variable to avoid a compile time warning
2012-01-04 19:32:41 +00:00
Neil Roberts
bdcbb8af4d Update the SDL winsys
The SDL winsys was missing a few minor features, such as the
implementation. This patch adds that in.

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2011-12-14 16:45:17 +00:00
Neil Roberts
ff5bfc4a86 Rename the EGL_X11 winsys to EGL_XLIB
Eventually we might want to have an XCB-based EGL winsys. We already
have xlib-specific API in CoglRenderer (eg, to set a foreign display)
so the application needs to be able to specifically select between XCB
and XLIB.

This also removes the POWERVR part while renaming
COGL_HAS_EGL_PLATFORM_POWERVR_X11_SUPPORT to
COGL_HAS_EGL_PLATFORM_XLIB_SUPPORT because the winsys is equally
applicable to Mesa.

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2011-12-14 16:40:26 +00:00
Rob Bradford
6e37cebc7a renderer: Make COGL_RENDERER / COGL_DRIVER env. variables case insensitive
This will make it much more user friendly :-)

Reviewed-by: Neil Roberts <neil@linux.intel.com>
2011-12-09 17:57:10 +00:00
Neil Roberts
a1e1527b69 Add a separate winsys vtable for each EGL platform
Instead of just having an "EGL" renderer, there is now a separate
winsys for each platform. Currently they just directly copy the vtable
for the EGL platform so it is still only possible to have one EGL
platform compiled into Cogl. However the intention is that the
winsys-specific code for each platform will be moved into override
functions in the corresponding platform winsys.

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2011-12-08 17:38:25 +00:00
Robert Bragg
09520a7d61 renderer: don't re-connect for display check
This ensure that cogl_renderer_check_onscreen_template() doesn't call
winsys->renderer_connect() if the renderer has already been connected
as that can fail with some backends.

Reviewed-by: Neil Roberts <neil@linux.intel.com>
2011-12-07 15:53:05 +00:00
Robert Bragg
c2729e4ea8 build: don't inc egl headers for non EGL builds
For example when building on windows we don't want to require EGL
headers when compiling cogl-renderer.c or cogl-texture-2d.c so we make
sure not to include cogl-winsys-egl-private.h if we aren't supporting
EGL.

Reviewed-by: Neil Roberts <neil@linux.intel.com>
2011-11-28 23:19:35 +00:00
Chun-wei Fan
91f91dc678 cogl-renderer.c: Fix includes
Only include cogl-xlib-renderer.h when XLIB support is available

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2011-11-14 18:37:57 +00:00
Zan Dobersek
d8c47e25f2 Remove inclusion of Xlib headers in Cogl headers
Xlib headers define many trivially named objects which can later cause
name collision problems when only cogl.h header is included in a program
or library. Xlib headers are now only included through including the
standalone header cogl-xlib.h.

https://bugzilla.gnome.org/show_bug.cgi?id=661174

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2011-11-01 15:55:53 +00:00
Robert Bragg
b72f255c0a Start to reduce dependence on glib
Since we've had several developers from admirable projects say they
would like to use Cogl but would really prefer not to pull in
gobject,gmodule and glib as extra dependencies we are investigating if
we can get to the point where glib is only an optional dependency.
Actually we feel like we only make minimal use of glib anyway, so it may
well be quite straightforward to achieve this.

This adds a --disable-glib configure option that can be used to disable
features that depend on glib.

Actually --disable-glib doesn't strictly disable glib at this point
because it's more helpful if cogl continues to build as we make
incremental progress towards this.

The first use of glib that this patch tackles is the use of
g_return_val_if_fail and g_return_if_fail which have been replaced with
equivalent _COGL_RETURN_VAL_IF_FAIL and _COGL_RETURN_IF_FAIL macros.

Reviewed-by: Neil Roberts <neil@linux.intel.com>
2011-11-01 12:03:02 +00:00
Damien Lespiau
c36652a4c3 renderer: Add cogl_renderer_get_n_fragment_texture_units()
Add a method on the renderer to know how many texture image units are
accessible from fragment shaders.

https://bugzilla.gnome.org/show_bug.cgi?id=657347

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2011-09-05 17:54:46 +01:00
Robert Bragg
2ac4002084 cogl: Add support for reading a cogl.conf config file
When cogl initializes we now check for a cogl/cogl.conf in any of the
system config dirs (determined using $XDG_CONFIG_DIRS on linux) we then
also check the user's config directory (determined using XDG_CONFIG_HOME
on linux) for a cogl/cogl.conf file. Options specified in the user
config file have priority over the system config options.

The config file has an .ini style syntax with a mandatory [global]
section and we currently understand 3 keynames: COGL_DEBUG, COGL_DRIVER
and COGL_RENDERER which have the same semantics as the corresponding
environment variables.

Options set using the environment variables have priority over options
set in the config files. To allow users to undo the enabling of debug
options in config files this patch also adds a check for COGL_NO_DEBUG
environment variable which will disable the specified options which may
have been enabled in config files.

Reviewed-by: Neil Roberts <neil@linux.intel.com>
2011-08-12 15:28:42 +01:00
Neil Roberts
d259a87602 Don't use the 'NULL' GModule to resolve GL symbols
Previously, _cogl_get_proc_address had a fallback to resolve the
symbol using g_module_open(NULL) to get the symbol from anywhere in
the address space. The EGL backend ends up using this on some drivers
because eglGetProcAddress isn't meant to return a pointer for core
functions. This causes problems if something in the process is linking
against a different GL library, for example Cairo may be linking
against libGL itself. In this case it may end up resolving symbols
from the GL library even if GLES is being used.

This patch removes the fallback. The EGL version now has its own
fallback instead which passes the existing libgl_module from the
renderer to g_module_symbol so that it should only get symbols from
that library or its dependency chain. The GLX and WGL winsys only call
glXGetProcAddress and wglGetProcAddress. The stub winsys does however
continue using the global symbol lookup.

The internal _cogl_get_proc_address function has been renamed to
_cogl_renderer_get_proc_address because it needs a connected renderer
to work so it could be considered to be a renderer method. The pointer
to the renderer is passed down to the winsys backends so that it can
use the data attached to the renderer to get the module pointers.

https://bugzilla.gnome.org/show_bug.cgi?id=655412

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2011-07-27 16:10:02 +01:00
Neil Roberts
03c4b20931 Specify the full filename when g_module_open'ing the GL library
Instead of using g_module_build_path with the short name of the GL
library (eg, "GL") and relying on glib to add the suffix and prefix,
the configure script now directly encodes the full name including the
version number (eg, "libGL.so.1"). This is necessary because distros
don't always install the non-versioned suffix for the library.

The GLES libraries are left without the version suffix because it's
not clear what should be placed here and I can't find any
documentation from Khronos to clarify this. Mesa seems to install a
file called libGLESv2.so.2 but the IMG SDK doesn't install any
versioned library. There is an example of dynamically loading
libGLESv2 in the Chromium source code and that does not use the
version suffix even though it does use the version suffix for GL. This
implies that it's at least fairly normal to load the unversioned name
for GLES.

https://bugzilla.gnome.org/show_bug.cgi?id=654593
2011-07-19 15:12:10 +01:00
Neil Roberts
b2e735ff7f Dynamically load the GL or GLES library
The GL or GLES library is now dynamically loaded by the CoglRenderer
so that it can choose between GL, GLES1 and GLES2 at runtime. The
library is loaded by the renderer because it needs to be done before
calling eglInitialize. There is a new environment variable called
COGL_DRIVER to choose between gl, gles1 or gles2.

The #ifdefs for HAVE_COGL_GL, HAVE_COGL_GLES and HAVE_COGL_GLES2 have
been changed so that they don't assume the ifdefs are mutually
exclusive. They haven't been removed entirely so that it's possible to
compile the GLES backends without the the enums from the GL headers.

When using GLX the winsys additionally dynamically loads libGL because
that also contains the GLX API. It can't be linked in directly because
that would probably conflict with the GLES API if the EGL is
selected. When compiling with EGL support the library links directly
to libEGL because it doesn't contain any GL API so it shouldn't have
any conflicts.

When building for WGL or OSX Cogl still directly links against the GL
API so there is a #define in config.h so that Cogl won't try to dlopen
the library.

Cogl-pango previously had a #ifdef to detect when the GL backend is
used so that it can sneakily pass GL_QUADS to
cogl_vertex_buffer_draw. This is now changed so that it queries the
CoglContext for the backend. However to get this to work Cogl now
needs to export the _cogl_context_get_default symbol and cogl-pango
needs some extra -I flags to so that it can include
cogl-context-private.h
2011-07-11 12:57:38 +01:00
Robert Bragg
89562dda73 work towards consistent platform file/symbol naming
we've got into a bit of a mess with how we name platform specific
symbols and files, so this is a first pass at trying to tidy that up.

All platform specific symbols should be named like
cogl_<platform>_symbol_name and similarly files should be named like
cogl-<platform>-filename.c

This patch tackles the X11 specific renderer/display APIs as a start.

Signed-off-by: Neil Roberts <neil@linux.intel.com>
2011-06-30 14:34:33 +01:00
Robert Bragg
3b64a439f0 replace public native_event APIs with typesafe APIs
This adds Xlib and Win32 typesafe replacements for
cogl_renderer_handle_native_event, cogl_renderer_add_native_filter,
cogl_renderer_remove_native_filter. The old functions are kept as an
implementation detail so we can share code.

Signed-off-by: Neil Roberts <neil@linux.intel.com>
2011-06-30 14:33:13 +01:00
Robert Bragg
b3a105c576 renderer: Expose winsys ID setter/getters
This adds API to let you override the choice of Cogl's winsys backend.
Previously it was only possible to override the winsys using the
COGL_RENDERER environment variable, but it's useful for something like
Clutter to be able to control the winsys via API without needing
environment variable tricks. This also adds API to query back the
winsys chosen by Cogl, in case you don't set an explicit override.

Signed-off-by: Neil Roberts <neil@linux.intel.com>
2011-06-30 14:33:11 +01:00
Robert Bragg
a1234ee8d1 Add internal _cogl_init() function
This adds a _cogl_init function for Cogl that we expect to be the first
thing called before anything else is done with Cogl. It's not a public
API so it's expected that all entry points for Cogl that might be the
first function used should call _cogl_init().

We currently call _cogl_init() in these functions:
  cogl_renderer_new
  cogl_display_new
  cogl_context_new
  cogl_android_set_native_window

_cogl_init() can be called multiple times, and only the first call has
any affect.

For example _cogl_init() gives us a place check and parse the COGL_DEBUG
environment variable.

Since we don't have any need to parse command line arguments (we can
always get user configuration options from the environment) our init
function doesn't require argc/argv pointers.

By saying up front that we aren't interested in command line arguments
that means we can avoid the mess that is GOption based library
initialization which is extremely fragile due to its lack of dependency
tracking between modules.

Signed-off-by: Neil Roberts <neil@linux.intel.com>
2011-06-30 14:33:11 +01:00
Robert Bragg
b934859dde renderer: set winsys on renderer before ->renderer_connect
When iterating through all the possible window systems trying to find
one we can successfully connect we now associated the current winsys
vtable with the renderer before calling winsys->renderer_connect in case
the implementation calls some other Cogl API that expects to be able to
determine the current winsys. For example calling _cogl_get_proc_address
when querying winsys extensions as part of a successful connect will
need to get at the current winsys vtable.
2011-06-01 20:44:42 +01:00
Robert Bragg
60b25615fd Add _cogl_egl_texture_2d_new_from_image API
This adds an internal texture_2d constructor that can wrap an EGLImage
as a CoglTexture2D. The plan is to utilize this for texture-from-pixmap
support with EGL as well as creating textures from wayland buffers.
2011-06-01 20:44:42 +01:00
Robert Bragg
b380fed23d Make stub winsys into a proper winsys backend
Instead of the stub winsys being a special case set of #ifdef'd code
used when COGL_HAS_FULL_WINSYS wasn't defined, the stub winsys now
implements a CoglWinsysVtable like all other winsys backends (it's just
that everything is a NOP). This way we can get rid of the
COGL_HAS_FULL_WINSYS define and also the stub winsys can be runtime
selected whereas before it was incompatible with all other winsys
backends.
2011-06-01 20:44:41 +01:00
Neil Roberts
6788c80342 Add a WGL winsys
This adds a full winsys to handle WGL and Win32.
2011-05-10 17:58:41 +01:00
Robert Bragg
31ee65784d winsys: Expose environment variable to choose winsys
This makes it possible to override the winsys that cogl uses by setting
the COGL_RENDERER environment variable e.g. to "GLX" or "EGL"
2011-05-05 14:46:01 +01:00
Robert Bragg
dc7383b714 Add a vtable of indirection to the winsys code
So that we can dynamically select what winsys backend to use at runtime
we need to have some indirection to how code accesses the winsys instead
of simply calling _cogl_winsys* functions that would collide if we
wanted to compile more than one backend into Cogl.
2011-05-05 14:46:01 +01:00
Neil Roberts
f6ae9decaa cogl-renderer: Move the XEvent filters to be generic for all renderers
Instead of having cogl_renderer_xlib_add_filter and friends there is
now cogl_renderer_add_native_filter which can be used regardless of
the backend. The callback function for the filter now just takes a
void pointer instead of an XEvent pointer which should be interpreted
differently depending on the backend. For example, on Xlib it would
still be an XEvent but on Windows it could be a MSG. This simplifies
the code somewhat because the _cogl_xlib_add_filter no longer needs to
have its own filter list when a stub renderer is used because there is
always a renderer available.

cogl_renderer_xlib_handle_event has also been renamed to
cogl_renderer_handle_native_event. This just forwards the event on to
all of the listeners. The backend renderer is expected to register its
own event filter if it wants to process the events in some way.
2011-04-20 18:17:06 +01:00
Robert Bragg
d40cdfa3e1 Moves all GLX code down from Clutter to Cogl
This migrates all the GLX window system code down from the Clutter
backend code into a Cogl winsys. Moving OpenGL window system binding
code down from Clutter into Cogl is the biggest blocker to having Cogl
become a standalone 3D graphics library, so this is an important step in
that direction.
2011-04-11 17:54:36 +01:00
Robert Bragg
bcd97f35ea Adds renderer,display,onscreen-template and swap-chain stubs
As part of the process of splitting Cogl out as a standalone graphics
API we need to introduce some API concepts that will allow us to
initialize a new CoglContext when Clutter isn't there to handle that for
us...

The new objects roughly in the order that they are (optionally) involved
in constructing a context are: CoglRenderer, CoglOnscreenTemplate,
CoglSwapChain and CoglDisplay.

Conceptually a CoglRenderer represents a means for rendering.  Cogl
supports rendering via OpenGL or OpenGL ES 1/2.0 and those APIs are
accessed through a number of different windowing APIs such as GLX, EGL,
SDL or WGL and more. Potentially in the future Cogl could render using
D3D or even by using libdrm and directly banging the hardware. All these
choices are wrapped up in the configuration of a CoglRenderer.

Conceptually a CoglDisplay represents a display pipeline for a renderer.
Although Cogl doesn't aim to provide a detailed abstraction of display
hardware, on some platforms we can give control over multiple display
planes (On TV platforms for instance video content may be on one plane
and 3D would be on another so a CoglDisplay lets you select the plane
up-front.)

Another aspect of CoglDisplay is that it lets us negotiate a display
pipeline that best supports the type of CoglOnscreen framebuffers we are
planning to create. For instance if you want transparent CoglOnscreen
framebuffers then we have to be sure the display pipeline wont discard
the alpha component of your framebuffers. Or if you want to use
double/tripple buffering that requires support from the display
pipeline.

CoglOnscreenTemplate and CoglSwapChain are how we describe our default
CoglOnscreen framebuffer configuration which can affect the
configuration of the display pipeline.

The default/simple way we expect most CoglContexts to be constructed
will be via something like:

 if (!cogl_context_new (NULL, &error))
   g_error ("Failed to construct a CoglContext: %s", error->message);

Where that NULL is for an optional "display" parameter and NULL says to
Cogl "please just try to do something sensible".

If you want some more control though you can manually construct a
CoglDisplay something like:

 display = cogl_display_new (NULL, NULL);
 cogl_gdl_display_set_plane (display, plane);
 if (!cogl_display_setup (display, &error))
   g_error ("Failed to setup a CoglDisplay: %s", error->message);

And in a similar fashion to cogl_context_new() you can optionally pass
a NULL "renderer" and/or a NULL "onscreen template" so Cogl will try to
just do something sensible.

If you need to change the CoglOnscreen defaults you can provide a
template something like:
  chain = cogl_swap_chain_new ();
  cogl_swap_chain_set_has_alpha (chain, TRUE);
  cogl_swap_chain_set_length (chain, 3);

  onscreen_template = cogl_onscreen_template_new (chain);
  cogl_onscreen_template_set_pixel_format (onscreen_template,
                                           COGL_PIXEL_FORMAT_RGB565);

  display = cogl_display_new (NULL, onscreen_template);
  if (!cogl_display_setup (display, &error))
    g_error ("Failed to setup a CoglDisplay: %s", error->message);
2011-04-11 17:54:35 +01:00