This adds a new CoglDriver for GL 3 called COGL_DRIVER_GL3. When
requested, the GLX, EGL and SDL2 winsyss will set the necessary
attributes to request a forward-compatible core profile 3.1 context.
That means it will have no deprecated features.
To simplify the explosion of checks for specific combinations of
context->driver, many of these conditionals have now been replaced
with private feature flags that are checked instead. The GL and GLES
drivers now initialise these private feature flags depending on which
driver is used.
The fixed function backends now explicitly check whether the fixed
function private feature is available which means the GL3 driver will
fall back to always using the GLSL progend. Since Rob's latest patches
the GLSL progend no longer uses any fixed function API anyway so it
should just work.
The driver is currently lower priority than COGL_DRIVER_GL so it will
not be used unless it is specificly requested. We may want to change
this priority at some point because apparently Mesa can make some
memory savings if a core profile context is used.
In GL 3, getting the combined extensions string with glGetString is
deprecated so this patch changes it to use glGetStringi to build up an
array of extensions instead. _cogl_context_get_gl_extensions now
returns this array instead of trying to return a const string. The
caller is expected to free the array.
Some issues with this patch:
• GL 3 does not support GL_ALPHA format textures. We should probably
make this a feature flag or something. Cogl uses this to render text
which currently just throws a GL error and breaks so it's pretty
important to do something about this before considering the GL3
driver to be stable.
• GL 3 doesn't support client side vertex buffers. This probably
doesn't matter because CoglBuffer won't normally use malloc'd
buffers if VBOs are available, but it might but worth making
malloc'd buffers a private feature and forcing it not to use them.
• GL 3 doesn't support the default vertex array object. This patch
just makes it create and bind a single non-default vertex array
object which gets used just like the normal default object. Ideally
it would be good to use vertex array objects properly and attach
them to a CoglPrimitive to cache the state.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit 66c9db993595b3a22e63f4c201ea468bc9b88cb6)
This adds a new "fixed-arbfp" progend so we now have 3 distinct ways of
setting up the state of a pipeline:
» fixed; where the vertex and fragment processing are implemented
using fixed function opengl apis.
» fixed-arbfp; where vertex processing is implemented using fixed
function opengl apis but fragment processing is implemented
using the ARB Fragment Processing language.
» glsl; there vertex and fragment processing are both implemented
using glsl.
This means we avoid unusual, combinations such as glsl for vertex
processing and arbfp for fragment processing, and also avoid pairing
fixed-function vertex processing with glsl fragment processing which we
happen to know hits some awkward code paths in Mesa that lead to poor
performance.
As part of this change, the progend now implies specific vertend and
fragend choices so instead of associating a vertend and fragend with a
pipeline we now just associate a progend choice.
When flushing a pipeline and choosing what progend to use, we now call a
progend->start() method that is able to determine if the vertend and
fragend together will be able to handle the given pipeline so the
vertend and fragend ->start() methods no longer need to return a boolean
status.
Since we now don't need to support glsl used in conjunction with fixed
function this will allow us to avoid ever using OpenGL builtin attribute
names, though this patch doesn't change that yet.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit cec381f50c7a2f2186bd4a8c5f38fecd5f099075)
As part of an effort towards being able to write non-opengl based
backends for Cogl this moves most of the opengl specific code under
drivers/gl. drivers/gl and drivers/gles have been moved to
drivers/gl/gl and drivers/gl/es respectively.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 7dc482facb0a265c7f48660079e7e12dd7a2813e)
