mutter/cogl/cogl-private.h
Neil Roberts 2616ae0fa9 Add a GL 3 driver
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)
2013-01-22 17:48:01 +00:00

102 lines
3.1 KiB
C

/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2010 Intel Corporation.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
*
*/
#ifndef __COGL_PRIVATE_H__
#define __COGL_PRIVATE_H__
#include <cogl/cogl-pipeline.h>
#include "cogl-context.h"
G_BEGIN_DECLS
CoglBool
_cogl_check_extension (const char *name, char * const *ext);
void
_cogl_clear (const CoglColor *color, unsigned long buffers);
void
_cogl_init (void);
void
_cogl_push_source (CoglPipeline *pipeline, CoglBool enable_legacy);
CoglBool
_cogl_get_enable_legacy_state (void);
/*
* _cogl_pixel_format_get_bytes_per_pixel:
* @format: a #CoglPixelFormat
*
* Queries how many bytes a pixel of the given @format takes.
*
* Return value: The number of bytes taken for a pixel of the given
* @format.
*/
int
_cogl_pixel_format_get_bytes_per_pixel (CoglPixelFormat format);
/*
* _cogl_pixel_format_has_aligned_components:
* @format: a #CoglPixelFormat
*
* Queries whether the ordering of the components for the given
* @format depend on the endianness of the host CPU or if the
* components can be accessed using bit shifting and bitmasking by
* loading a whole pixel into a word.
*
* XXX: If we ever consider making something like this public we
* should really try to think of a better name and come up with
* much clearer documentation since it really depends on what
* point of view you consider this from whether a format like
* COGL_PIXEL_FORMAT_RGBA_8888 is endian dependent. E.g. If you
* read an RGBA_8888 pixel into a uint32
* it's endian dependent how you mask out the different channels.
* But If you already have separate color components and you want
* to write them to an RGBA_8888 pixel then the bytes can be
* written sequentially regardless of the endianness.
*
* Return value: %TRUE if you need to consider the host CPU
* endianness when dealing with the given @format
* else %FALSE.
*/
CoglBool
_cogl_pixel_format_is_endian_dependant (CoglPixelFormat format);
/*
* COGL_PIXEL_FORMAT_CAN_HAVE_PREMULT(format):
* @format: a #CoglPixelFormat
*
* Returns TRUE if the pixel format can take a premult bit. This is
* currently true for all formats that have an alpha channel except
* COGL_PIXEL_FORMAT_A_8 (because that doesn't have any other
* components to multiply by the alpha).
*/
#define COGL_PIXEL_FORMAT_CAN_HAVE_PREMULT(format) \
(((format) & COGL_A_BIT) && (format) != COGL_PIXEL_FORMAT_A_8)
G_END_DECLS
#endif /* __COGL_PRIVATE_H__ */