mutter/cogl/cogl-internal.h
Neil Roberts ff11a2b207 Use GL_ARB_texture_swizzle to emulate GL_ALPHA textures
The core profile of GL3 has removed support for component-alpha
textures. Previously the GL3 driver would just ignore this and try to
create them anyway. This would generate a GL error on Mesa.

To fix this the GL texture driver will now create a GL_RED texture
when GL_ALPHA textures are not supported natively. It will then set a
texture swizzle using the GL_ARB_texture_swizzle extension so that the
alpha component will be taken from the red component of the texture.
The swizzle is part of the texture object state so it only needs to be
set once when the texture is created.

The ‘gen’ virtual function of the texture driver has been changed to
also take the internal format as a parameter. The GL driver will now
set the swizzle as appropriate here.

The GL3 driver now reports an error if the texture swizzle extension
is not available because Cogl can't really work properly without out
it. The extension is part of GL 3.3 so it is quite likely that it has
wide support from drivers. Eventually we could get rid of this
requirement if we have our own GLSL front-end and we could generate
the swizzle ourselves.

When uploading or downloading texture data to or from a
component-alpha texture, we can no longer rely on GL to do the
conversion. The swizzle doesn't have any effect on the texture data
functions. In these cases Cogl will now force an intermediate buffer
to be used and it will manually do the conversion as it does for the
GLES drivers.

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

(cherry picked from commit 32bacf81ebaa3be21a8f26af07d8f6eed6607652)
2013-01-22 17:48:04 +00:00

134 lines
4.5 KiB
C

/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2007,2008,2009,2010 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_INTERNAL_H
#define __COGL_INTERNAL_H
#include "cogl-bitmask.h"
#include "cogl-gl-header.h"
#ifdef COGL_HAS_XLIB_SUPPORT
#include <X11/Xutil.h>
#endif
#ifdef COGL_GL_DEBUG
const char *
_cogl_gl_error_to_string (GLenum error_code);
#define GE(ctx, x) G_STMT_START { \
GLenum __err; \
(ctx)->x; \
while ((__err = (ctx)->glGetError ()) != GL_NO_ERROR) \
{ \
g_warning ("%s: GL error (%d): %s\n", \
G_STRLOC, \
__err, \
_cogl_gl_error_to_string (__err)); \
} } G_STMT_END
#define GE_RET(ret, ctx, x) G_STMT_START { \
GLenum __err; \
ret = (ctx)->x; \
while ((__err = (ctx)->glGetError ()) != GL_NO_ERROR) \
{ \
g_warning ("%s: GL error (%d): %s\n", \
G_STRLOC, \
__err, \
_cogl_gl_error_to_string (__err)); \
} } G_STMT_END
#else /* !COGL_GL_DEBUG */
#define GE(ctx, x) ((ctx)->x)
#define GE_RET(ret, ctx, x) (ret = ((ctx)->x))
#endif /* COGL_GL_DEBUG */
#define COGL_ENABLE_ALPHA_TEST (1<<1)
#define COGL_ENABLE_VERTEX_ARRAY (1<<2)
#define COGL_ENABLE_COLOR_ARRAY (1<<3)
void
_cogl_enable (unsigned long flags);
unsigned long
_cogl_get_enable (void);
void
_cogl_transform_point (const CoglMatrix *matrix_mv,
const CoglMatrix *matrix_p,
const float *viewport,
float *x,
float *y);
#define COGL_DRIVER_ERROR (_cogl_driver_error_quark ())
typedef enum { /*< prefix=COGL_DRIVER_ERROR >*/
COGL_DRIVER_ERROR_UNKNOWN_VERSION,
COGL_DRIVER_ERROR_INVALID_VERSION,
COGL_DRIVER_ERROR_NO_SUITABLE_DRIVER_FOUND,
COGL_DRIVER_ERROR_FAILED_TO_LOAD_LIBRARY
} CoglDriverError;
typedef enum
{
COGL_PRIVATE_FEATURE_TEXTURE_2D_FROM_EGL_IMAGE = 1L<<0,
COGL_PRIVATE_FEATURE_MESA_PACK_INVERT = 1L<<1,
COGL_PRIVATE_FEATURE_STENCIL_BUFFER = 1L<<2,
COGL_PRIVATE_FEATURE_OFFSCREEN_BLIT = 1L<<3,
COGL_PRIVATE_FEATURE_FOUR_CLIP_PLANES = 1L<<4,
COGL_PRIVATE_FEATURE_PBOS = 1L<<5,
COGL_PRIVATE_FEATURE_VBOS = 1L<<6,
COGL_PRIVATE_FEATURE_EXT_PACKED_DEPTH_STENCIL = 1L<<7,
COGL_PRIVATE_FEATURE_OES_PACKED_DEPTH_STENCIL = 1L<<8,
COGL_PRIVATE_FEATURE_TEXTURE_FORMAT_BGRA8888 = 1L<<9,
COGL_PRIVATE_FEATURE_UNPACK_SUBIMAGE = 1L<<10,
COGL_PRIVATE_FEATURE_SAMPLER_OBJECTS = 1L<<11,
COGL_PRIVATE_FEATURE_FIXED_FUNCTION = 1L<<12,
COGL_PRIVATE_FEATURE_READ_PIXELS_ANY_FORMAT = 1L<<13,
COGL_PRIVATE_FEATURE_ANY_GL = 1L<<14,
COGL_PRIVATE_FEATURE_ALPHA_TEST = 1L<<15,
COGL_PRIVATE_FEATURE_FORMAT_CONVERSION = 1L<<16,
COGL_PRIVATE_FEATURE_QUADS = 1L<<17,
COGL_PRIVATE_FEATURE_BLEND_CONSTANT = 1L<<18,
COGL_PRIVATE_FEATURE_QUERY_FRAMEBUFFER_BITS = 1L<<19,
COGL_PRIVATE_FEATURE_BUILTIN_POINT_SIZE_UNIFORM = 1L<<20,
COGL_PRIVATE_FEATURE_QUERY_TEXTURE_PARAMETERS = 1L<<21,
COGL_PRIVATE_FEATURE_ALPHA_TEXTURES = 1L<<22,
COGL_PRIVATE_FEATURE_TEXTURE_SWIZZLE = 1L<<23
} CoglPrivateFeatureFlags;
/* Sometimes when evaluating pipelines, either during comparisons or
* if calculating a hash value we need to tweak the evaluation
* semantics */
typedef enum _CoglPipelineEvalFlags
{
COGL_PIPELINE_EVAL_FLAG_NONE = 0
} CoglPipelineEvalFlags;
uint32_t
_cogl_driver_error_quark (void);
#endif /* __COGL_INTERNAL_H */