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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)
206 lines
7.3 KiB
C
206 lines
7.3 KiB
C
/*
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* Cogl
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*
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* An object oriented GL/GLES Abstraction/Utility Layer
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*
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* Copyright (C) 2007,2008,2009 Intel Corporation.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*
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*
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*/
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#ifndef __COGL_TEXTURE_DRIVER_H
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#define __COGL_TEXTURE_DRIVER_H
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typedef struct _CoglTextureDriver CoglTextureDriver;
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struct _CoglTextureDriver
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{
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/*
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* A very small wrapper around glGenTextures() that ensures we default to
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* non-mipmap filters when creating textures. This is to save some memory as
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* the driver will not allocate room for the mipmap tree.
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*/
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GLuint
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(* gen) (CoglContext *ctx,
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GLenum gl_target,
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CoglPixelFormat internal_format);
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/*
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* This sets up the glPixelStore state for an upload to a destination with
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* the same size, and with no offset.
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*/
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/* NB: GLES can't upload a sub region of pixel data from a larger source
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* buffer which is why this interface is limited. The GL driver has a more
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* flexible version of this function that is uses internally */
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void
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(* prep_gl_for_pixels_upload) (CoglContext *ctx,
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int pixels_rowstride,
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int pixels_bpp);
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/*
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* This uploads a sub-region from source_bmp to a single GL texture
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* handle (i.e a single CoglTexture slice)
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*
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* It also updates the array of tex->first_pixels[slice_index] if
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* dst_{x,y} == 0
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*
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* The driver abstraction is in place because GLES doesn't support the pixel
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* store options required to source from a subregion, so for GLES we have
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* to manually create a transient source bitmap.
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*
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* XXX: sorry for the ridiculous number of arguments :-(
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*/
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void
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(* upload_subregion_to_gl) (CoglContext *ctx,
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GLenum gl_target,
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GLuint gl_handle,
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CoglBool is_foreign,
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int src_x,
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int src_y,
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int dst_x,
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int dst_y,
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int width,
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int height,
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CoglBitmap *source_bmp,
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GLuint source_gl_format,
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GLuint source_gl_type);
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/*
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* Replaces the contents of the GL texture with the entire bitmap. On
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* GL this just directly calls glTexImage2D, but under GLES it needs
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* to copy the bitmap if the rowstride is not a multiple of a possible
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* alignment value because there is no GL_UNPACK_ROW_LENGTH
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*/
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void
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(* upload_to_gl) (CoglContext *ctx,
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GLenum gl_target,
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GLuint gl_handle,
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CoglBool is_foreign,
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CoglBitmap *source_bmp,
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GLint internal_gl_format,
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GLuint source_gl_format,
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GLuint source_gl_type);
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/*
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* Replaces the contents of the GL texture with the entire bitmap. The
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* width of the texture is inferred from the bitmap. The height and
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* depth of the texture is given directly. The 'image_height' (which
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* is the number of rows between images) is inferred by dividing the
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* height of the bitmap by the depth.
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*/
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void
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(* upload_to_gl_3d) (CoglContext *ctx,
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GLenum gl_target,
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GLuint gl_handle,
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CoglBool is_foreign,
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GLint height,
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GLint depth,
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CoglBitmap *source_bmp,
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GLint internal_gl_format,
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GLuint source_gl_format,
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GLuint source_gl_type);
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/*
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* This sets up the glPixelStore state for an download to a destination with
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* the same size, and with no offset.
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*/
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/* NB: GLES can't download pixel data into a sub region of a larger
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* destination buffer, the GL driver has a more flexible version of
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* this function that it uses internally. */
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void
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(* prep_gl_for_pixels_download) (CoglContext *ctx,
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int image_width,
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int pixels_rowstride,
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int pixels_bpp);
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/*
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* This driver abstraction is needed because GLES doesn't support
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* glGetTexImage (). On GLES this currently just returns FALSE which
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* will lead to a generic fallback path being used that simply
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* renders the texture and reads it back from the framebuffer. (See
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* _cogl_texture_draw_and_read () )
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*/
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CoglBool
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(* gl_get_tex_image) (CoglContext *ctx,
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GLenum gl_target,
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GLenum dest_gl_format,
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GLenum dest_gl_type,
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uint8_t *dest);
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/*
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* It may depend on the driver as to what texture sizes are supported...
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*/
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CoglBool
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(* size_supported) (CoglContext *ctx,
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GLenum gl_target,
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GLenum gl_intformat,
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GLenum gl_format,
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GLenum gl_type,
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int width,
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int height);
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CoglBool
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(* size_supported_3d) (CoglContext *ctx,
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GLenum gl_target,
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GLenum gl_format,
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GLenum gl_type,
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int width,
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int height,
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int depth);
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/*
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* This driver abstraction is needed because GLES doesn't support setting
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* a texture border color.
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*/
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void
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(* try_setting_gl_border_color) (CoglContext *ctx,
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GLuint gl_target,
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const GLfloat *transparent_color);
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/*
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* It may depend on the driver as to what texture targets may be used when
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* creating a foreign texture. E.g. OpenGL supports ARB_texture_rectangle
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* but GLES doesn't
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*/
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CoglBool
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(* allows_foreign_gl_target) (CoglContext *ctx,
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GLenum gl_target);
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/*
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* glGenerateMipmap semantics may need to be emulated for some
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* drivers. E.g. by enabling auto mipmap generation an re-loading a
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* number of known texels.
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*/
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void
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(* gl_generate_mipmaps) (CoglContext *ctx,
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GLenum texture_target);
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/*
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* The driver may impose constraints on what formats can be used to store
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* texture data read from textures. For example GLES currently only supports
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* RGBA_8888, and so we need to manually convert the data if the final
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* destination has another format.
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*/
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CoglPixelFormat
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(* find_best_gl_get_data_format) (CoglContext *context,
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CoglPixelFormat format,
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GLenum *closest_gl_format,
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GLenum *closest_gl_type);
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};
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#endif /* __COGL_TEXTURE_DRIVER_H */
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