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03-08-2006, 02:16 AM
Hi, I searched on this forum and saw a post on how the GL_SGIS_texture_edge_clamp extension is commonly misnamed by vendors as GL_EXT_texture_edge_clamp. If you don't mind me asking, is this the same case with the following extensions as well:?

GL_SGIS_texture_lod - GL_EXT_texture_lod
and
GL_EXT_color_table - GL_SGI_color_table

Thanks,
Josh

mikael_aronsson
03-08-2006, 06:22 AM
I think the GL_EXT_... is when they get an "official" status as an OpenGL extension (part of the OpenGL spec), the other names is the original extension name that depends on the vendor that implemented it... or... ?

03-08-2006, 06:37 AM
Yeah, I thought so too, though yet both the GL_EXT_texture_lod and GL_EXT_color_table extensions do not exist in the extension registry, only their SGI/SGIS counterparts do. For other extensions that have been upgraded and renamed they will usually say something in the Revision History like,

0.2, 10/28/99 prbrown1: Renamed to ARB_texture_compression. Significant functional changes.

In fact, my NVIDIA card has both GL_SGIS_texture_lod and GL_EXT_texture_lod in the extensions string. Is this implying they are different?

Bob
03-08-2006, 02:25 PM
Originally posted by mikael_aronsson:
I think the GL_EXT_... is when they get an "official" status as an OpenGL extension (part of the OpenGL spec), the other names is the original extension name that depends on the vendor that implemented it... or... ? An extension is per definition something NOT in the core. The EXT name just indicates that multiple vendors supports the extensions, instead of a single vendor extension. ARB is the next step from EXT towards being in the core, but still an extension and still not in the core.



Originally posted by <Josh>:
Yeah, I thought so too, though yet both the GL_EXT_texture_lod and GL_EXT_color_table extensions do not exist in the extension registry, only their SGI/SGIS counterparts do. For other extensions that have been upgraded and renamed they will usually say something in the Revision History like,

0.2, 10/28/99 prbrown1: Renamed to ARB_texture_compression. Significant functional changes.

In fact, my NVIDIA card has both GL_SGIS_texture_lod and GL_EXT_texture_lod in the extensions string. Is this implying they are different? SGIS_texture_lod is a part of OpenGL 1.2 and EXT_color_table is a part of the imaging subset (optional part of the core, check extension string for ARB_imaging). Don't bother with these extensions as they have been a part of the core for 8 year or so now. Check for version number and for the imaging subset and use those functions instead.

It shouldn't matter whether SGIS_texture_lod is actually called EXT_texture_lod, or whatever. What should matter is that the 1.2 specification includes these functions, and that's what you should prefer to use.