I am trying to use DXT5 compressed format. I load this with GL_COMPRESSED_RGBA_S3TC_DXT5_EXT, but I can't find any option for sRGB. (for instance, non-compressed textures use GL_SRGB8_ALPHA8)

I think https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_sRGB.txt adds the compressed sRGB formats  

50 minutes ago, Hodgman said:

I think https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_sRGB.txt adds the compressed sRGB formats  

Thanks for the answer. I looked into that. Is it not actually EXT_texture_compression_s3tc_srgb?

Edit: maybe that's for OpenGL ES. Very confusing

17 hours ago, Ed Welch said:

Thanks for the answer. I looked into that. Is it not actually EXT_texture_compression_s3tc_srgb?

Edit: maybe that's for OpenGL ES. Very confusing

Look at issue 9:

Quote

9) Should S3TC compressed sRGB formats be supported?

RESOLVED:  Yes, but only if EXT_texture_compression_s3tc is also
advertised.  For competitive reasons, we expect OpenGL will need
an S3TC-based block compression format for sRGB data.

Rather than expose a separate "sRGB_compression" extension,
it makes more sense to specify a dependency between
EXT_texture_compression_s3tc and this extension such that when
BOTH extensions are exposed, the GL_COMPRESSED_SRGB*_S3TC_DXT*_EXT
tokens are accepted.

So if you have both EXT_texture_sRGB and EXT_texture_compression_s3tc you should have support for compressed sRGB textures. Looking in glext.h it looks like GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT is the one you want.