Why only OGL ES?
I thought that you add texture format support for all OGL's. And just plug different APIs (which should be trivial). "Desktop" OGL have bigger requirements for texture support ?
Phoronix: Intel Merges ETC2 Texture Compression In Mesa
ETC2, the new royalty-free texture compression method that's required by OpenGL ES 3.0, now has support within mainline Mesa. However, for now this ETC2 support is limited to the Intel DRI driver...
http://www.phoronix.com/vr.php?view=MTI0NTc
Why only OGL ES?
I thought that you add texture format support for all OGL's. And just plug different APIs (which should be trivial). "Desktop" OGL have bigger requirements for texture support ?
Desktop OpenGL only has ETC2 texture support added in version 4.3.
They have a long way to go before reaching OpenGL 4.3.
So it's more practical to focus on OpenGL ES 3.0 as a target first.
Yeah, I couldn't find a standalone extension that would add just ETC2 to "normal" GL. The official one is the ES3 compatibility one which needs many other things too.