Wine and Linux: Perfect mode possible with Intel IGP
 

Just a heads up for anyone using integrated intel drivers running on 12.0.0 MESA or higher, with a little trick I was able to enable perfect rendering:

MESA_EXTENSION_OVERRIDE='GL_ATI_fragment_shader' wine il2fb.exe

Seems GL_ATI_fragment_shader was implemented in some version of mesa 12 now and I could set Water=1 and had no glitches on Haswell HD 4600, TypeClouds=1 looked ok too.

Normally overriding means you tell the application your card has a feature it doesn't have , so something should be missing, but increased view distance, shorelines , transparent and water wave effects looked ok.

il2 seems to look for the ATI or NV extensions to turn on perfect rendering, I first tried NV extensions but it was a mass glitch fest until I researched if perfect would be possible on newer AMD cards like rx 470 / 480 and searched for their GL extension.
Linux and intel gaming , seems I am in the 1% of the 1% :-D

Thanks for the heads up. I have run IL2 with wine before and probably will again as I have never spent a dime on windoze and never will.

Also many thanks for this information. I'm going to give it a go!