for some reason, my company use openGL with GLX on linux and with WGL under windows.
I can’t find any tutorial on how to code openGL with GLX, everything I can found is GL+ GLUT,
I wonder if anybody knows where I can found a GL+GLX tutorial.
Your company does that because that’s exactly the right thing to do, those are the equivalent interface APIs provided on those platforms. The only alternative is to abstract that away beneath a library someone else wrote to hide the platform specific details and that can have disadvantages.
You should probably get this book:
“OpenGL: Programming For The X Window System”
by Mark J. Kilgard
It’s a bit dated now but it will give you what you need. The most significant omission will probably be glXGetProcAddress, but you know about that now that I’ve told you :-).
glx sample at the middle of the page