I have experience with game programming mainly in allegro or drawing everything on native windows (No graphic libraries). Now I am interested in learning OpenGL for game development. I have found several OpenGL tutorials, but right now I only want to set up my environment so that I can be able to open windows and draw on them. I use Mac OS, but I am very interested in making all of my code as cross-platform as possible, so I would like to know how to set up (download, install, make a hello world kind of thing) OpenGL on a mac, but preferably without using Xcode or Apple depending stuff. I already checked to see whether my mac supports newer OpenGL and it does, so I will try to use the most recent standards.
I am ok with writing makefiles to link libraries and that kind of stuff that usually Xcode does for the sake of portability.
I keep wondering if I will need to always write some platform specific code when creating a mainly cross-platform game... and my guess is I will, but I want to minimize it. Anyway, I would like to know your advice for me. I hope my question is clear, but feel free to ask any detail you might need to know.