Hello experts
im beginner in the world of opengl , i do have experience in wrappers engines / renders like
Ogre , cocos2d-x , irrlicht .
now i like to learn the infrastructure and work with pure openGL to learn .
so is i like to build simple app
that could compile in PC,mac ,Linux and mobile ( openes ) what shell i do , do i need SDL ?
is there other cross platform alternatives ?

For desktop there are many possibilities. There is SDL, SFML and GLFW out of the top of my head. For Windows you will also want GLEW or something like that.

You could also do it by hand without any of those libraries (after all their key job is just to create a window and an OpenGL context for that window), but that would mean writing a lot of boring platform-dependent code.

I'm not familiar enough with mobile platform to give solid advice here.

Thanks !
i was looking for combining also mobile