Create an OpenGL context for an OpenGL window, and make it current.
Windows users new to OpenGL should note that, for historical reasons, GL
functions added after OpenGL version 1.1 are not available by default.
Those functions must be loaded at run-time, either with an OpenGL
extension-handling library or with SDL_GL_GetProcAddress() and its related
functions.
Create an OpenGL context for an OpenGL window, and make it current.
Windows users new to OpenGL should note that, for historical reasons, GL functions added after OpenGL version 1.1 are not available by default. Those functions must be loaded at run-time, either with an OpenGL extension-handling library or with SDL_GL_GetProcAddress() and its related functions.
SDL_GLContext is opaque to the application.