Function gl46::load_global_gl_with

pub fn load_global_gl_with<F>(get_proc_address: F) -> usize where
    F: FnMut(*const c_char) -> *mut c_void, 

Loads all global functions using the get_proc_address given.

The closure should, when given a null-terminated name of a function, return a pointer to that function. If the function isn't available, then a null pointer should be returned instead.

This allows you to call SDL_GL_GetProcAddress, wglGetProcAddress, or similar function, depending on your OS.

This returns the number of functions it loaded. You can compare it to theNUMBER_OF_GENERATED_GL_COMMANDS value, if you want.