Open a game controller for use.
int joystick_index);SDL_GameController* SDL_GameControllerOpen(
the device_index of a device, up to SDL_NumJoysticks()
Returns a gamecontroller identifier or NULL if an error occurred; call SDL_GetError() for more information.
joystick_index is the same as the
device_index passed to SDL_JoystickOpen().
The index passed as an argument refers to the N'th game controller on the system. This index is not the value which will identify this controller in future controller events. The joystick's instance id (SDL_JoystickID) will be used there instead.
This function is available since SDL 2.0.0.