xwindows指的是unix下的窗口,sdl:
Simple DirectMedia Layer is a cross-platform multimedia library designed to provide low level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL, and 2D video framebuffer. It is used by MPEG playback software, emulators, and many popular games, including the award winning Linux port of "Civilization: Call To Power."
网址在:http://www.libsdl.org/
SDL是一个跨平台的2D图形、多媒体库。
在Linux,SDL使用xwindows,在Windows下,好像是基于OpenGL.