The CRT X-Y Library (libcrtxy) allows you to write vector-based video games (like Asteroids, Lunar Lander, and Battlezone from the 1970s and 80s). The end-user (and/or packager of your software) determines how lines are rendered, depending on the capabilities of their system. This choice includes anti-aliasing, alpha blending, blurring, and even the display size and depth. Fixed-point math is used, and sine and cosine trigonometric functions (using look-up tables) are provided. The library is based on libSDL and uses SDL as the video backend.
PicoGUI aims to be a complete GUI environment for handheld computers and other embedded systems. It uses a client/server model, like the X window system, but while an X server is given raw drawing commands, the PicoGUI server integrates a widget set, making PicoGUI clients small and efficient. PicoGUI also has the goal of allowing client/server connections over a variety of mechanisms. It is most commonly used with Linux, but is designed to be portable to any OS. PicoGUI has a variety of video and input drivers which allow it to interface with the Linux framebuffer device, SDL, the X window system, and several other devices.