Glitz is a portable 2D graphics library that uses OpenGL to render hardware accelerated graphics. It supports many of the latest OpenGL features, such as efficient off-screen rendering using pbuffers. Rendering can be carried out by arbitrary OpenGL layers, thanks to glitz's extensible backend system. Glitz is designed to match the X Render Extension semantics and provides a general way for accelerating this imaging model. Glitz can be used as a stand-alone layer above OpenGL but is also designed to act as a backend for cairo, providing it with OpenGL accelerated output.