Cinder is a peer-reviewed, free, open source C++ library for creative coding.
Note for upgrading
This branch has had the development branch glNext merged recently. Please see this forum post for information on updating your projects. Additionally, to update you'll need to add a new submodule:
git pull git submodule update --init
Cinder supports Mac OS X, Windows and iOS. It requires Xcode 5.1 or later for development on the Mac, and Visual C++ 2013 or later on Windows.