CHAI 3D is an open source set of C++ libraries for computer haptics, visualization and interactive real-time simulation. CHAI 3D supports several commercially-available three-, six- and seven-degree-of-freedom haptic devices, and makes it simple to support new custom force feedback devices. CHAI 3D is especially suitable for education and research purposes, offering a light platform on which extensions can be developed. CHAI 3D’s support for multiple haptic devices also makes it easy to send your applications to remote sites that may use different hardware.
http://www.chai3d.org/
A modern open-source, cross-platform toolkit for graphical applications implemented in C, C++, Perl and Ada (with bindings to other languages in development). Designed for ease of integration, it follows the philosophy of building the GUI around the application and not the other way around. Unlike most other GUI toolkits, Agar takes maximum advantage of hardware graphics acceleration when it is available via OpenGL, but it also supports traditional framebuffer interfaces such as SDL direct video. The Agar API is entirely thread-safe when Agar is compiled with optional threads support.
The distribution includes two libraries: Agar-GUI implements the base Agar GUI system and a comprehensive set of standard widgets. Agar-GUI is object-oriented and relies heavily on inheritance, virtual functions and virtual filesystems. This functionality is implemented by the GUI-independent Agar-Core library, which also includes various utility and portability interfaces. The Agar distribution also includes some more specialized libraries aimed at specific applications (see below). Some of our other toolkits which extend (and rely on) Agar include FreeSG, Edacious and cadtools.
Agar is free software. Its source code is freely usable and re-usable by everyone under a BSD license, which allows use in commercial applications free of charge. Agar is stable, well-maintained and has been growing organically since early 2002. The Agar project is sponsored by Csoft.net: Security conscious, high-availability Unix hosting on redundant server arrays.

Please visit http://libagar.org/ to download it.