QGLViewer is an open source library which enables you to quickly start the development of a new 3D application. It is designed for 3D C++ developers, who can very easily display and move around a 3D scene by simply providing the OpenGL orders that define their 3D geometry. The viewer provides some usefull classical functionalities such as a camera trackball, screenshot saving, manipulated frames with possible constraints, stereo display...
QGLViewer is not a 3D viewer that can be used directly to view 3D scenes in various formats, it is actually more likely to be the starting point for the coding of such a viewer.
See the project main page for details on the project and installation steps.