GLUI is a GLUT-based C++ user interface library which provides controls such as buttons, checkboxes, radio buttons, and spinners to OpenGL applications. It is window-system independent, using GLUT or FreeGLUT.
QwtPlot3D is a graphics extension to the Qt GUI application framework. It provides a 3D plotting widget for scientific data and mathematical expressions. It compares to the existing Qwt Project.