Thoughts the ForcePAD application
ForcePAD was developed as part of my PhD thesis almost 20 years ago. The application was developed in C++ using OpenGL for graphics and FLTK for the user interface. At the time, it was state-of-the-art and compiled on all platforms, such as Linux, Windows, and SGI Irix 6.5(!). The application was used extensively in teaching and is still used today.