Old 3D modelling program, C++ for DOS with VESA support and software texturing/lighting engine. A live version of this can be found here: http://www.cw-3d.com/clay/downloads/cwDOS3.0/public/index.html
I maintained this version around 1997-2000 before switching over to windows. 3.x was the first version to be written in C++ rather than Pascal and was largely a direct port from pascal to C++, a process that took several months IIRC. The move to SVGA allowed me to expand the capabilities of the software rendering engine considerably and this version supports texture mapping, coloured lighting, smooth shading and highlight preserving transparency effects.