The software is used by designers for modeling 3D graphics for games and simulations - most notably it is used by the scenery creators at Laminar Research on the X-Plane (simulator). The .ac format has also been used in FlightGear for scenery objects and aircraft models. AC3D's modeling is polygon/subdivision-surface based. Unlike some other 3D software, AC3D refers to 'surfaces' rather than 'polygons'. An AC3D surface can be a polygon, polygon-outline or line. An AC3D object is a collection of surfaces.
Windows, OSX, IOS and Linux.