GravityLoops, a gravity simulator in Interlisp and LOOPS

This article details the creation of GravityLoops, a gravity simulator developed on Medley using Interlisp and its object-oriented extension LOOPS. The project adapts a force-based simulation design from a 1989 Dr. Dobb's Journal article by Todd King. The author explains their motivation to learn LOOPS through a complex but manageable project, leveraging LOOPS features like gauges and graphical meters. The design involves creating classes for bodies and a universe, with plans for GUI elements and screen buffering for smooth animation. The article covers technical aspects of adapting C++ code to LOOPS, class design, and integration with the Interlisp environment, making it relevant to programming, retro computing, and object-oriented design.