How it works

Arcade uses a physics engine to model structural behavior. A physics engine models a collection of masses in motion, and can include several potential sources of force, including gravity, viscous drag, applied loads, and structural elements connecting the masses. This approach has been widely used in computer graphics and games. In structural engineering, the approach is called explicit analysis. This method requires smaller time steps than more conventional implicit analysis, but makes it possible to analyze structures which are unstable. See the publications page to get papers about the program.

The program is written in C++ (about 90,000 total lines at this point). It uses the OpenGL API for graphics and the Microsoft Foundation Classes for the interface.

Where it's headed

In June of 2003, the project received NSF funding (CCLI #0230573) to develop the program and related materials for classroom testing beginning in January of 2004. The release 3.0 in the fall of 2004 introduced graphing features, which have proven extremely useful. The release of 4.0 in the fall of 2006 introduced (long overdue) undo/redo functions, as well as a slide show organizer. Version 4.2 released in fall of 2007 introduces text-based scripting, which includes access to a new element for modeling reinforced concrete.

Acknowledgements

I had the idea for this project in 2000 while looking at assignments from Dave Brogan's course in Advanced Computer graphics. The lecture notes from Andrew Witkin's and David Baraff's 1997 SIGGRAPH workshop on physical modeling were especially useful in learning the algorithms. Dave Luebke also offered a lot of helpful advice.

The project also owes a huge debt to all the people in the world who give away so much useful information and software on the web, particularly at web sites such as www.codeguru.com, www.experts-exchange.com, and www.codeproject.com. Irrespective of the hype about the web, there is no doubt that it has fundamentally changed the way that people can work and learn.