fbox2d is a port for box2d c++ physics lib. One principle of the fbox2d is to make the class names and function interfaces as similar with the c++ version as possible. The main differences between fbox2d and box2d c++ version are:

• because AS3 doesn’t support polymorphism, many functions are renamed. Some constructors are changed to static functions;
• to optimize, many local variables are moved outside of function bodies and changed to static.