Effect: Physics - JavaFX Special Effects - page 115

This code shows that the strategy is to create a Phys2D World and then mirror the Bodies in that
World with JavaFX Nodes . In order to mirror the Bodies, a new class called WorldNode is created—a
simple JavaFX class that contains two sequences and an abstract function called update . In this way, a
Node will be created that extends WorldNode so that each Node in the Scene maintains a reference to its
corresponding Bodies in the World . Looking at the variables in the code, we can see that worldNodes
maintains a reference to all WorldNodes in the application, world is a Phys2D World and maintains a
reference to the bodies in each WorldNode, and group contains all WorldNodes in the scene. The function
addWorldNode shows these relationships, as this method is how content is added to the application. Note
that there is a reference to something called a Joint in the code, which will be described in a later
example.
The function simpleBalls shows how addWorldNode is called, which produces a scene like the one in
Figure 6-1.
Figure 6-1. One falling ball