Killer Game Programming in Java

Making and Moving the Figure

The Figure class carries out three main tasks:

• It builds the figure by connecting Limb objects. The resulting figure is translated into a Java 3D subgraph.

• It processes limb-related operations, such as updateLimb() calls.

• It processes figure movement operations, such as doRotateY().

Building the Figure

The construction of the figure starts in Figure():

    //globals
    private ArrayList limbs;
      // Arraylist of Limb objects, indexed by limb number
    private HashMap limbNames;
      // holds (limb name, limb number) pairs

    private TransformGroup figureTG;
      // the top-level TG for the entire figure



    public Figure()
    {
      yCount = 0;     // the figure is on the floor initially
      t3d = new Transform3D();   // used for repeated calcs
      toMove = new Transform3D();
      toRot = new Transform3D();

      limbs = new ArrayList();
      limbNames = new HashMap();

      // construct the figure from connected Limb objects
      buildTorso();
      buildHead();

      buildRightArm();
      buildLeftArm();

      buildRightLeg();
      buildLeftLeg();

      printLimbsInfo();

      buildFigureGraph();   // convert figure into a Java 3D subgraph
    }  // end of Figure()

The figure's Limb objects are stored in the limbs ArrayList. Each Limb object has a unique ID (its limb number), which is used as its index position in the ArrayList.

The other important data structure is the limbNames HashMap. The HashMap stores (limb name, limb number) pairs, with the name being the key and the limb number the value. At runtime, the HashMap is employed to determine a limb's number when a name is supplied ...