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public MyBehavior(TransformGroup aTransformGroup)
{
     transformGroup = aTransformGroup;
     wakeupCondition = new WakeupOnTransformChange(transformGroup);
}

public void initialize()
{
     wakeupOn(wakeupCondition);
}

public void processStimulus(Enumeration e)
{
     doWork();
     wakeupOn(wakeupCondition);
}

public void doWork()
{
     // doing something here
}
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// Creating PlatformGeometry
PlatformGeometry hudPlatformGeometry = new PlatformGeometry();
hudPlatformGeometry.setCapability(PlatformGeometry.ALLOW_CHILDREN_WRITE);
hudPlatformGeometry.setCapability(PlatformGeometry.ALLOW_CHILDREN_READ);
hudPlatformGeometry.setCapability(PlatformGeometry.ALLOW_CHILDREN_EXTEND);

// Creating GraphicsConfiguration
GraphicsConfigTemplate3D gTempl3D = new GraphicsConfigTemplate3D();
gTempl3D.setDoubleBuffer(GraphicsConfigTemplate3D.PREFERRED);
gTempl3D.setSceneAntialiasing(GraphicsConfigTemplate3D.PREFERRED);
gTempl3D.setStereo(GraphicsConfigTemplate3D.PREFERRED);
GraphicsConfiguration graphicsConfig = GraphicsEnvironment.getLocalGraphicsEnvironment().
                      getDefaultScreenDevice().getBestConfiguration(gTempl3D);

// Assign GraphicsConfiguration to the Canvas3D
Canvas3D aCanvas = new Canvas3D(graphicsConfig);

// Create the PhysicalHUD
PhysicalHUD hud = new PhysicalHUD(MAX_NUM_OF_HUD_LAYERS, aCanvas3D, hudPlatformGeometry, 4f);

// Create a Viewer using aCanvas and hudPlatformGeometry
Viewer ptiViewer = new Viewer(aCanvas);
ViewingPlatform ptiPlatform = new ViewingPlatform();
ptiViewer.setViewingPlatform(ptiPlatform);

ptiPlatform.setPlatformGeometry(hudPlatformGeometry);

// Constructor
public My3DBehavior(TransformGroup aTransformGroup)
{
   transformGroup = aTransformGroup;
   wakeupCondition = new WakeupOnTransformChange(transformGroup);
}

// Initialize the behavior to wake up on a transform 
// change.
public void initialize()
{
   wakeupOn(wakeupCondition);
}

// TransformGroup has been modified!
public void processStimulus(Enumeration e)
{
   System.out.println("TransformGroup has been modified!");
   doWork();
   // Reset the wake up condition.
   wakeupOn(wakeupCondition);
}