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Killer Game Programming in Java
book

Killer Game Programming in Java

by Andrew Davison
May 2005
Intermediate to advanced content levelIntermediate to advanced
998 pages
26h
English
O'Reilly Media, Inc.
Content preview from Killer Game Programming in Java

Updating the Alien Sprite

TimeBehavior acts as a Timer-like object for calling the update() method in AlienSprite every 500 milliseconds. The two are linked together by WrapTour3D in its addAlien() method:

    private void addAlien()
    {
      AlienSprite al =  new AlienSprite("hand1.obj", obs, bob);   // alien
      al.setPosition(-6.0, -6.0);
      sceneBG.addChild( al.getTG() );

      TimeBehavior alienTimer = new TimeBehavior(500, al);  // alien's controls
      alienTimer.setSchedulingBounds( bounds );
      sceneBG.addChild( alienTimer );
    }

The TimeBehavior class is simpler than TouristControls since its processStimulus() method being called is enough to trigger the call to update():

    public class TimeBehavior extends Behavior
    {
      private WakeupCondition timeOut;
      private AlienSprite alien;

      public TimeBehavior(int timeDelay, AlienSprite as)
      { alien = as;
        timeOut = new WakeupOnElapsedTime(timeDelay);
      }

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


      public void processStimulus( Enumeration criteria )
      { alien.update();      // ignore criteria
        wakeupOn( timeOut ); // re-register
      }
    }

The wakeup criterion is an instance of WakeupOnElapsedTime.

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Publisher Resources

ISBN: 0596007302Supplemental ContentErrata Page