[JAVA][Beginning Java 8 Games Development]

Chapter 17 ■ Enhancing Game Play: Creating a Scoring Engine, Adding Treasure and an Enemy Auto-Attack Engine
Figure 17-35. Use the Run ➤ Project to test your code; left half shows left side attack, right half shows right side attack
To keep our use of JavaFX Scene Graph Node objects optimized, we will reuse Projectile objects once they hit the
InvinciBagel. This “bullet recycling” will be done using Java programming logic in several methods that we’ll put into
place as we continue to write more and more advanced game play program logic throughout this chapter.
Now we are ready to make the Enemy move on and off-screen, to add the element of surprise. We will be coding
this animation rather than using another Animation class, since we are trying to do everything using only one
AnimationTimer class (object) as an optimization strategy, which is working out amazingly well thus far.
Adding the Element of Surprise: Animating Your Enemy Attack
To animate our Enemy onto the Stage we will need to define boolean variables that hold the “on-screen off-screen”
state, which I will call onScreen, as well as one that will serve as a switch that I can flip once the Enemy is visible on
the screen, telling him to mount his attack, which I will name callAttack. We will also need integer variables to hold
the current Enemy sprite right and left side X location, named spriteMoveR and spriteMoveL, and a destination
variable that holds where we want the Enemy to stop and fire his Projectile objects. The Java declaration statements
can be seen highlighted near the top of Figure 17-36, and should look like the following Java code:
boolean onScreen = false;
boolean callAttack = false;
int spriteMoveR, spriteMoveL, destination;
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