[JAVA][Beginning Java 8 Games Development]

Chapter 13 ■ Animating Your Action Figure States: Setting the Image States Based on KeyEvent Processing
InvinciBagel Animation: The .setImageState( ) Method
In this chapter, we are going to create one (fairly complex) method called .setImageState(), which will set our
InvinciBagel character’s animation or motion state based upon which keys are being pressed at any given moment.
Calling a .setImageState() method right before the .moveInvinciBagel() method in the .update() method will serve to
combine one of the character’s nine image cels (frames) with the motion of the character. This will create the illusion
of animation, and will achieve this without using any animation timelines whatsoever. From a game optimization
standpoint, this means that the JavaFX engine that is running our GamePlayLoop can focus its resources on just that
single animation (pulse) engine. As you can see in Figure 13-1, we need to add a .setImageState(); method call,
inside of the .update() method before the .moveInvinciBagel() method call and after the .setBoundaries() method call.
After you do this, you’ll have to create an empty method to get rid of the error highlight. The Java code looks like this:
private void setImageState() { The Method Body we'll develop in this chapter goes in here }
Figure 13-1. Create the private void setImageState( ) method; place a setImageState( ) method call in .update( ) method
As you can see in Figure 13-1, this empty code framework doesn’t generate any red error or yellow warning
highlights in the code. We are currently very organized, accomplishing all our KeyEvent handling, boundary
detection, sprite animation, and sprite movement, by using only four method calls inside of this Bagel class
.update() method.
The first thing that we want to check for is no movement: that is, no keys pressed, so that we can correctly
implement the “waiting” InvinciBagel state we used in the previous chapter to develop a sprite movement algorithm.
The InvinciBagel Wait State: If No Key Pressed Set imageState(0)
The first conditional if( ) statement that we put into place will be the default or “no keys pressed” state, which is sprite
zero that shows the InvinciBagel waiting impatiently to be moved and animated. What we want to look for inside of
the if evaluation area inside of the parenthesis is a false value for each of the up, down, left, and right variables, all at
the same moment of time. Up until now, we have been looking for a true value, using the .isUp(), .isDown(), .isLeft(),
and .isRight() method calls off of the invinciBagel object reference. In this situation we want to look for a false value.
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