[JAVA][Beginning Java 8 Games Development]

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Chapter 13 ■ Animating Your Action Figure States: Setting the Image States Based on KeyEvent Processing Mirroring Sprites: Quadrupling Your Image Assets from 9 to 36 Now let’s go back into the existing .isLeft() and .isRight() conditional evaluation statements, which are going to become quite “robust” (complicated) over the course of this chapter, and let’s add our spite mirroring capability. The JavaFX API has its mirroring capability “hidden” in the ImageView class’s .setScaleX() method call. Although we are not going to scale our Image assets, as doing so causes artifacts in our pristine PNG32 image assets, there is a little known trick that you can pass a -1 (negative 100% scaling factor) value into a .setScaleX() method, to flip or mirror the Image asset around the Y axis (or into the .setScaleY() method, to flip or mirror around the X axis). Clearly we will need to also “undo” this in the other conditional if() structure by passing a 1 (positive 100% scaling factor) into the same method call, which does not make a whole lot of sense (normally) as our Image scale is already 100% (not scaled) but in light that the -1 scale-flip factor might have been set previously, this is how we make sure that mirroring is disabled and we are again using our original sprite Image assets for that particular state. Your newly upgraded Java statements implementing sprite mirroring should now look like the following code, which is also shown highlighted in Figure 13-5: if(invinciBagel.isRight()) { spriteFrame.setImage(imageStates.get(1)); spriteFrame.setScaleX(1); } if(invinciBagel.isLeft()) { spriteFrame.setImage(imageStates.get(1)); spriteFrame.setScaleX(-1); } Figure 13-5. Add a .setScaleX() method call to the .isRight() and .isLeft() evaluations to flip the sprite around the Y axis As you can see in Figure 13-5, your Java code is still error-free. It is interesting to note that we are calling the sprite mirroring method on the spriteFrame ImageView object, and not on the Image assets inside of this ImageView. This is of tantamount importance, because it means that we can use this one single line of code inside of .isRight() and .isLeft() to flip whatever sprite state (image) is showing inside of an ImageView! That’s highly optimized programming! Now that our sprite mirroring code is in place, we need to take care of the issue of having the run cycle that is implemented by alternating imageStates(1) and imageStates(2) accomplished using our conditional if() processing. 278 www.it-ebooks.info
Chapter 13 ■ Animating Your Action Figure States: Setting the Image States Based on KeyEvent Processing Animating Your Run Cycle: Creating a Nested If-Else Structure The next step in our sprite animation for this chapter is to actually animate a run cycle for our character, which we would normally do with JavaFX KeyFrame and Timeline classes, but which we will do here in little more than a dozen lines of code. Since we are already using the AnimationTimer class, this is the optimal approach, and can be done using only a single Boolean variable. Since we have two cels for our run cycle, we can use this Boolean variable and alternate its value between true and false. If this Boolean value, which we will call animator, is false, we will show the cel in imageStates(1), which is our starting to run position (foot touching the ground). If animator is true, we will show the cel in imageStates(2), which is our full-out run position (both feet in full motion). Create the Boolean animator variable at the top of the Bagel.java class. NetBeans was giving me a “variable not initialized” warning, so I explicitly set it equal to the default Boolean value of false, as I want the run cycle to always start with a foot pushing off of the ground. The variable declaration statement should look like the following, and is shown at the very top of Figure 13-6: boolean animator = false; Figure 13-6. Nest an if-else logic structure alternating between sprite cels 1 and 2 using the boolean animator variable Since we want the run cycle to always start with the imageStates(1) foot pushing off the ground cel, we will add an animator=false; line of code inside of our “no arrow keys pressed” code statement. This statement will now do two different things: setting the imageStates(0) waiting sprite Image reference; and making sure that the animator variable is initialized to a false value, which ensures the run cycle starts with a foot on the ground, just like it would in real life. The new Java code for the “no arrow keys pressed” conditional if() structure should look like the following: if( !invinciBagel.isRight() && !invinciBagel.isLeft() && !invinciBagel.isDown() && !invinciBagel.isUp() ) { spriteFrame.setImage(imageStates.get(0)); animator=false; } www.it-ebooks.info 279
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Contents at a Glance About the Auth
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Introduction The Java Programming L
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■ Introduction In Chapter 13 you
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Chapter 1 ■ Setting Up a Java 8 G
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Chapter 2 Setting Up Your Java 8 ID
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Chapter 2 ■ Setting Up Your Java
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Profiling Your Java 8 Game Applicat
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Chapter 3 ■ A Java 8 Primer: An I
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Chapter 5 An Introduction to Game D
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Chapter 8 Creating Your Actor Engin
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Chapter 8 ■ Creating Your Actor E
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Chapter 9 Controlling Your Action F
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Chapter 9 ■ Controlling Your Acti
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Chapter 10 Directing the Cast of Ac
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Chapter 17 Enhancing Game Play: Cre
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Chapter 17 ■ Enhancing Game Play:
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■ index Background image (cont.)
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■ index InvinciBagel animation (c
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■ index Modifier keywords access
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Beginning Java 8 Games Development
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This Java 8 Game Development book i
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■ Contents NetBeans 8.0 Is User I
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■ Contents ■■Chapter 5: An In
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■ Contents Creating a Hero Superc
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■ Contents Organizing the .update
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■ Contents Optimizing the Scene G
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About the Author Wallace Jackson ha
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Acknowledgments I would like to ack
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