[JAVA][Beginning Java 8 Games Development]

Chapter 16 ■ Collision Detection: Creating SVG Polygons for the Game Actors and Writing Code to Detect Collision
This is the first (easy) part of determining collisions, in this first checkCollision() method, called from inside of
the .update() method, by the pulse event manager. This iterates through the List CURRENT_CAST and calls
the collide(object); method, for each Actor object, to see if the InvinciBagel character has collided with it. As you
can see in Figure 16-31, this Java code is error-free, and the next Java method body that we will code is the public
boolean collide() method, which we declared for use previously inside of our abstract Hero class, in Chapter 8.
Figure 16-31. Add a for loop, counting from 0 to number of objects in the CURRENT_CAST using .getCurrentCast().size()
Before we code the .collide() method, which is one of the more difficult method bodies that we’ll be coding during
this entire book, we’ll need to look at some of the more complex topics relating to the javafx.scene package’s Node class,
and its Bounds property, and .getBoundsInLocal() and .getBoundsInparent() method call. We will also be looking at
the javafx.scene.shape package’s Shape class, and its .intersect(Shape shape1, Shape shape2) method call. We will
be using all of these inside of our public boolean collide(Actor object) {...} method, so we will need to have this
advanced knowledge in place first, before we write this complex and dense (but exciting) Java structure.
Locating a Node Object: Using the Bounds Object
The first thing that we need to look at regarding collision detection is the javafx.geometry package’s Bounds class.
This public abstract class (and the objects that it creates) is utilized in the javafx.scene package’s Node class to hold
the boundaries for the Node. As you may have surmised, this is one of the things that we will leverage to determine
collision detection, in conjunction with our collision SVGPath Shape data, which we will get into after we take a look
at how this Bounds object, and its related .getBoundsInLocal() and .getBoundsInParent() methods, can work for us.
This Bounds class was created from scratch, using the java.lang.Object master class, and contains X, Y, and Z
coordinates, as well as width, height, and depth values. Since we will be working in 2D, we will be using the X and
Y, as well as the width and height, values (properties) of the Bounds object. The Bounds class has a single direct
known subclass, called BoundingBox. In case you are wondering, a “direct subclass” means the BoundingBox class
declaration says BoundingBox extends Bounds, and a “known” class is one that has been officially added into the
Java 8 JDK.
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