| Listing 5 . Beginning of the Animate class and the run method. |
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class Animate extends Thread{
//Declare a general purpose variable of type Point3D.// It will be used for a variety of purposes.
GM01.Point3D tempPrey;//Declare two general purpose variables of type// Vector3D. They will be used for a variety of
// purposes.GM01.Vector3D tempVectorA;
GM01.Vector3D tempVectorB;//--------------------------------------------------//public void run(){
//This method is executed when start is called on// this Thread object.
//Create a new empty container for the prey objects.//Note the use of "Generics" syntax.
preyObjects = new ArrayList<GM01.Point3D>();//Create a new empty container for the vectors. The
// only reason the vectors are saved is so that they// can be displayed later
displayVectors = new ArrayList<GM01.Vector3D>(); |
Importance of the game-math library named GM01
The code in Listing 5 is straightforward and shouldn't require an explanation beyond the embedded comments. However, I will emphasize the heavy use of thegame-math library classes named GM01.Point3D and GM01.Vector3D in the code in Listing 5 .
This entire game program is heavily dependent on the use of the ColMatrix3D , Point3D , Vector3D , and Line3D classes along with some of the static methods in the game-math library named GM01 . If you were to start from scratch and write thisgame program without the availability of the game-math library, the program would be much longer andwould be much more complex.
Create the population of prey fish
Listing 6 creates the population of prey fish and positions them at random locations in 3D space. Listing 6 also stores references to the prey fish objects in the preyObjects container, which was created in Listing 5 .
| Listing 6 . Create the population of prey fish. |
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for(int cnt = 0;cnt<numberPoints;cnt++){
preyObjects.add(new GM01.Point3D(new GM01.ColMatrix3D(
100*(random.nextDouble()-0.5),100*(random.nextDouble()-0.5),
100*(random.nextDouble()-0.5))));//Populate the displayVectors collection with// dummy vectors.
displayVectors.add(tempVectorA);}//end for loop |
In addition, Listing 6 populates a container named displayVectors that was also created in Listing 5 to store a direction vector belonging to each prey fish. This container is populated with dummy vectors in Listing 6 , simply to set the size of the container to be the same as the size of thecontainer containing references to the prey fish objects. (There is probably a more efficient way to set the size of that container.)
Note that each prey fish object is actually represented by an object of the game-math library class named GM01.Point3D .
Create and position the predator object
Listing 7 creates an object of the GM01.Point3D class that will represent the predator in the game.
| Listing 7 . Create and position the predator object. |
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predator = new GM01.Point3D(
new GM01.ColMatrix3D(-100,100,-100)); |
The initial position given to the predator in Listing 7 causes it to appear in the game near the top center of the screen when the user clicksthe Start button. You could also make the initial position of the predator random if you think that would improve the game.