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Listing 15 . Source code for the program named PointLine02.

/*PointLine02.java Copyright 2008, R.G.BaldwinThe purpose of this program is to introduce the use of a game-math class library named GM2D01. The class nameGM2D01 is an abbreviation for GameMath2D01. The program instantiates objects from the following statictop-level classes belonging to the class named GM2D01 and then displays the contents of those objects in twodifferent ways on the standard output device. ColMatrixPoint VectorLine Tested using JDK 1.6 under WinXP.*********************************************************/ class PointLine02{public static void main(String[] args){System.out.println( "Instantiate and display the contents\n"+ "of a new ColMatrix object"); GM2D01.ColMatrix colMatrix =new GM2D01.ColMatrix(2.5,6.8); System.out.println(colMatrix);try{ System.out.println(colMatrix.getData(0));System.out.println(colMatrix.getData(1)); //This statement will throw an exception on purposeSystem.out.println(colMatrix.getData(2)); }catch(Exception e){System.out.println("Bad index"); }//end catchSystem.out.println(/*blank line*/); System.out.println("Instantiate and display the contents\n" + "of a new Point object");colMatrix = new GM2D01.ColMatrix(3.4,9.7); GM2D01.Point point = new GM2D01.Point(colMatrix);System.out.println(point); try{System.out.println(point.getData(0)); System.out.println(point.getData(1));//This statement will throw an exception on purpose System.out.println(point.getData(-1));}catch(Exception e){ System.out.println("Bad index");}//end catchSystem.out.println(/*blank line*/); System.out.println("Instantiate and display the contents\n" + "of a new Vector object");colMatrix = new GM2D01.ColMatrix(-1.9,7.5); GM2D01.Vector vector = new GM2D01.Vector(colMatrix);System.out.println(vector); try{System.out.println(vector.getData(0)); System.out.println(vector.getData(1));//This statement will throw an exception on purpose System.out.println(vector.getData(2));}catch(Exception e){ System.out.println("Bad index");}//end catchSystem.out.println(/*blank line*/); System.out.println("Instantiate and display the contents\n" + "of a new Line object");GM2D01.ColMatrix colMatrixTail = new GM2D01.ColMatrix(1.1,2.2);GM2D01.ColMatrix colMatrixHead = new GM2D01.ColMatrix(3.3,4.4);GM2D01.Point pointTail =new GM2D01.Point(colMatrixTail); GM2D01.Point pointHead =new GM2D01.Point(colMatrixHead);GM2D01.Line line = new GM2D01.Line(pointTail,pointHead);System.out.println(line); pointTail = line.getTail();System.out.println(pointTail); pointHead = line.getHead();System.out.println(pointHead); }//end main}//end controlling class PointLine02

Listing 16 . Source code for the game-programming math library named GM2D01.

/*GM2D01.java Copyright 2008, R.G.BaldwinThe name GM2D01 is an abbreviation for GameMath2D01. This is a game-math class, which will be expanded overtime. The class is provided solely for educational purposes. No effort has been expended to optimize it inany way. Rather, it was designed and implemented for maximum clarity in order to help students understandthe programming details of various mathematical operations commonly used in game programming.Each time the class is expanded or modified, it will be given a new name by incrementing the two digits at theend of the name. No attempt will be made to maintain backward compatibility from one version of the class tothe next. This class contains a number of static top-level classes.This organizational approach was used primarily for the purpose of gathering such classes under a single namingumbrella while avoiding name conflicts within a single package. For example, as time passes, and this library isexpanded, my default package may contain class files with the following names:GM2D01$Point.class GM2D02$Point.classGM2D03$Point.class All real-number values used in this class are maintainedas type double. Tested using JDK 1.6 under WinXP.*********************************************************/ public class GM2D01{//An object of this class represents a 2D column matrix. // An object of this class is the fundamental building// block for several of the other classes in the // library.public static class ColMatrix{ double[]data = new double[2];ColMatrix(double data0,double data1){data[0] = data0;data[1] = data1;}//end constructorpublic String toString(){ return data[0]+ "," + data[1];}//end overridden toString methodpublic double getData(int index){ if((index<0) || (index>1)) throw new IndexOutOfBoundsException();return data[index];}//end getData}//end class ColMatrix //====================================================//public static class Point{GM2D01.ColMatrix point;Point(GM2D01.ColMatrix point){ this.point = point;}//end constructorpublic String toString(){ return point.getData(0) + "," + point.getData(1);}//end toStringpublic double getData(int index){ if((index<0) || (index>1)) throw new IndexOutOfBoundsException();return point.getData(index); }//end getData}//end class Point//====================================================//public static class Vector{ GM2D01.ColMatrix vector;Vector(GM2D01.ColMatrix vector){this.vector = vector; }//end constructorpublic String toString(){return vector.getData(0) + "," + vector.getData(1); }//end toStringpublic double getData(int index){if((index<0) || (index>1)) throw new IndexOutOfBoundsException();return vector.getData(index); }//end getData}//end class Vector//====================================================////A line is defined by two points. One is called the // tail and the other is called the head.public static class Line{ GM2D01.Point[]line = new GM2D01.Point[2];Line(GM2D01.Point tail,GM2D01.Point head){this.line[0] = tail;this.line[1] = head;}//end constructorpublic String toString(){ return "Tail = " + line[0].getData(0) + "," + line[0].getData(1) + "\nHead = " + line[1].getData(0) + "," + line[1].getData(1); }//end toStringpublic GM2D01.Point getTail(){return line[0];}//end getTailpublic GM2D01.Point getHead(){ return line[1]; }//end getTail}//end class Line}//end class GM2D01

Exercises

Exercise 1

Without using the game math library, use the programming environment of your choice to write a program that drawsa diagonal line from the upper-left to the lower-right corner of a window as shown in Figure 7 .

Figure 7 Graphic output from Exercise 1.

Missing image.

Exercise 2

Using Java and the game math library named GM2D01 , write a program that:

  • Creates a new GM2D01.Point object with coordinate values of 3.4 and 9.7.
  • Uses the overridden toString method to get and display the location of the point in 2D space in the format shown by the first lineof text in Figure 8 .
  • Uses the getData method to get and display the location of the point in 2D space in the format shown by the last two lines of text in Figure 8 .

Your screen output should display numeric values in the format shown in Figure 8 where each ? character represents a single digit.

Figure 8 . Text output from Exercise 2.
?.?,?.? ?.??.?

Exercise 3

Using Java and the game math library named GM2D01 , write a program that:

  • Represents a line segment using a GM2D01.Line object with the ends of the line segment being located at the followingcoordinates:
    • x=2.2, y=5.3
    • x=5.2, y=9.3
  • Displays the information shown in Figure 9 to describe the line segment.

Your screen output should display numeric values in the format shown in Figure 9 where each ? character represents a single digit. (Note that the number of digits to the right of the decimal point in the last line of text may be greateror less than that shown in Figure 9 .)

Figure 9 . Text output from Exercise 3.
Tail = ?.?,?.? Head = ?.?,?.?Length = ?.???

-end-

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Source:  OpenStax, Game 2302 - mathematical applications for game development. OpenStax CNX. Jan 09, 2016 Download for free at https://legacy.cnx.org/content/col11450/1.33
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