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The Input class also provides two methods named getAbsoluteMouseX and getAbsoluteMouseY . I'm not certain how these two methods differ from the two methods that were calledin Listing 4 , but I haven't spent any time investigating the difference.
The end of the update method
Listing 4 also signals the end of the update method and the end of this discussion.
I encourage you to copy the code from Listing 5 . Compile the code and execute it,making changes, and observing the results of your changes. Make certain that you can explain why your changes behave as they do.
In this module, you learned how to use the following methods of the Input class to get user input:
In the next module, you will learn how to use objects of the SpriteSheet class and the Animation class to perform simple sprite sheet animation.
This section contains a variety of miscellaneous information.
Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.
I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.
In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.
Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.
A complete listing of the program discussed in this module is provided in Listing 5 .
| Listing 5 . Source code for the program named Slick0170. |
|---|
/*Slick0170java
Copyright 2013, R.G.BaldwinCause a ladybug sprite to move inside the game window by
pressing the arrow keys or the left and right mousebuttons. The mouse pointer must be inside the game window
for the mouse buttons to move the sprite.Right arrow or right mouse button: move right
Left arrow or left mouse button: move leftUp arrow: move up
Down arrow: move downThe program also gets and displays the X and Y
coordinates of the mouse pointer.Much of this program is identical to the earlier program
named Slick0150a.java.Tested using JDK 1.7 under WinXP
*********************************************************/import org.newdawn.slick.AppGameContainer;
import org.newdawn.slick.BasicGame;import org.newdawn.slick.GameContainer;
import org.newdawn.slick.Graphics;import org.newdawn.slick.Image;
import org.newdawn.slick.SlickException;import org.newdawn.slick.Input;
public class Slick0170 extends BasicGame{Image bug = null;Image background = null;float backgroundWidth;
float backgroundHeight;float bugX = 100;float bugY = 100;
float bugWidth;float bugHeight;float xStep = 4.0f;//horizontal step size
float yStep = 3.0f;//vertical step sizefloat bugScale = 0.75f;//drawing scale factor//Frame rate we would like to see and maximum frame// rate we will allow.
int targetFPS = 60;//This is new code relative to Slick0150a.javaint mouseX = 0;
int mouseY = 0;//----------------------------------------------------//
public Slick0170(){//constructor//Set the title
super("Slick0170, baldwin");}//end constructor
//----------------------------------------------------//public static void main(String[] args)throws SlickException{
AppGameContainer app = new AppGameContainer(new Slick0170(),414,307,false);
app.start();}//end main
//----------------------------------------------------//@Override
public void init(GameContainer gc)throws SlickException {
bug = new Image("ladybug.png");background = new Image("background.jpg");backgroundWidth = background.getWidth();
backgroundHeight = background.getHeight();bugWidth = bug.getWidth()*bugScale;bugHeight = bug.getHeight()*bugScale;System.out.println(
"backgroundWidth: " + backgroundWidth);System.out.println(
"backgroundHeight: " + backgroundHeight);System.out.println("bugWidth: " + bugWidth);
System.out.println("bugHeight: " + bugHeight);gc.setTargetFrameRate(targetFPS);//set frame rate}//end init
//----------------------------------------------------//@Override
public void update(GameContainer gc, int delta)throws SlickException{
//Most of the code in this method is different from// the code in Slick0150a.java.//Get a reference to the Input object.
Input input = gc.getInput();//Control horizontal bug position by pressing the// arrow keys or pressing the left and right mouse
// buttons.if(input.isKeyDown(Input.KEY_RIGHT) ||
input.isMouseButtonDown(Input.MOUSE_RIGHT_BUTTON)){bugX += xStep;
}//end ifif(input.isKeyDown(Input.KEY_LEFT) ||input.isMouseButtonDown(Input.MOUSE_LEFT_BUTTON)){
bugX -= xStep;}//end if//Control vertical bug position by pressing the arrow
// keys. Vertical bug position cannot be controlled by// pressing mouse buttons.
if(input.isKeyDown(Input.KEY_UP)){bugY -= yStep;
}//end ifif(input.isKeyDown(Input.KEY_DOWN)){bugY += yStep;
}//end if//Test for collisions with the sides of the game// window and stop moving the bug when a collision
// occurs.if(bugX + bugWidth>= backgroundWidth){
//Set the position to the right edge less the width// of the sprite.
bugX = backgroundWidth - bugWidth;}//end if//Continue testing for collisions with the edges.
if(bugX<= 0){
bugX = 0;}//end ifif(bugY + bugHeight>= backgroundHeight){
bugY = backgroundHeight - bugHeight;}//end ifif(bugY<= 0){
bugY = 0;}//end if//Get and save the X and Y coordinates of the mouse
// pointer.mouseX = input.getMouseX();
mouseY = input.getMouseY();}//end update//----------------------------------------------------//
public void render(GameContainer gc, Graphics g)throws SlickException{
//set the drawing mode to honor transparent pixelsg.setDrawMode(g.MODE_NORMAL);//Draw the background to erase the previous picture.
background.draw(0,0);//Draw the bug in its new location.bug.draw(bugX,bugY,bugScale);//Display the location of the mouse pointer. This is
// new code relative to Slick0150a.javag.drawString(
"X: " + mouseX + " Y: " + mouseY,100f,10f);}//end render
}//end class Slick0170//======================================================// |
-end-
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