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Complete program listings
Listing 9 and Listing 10 provide complete listings of the programs discussed in this module.
| Listing 9 . Source code for the program named Slick0150a. |
|---|
/*Slick0150a.java
Copyright 2012, R.G.BaldwinCause a ladybug sprite to bounce around inside the game
window.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;public class Slick0150a extends BasicGame{Image bug = null;
Image background = null;float backgroundWidth;float backgroundHeight;float bugX = 100;
float bugY = 100;float bugWidth;
float bugHeight;float bugXDirection = 1.0f;//initial direction to rightfloat bugYDirection = 1.0f;//initial direction is downfloat xStep = 4.0f;//horizontal step size
float yStep = 3.0f;//vertical step sizefloat bugScale = 0.75f;//drawing scale factor//Used to compute and display the time required for the// bug to make each round trip across the game window
// and back.long oldTime = 0;
long traversalTime = 0;//Frame rate we would like to see and maximum frame// rate we will allow.
int targetFPS = 60;//----------------------------------------------------//
public Slick0150a(){//constructor//Set the title
super("Slick0150a, baldwin");
}//end constructor//----------------------------------------------------//
public static void main(String[]args)
throws SlickException{AppGameContainer app = new AppGameContainer(
new Slick0150a(),414,307,false);app.start();
}//end main//----------------------------------------------------//
@Overridepublic void init(GameContainer gc)
throws SlickException {oldTime = gc.getTime();
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{
//Compute new location for the sprite.//The following code assumes a constant frame rate// and does not correct for variations in delta.
// The step size is always the same regardless of// delta (how often the steps are taken).
bugX += bugXDirection*xStep;bugY += bugYDirection*yStep;//Test for collisions with the sides of the game
// window and reverse direction when a collision// occurs.
if(bugX+bugWidth>= backgroundWidth){
//A collision has occurred.bugXDirection = -1.0f;//reverse direction
//Set the position to the right edge less the width// of the sprite.
bugX = backgroundWidth - bugWidth;//Compute traversal time for the bug to make one// round trip across the game window and back.
long currentTime = gc.getTime();traversalTime = currentTime - oldTime;
oldTime = currentTime;}//end if//Continue testing for collisions with the edges.
if(bugX<= 0){
bugXDirection = 1.0f;bugX = 0;
}//end ifif(bugY+bugHeight>= backgroundHeight){
bugYDirection = -1.0f;bugY = backgroundHeight - bugHeight;
}//end ifif(bugY<= 0){
bugYDirection = 1.0f;bugY = 0;
}//end if}//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 traversal time computed in the update
// method.g.drawString(
"traversalTime: "+traversalTime,100f,10f);}//end render
}//end class Slick0150a |
Read also:
OpenStax, Anatomy of a game engine. OpenStax CNX. Feb 07, 2013 Download for free at https://legacy.cnx.org/content/col11489/1.13
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