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Help With Project Please. If statements

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Join Date: Dec 2007
Posts: 2
#1: Dec 13 '07
Ok I was doing this project but now Im halfway stuck. This project contains 3 class at the moment. Im mainly trying to make this applet like the game pong. I have the paddle and a ball and background and stuff.

Now my main problem is that I need to make the ball bounce back after it touches the paddle...Right now the ball goes through the paddle.

And the paddle is moved using arrow keys. So now I need like a code for me to make the ball bounce back when it touches the paddle. And I think this can be done using if statement..not sure. But any help will be greatly appreciated...but here are my classes and codes for them.

ImagePong

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  1. /**
  2.  * Balloon.java uses a PNG file that is displayed by the applet
  3.  * 
  4.  * @author Sulav
  5.  * @version 11/29/07
  6.  */
  7. //_________________import statements______________________________________
  8. import java.awt.*;
  9. import javax.swing.ImageIcon;  // needed to use image files from disk
  10.  
  11. public class ImagePong
  12. {
  13.  
  14.    //________________instance variables/properties_________________________
  15.    Image frame2;  //object holds the actual graphic
  16.    Image frame1;  //object holds the actual graphic
  17.  
  18.    int x=0, y=0, xSpeed=15, ySpeed=15, maxX=500,  maxY=500;
  19.     Color c;
  20.  
  21.    int x2=0, y2=0, x2Speed=15, y2Speed=15, max2X=500,  max2Y=500;
  22.  
  23.  
  24.  
  25.    //__________constructors_______________________________________________
  26.  
  27.    public ImagePong()
  28.    {   //pong.png must be in your project directory
  29.        frame1 = new ImageIcon("./paddle2.jpg").getImage();  //load the graphic
  30.        x = 190; y = 450;
  31.  
  32.        frame2 = new ImageIcon("./back.jpg").getImage();  //load the graphic
  33.        x2 = 1; y2 = 1;
  34.  
  35.  
  36.  
  37.     }  //end of Balloon() constructor
  38.  
  39.     //____________________methods___________________________________
  40.     // getImage() sends back the current image
  41.     public Image getImage()
  42.     {
  43.         return frame1;
  44.     } // end of getImage()
  45.  
  46.     public Image getImage2()
  47.     {
  48.         return frame2;
  49.     } // end of getImage()
  50.  
  51.  
  52.     // getX() sends back the x position
  53.     public int getX()
  54.     {
  55.         return x;
  56.     } // end of getX
  57.  
  58.     //get Y () sends back the y position )
  59.  
  60.     public int getY()
  61.     {
  62.         return y;
  63.     } // end of getY
  64.  
  65.  
  66.  
  67.  
  68.  
  69.     // getX() sends back the x position
  70.     public int getX2()
  71.     {
  72.         return x2;
  73.     } // end of getX
  74.  
  75.  
  76.    //get Y () sends back the y position )
  77.  
  78.     public int getY2()
  79.     {
  80.         return y2;
  81.     } // end of getY
  82.  
  83.  
  84.  
  85.     public void setXSpeed (int newXSpeed)
  86.     {
  87.         xSpeed=newXSpeed;
  88.         xSpeed=newXSpeed;
  89.     }
  90.     public void setYSpeed (int newYSpeed)
  91.     {
  92.         ySpeed=newYSpeed;
  93.         ySpeed=newYSpeed;
  94.     }
  95.     public void moveRight()
  96.     {
  97.         if(x<maxX + 12)
  98.         {
  99.             x+=xSpeed;
  100.         }
  101.     }
  102.  
  103.      public void moveLeft()
  104.     {
  105.         if(x<maxX + 12)
  106.         {
  107.             x-=xSpeed;
  108.         }
  109.     }
  110.  
  111. } // end of Balloon class


ImageMover(Applet)

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  1. /**
  2.  * ImageMover.java animates an image in the applet window.
  3.  * It uses double buffering to provide nice smooth animation
  4.  * 
  5.  * @author Sulav
  6.  * @version 11/29/07
  7.  */
  8.  
  9. import java.applet.*;
  10. import java.awt.*;
  11. import java.awt.event.*;
  12.  
  13. public class ImageMover extends Applet implements Runnable, KeyListener
  14. {
  15.  
  16.    private Image buffer;  //holds  a copy of the applet window
  17.    private Graphics gBuffer;  // the copy's graphics page
  18.    private ImagePong back; //create a paddle object to be animated
  19.    private ImagePong paddle; //create a background object to be animated
  20.    private Thread t;  //create the thread to do it
  21.    private Ball pingpong; //thing being bounced
  22.  
  23.    public void init()
  24.    {
  25.        // create graphics buffer, the size of the applet
  26.        buffer=createImage(this.getWidth(),this.getHeight());
  27.        gBuffer=buffer.getGraphics();
  28.  
  29.  
  30.          // Initialize drawing colors
  31.         setBackground(Color.black);
  32.         setForeground(Color.white);
  33.  
  34.         pingpong = new Ball(this.getWidth(), this.getHeight(), Color.red);
  35.         addKeyListener(this);  // register the KeyListener with the applet
  36.        // create the Balloon object and thread to control animation
  37.  
  38.        paddle = new ImagePong();
  39.        back = new ImagePong();
  40.  
  41.        t = new Thread(this);
  42.        t.start();
  43.     } // end of init()
  44.  
  45.    // run() is used by the Thread T to keep the balloon moving
  46.    public void run()
  47.    {
  48.        // run this loop forever
  49.        while(true)
  50.        {
  51.            pingpong.move(); 
  52.            // move the balloon given the size of the applet window
  53.            //pong.move(this.getWidth(), this.getHeight());
  54.            repaint();
  55.            try {t.sleep(20);}  //pause a little to slow things down
  56.            catch (Exception e) {}
  57.  
  58.  
  59.  
  60.     }
  61.  
  62.     }   //end of run
  63.  
  64.       // method to stop the thread from going. will cause a warning when compiled
  65.     public void stop()
  66.     {
  67.         t.stop();
  68.     } // end of stop() method
  69.  
  70.     // update() needs to run paint() so Java doesnt erase the window
  71.     public void update(Graphics g)
  72.     {
  73.         paint(g);
  74.     } // end of update()
  75.  
  76.     // paint() paints the applet window
  77.     public void paint(Graphics g)
  78.     {
  79.         pingpong.draw(g);
  80.         // set the drawing color and cover the buffer witha  gilled rectangle
  81.         gBuffer.setColor(Color.black);
  82.         gBuffer.fillRect(0, 0, this.getWidth(), this.getHeight());
  83.  
  84.         //draw the balloon image in the BUFFER at its own coordinates
  85.         //gBuffer.drawImage(paddle.getImage(), paddle.getX(),
  86.                        //  paddle.getY(), this);
  87.  
  88.  
  89.  
  90.         // draw the balloon image in the BUFFER at its own coordinates
  91.         gBuffer.drawImage(back.getImage2(), back.getX2(),
  92.                           back.getY2(), this);
  93.  
  94.          // draw the balloon image in the BUFFER at its own coordinates
  95.  
  96.          gBuffer.drawImage(paddle.getImage(), paddle.getX(),
  97.                           paddle.getY(), this);                  
  98.         // now draw the iamge to the applet window
  99.         g.drawImage (buffer, 0, 0, this);
  100.  
  101.      } // end of paint()
  102.  
  103.  
  104.      public void keyPressed(KeyEvent event) {
  105.         int keyCode = event.getKeyCode();  //get the key hit
  106.  
  107.         if (keyCode == KeyEvent.VK_D)
  108.         {
  109.            paddle.moveRight();
  110.         }
  111.  
  112.  
  113.         if (keyCode == KeyEvent.VK_A)
  114.         {
  115.            paddle.moveLeft();
  116.         }
  117.  
  118.         event.consume();  //keep anything else from using the key
  119.         repaint();  // signal Java to redraw the window
  120.     }
  121.     public void keyReleased(KeyEvent event) {
  122.         event.consume();  // ignore keyReleased
  123.     }
  124.     public void keyTyped(KeyEvent event) {
  125.         event.consume();  // ignore keyTyped
  126.     }
  127.   } // end of ImageViewer class   

Ball

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  1. /**
  2.  * Ball.java is the object that will get bounced around
  3.  * 
  4.  * @author Sulav
  5.  * @version 11/16/07
  6.  */
  7. import java.awt.*;
  8. import java.awt.geom.*;
  9.  
  10. public class Ball
  11. {
  12.      // set constants for colors
  13.      final Color blue = Color.black, green = Color.white;
  14.  
  15.      // variables for location, speed, and direction of ball size of window
  16.      int x, y, horVel = 13, vertVel = 16, maxX, maxY;
  17.      Color c;
  18.  
  19.      public Ball(int mx, int my, Color c)
  20.      {
  21.          maxX = mx; // set the max variables
  22.          maxY = my;
  23.          this.c = c;
  24.  
  25.          //frame2 = new ImageIcon("./pong.jpg").getImage();
  26.  
  27.          // give the ball a random starting position
  28.          x = (int) (Math.random() * maxX) + 1;
  29.          y = (int) (Math.random() * maxY) + 1;
  30.  
  31.         }
  32.  
  33.         public void draw(Graphics g)
  34.         {
  35.             Graphics2D g2 = (Graphics2D) g;  //supersize the drawing page
  36.  
  37.             GradientPaint grad = new GradientPaint(x+20, y-20, green, x+20, y+60, blue);
  38.             //g2.setPaint(grad);
  39.             g2.setPaint(c);
  40.             g2.fill (new Ellipse2D.Double(x, y, 40, 40));
  41.         } // end of draw()
  42.  
  43.         public void move()
  44.         {
  45.             y+=vertVel;  // add the horizontal velocity to x
  46.             x+=horVel;
  47.  
  48.             if ((y > maxY) || (y < 1)) //checking left, right boundaries
  49.             {
  50.                 vertVel = -vertVel;  //reverse direction if at left/right edge
  51.             }
  52.  
  53.              if ((x > maxY) || (x < 1)) //checking left, right boundaries
  54.             {
  55.                 horVel = -horVel;  //reverse direction if at left/right edge
  56.             }
  57.  
  58.         } // end of move() method
  59.     } //end of Ball class

BigDaddyLH's Avatar
Moderator
  
Join Date: Dec 2007
Location: Kelowna, BC Canada
Posts: 1,212
#2: Dec 13 '07

re: Help With Project Please. If statements

Quote:

Originally Posted by Fool

So now I need like a code for me to make the ball bounce back when it touches the paddle.

You know how to make the ball bounce, because it is bouncing off the edges, right? Do you know how to detect if the ball is touching the paddle?
Reply

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