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Thread: Help with code- horizontal to vertical bouncing balls

  1. #1
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    Default Help with code- horizontal to vertical bouncing balls

    Hi all, I'm new to java and I need help changing the direction of these balls from a horizontal axis to a vertical axis bouncing in the center. I've tried reversing the integers but there seems to be something i've missed.

     package package_bouncingball;
     
    import java.applet.*; 
    import java.awt.*; 
    import javax.swing.*;
    import javax.swing.event.*;
     
    public class Class_bouncingball extends Applet implements Runnable 
     
    {
     
     
      int x_pos1 = 150; 
      int y_pos1 = 200; 
      int radius1 = 20; 
     
      int x_pos2 = 250; 
      int y_pos2 = 200; 
      int radius2 = 20;
     
      private float ballspeedx1 = -3;   
      private float ballspeedy1 = 0;
     
      private float ballspeedx2 = 3;   
      private float ballspeedy2 = 0; 
     
     
      public void init() {} 
     
      public void start() { 
      Thread th = new Thread (this); 
       th.start (); } 
       public void stop() {} 
      public void destroy() {} 
      public void run () {
    Thread.currentThread().setPriority(Thread.MIN_PRIORITY); 
    while (true) 
    { 
      x_pos1 += ballspeedx1;
      y_pos1 += ballspeedy1;
      x_pos2 += ballspeedx2;
      y_pos2 += ballspeedy2;  
     
     
      repaint();
     
      if (x_pos1  < 100) {
        ballspeedx1 = -ballspeedx1; 
        x_pos1 = 100; 
      } 
      if (x_pos2  < 100) {
        ballspeedx2 = -ballspeedx2; 
        x_pos2 = 100; 
      }  
     
      if (x_pos1  > 300) {
        ballspeedx1 = -ballspeedx1; 
        x_pos1 = 300; 
      } 
      if (x_pos2  > 300) {
        ballspeedx2 = -ballspeedx2; 
        x_pos2 = 300; 
      }                                       
     
    if (Math.abs(x_pos2-x_pos1)<radius1+radius2){
        ballspeedx1 = -ballspeedx1;
        ballspeedx2 = -ballspeedx2;
      }
     
      try { Thread.sleep (20); } 
     
     
     
      catch (InterruptedException ex) {} 
     
    Thread.currentThread().setPriority(Thread.MAX_PRIORITY); }} 
     
    public void paint (Graphics g) {
     
    g.setColor (Color.red); 
    g.fillOval (x_pos1 - radius1, y_pos1 - radius1, 2 * radius1, 2 * radius1); 
     
    g.setColor (Color.blue); 
    g.fillOval (x_pos2 - radius2, y_pos2 - radius2, 2 * radius2, 2 * radius2); 
     
     
    g.setColor(Color.black);
    g.drawLine(80,80,80,320); // left
    g.drawLine(320,80,320,320); // right
    g.drawLine(80,80,320,80);  // 
    g.drawLine(80,320,320,320); // 
      }
     
    }


  2. #2
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    Default Re: Help with code- horizontal to vertical bouncing balls

    Quick question. What happens to a number when you multiply it by -1?

  3. #3
    Super Moderator Norm's Avatar
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    Default Re: Help with code- horizontal to vertical bouncing balls

    changing the direction of these balls from a horizontal axis to a vertical axis
    x values are for horizontal movement, y values for vertical movement. Change the code to change the y values, not the x values.
    If you don't understand my answer, don't ignore it, ask a question.

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