Writing a Pong game - enhancing my default code.

[DeagleFace]

Hi :)

If you read my introduction post then hello again, if not then hello anyway :)

Basically, I am struggling with Java out of the 6 languages I am learning the most and getting fairly stressed about a piece of work I need to complete.

I have a framework code for a game of pong which you will see below, all it includes currently is a ball moving across the screen and the position of the ball being displayed above.

I am not expecting someone to use their time to write me a bunch of code, but need a real pointer in the right direction or some kind of decent tutorials that relate to the framework code I am supplied with; so I can build upon it.

The code compiles as it is currently

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.awt.Color;
/*
 * Note If you change S (Speed) collision detection will be
 *      more complex as the ball edge may be within the bat
 *      Ignores concurrency issues (x, y, x_inc, y_inc access)
 */

class Main
{
  public static void main( String args[] ) // 
  {                                        // 
    System.out.println("Application");
    Application app = new Application();
    app.setVisible(true);
    app.run();
  }                                        // 
}

class Application extends JFrame            // So graphical 
{
  private static final int H = 600;         // Height of window 
  private static final int W = 800;         // Width  of window 

  public Application()
  {
    setSize( W, H );                        // Size of application 
    addKeyListener( new Transaction() );    // Called when key press 
    setDefaultCloseOperation(EXIT_ON_CLOSE);
  }


  public void update( Graphics g )          // Called by repaint 
  {                                         // 
    drawPicture( (Graphics2D) g );          // Draw Picture 
  }

  public void paint( Graphics g )           // When 'Window' is first 
  {                                         //  shown or damaged 
    drawPicture( (Graphics2D) g );          // Draw Picture 
  }

  private Dimension     theAD;              // Alternate Dimension 
  private BufferedImage theAI;              // Alternate Image 
  private Graphics2D    theAG;              // Alternate Graphics 

  public void drawPicture( Graphics2D g )   // Double buffer 
  {                                         //  allow re-size 
    Dimension d    = getSize();             // Size of curr. image 

    if (  ( theAG == null )  ||
          ( d.width  != theAD.width ) ||
          ( d.height != theAD.height ) )
    {                                       // New size 
      theAD = d;
      theAI = (BufferedImage) createImage( d.width, d.height );
      theAG = theAI.createGraphics();
      AffineTransform at = new AffineTransform();
      at.setToIdentity();
      at.scale( ((double)d.width)/W, ((double)d.height)/H );
      theAG.transform(at);
    }

    drawActualPicture( theAG );             // Draw Actual Picture 
    g.drawImage( theAI, 0, 0, this );       //  Display on screen 
  }

  // The ball position and how to increment to next position 

  private int x = W/2, x_inc = 1;
  private int y = H/2, y_inc = 1;

  // Called on key press  

  class Transaction implements KeyListener  // When character typed 
  {
    public void keyPressed(KeyEvent e)      // Obey this method 
    {
     // Key typed includes specials 
     switch ( e.getKeyCode() )              // Character is 
     {
       case KeyEvent.VK_LEFT:               // Left Arrow 
         x_inc = -1;
         break;
       case KeyEvent.VK_RIGHT:              // Right arrow 
         x_inc = 1;
         break;
       case KeyEvent.VK_UP:                 // Up arrow 
         y_inc = -1;
         break;
       case KeyEvent.VK_DOWN:               // Down arrow 
         y_inc = 1;
         break;
      }
      // x,y could send to a server instead of calling  
      repaint();                            // Call update method 
    }

    public void keyReleased(KeyEvent e)
    {
      // Called on key release including specials 
    }

    public void keyTyped(KeyEvent e)
    {
      // Normal key typed 
      char c = e.getKeyChar();              // Typed 
      repaint();                            // Redraw screen 
    }
  }

  private static final int B = 6;           // Border offset 
  private static final int M = 26;          // Menu offset 
  private static final int BALL_SIZE = 10;  // Ball diameter 
  private static final int HALF_BALL_SIZE = BALL_SIZE/2;

  // Code called to draw the current state of the game 

  public void drawActualPicture( Graphics2D g )
  {
    // White background 

    g.setPaint( Color.white );
    g.fill( new Rectangle2D.Double( 0, 0, W, H ) );

    Font font = new Font("Calibri",Font.BOLD,24); 
    g.setFont( font ); 

    // Blue playing border 

    g.setPaint( Color.blue );              // Paint Colour 
    g.draw( new Rectangle2D.Double( B, M, W-B*2, H-M-B ) );

    // Display state of game 

    g.setPaint( Color.blue );
    FontMetrics fm = getFontMetrics( font );
    String fmt  = "Bouncing Ball x=%4d y = %4d";
    String text = String.format( fmt, x, y );
    g.drawString( text, W/2-fm.stringWidth(text)/2, M*2 );

    // The ball at the current x, y position (width, height) 

    g.setPaint( Color.red );
    g.fill( new Ellipse2D.Double( x-HALF_BALL_SIZE, y-HALF_BALL_SIZE, 
                                  BALL_SIZE,     BALL_SIZE ) );
  }
    

  // Main program loop 

  public void run()
  {
    final int S = 1;                    // Speed 1 - 5 
    try
    {
      while ( true )
      {
        if ( x >= W-B-HALF_BALL_SIZE ) x_inc = -1*S;
        if ( x <= 0+B+HALF_BALL_SIZE ) x_inc = 1*S;
        if ( y >= H-B-HALF_BALL_SIZE ) y_inc = -1*S;
        if ( y <= 0+M+HALF_BALL_SIZE ) y_inc = 1*S;
  
        x += x_inc;
        y += y_inc;
  
        repaint();                      // Now display 

        Thread.sleep( 10 );             // 100 Hz 
      }
    } catch ( Exception e ) {};
  }

}

The minimum objectives I would like to achieve are
- Insert 2 paddles that can be moved using W/S and UP/DOWN which the ball collides with
- Insert a score for both players at top of screen rather than current text
- Change the background image to something over than a basic colour.

Thankyou for any replies.


In the meantime I will work on my C program in arduino to take random numbers and display them in binary :)

[Fubarable]

You might get a decent answer here, but my experience here has been that we do much better answering specific questions regarding your attempts to implement something. So why not try to implement these objectives first and then ask any specific questions regarding your attempts if they don't work as you desire?

[DeagleFace]

You might get a decent answer here, but my experience here has been that we do much better answering specific questions regarding your attempts to implement something. So why not try to implement these objectives first and then ask any specific questions regarding your attempts if they don't work as you desire?

More because I don't really have any idea where to start. What I would like to do first and foremost is place 2 bats either side of the game window. Once I have achieved that, I will hopefully advance on it with collision and movement.

[DeagleFace]

I will be trying to help myself while doing this of course.

The first thing I notice when thinking about trying to implement this is

g.setPaint( Color.blue );
    FontMetrics fm = getFontMetrics( font );
    String fmt  = "Bouncing Ball x=%4d y = %4d";
    String text = String.format( fmt, x, y );
    g.drawString( text, W/2-fm.stringWidth(text)/2, M*2 );

    // The ball at the current x, y position (width, height) 

    g.setPaint( Color.red );
    g.fill( new Ellipse2D.Double( x-HALF_BALL_SIZE, y-HALF_BALL_SIZE, 
                                  BALL_SIZE,     BALL_SIZE ) );

So could I use this

g.setPaint( Color. );
g.fill( new Rectangle2D.Double());

to create further shapes and position them on the page? I had a fiddle, but could not figure out how to set the positioning properties, and somehow turned my whole window green.

[sunde887]

Here is some code I used to make Pong a while ago. I'd recommend you read it and see if it can help you out.
https://github.com/hegek87/Pong/tree/master/src/src

[DeagleFace]

Here is some code I used to make Pong a while ago. I'd recommend you read it and see if it can help you out.
https://github.com/hegek87/Pong/tree/master/src/src

Cheers Ill take a look through, if I find any problems with specific parts ill throw a PM your way.

[DeagleFace]

Hi guys, I have now got 2 rectangular shapes which I am calling my paddles on the screen with the following code.

    //paddle1
    g.setPaint( Color.blue );
    g.fill( new Rectangle2D.Double(50, 250, 10, 100));
    
    //paddle2
    g.setPaint ( Color.blue );
    g.fill( new Rectangle2D.Double(750, 250, 10, 100));

Is there someone that can show me how to add collision detection to the bats so that the ball will bounce off of them?