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Thread: Grass disappearing :(

  1. #1
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    Default Grass disappearing :(

    For some reason when the "Grass" is drawn, it disappears immediately! I have no idea why this shouldn't work. It works perfectly when it's just the specified part of the code alone.

    This is the full code which doesn't work, the green lines disappear immediately:

    import java.applet.Applet;
    import java.awt.Color;
    import java.awt.Graphics;
    import java.awt.event.KeyEvent;
    import java.awt.event.KeyListener;
     
    public class Drawing4 extends Applet implements KeyListener{
    	int PlayerX = 0;
    	int PlayerY = 0;
    	int GrassX = 5;
    	public void init()
    	{
    		this.addKeyListener(this);
    		resize(501, 502);
    	}
    	public void paint(Graphics g)
    	{
    		g.setColor(Color.green);
    		while(GrassX < 500)
    		{
    			g.drawLine(GrassX, 0, GrassX, 500);
    			GrassX = GrassX + 5;
    		}
    		g.setColor(Color.black);
    		g.drawLine(0,0,500,0);
    		g.drawLine(500,500,500,0);
    		g.drawLine(500,500,0,500);
    		g.drawLine(0,500,0,0);
    		g.setColor(Color.red);
    		g.fillRect(PlayerX, PlayerY, 10, 10);
    	}
    	public void keyPressed(KeyEvent arg0){}
    	public void keyReleased(KeyEvent e) 
    	{
    		char key = e.getKeyChar();
    		if(key == 'w')
    		{
    			PlayerY = PlayerY - 10;
    		}
    		if(key == 'a')
    		{
    			PlayerX = PlayerX - 10;
    		}
    		if(key == 's')
    		{
    			PlayerY = PlayerY + 10;
    		}
    		if(key == 'd')
    		{
    			PlayerX = PlayerX + 10;
    		}
    		repaint();
    	}	
    	public void keyTyped(KeyEvent arg0){}
    }


    But alone the code does work:

    import java.applet.Applet;
    import java.awt.Color;
    import java.awt.Graphics;
     
    public class testing extends Applet{
    	public void init()
    	{
    		resize(501,501);
    	}
    	public void paint(Graphics g)
    	{
    		int GrassX = 5;
    		g.setColor(Color.green);
    		while(GrassX < 500)
    		{
    			g.drawLine(GrassX, 0, GrassX, 500);
    			GrassX = GrassX + 5;
    		}
    	}
    }


  2. #2
    Moderators helloworld922's Avatar
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    Default Re: Grass disappearing :(

    You've declared the GrassX variable in the class instance variables list. This means on each successive call to paint, the value will be whatever it was before, so in this case the first call would have GrassX be 0 and end with 500, then the next call would have GrassX already as 500, and not draw any grass.

  3. The Following User Says Thank You to helloworld922 For This Useful Post:

    The_Mexican (July 18th, 2010)

  4. #3
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    Default Re: Grass disappearing :(

    Aha! Thanks!