import java.applet.*;
import java.awt.*;

/* Moving Radar Beam
	by Carman Neustaedter

	August 14, 2001
*/

public class RadarBeam extends Applet implements Runnable
{

	Thread t;    // create a field that will be used for an instance of a thread
		  // (a thread object)

	private int width, height;
	private int startAngle;

	private Image bufferImage;
	private Graphics buffer;

	public void init()
	{
		setBackground(Color.black);
		setForeground(Color.green);

		width=size().width;
		height=size().height;
		startAngle = 90;         // start at the top of the circle

		t = new Thread(this); // create a new thread object
		t.start();		    // start the thread running


		bufferImage=createImage(width, height);
		// create a buffer image the size of our applet

		buffer=bufferImage.getGraphics();
		// place our buffer image inside the buffer


	}
	
	public void run()
	{
		while(true)	
		{
			repaint();
		
			try{
				t.sleep(5);
			}catch(InterruptedException e) { ; }

			startAngle++;


		}
	}
	public void paint(Graphics g)
	{

		buffer.setColor(Color.black);
		buffer.fillRect(0,0, width, height);

		// my radar lines
		buffer.setColor(Color.green);
		buffer.drawOval(0, 0, width-1, height-1);

		for( int i=10; i < 120; i+=20)
			buffer.drawOval(i, i, width-i*2, height-i*2);

		buffer.fillArc(0,0, width, height, startAngle, 10);	

	

		// enemy attack
		buffer.setColor(Color.black);
		buffer.fillOval(30,60, 10, 10);	
		buffer.fillOval(150,120, 5, 5);	
		buffer.fillOval(90,200, 7, 7);	

		buffer.setColor(Color.green);
		if ((startAngle % 100) == 0)
			buffer.fillOval(120, 70, 10, 10);


		g.drawImage(bufferImage, 0, 0, this);
		// copy buffer image to the applet

		// "this" means the current object will be the one that is copied


	}
	public void update(Graphics g)
	{
		paint(g);
	}

}