import java.awt.*;



class Star {

	int	H, V;

	int	x, y, z;

	int	type;



	Star( int width, int height, int depth, int type )

		{

		this.type = type;

		H = width/2;

		V = height/2;

		x = (int)(Math.random()*width) - H;

		y = (int)(Math.random()*height) - V;

		if( (x == 0) && (y == 0 ) ) x = 10;

		z = (int)(Math.random()*depth);

		}



	public void Draw( Graphics g, double rot )

		{

		double	X, Y;

		int	h, v, hh, vv;

		int	d;

		z-=2;

		if( z < -63 ) z = 100;

		hh = (x*64)/(64+z);

		vv = (y*64)/(64+z);

		X = (hh*Math.cos(rot))-(vv*Math.sin(rot));

		Y = (hh*Math.sin(rot))+(vv*Math.cos(rot));

		h = (int)X+H;

		v = (int)Y+V;

		if( (h < 0) || (h > (2*H))) z = 100;

		if( (v < 0) || (v > (2*H))) z = 100;

		GrayMe(g);

		if( type == 0 )

			{

			d=(100-z)/50;

			if( d == 0 ) d = 1;

			g.fillRect( h, v, d, d );

			}

		else

			{

			d=(100-z)/20;

			g.drawLine( h-d, v, h+d, v );

			g.drawLine( h, v-d, h, v+d );

			if( z < 50 ) {

				d/=2;

				g.drawLine( h-d, v-d, h+d, v+d );

				g.drawLine( h+d, v-d, h-d, v+d );

				}

			}

		}



	public void GrayMe(Graphics g)

		{

/*		if( z > 75 )

			{

			g.setColor( Color.darkGray );

			}

		else*/ if ( z > 50 )

			{

			g.setColor( Color.gray );

			}

		else if ( z > 25 )

			{

			g.setColor( Color.lightGray );

			}

		else

			{

			g.setColor( Color.white );

			}

		}

	}



public class StarField extends java.applet.Applet implements Runnable

	{

	int		Width, Height;

	Thread		me = null;

	boolean		suspend = false;

	Image		im;

	Graphics	offscreen;

	double		rot, dx, ddx;



	int		speed, stars, type;

	double		defddx, max;

	Star		pol[];		/* Points of light */

	

	public void init()

		{

		rot = 0;

		dx=0;

		ddx=0;

		Width = size().width;

		Height = size().height;



		String	theSpeed = getParameter( "speed" );

		Show( "speed", theSpeed );

		speed = (theSpeed == null ) ? 50 : Integer.valueOf( theSpeed ).intValue();



		String	theStars = getParameter( "stars" );

		Show( "stars", theStars );

		stars = (theStars == null ) ? 30 : Integer.valueOf( theStars ).intValue();



		String theType = getParameter( "type" );

		Show( "type", theType );

		type = (theType == null ) ? 0 : Integer.valueOf( theType ).intValue();



		String theRot = getParameter( "spin" );

		Show( "spin", theRot );

		rot = (theRot == null) ? 0 : Double.valueOf( theRot ).doubleValue();



		String theMax = getParameter( "maxspin" );

		Show( "maxspin", theRot );

		max = (theMax == null) ? .1 : Double.valueOf( theMax ).doubleValue();



		String theddx = getParameter( "ddx" );

		Show( "ddx", theddx );

		defddx = (theddx == null) ? .005 : Double.valueOf( theddx ).doubleValue();



		try

			{

			im = createImage( Width, Height );

			offscreen = im.getGraphics();

			}

		catch( Exception e)

			{

			offscreen = null;

			}

		pol = new Star[stars];

		for( int i = 0; i < stars; i++ )

			pol[i] = new Star( Width, Height, 100, type );

		}



	public void paint( Graphics g )

		{

		if( offscreen != null )

			{

			paintMe( offscreen );

			g.drawImage( im, 0, 0, this );

			}

		else

			{

			paintMe( g );

			}

		}





	public void paintMe( Graphics g )

		{

		g.setColor( Color.black );

		g.fillRect( 0, 0, Width, Height );

		//g.setColor( Color.gray );

		for( int i = 0; i < stars; i++ )

			pol[i].Draw( g, rot );

		}



	public void start()

		{

		if( me == null )

			{

			me = new Thread( this );

			me.start();

			}

		}



	public void stop()

		{

		if( me != null )

			{

			me.stop();

			me = null;

			}

		}



	public void run()

		{

		while( me != null )

			{

			rot += dx;

			dx += ddx;

			if( dx > max ) ddx=-defddx;

			if( dx < -max) ddx=defddx;

			try { Thread.sleep( speed ); }

			catch (InterruptedException e){}

			repaint();

			}

		}



	public void update( Graphics g )

		{

		paint( g );

		}



	public boolean mouseDown( java.awt.Event evt, int x, int y )

		{

		ddx = (ddx == 0) ? defddx : 0;

		return true;

		}



	public void Toggle( )

		{

		if( me != null )

			{

			if( suspend )

				{

				me.resume();

				}

			else

				{

				me.suspend();

				}

			suspend = !suspend;

			}

		}



	public void Show( String theString, String theValue )

		{

		if( theValue == null )

			{

			System.out.println( theString + " : null");

			}

		else

			{

			System.out.println( theString + " : " + theValue );

			}

		}

	}