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

public class Worm extends Applet{
	Image ballpic;
	int numsegments = 10;
	float segmentx[], segmenty[], segmentlength[];
	int dragx, dragy;

	public void init(){
		int n;
		setBackground(Color.black);

		ballpic = getImage(getDocumentBase(), "ball.gif");
		segmentx = new float[numsegments];
		segmenty = new float[numsegments];
		segmentlength = new  float[numsegments];

		for(n = 0; n < numsegments; n++){
			segmentlength[n] = (float)23;
			segmentx[n] = segmenty[n] = (float)0;
		}
	}

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

	public void animate_worm(Graphics g){
		int n, oldx[], oldy[];
		float dist, slope, deltax, deltay;

		oldx = new int[numsegments];
		oldy = new int[numsegments];
		for(n = 0; n < numsegments; n++){
			oldx[n] = (int)segmentx[n];
			oldy[n] = (int)segmenty[n];
		}


		segmentx[0] = dragx;
		segmenty[0] = dragy;
		for(n = 1; n < numsegments; n++){
			deltax = segmentx[n] - segmentx[n - 1];
			deltay = segmenty[n] - segmenty[n - 1];
			dist = (float)Math.pow(deltax * deltax + deltay * deltay, .5);

			if(dist != 0){
				slope = segmentlength[n] / dist;
				segmentx[n] = -slope * (segmentx[n - 1] - segmentx[n]) + segmentx[n - 1];
				segmenty[n] = -slope * (segmenty[n - 1] - segmenty[n]) + segmenty[n - 1];
			}
		}

		g.setColor(new Color(0, 0, 0));
		for(n = 0; n < numsegments; n++){
			g.fillOval((int)oldx[n], (int)oldy[n],
				ballpic.getWidth(this), 
				ballpic.getHeight(this));
		}
		for(n = numsegments - 1; n >= 0; n--){
			g.drawImage(ballpic, (int)segmentx[n], (int)segmenty[n], this);
		}
	}

	public boolean mouseMove(Event evt, int x, int y){
		dragx = x - 1;
		dragy = y - 2;

		repaint();
		return true;
	}
}