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

public class SecondControl extends Applet implements Runnable, KeyListener {

 int key;
 boolean gravity = true;
 boolean bounce = true;
 double x;
 double y;
 double xSpeed;
 double ySpeed;

 boolean keyLock = false;
 boolean going = false;

 static int WIDTH = 1000;
 static int HEIGHT = 600;
 static int DELAY = 10;
 static int SIZE = 20;
 static double FRICTION = .01;
 static double SPEED_CHANGE = 2.0;
 static double BOUNCE_DAMPENER = .3;
 static double GRAVITY = .14;

 Thread t;

 Image img;
 Graphics gra;

 public void init() {
  addKeyListener(this);

  img = createImage(WIDTH, HEIGHT);
  gra = img.getGraphics();

  t = new Thread(this);
  t.start();
  going = true;

 }
 public void run() {
  while(true) {
   keyLock = true;
   x+=xSpeed;
   y+=ySpeed;

//gravity accelerates downwards
   if(gravity) {
    ySpeed+=GRAVITY;
   }

//friction slowly decelerates the ball
   if(xSpeed < -1* FRICTION){
    xSpeed+=FRICTION;
   } else if(xSpeed > FRICTION) {
    xSpeed-=FRICTION;
   } else {
    xSpeed = 0;
   }
   if(ySpeed < -1* FRICTION){
    ySpeed+=FRICTION;
   } else if(ySpeed > FRICTION) {
    ySpeed-=FRICTION;
   } else {
    ySpeed = 0;
   }

//wall behavior
   if(x<0) {
    if(bounce) {
     x = 0;
     xSpeed = (float)(-1+BOUNCE_DAMPENER)*xSpeed;
    } else {
     x = WIDTH-SIZE;
     xSpeed = (float)(1-BOUNCE_DAMPENER)*xSpeed;
    }
   } else if(x>(WIDTH-SIZE)) {
    if(bounce) {
     x = WIDTH-SIZE;
     xSpeed = (float)(-1+BOUNCE_DAMPENER)*xSpeed;
    } else {
     x = 0;
     xSpeed = (float)(1-BOUNCE_DAMPENER)*xSpeed;
    }
   }
   if(y<0) {
    if(bounce) {
     y = 0;
     ySpeed = (float)(-1+BOUNCE_DAMPENER)*ySpeed;
    } else {
     y = HEIGHT-SIZE;
     ySpeed = (float)(1-BOUNCE_DAMPENER)*ySpeed;
    }
   } else if(y>(HEIGHT-SIZE)) {
    if(bounce) {
     y = HEIGHT-SIZE;
     ySpeed = (float)(-1+BOUNCE_DAMPENER)*ySpeed;
    } else {
     y = 0;
     ySpeed = (float)(1-BOUNCE_DAMPENER)*ySpeed;
    }
   }
   keyLock = false;
   repaint();
   try {
    t.sleep(DELAY);
   } catch(InterruptedException exc) { ; }
  }
 }
 public void update(Graphics g) {
  paint(g);
 }
 public void paint(Graphics g) {
  gra.setColor(Color.white);
  gra.fillRect(0,0,WIDTH, HEIGHT);

  gra.setColor(Color.blue);

  gra.fillOval((int)Math.floor(x),(int)Math.floor(y),SIZE,SIZE);
  g.drawImage(img, 0, 0, this);
 }
 public void keyPressed(KeyEvent evt) {
  key = evt.getKeyCode();
  if(keyLock == false) {
   switch(key){
    case KeyEvent.VK_DOWN: {
     ySpeed+=SPEED_CHANGE;
     break;
    }
    case KeyEvent.VK_UP: {
     ySpeed-=SPEED_CHANGE;
     break;
    }
    case KeyEvent.VK_RIGHT: {
     xSpeed+=SPEED_CHANGE;
     break;
    }
    case KeyEvent.VK_LEFT: {
     xSpeed-=SPEED_CHANGE;
     break;
    }
    case KeyEvent.VK_G: {
     gravity=!gravity;
     break;
    }
    case KeyEvent.VK_P: {
        if(going) {
            t.suspend();
            going = false;
        } else {
            t.resume();
            going = true;
        }
        break;
    }
    case KeyEvent.VK_B: {
     bounce=!bounce;
     break;
    }
   }
  }
 }
 public void keyReleased(KeyEvent evt) { ; }
 public void keyTyped(KeyEvent evt) { ; }

}