text: const Engine = Matter.Engine;
  const World = Matter.World;
  const Bodies = Matter.Bodies;
  const Constraint = Matter.Constraint;
  var engine, world, backgroundImg;
  var canvas, angle, tower, ground, cannon,boat;
  var balls = [];
  var boats = [];
  
  
  function preload() {
    backgroundImg = loadImage("./assets/background.gif");
    towerImage = loadImage("./assets/tower.png");
    
  }
  
  function setup() {
    canvas = createCanvas(1200,600);
    engine = Engine.create();
    world = engine.world;
    angle = -PI / 4;
    ground = new Ground(0, height - 1, width * 2, 1);
    tower = new Tower(150, 350, 160, 310);
    cannon = new Cannon(180, 110, 100, 50, angle);
    boat= new Boat(width,height-100,200,200,-100);
    
  
    
  }
  
  function draw() {
    background(189);
    image(backgroundImg, 0, 0, width, height);
  
   
  
    Engine.update(engine);
    ground.display();
  
   
  
    for (var i = 0; i < balls.length; i++) 
    {
      showCannonBalls(balls[i], i);
      for(var j=0;j<boats.length;j++){
        if(balls[i]!==undefined && boats[j]!==undefined){
          var collision=Matter.SAT.collides(balls[i].body,boats[j].body);
          if(collision.collided){
            boats[j].remove(j);
            Matter.World.remove(world,balls[i].body);
            balls.splice(i,1);
            i--;
          }
        }
      }
    }
    showBoats();
  
    cannon.display();
    tower.display();
    Matter.Body.setVelocity(boat.body,{x:-0.9,y:0});
    //boat.display();
  
    
  }
  
  function keyPressed() {
    if (keyCode === DOWN_ARROW) {
      var cannonBall = new CannonBall(cannon.x, cannon.y);
      balls.push(cannonBall);
    }
  }
  
  //function to show the ball
  function showCannonBalls(ball, index) {
    ball.display();
    if (ball.body.position.x >= width || ball.body.position.y >= height - 50) {
      Matter.World.remove(world, ball.body);
      balls.splice(index, 1);
    }
  }
  
  
  
  function keyReleased() {
    if (keyCode === DOWN_ARROW) { 
      balls[balls.length - 1].shoot();
    }
  }
  
  
  function showBoats(){
    if(boats.length>0){
      if(boats.length<4 && boats[boats.length-1].body.position.x<width-300){
        var positions=[-67,-80,-87,-95];
        var position=random(positions);
        boat=new Boat(width,height-100,200,200,position);
        boats.push(boat);
      }
      for(var i=0;i<boats.length;i++){
        Matter.Body.setVelocity(boats[i].body,{x:-0.9,y:0});
        boats[i].display();
      }
    }
    else{
      var boat=new Boat(width,height-100,200,200,-100);
      boats.push(boat);
    }
  }