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;
  var cannonBall;
  
  function preload() {
    backgroundImg = loadImage("./assets/background.gif");
    towerImage = loadImage("./assets/tower.png");
  }
  
  function setup() {
    canvas = createCanvas(1200, 600);
    engine = Engine.create();
    world = engine.world;
    angleMode(RADIANS)
    angle = -PI / 4
  
    ground = Bodies.rectangle(0, height - 1, width * 2, 1, { isStatic: true });
    World.add(world, ground);
  
    tower = Bodies.rectangle(160, 350, 160, 310, { isStatic: true });
    World.add(world, tower);
  
    cannon = new Cannon(180, 110, 130, 100, angle);
    cannonBall = new CannonBall(cannon.x, cannon.y);
  }
  
  function draw() {
    background(189);
    image(backgroundImg, 0, 0, width, height);
  
    Engine.update(engine);
  
    rect(ground.position.x, ground.position.y, width * 2, 1);
    push();
    imageMode(CENTER);
    image(towerImage, tower.position.x, tower.position.y, 160, 310);
    pop();
  
    cannon.display();
    cannonBall.display();
  }
   function keyReleased(){
    if(keyCode===DOWN_ARROW){
      cannonBall.shoot()
  
    }
  
   }
  
  