text: class Stone{
      constructor(x,y,r){
          var options = {
              restitution: 0.8
          };
          this.body = Bodies.circle(x,y,r,options);
          World.add(world,this.body);
  
  
          this.radius = r;
          
      }
      display(){
          ellipseMode(CENTER);
          push()
          strokeWeight(2);
          translate(this.body.position.x,this.body.position.y);
          fill("white");
          ellipse(0,0,this.radius,this.radius);
          noStroke();
          pop()
      }
  }