public GameWorld(ContentManager content)
{
background = content.Load<Texture2D>("spr_background");
cannon = new Cannon(content);
ball = new Ball(content);
paintCans = new List<PaintCan>();
paintCans.Add(new PaintCan(content, 450.0f, Color.Red));
paintCans.Add(new PaintCan(content, 575.0f, Color.Green));
paintCans.Add(new PaintCan(content, 700.0f, Color.Blue));
}