text: var dustObj = function()
  {
    this.x = []
    this.y = []
    this.amp = []
    this.Num = []
  
    this.alpha
  }
  
  dustObj.prototype.num = 30
  dustObj.prototype.init = function()
  {
    for(var i = 0; i < this.num; i++)
    {
      this.x[i] = Math.random() * canWidth
      this.y[i] = Math.random() * canHeight
      this.amp[i] = Math.random() * 50 + 30
      this.Num[i] = Math.floor(Math.random() * 7)
    }
    this.alpha = 0
  }
  
  dustObj.prototype.draw = function()
  {
    this.alpha += deltaTime * 0.0005
    var l = Math.sin(this.alpha)
    for(var i = 0; i < this.num; i++)
    {
      var No = this.Num[i]
      ctx1.drawImage(dustPic[No], this.x[i] + this.amp[i] * l, this.y[i])
    }
  }
  