Parallax scrolling

Parallax

$ ->
  _window = $(window)

  scroll_div = (win, div, init=false) ->
    _scrolltop = win.scrollTop()
    _top = div.offset().top
    _offset = div.data("offsetY") || 0
    _speed = div.data("speed") || 0

    console.log "#{_scrolltop} + #{win.height()} > #{_top}"

    if _scrolltop + win.height() > _top and _top + div.height() > _scrolltop
      _pos = _scrolltop / _speed + _offset

      if init then _pos *= -1
      else _pos += _offset

      div.css backgroundPosition: "50% #{_pos}px"


  # $( "section[data-type=\"background\"]" ).each ->
  $(".parallax").each ->
    _self = $(this)

    scroll_div _window, _self, true

    $(window).scroll ->
      scroll_div _window, _self, false