$( window ).load( function(e){
 waterfall();
 var dataInt = { 'data': [{ 'src': '1.jpg' },{ 'src': '2.jpg' },{ 'src': '3.jpg' },{ 'src': '4.jpg' }]};
 $(window).scroll(function(){
  if( checkscrollside() ){
   $.each( dataInt.data, function(index,value){
    var $oPin = $('<div>').addClass('pin').appendTo( $("#main") );
    var $oBox = $('<div>').addClass('box').appendTo( $oPin );
    $('<img>').attr('src','./images/' + $(value).attr('src')).appendTo( $oBox );
   });
   waterfall();
  }
 });
 function waterfall(){
  var $aPin = $( "#main>div" );
  var iPinW = $aPin.eq(0).outerWidth();
  var num = Math.floor( $(window).width() / iPinW );
  $( "#main" ).css({
   'width' : iPinW * num,
   'margin' : '0 auto'
  });

  var pinHArr = [];
  $aPin.each(function( index, value ){
   var pinH = $aPin.eq( index ).height();
   if( index < num ){
    pinHArr[ index ] = pinH;
   }else{
    var minH = Math.min.apply( null, pinHArr );
    var minHIndex = $.inArray( minH, pinHArr );
    $( value ).css({
     'position': 'absolute',
     'top': minH + 15,
     'left': $aPin.eq( minHIndex ).position().left
    });
    pinHArr[ minHIndex ] += $aPin.eq( index ).height() + 15;
   }
  });
 }
 function checkscrollside(){
  var $aPin = $("#main>div");
  var lastPinH = $aPin.last().get(0).offsetTop + Math.floor( $aPin.last().height()/2);
  var scrollTop = $( window ).scrollTop();
  var documentH = $( document ).height();
  return (lastPinH < scrollTop + documentH ) ? true : false;
 }
});