AddClass.js

function animate() {
    var scrollTop = $(window).scrollTop();

    $('.animate').each(function(){
        var from = $(this).attr('data-from');
        var to = $(this).attr('data-to');
        var trigger = $(this).attr('data-trigger');

        if(isNumber(trigger)){
        	var triggerNum = trigger;
        }else{
        	var triggerNum = $(trigger).offset().top;
        }

        console.log(trigger, from, to);

        if(scrollTop >= triggerNum){
            $(this).removeClass(from).addClass(to);
        }else{
            $(this).removeClass(to).addClass(from);
        }
    });

    $(window).scroll(function(){
        var scrollTop = $(window).scrollTop();

        $('.animate').each(function(){
            var from = $(this).attr('data-from');
            var to = $(this).attr('data-to');
            var trigger = $(this).attr('data-trigger');

	        if(isNumber(trigger)){
	        	var triggerNum = trigger;
	        }else{
	        	var triggerNum = $(trigger).offset().top;
	        }

            $('.teste').html(scrollTop +' - '+  triggerNum);

            if(scrollTop >= triggerNum){
                $(this).removeClass(from).addClass(to);
                //console.log('classe 1');
            }else{
                $(this).removeClass(to).addClass(from);
                //console.log('classe 2');
            }
            
        });
    });
}

function isNumber(n) {
    return !isNaN(parseFloat(n)) && isFinite(n);
}

animate();