$.fn.center = function(valor, marginTop, marginLeft){

	

	var marginTop 	= (marginTop==undefined) 	? 0 : marginTop;

	var marginLeft 	= (marginLeft==undefined) 	? 0 : marginLeft;

	

	

	if(valor == 'v' || valor == 'vh' || valor == 'hv'){

		var totalW 		= $(window).width() + marginLeft;

		var width 		= $(this).width();

		var telaW		= (totalW/2) - (width/2);

		

		$(this).css('position', 'absolute').css('left', telaW + 'px');

	}

	if(valor == 'h' || valor == 'vh' || valor == 'hv'){

	

		var totalH 		= $(window).height() + marginTop;

		var height 		= $(this).height();

		var telaH		= (totalH/2) - (height/2);

		

		$(this).css('position', 'absolute').css('top', telaH + 'px');

	}

};