Order by two different conditions, but with a joined result in order to be able to use pagination

orderby-multiple.twig

{% set currentDay = date(now)|date('Y-m-d') %}
{% set comingQuery = craft.entries.section('agenda')
  .geplandeDatum(['and', '>= '~currentDay])
  .orderBy('geplandeDatum ASC')
  .ids()
%}
{% set pastQuery = craft.entries.section('agenda')
  .geplandeDatum(['and', '<'~currentDay])
  .orderBy('geplandeDatum DESC')
  .ids()
%}
{% set ids = comingQuery|merge(pastQuery) %}
{% set query = craft.entries.id( ids ).fixedOrder(true) %}