--- a/src/basics.h	Fri Mar 23 21:30:24 2018 +0200
+++ b/src/basics.h	Fri Mar 23 21:36:37 2018 +0200
@@ -131,6 +131,9 @@
 
 Q_DECLARE_METATYPE (Vertex)
 uint qHash(const Vertex& key);
+QDataStream& operator<<(QDataStream& out, const Vertex& vertex);
+QDataStream& operator>>(QDataStream& in, Vertex& vertex);
+
 
 static inline qreal abs(const QVector3D &vector)
 {