diff --git a/libs/geom/include/psemek/geom/quaternion.hpp b/libs/geom/include/psemek/geom/quaternion.hpp
index c5199419..c1ee3288 100644
--- a/libs/geom/include/psemek/geom/quaternion.hpp
+++ b/libs/geom/include/psemek/geom/quaternion.hpp
@@ -224,6 +224,20 @@ namespace psemek::geom
 		return {res[0], res[1], res[2]};
 	}
 
+	// v0 & v1 assumed to be normalized
+	template <typename T>
+	quaternion<T> shortest_arc(vector<T, 3> const & v0, vector<T, 3> const & v1)
+	{
+		auto axis = cross(v0, v1);
+		quaternion<T> result;
+		result[0] = axis[0];
+		result[1] = axis[1];
+		result[2] = axis[2];
+		result[3] = T{1} + dot(v0, v1);
+		result.coords = normalized(result.coords);
+		return result;
+	}
+
 	template <typename T>
 	T angle(quaternion<T> const & q0, quaternion<T> const & q1)
 	{