diff --git a/libs/geom/include/psemek/geom/vector.hpp b/libs/geom/include/psemek/geom/vector.hpp
index 516730a3..672ecda5 100644
--- a/libs/geom/include/psemek/geom/vector.hpp
+++ b/libs/geom/include/psemek/geom/vector.hpp
@@ -233,8 +233,15 @@ namespace psemek::geom
 			;
 	}
 
+	// TODO: generic implementation (shares internals with det)
 	template <typename T>
-	vector<T, 3> cross(vector<T, 3> const & v0, vector<T, 3> const & v1)
+	vector<T, 2> ort(vector<T, 2> const & v0)
+	{
+		return {-v0[1], v0[0]};
+	}
+
+	template <typename T>
+	vector<T, 3> ort(vector<T, 3> const & v0, vector<T, 3> const & v1)
 	{
 		return vector<T, 3>{
 			v0[1] * v1[2] - v0[2] * v1[1],
@@ -243,6 +250,12 @@ namespace psemek::geom
 		};
 	}
 
+	template <typename T>
+	vector<T, 3> cross(vector<T, 3> const & v0, vector<T, 3> const & v1)
+	{
+		return ort(v0, v1);
+	}
+
 	template <typename T>
 	T lerp(T const & x0, T const & x1, T const & t)
 	{