From fe4abc521a716611a63383cd2b142cedcee0e437 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Mon, 21 Jun 2021 17:25:51 +1000
Subject: [PATCH] AP_Math: make vector3 xy() method return a reference

---
 libraries/AP_Math/vector3.cpp |  7 -------
 libraries/AP_Math/vector3.h   | 12 +++++++++---
 2 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/libraries/AP_Math/vector3.cpp b/libraries/AP_Math/vector3.cpp
index 921c852ed7..71ffc08944 100644
--- a/libraries/AP_Math/vector3.cpp
+++ b/libraries/AP_Math/vector3.cpp
@@ -617,13 +617,6 @@ bool Vector3<T>::segment_plane_intersect(const Vector3<T>& seg_start, const Vect
     return true;
 }
 
-// return xy components of a vector3
-template <typename T>
-Vector2<T> Vector3<T>::xy()
-{
-    return Vector2<T>{x,y};
-}
-
 // define for float and double
 template class Vector3<float>;
 template class Vector3<double>;
diff --git a/libraries/AP_Math/vector3.h b/libraries/AP_Math/vector3.h
index 150c040332..d3ac153eab 100644
--- a/libraries/AP_Math/vector3.h
+++ b/libraries/AP_Math/vector3.h
@@ -192,9 +192,15 @@ public:
     // rotate vector by angle in radians in xy plane leaving z untouched
     void rotate_xy(float rotation_rad);
 
-    // return xy components of a vector3
-    Vector2<T> xy();
-    
+    // return xy components of a vector3 as a vector2.
+    // this returns a reference to the original vector3 xy data
+    const Vector2<T> &xy() const {
+        return *(const Vector2<T> *)this;
+    }
+    Vector2<T> &xy() {
+        return *(Vector2<T> *)this;
+    }
+
     // gets the length of this vector squared
     T  length_squared() const
     {