From 5f996de8bc5344da54961800ccc3017cf2e8b0b6 Mon Sep 17 00:00:00 2001
From: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
Date: Mon, 18 Jul 2022 02:36:23 +0200
Subject: [PATCH] Backport PR #23430: Fix divide by 0 runtime warning

---
 lib/mpl_toolkits/mplot3d/proj3d.py     |  2 +-
 lib/mpl_toolkits/tests/test_mplot3d.py | 10 ++++++----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/lib/mpl_toolkits/mplot3d/proj3d.py b/lib/mpl_toolkits/mplot3d/proj3d.py
index c9d5a7d65038..7c8ae74cb93a 100644
--- a/lib/mpl_toolkits/mplot3d/proj3d.py
+++ b/lib/mpl_toolkits/mplot3d/proj3d.py
@@ -21,7 +21,7 @@ def _line2d_seg_dist(p1, p2, p0):
 
     x01 = np.asarray(p0[0]) - p1[0]
     y01 = np.asarray(p0[1]) - p1[1]
-    if np.all(p1 == p2):
+    if np.all(p1[0:2] == p2[0:2]):
         return np.hypot(x01, y01)
 
     x21 = p2[0] - p1[0]
diff --git a/lib/mpl_toolkits/tests/test_mplot3d.py b/lib/mpl_toolkits/tests/test_mplot3d.py
index ebf3e15cf124..2c7a9feee9e2 100644
--- a/lib/mpl_toolkits/tests/test_mplot3d.py
+++ b/lib/mpl_toolkits/tests/test_mplot3d.py
@@ -1004,11 +1004,13 @@ def test_lines_dists():
 def test_lines_dists_nowarning():
     # Smoke test to see that no RuntimeWarning is emitted when two first
     # arguments are the same, see GH#22624
-    p0 = (10, 30)
-    p1 = (20, 150)
-    proj3d._line2d_seg_dist(p0, p0, p1)
+    p0 = (10, 30, 50)
+    p1 = (10, 30, 20)
+    p2 = (20, 150)
+    proj3d._line2d_seg_dist(p0, p0, p2)
+    proj3d._line2d_seg_dist(p0, p1, p2)
     p0 = np.array(p0)
-    proj3d._line2d_seg_dist(p0, p0, p1)
+    proj3d._line2d_seg_dist(p0, p0, p2)
 
 
 def test_autoscale():