From 05098c0c13bc2622f48b4b0f1b01d53d0cc11949 Mon Sep 17 00:00:00 2001
From: Jan Petykiewicz <jan@mpxd.net>
Date: Sat, 14 Feb 2026 19:15:54 -0800
Subject: [PATCH] [remove_colinear_vertices] keep two vertices if all were
 colinear

---
 masque/utils/vertices.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/masque/utils/vertices.py b/masque/utils/vertices.py
index 5fddd52..36d2e59 100644
--- a/masque/utils/vertices.py
+++ b/masque/utils/vertices.py
@@ -51,6 +51,10 @@ def remove_colinear_vertices(vertices: ArrayLike, closed_path: bool = True) -> N
     if not closed_path:
         slopes_equal[[0, -1]] = False
 
+    if slopes_equal.all() and vertices.shape[0] > 0:
+        # All colinear, keep the first and last
+        return vertices[[0, vertices.shape[0] - 1]]
+
     return vertices[~slopes_equal]