From c5428a4ea5e4d3d801049601d605fe0af9e67a2c Mon Sep 17 00:00:00 2001
From: Stefan Harmuth <pennywise@drock.de>
Date: Sun, 14 Aug 2022 12:32:37 +0200
Subject: [PATCH] keep a more accurate track of boundaries

---
 tools/grid.py | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/tools/grid.py b/tools/grid.py
index 91be2bd..7a5863b 100644
--- a/tools/grid.py
+++ b/tools/grid.py
@@ -34,22 +34,29 @@ class Grid:
     def __init__(self, default=False):
         self.__default = default
         self.__grid = {}
-        self.minX = 0
-        self.minY = 0
-        self.maxX = 0
-        self.maxY = 0
-        self.minZ = 0
-        self.maxZ = 0
+        self.minX = None
+        self.minY = None
+        self.maxX = None
+        self.maxY = None
+        self.minZ = None
+        self.maxZ = None
         self.mode3D = False
 
     def __trackBoundaries(self, pos: Coordinate):
-        self.minX = pos.x if pos.x < self.minX else self.minX
-        self.minY = pos.y if pos.y < self.minY else self.minY
-        self.maxX = pos.x if pos.x > self.maxX else self.maxX
-        self.maxY = pos.y if pos.y > self.maxY else self.maxY
+        if self.minX is None:
+            self.minX, self.maxX, self.minY, self.maxY = pos.x, pos.x, pos.y, pos.y
+        else:
+            self.minX = pos.x if pos.x < self.minX else self.minX
+            self.minY = pos.y if pos.y < self.minY else self.minY
+            self.maxX = pos.x if pos.x > self.maxX else self.maxX
+            self.maxY = pos.y if pos.y > self.maxY else self.maxY
+
         if self.mode3D:
-            self.minZ = pos.z if pos.z < self.minZ else self.minZ
-            self.maxZ = pos.z if pos.z > self.maxZ else self.maxZ
+            if self.minZ is None:
+                self.minZ = self.maxZ = pos.z
+            else:
+                self.minZ = pos.z if pos.z < self.minZ else self.minZ
+                self.maxZ = pos.z if pos.z > self.maxZ else self.maxZ
 
     def rangeX(self, pad: int = 0, reverse=False):
         if reverse: