From 4e6d0d7f0858cb7d972690f5387fb0bfbc2014ff Mon Sep 17 00:00:00 2001
From: John Lewin <lewin76@gmail.com>
Date: Wed, 28 Mar 2018 17:14:46 -0700
Subject: [PATCH] Center on bounding box

When grouping items, move them to be centered on their bounding box
---
 PartPreviewWindow/View3D/UndoCommands/GroupCommand.cs | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/PartPreviewWindow/View3D/UndoCommands/GroupCommand.cs b/PartPreviewWindow/View3D/UndoCommands/GroupCommand.cs
index 94f4db6dc..66a222d1e 100644
--- a/PartPreviewWindow/View3D/UndoCommands/GroupCommand.cs
+++ b/PartPreviewWindow/View3D/UndoCommands/GroupCommand.cs
@@ -30,6 +30,7 @@ either expressed or implied, of the FreeBSD Project.
 using MatterHackers.Agg.UI;
 using MatterHackers.DataConverters3D;
 using MatterHackers.Localizations;
+using MatterHackers.MatterControl.DesignTools.Operations;
 using MatterHackers.MeshVisualizer;
 
 namespace MatterHackers.MatterControl.PartPreviewWindow
@@ -56,18 +57,26 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 				{
 					Name = "Group".Localize()
 				};
+
+				// When grouping items, move them to be centered on their bounding box
 				newGroup.Children.Modify((gChildren) =>
 				{
 					selectedItem.Children.Modify((sChildren) =>
 					{
-						foreach(var child in sChildren)
+						var center = selectedItem.GetAxisAlignedBoundingBox().Center;
+
+						foreach (var child in sChildren)
 						{
+							child.Translate(-center.X, -center.Y, 0);
 							gChildren.Add(child);
 						}
 
+						newGroup.Translate(center.X, center.Y, 0);
+
 						sChildren.Clear();
 					});
 				});
+
 				scene.Children.Add(newGroup);
 				scene.SelectedItem = null;
 				item = newGroup;