From 8ed1fec49c613e5393671c4f481d35e2601ba9db Mon Sep 17 00:00:00 2001
From: Chris Forbes <chrisf@ijw.co.nz>
Date: Tue, 15 Dec 2009 21:17:38 +1300
Subject: [PATCH] added M-n support to center on a group

---
 OpenRa.Game/Controller.cs        |  2 +-
 OpenRa.Game/Graphics/Viewport.cs | 19 ++++++++++++-------
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/OpenRa.Game/Controller.cs b/OpenRa.Game/Controller.cs
index e899d9bdbd..954d71a098 100644
--- a/OpenRa.Game/Controller.cs
+++ b/OpenRa.Game/Controller.cs
@@ -164,7 +164,7 @@ namespace OpenRa.Game
 
 			if (keys.HasModifier(Keys.Alt))
 			{
-				// center on this group
+				Game.viewport.Center(cache[group]);
 				return;
 			}
 
diff --git a/OpenRa.Game/Graphics/Viewport.cs b/OpenRa.Game/Graphics/Viewport.cs
index f0345a5b0e..2655c25555 100644
--- a/OpenRa.Game/Graphics/Viewport.cs
+++ b/OpenRa.Game/Graphics/Viewport.cs
@@ -83,15 +83,20 @@ namespace OpenRa.Game.Graphics
 			return (1 / 24.0f) * (new float2(mi.Location.X, mi.Location.Y) + Location);
 		}
 
+		public void Center(IEnumerable<Actor> actors)
+		{
+			if (!actors.Any()) return;
+
+			var avgPos = (1f / actors.Count()) * actors
+				.Select(a => a.CenterLocation)
+				.Aggregate((a, b) => a + b);
+
+			scrollPosition = avgPos - .5f * new float2(Width, Height);
+		}
+
 		public void GoToStartLocation()
 		{
-			var unit = Game.world.Actors
-				.FirstOrDefault(a => a.Owner == Game.LocalPlayer);
-
-			if (unit == null)
-				return;
-
-			scrollPosition = unit.CenterLocation - .5f * new float2(Width, Height);
+			Center(Game.world.Actors.Where(a => a.Owner == Game.LocalPlayer));
 		}
 	}
 }