Do the right thing when stances change

OpenRA.Game/Network/UnitOrders.cs

@@ -66,9 +66,14 @@ namespace OpenRA.Network
 			case "SetStance":
 				{
 					var targetPlayer = order.Player.World.players[order.TargetLocation.X];
+					var oldStance = order.Player.Stances[targetPlayer];
 					order.Player.Stances[targetPlayer] = (Stance)order.TargetLocation.Y;
+					
+					if (targetPlayer == world.LocalPlayer)
+						world.WorldActor.traits.Get<Shroud>().UpdatePlayerStance(world, order.Player, oldStance, order.Player.Stances[targetPlayer]);
+					
 					Game.Debug("{0} has set diplomatic stance vs {1} to {2}".F(
-						order.Player.PlayerName, targetPlayer.PlayerName, (Stance)order.TargetLocation.Y));
+						order.Player.PlayerName, targetPlayer.PlayerName, order.Player.Stances[targetPlayer]));
 					break;
 				}
 			default:

OpenRA.Game/Traits/World/Shroud.cs

@@ -102,6 +102,24 @@ namespace OpenRA.Traits
 			Dirty();
 		}
 		
+		public void UpdatePlayerStance(World w, Player player, Stance oldStance, Stance newStance)
+		{
+			if (oldStance == newStance)
+				return;
+			
+			// No longer our ally; remove unit vis
+			if (oldStance == Stance.Ally)
+			{
+				var toRemove = new List<Actor>(vis.Select(a => a.Key).Where(a => a.Owner == player));
+				foreach (var a in toRemove)
+					RemoveActor(a);
+			}
+			// Is now our ally; add unit vis
+			if (newStance == Stance.Ally)
+				foreach (var a in w.Queries.OwnedBy[player])
+					AddActor(a);
+		}
+
 		public static IEnumerable<int2> GetVisOrigins(Actor a)
 		{
 			if (a.Info.Traits.Contains<BuildingInfo>())
@@ -135,7 +153,9 @@ namespace OpenRA.Traits
 
 		public void UpdateActor(Actor a)
 		{
-			if (a.Owner == null || a.Owner != a.Owner.World.LocalPlayer) return;
+			if (a.Owner == null || a.Owner.World.LocalPlayer == null 
+			    || a.Owner.Stances[a.Owner.World.LocalPlayer] != Stance.Ally) return;
+
 			RemoveActor(a); AddActor(a);
 		}