Add PlaceBuildingVariant trait.

OpenRA.Mods.Common/Traits/Buildings/PlaceBuildingVariants.cs

@@ -0,0 +1,28 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2019 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[Desc("Place a different building when PlaceBuilding's ToggleVariantKey hotkey is pressed while the PlaceBuildingOrderGenerator is active.")]
+	public class PlaceBuildingVariantsInfo : TraitInfo<PlaceBuildingVariants>, Requires<BuildingInfo>, Requires<BuildableInfo>
+	{
+		[FieldLoader.Require]
+		[ActorReference(typeof(BuildingInfo))]
+		[Desc("Variant actors that can be cycled between when placing a structure.")]
+		public readonly string[] Actors = null;
+
+		public override object Create(ActorInitializer init) { return new PlaceBuildingVariants(); }
+	}
+
+	public class PlaceBuildingVariants { }
+}