Add UpgradeOnTerrain.

OpenRA.Mods.Common/OpenRA.Mods.Common.csproj

@@ -498,6 +498,7 @@
     <Compile Include="Traits\Upgrades\UpgradableTrait.cs" />
     <Compile Include="Traits\Upgrades\UpgradeActorsNear.cs" />
     <Compile Include="Traits\Upgrades\UpgradeOnDamage.cs" />
+    <Compile Include="Traits\Upgrades\UpgradeOnTerrain.cs" />
     <Compile Include="Traits\Upgrades\UpgradeManager.cs" />
     <Compile Include="Traits\Valued.cs" />
     <Compile Include="Traits\Voiced.cs" />

OpenRA.Mods.Common/Traits/Upgrades/UpgradeOnTerrain.cs

@@ -0,0 +1,69 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2016 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 System.Linq;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	public class UpgradeOnTerrainInfo : ITraitInfo, Requires<UpgradeManagerInfo>
+	{
+		[UpgradeGrantedReference]
+		public readonly string[] Upgrades = { "terrain" };
+
+		[Desc("Terrain names to trigger the upgrade.")]
+		public readonly string[] TerrainTypes = { };
+
+		public object Create(ActorInitializer init) { return new UpgradeOnTerrain(init, this); }
+	}
+
+	public class UpgradeOnTerrain : ITick
+	{
+		readonly Actor self;
+		readonly UpgradeOnTerrainInfo info;
+		readonly UpgradeManager manager;
+
+		bool granted;
+		string previousTerrain;
+
+		public UpgradeOnTerrain(ActorInitializer init, UpgradeOnTerrainInfo info)
+		{
+			self = init.Self;
+			this.info = info;
+			manager = self.Trait<UpgradeManager>();
+		}
+
+		public void Tick(Actor self)
+		{
+			var currentTerrain = self.World.Map.GetTerrainInfo(self.Location).Type;
+			var wantsGranted = info.TerrainTypes.Contains(currentTerrain);
+			if (currentTerrain != previousTerrain)
+			{
+				if (wantsGranted && !granted)
+				{
+					foreach (var up in info.Upgrades)
+						manager.GrantUpgrade(self, up, this);
+
+					granted = true;
+				}
+				else if (!wantsGranted && granted)
+				{
+					foreach (var up in info.Upgrades)
+						manager.RevokeUpgrade(self, up, this);
+
+					granted = false;
+				}
+			}
+
+			previousTerrain = currentTerrain;
+		}
+	}
+}