Add UpgradeOnMovement trait

This provides upgrades when an actor is moving. To avoid 'hiccups' for ground units, air units are considered moving as soon as they are airborne.

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

@@ -499,6 +499,7 @@
     <Compile Include="Traits\Upgrades\UpgradeActorsNear.cs" />
     <Compile Include="Traits\Upgrades\UpgradeOnDamageState.cs" />
     <Compile Include="Traits\Upgrades\UpgradeOnTerrain.cs" />
+    <Compile Include="Traits\Upgrades\UpgradeOnMovement.cs" />
     <Compile Include="Traits\Upgrades\UpgradeManager.cs" />
     <Compile Include="Traits\Valued.cs" />
     <Compile Include="Traits\Voiced.cs" />

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

@@ -0,0 +1,75 @@
+#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 UpgradeOnMovementInfo : UpgradableTraitInfo, Requires<UpgradeManagerInfo>, Requires<IMoveInfo>
+	{
+		[UpgradeGrantedReference, FieldLoader.Require]
+		[Desc("The upgrades to grant.")]
+		public readonly string[] Upgrades = { };
+
+		[Desc("Apply upgrades on straight vertical movement as well.")]
+		public readonly bool ConsiderVerticalMovement = false;
+
+		public override object Create(ActorInitializer init) { return new UpgradeOnMovement(init.Self, this); }
+	}
+
+	public class UpgradeOnMovement : UpgradableTrait<UpgradeOnMovementInfo>, ITick
+	{
+		readonly UpgradeManager manager;
+		readonly IMove movement;
+
+		bool granted;
+
+		public UpgradeOnMovement(Actor self, UpgradeOnMovementInfo info)
+			: base(info)
+		{
+			manager = self.Trait<UpgradeManager>();
+			movement = self.Trait<IMove>();
+		}
+
+		void Revoke(Actor self)
+		{
+			if (!granted)
+				return;
+
+			foreach (var up in Info.Upgrades)
+				manager.RevokeUpgrade(self, up, this);
+
+			granted = false;
+		}
+
+		void ITick.Tick(Actor self)
+		{
+			if (IsTraitDisabled)
+			{
+				Revoke(self);
+				return;
+			}
+
+			var isMovingVertically = Info.ConsiderVerticalMovement ? movement.IsMovingVertically : false;
+			var isMoving = !self.IsDead && (movement.IsMoving || isMovingVertically);
+			if (isMoving && !granted)
+			{
+				foreach (var up in Info.Upgrades)
+					manager.GrantUpgrade(self, up, this);
+
+				granted = true;
+			}
+			else if (!isMoving)
+				Revoke(self);
+		}
+	}
+}