Adds the RequiresPrerequisites field into ProvidesCustomPrerequisite and all the logic behind it.

OpenRA.Mods.RA/Player/ProvidesCustomPrerequisite.cs

@@ -20,31 +20,30 @@ namespace OpenRA.Mods.RA
 		[Desc("The prerequisite type that this provides")]
 		public readonly string Prerequisite = null;
 
+		[Desc("Only grant this prerequisite when you have these prerequisites")]
+		public readonly string[] RequiresPrerequisites = { };
+
 		[Desc("Only grant this prerequisite for certain factions")]
 		public readonly string[] Race = { };
 
-		[Desc("Should the prerequisite remain enabled if the owner changes?")]
-		public readonly bool Sticky = true;
+		[Desc("Should it recheck everything when it is captured?")]
+		public readonly bool ResetOnOwnerChange = false;
 		public object Create(ActorInitializer init) { return new ProvidesCustomPrerequisite(init, this); }
 	}
 
 	public class ProvidesCustomPrerequisite : ITechTreePrerequisite, INotifyOwnerChanged
 	{
-		ProvidesCustomPrerequisiteInfo info;
+		readonly ProvidesCustomPrerequisiteInfo info;
+
 		bool enabled = true;
 
 		public ProvidesCustomPrerequisite(ActorInitializer init, ProvidesCustomPrerequisiteInfo info)
 		{
 			this.info = info;
 
-			if (info.Race.Any())
-			{
-				var race = init.self.Owner.Country.Race;
-				if (init.Contains<RaceInit>())
-					race = init.Get<RaceInit, string>();
+			var race = init.Contains<RaceInit>() ? init.Get<RaceInit, string>() : init.self.Owner.Country.Race; 
 
-				enabled = info.Race.Contains(race);
-			}
+			Update(init.self.Owner, race);
 		}
 
 		public IEnumerable<string> ProvidesPrerequisites
@@ -60,8 +59,19 @@ namespace OpenRA.Mods.RA
 
 		public void OnOwnerChanged(Actor self, Player oldOwner, Player newOwner)
 		{
-			if (!info.Sticky && info.Race.Any())
-				enabled = info.Race.Contains(self.Owner.Country.Race);
+			if (info.ResetOnOwnerChange)
+				Update(newOwner, newOwner.Country.Race);
+		}
+
+		void Update(Player owner, string race)
+		{
+			enabled = true;
+
+			if (info.Race.Any())
+				enabled = info.Race.Contains(race);
+
+			if (info.RequiresPrerequisites.Any() && enabled)
+				enabled = owner.PlayerActor.Trait<TechTree>().HasPrerequisites(info.RequiresPrerequisites);
 		}
 	}
 

OpenRA.Mods.RA/Player/TechTree.cs

@@ -61,6 +61,13 @@ namespace OpenRA.Mods.RA
 			watchers.RemoveAll(x => x.RegisteredBy == tte);
 		}
 
+		public bool HasPrerequisites(IEnumerable<string> prerequisites)
+		{
+			var ownedPrereqs = TechTree.GatherOwnedPrerequisites(player);
+			return prerequisites.All(p => !(p.Replace("~", "").StartsWith("!")
+					^ !ownedPrereqs.ContainsKey(p.Replace("!", "").Replace("~", ""))));
+		}
+
 		static Cache<string, List<Actor>> GatherOwnedPrerequisites(Player player)
 		{
 			var ret = new Cache<string, List<Actor>>(x => new List<Actor>());
@@ -69,7 +76,7 @@ namespace OpenRA.Mods.RA
 
 			// Add all actors that provide prerequisites
 			var prerequisites = player.World.ActorsWithTrait<ITechTreePrerequisite>()
-				.Where(a => a.Actor.Owner == player && !a.Actor.IsDead() && a.Actor.IsInWorld);
+				.Where(a => a.Actor.Owner == player && a.Actor.IsInWorld && !a.Actor.IsDead());
 
 			foreach (var b in prerequisites)
 			{

mods/ra/rules/structures.yaml

@@ -695,6 +695,12 @@ WEAP:
 	ProvidesCustomPrerequisite@soviet:
 		Race: soviet
 		Prerequisite: vehicles.soviet
+	ProvidesCustomPrerequisite@alliedstructure:
+		RequiresPrerequisites: structures.allies
+		Prerequisite: vehicles.allies
+	ProvidesCustomPrerequisite@sovietstructure:
+		RequiresPrerequisites: structures.soviet
+		Prerequisite: vehicles.soviet
 	PrimaryBuilding:
 	IronCurtainable:
 	ProductionBar: