fix helicopters landing in silly places

OpenRA.Mods.RA/Air/Aircraft.cs

@@ -25,6 +25,7 @@ namespace OpenRA.Mods.RA.Air
 		public readonly int InitialFacing = 128;
 		public readonly int ROT = 255;
 		public readonly int Speed = 1;
+		public readonly string[] LandableTerrainTypes = { };
 
 		public virtual object Create( ActorInitializer init ) { return new Aircraft( init , this ); }
 	}
@@ -102,5 +103,17 @@ namespace OpenRA.Mods.RA.Air
 			var angle = facing * Math.PI / 128.0;
 			return new int2( (int)Math.Truncate( 1024 * Math.Sin( angle ) ), (int)Math.Truncate( 1024 * Math.Cos( angle ) ) );
 		}
+
+		public bool CanLand(int2 cell)
+		{
+			if (!self.World.Map.IsInMap(cell))
+				return false;
+
+			if (self.World.WorldActor.Trait<UnitInfluence>().AnyUnitsAt(cell))
+				return false;
+
+			var type = self.World.GetTerrainType(cell);
+			return Info.LandableTerrainTypes.Contains(type);
+		}
 	}
 }

OpenRA.Mods.RA/Air/HeliLand.cs

@@ -25,7 +25,7 @@ namespace OpenRA.Mods.RA.Air
 			if (aircraft.Altitude == 0)
 				return NextActivity;
 
-			if (requireSpace && !aircraft.CanEnterCell(self.Location))
+			if (requireSpace && !aircraft.CanLand(self.Location))
 				return this;
 			
 			--aircraft.Altitude;

mods/cnc/rules/vehicles.yaml

@@ -468,6 +468,7 @@ TRAN:
 		ROT: 5
 		Speed: 15
 		InitialFacing: 0
+		LandableTerrainTypes: Clear,Rough,Road,Ore,Beach
 	Health:
 		HP: 90
 	Armor:

mods/ra/rules/vehicles.yaml

@@ -802,6 +802,7 @@ TRAN:
 		InitialFacing: 0
 		ROT: 5
 		Speed: 12
+		LandableTerrainTypes: Clear,Rough,Road,Ore,Beach
 	RenderUnitRotor:
 		PrimaryOffset: 0,14,0,-8
 		SecondaryOffset: 0,-14,0,-5