Use CellLayer for resources.

OpenRA.Game/Map/TileReference.cs

@@ -23,4 +23,18 @@ namespace OpenRA
 
 		public override int GetHashCode() { return Type.GetHashCode() ^ Index.GetHashCode(); }
 	}
+
+	public struct ResourceTile
+	{
+		public readonly byte Type;
+		public readonly byte Index;
+
+		public ResourceTile(byte type, byte index)
+		{
+			Type = type;
+			Index = index;
+		}
+
+		public override int GetHashCode() { return Type.GetHashCode() ^ Index.GetHashCode(); }
+	}
 }