Load subcells and default subcell index from mod.yaml

OpenRA.Game/Manifest.cs

@@ -37,6 +37,20 @@ namespace OpenRA
 		public readonly Size TileSize = new Size(24, 24);
 		public readonly TileShape TileShape = TileShape.Rectangle;
 
+		[Desc("(x,y,z) offset of the full cell and each sub-cell", "x & y: -512 ... 512, Z >= 0")]
+		public readonly WVec[] SubCellOffsets =
+		{
+			new WVec(0, 0, 0),       // full cell - index 0
+			new WVec(-299, -256, 0), // top left - index 1
+			new WVec(256, -256, 0),  // top right - index 2
+			new WVec(0, 0, 0),       // center - index 3
+			new WVec(-299, 256, 0),  // bottom left - index 4
+			new WVec(256, 256, 0),   // bottom right - index 5
+		};
+
+		[Desc("Default subcell index used if SubCellInit is absent", "0 - full cell, 1 - first sub-cell")]
+		public readonly int SubCellDefaultIndex = 3;
+
 		public Manifest(string mod)
 		{
 			var path = new[] { "mods", mod, "mod.yaml" }.Aggregate(Path.Combine);
@@ -87,6 +101,35 @@ namespace OpenRA
 			if (yaml.ContainsKey("TileShape"))
 				TileShape = FieldLoader.GetValue<TileShape>("TileShape", yaml["TileShape"].Value);
 
+			// Read subcell information
+			// sub-cell index 0 is the full cell
+			if (yaml.ContainsKey("SubCells"))
+			{
+				var subcells = yaml["SubCells"].ToDictionary();
+
+				// Read (x,y,z) offset (relative to cell center) pairs for positioning subcells
+				if (subcells.ContainsKey("Offsets"))
+				{
+					SubCellOffsets = FieldLoader.GetValue<WVec[]>("Offsets", subcells["Offsets"].Value);
+
+					foreach (var i in SubCellOffsets)
+						if (i.X < -512 || i.X > 512 || i.Y < -512 || i.Y > 512 || i.Z < 0)
+							throw new InvalidDataException("Subcell offsets must be in bounds (X & Y: -512 ... 512, Z > 0)");
+				}
+
+				// Read default subcell index used when creating actors that share cells without SubCellInit
+				if (subcells.ContainsKey("DefaultIndex"))
+					SubCellDefaultIndex = FieldLoader.GetValue<int>("DefaultIndex", subcells ["DefaultIndex"].Value);
+
+				// Otherwise set the default subcell index to the middle subcell entry
+				else
+					SubCellDefaultIndex = SubCellOffsets.Length / 2; // default is the middle subcell entry
+			}
+
+			// validate default index - 0 for no subcells, otherwise > 1 & <= subcell count (offset triples count - 1)
+			if (SubCellDefaultIndex < (SubCellOffsets.Length > 1 ? 1 : 0) || SubCellDefaultIndex >= SubCellOffsets.Length)
+				throw new InvalidDataException("Subcell default index must be a valid index into the offset triples and must be greater than 0 for mods with subcells");
+
 			// Allow inherited mods to import parent maps.
 			var compat = new List<string>();
 			compat.Add(mod);

OpenRA.Game/Map/Map.cs

@@ -78,16 +78,8 @@ namespace OpenRA
 
 		public readonly TileShape TileShape;
 		[FieldLoader.Ignore]
-		public readonly WVec[] SubCellOffsets = 
-		{
-			new WVec(0, 0, 0),
-			new WVec(-299, -256, 0),
-			new WVec(256, -256, 0),
-			new WVec(0, 0, 0),
-			new WVec(-299, 256, 0),
-			new WVec(256, 256, 0),
-		};
-		public readonly int SubCellsDefaultIndex = 3;
+		public readonly WVec[] SubCellOffsets;
+		public readonly int SubCellDefaultIndex;
 
 		[FieldLoader.LoadUsing("LoadOptions")]
 		public MapOptions Options;
@@ -257,6 +249,8 @@ namespace OpenRA
 			MapTiles = Exts.Lazy(() => LoadMapTiles());
 			MapResources = Exts.Lazy(() => LoadResourceTiles());
 			TileShape = Game.modData.Manifest.TileShape;
+			SubCellOffsets = Game.modData.Manifest.SubCellOffsets;
+			SubCellDefaultIndex = Game.modData.Manifest.SubCellDefaultIndex;
 
 			// The Uid is calculated from the data on-disk, so
 			// format changes must be flushed to disk.

OpenRA.Game/Traits/World/ActorMap.cs

@@ -33,8 +33,6 @@ namespace OpenRA.Traits
 			public Actor Actor;
 		}
 
-		static readonly int[] SubCells = { 1, 2, 3, 4, 5 };
-
 		readonly ActorMapInfo info;
 		readonly Map map;
 		readonly CellLayer<InfluenceNode> influence;
@@ -87,18 +85,18 @@ namespace OpenRA.Traits
 
 		public bool HasFreeSubCell(CPos a)
 		{
-			if (!AnyUnitsAt(a))
-				return true;
-
-			return SubCells.Any(b => !AnyUnitsAt(a, b));
+			return FreeSubCell(a) >= 0;
 		}
 
-		public int? FreeSubCell(CPos a)
+		public int FreeSubCell(CPos a)
 		{
-			if (!HasFreeSubCell(a))
-				return null;
+			if (!AnyUnitsAt(a))
+				return map.SubCellDefaultIndex;
 
-			return SubCells.First(b => !AnyUnitsAt(a, b));
+			for (var i = 1; i < map.SubCellOffsets.Length; ++i)
+				if (!AnyUnitsAt(a, i))
+					return i;
+			return -1;
 		}
 
 		public bool AnyUnitsAt(CPos a)