Change indexes into tile arrays to be stored as bytes to save memory.

The index value needs only be big enough to handle all defined terrain types. This is a low number so we can save memory by defining it as a byte. This particularly saves memory for the CustomTerrain field in the Map class, which defines a cell layer for the map using tile indexes, so we can reduce the size of that layer 4x as a result.

OpenRA.Game/Graphics/Minimap.cs

@@ -115,7 +115,7 @@ namespace OpenRA.Graphics
 						var mapX = x + b.Left;
 						var mapY = y + b.Top;
 						var custom = map.CustomTerrain[mapX, mapY];
-						if (custom == -1)
+						if (custom == byte.MaxValue)
 							continue;
 						colors[y * stride + x] = world.TileSet[custom].Color.ToArgb();
 					}

OpenRA.Game/Map/Map.cs

@@ -121,7 +121,7 @@ namespace OpenRA
 
 		[FieldLoader.Ignore] public Lazy<CellLayer<TerrainTile>> MapTiles;
 		[FieldLoader.Ignore] public Lazy<CellLayer<ResourceTile>> MapResources;
-		[FieldLoader.Ignore] public CellLayer<int> CustomTerrain;
+		[FieldLoader.Ignore] public CellLayer<byte> CustomTerrain;
 
 		[FieldLoader.Ignore] Lazy<TileSet> cachedTileSet;
 		[FieldLoader.Ignore] Lazy<Ruleset> rules;
@@ -280,9 +280,9 @@ namespace OpenRA
 			var br = Map.MapToCell(TileShape, new CPos(Bounds.Right - 1, Bounds.Bottom - 1));
 			Cells = new CellRegion(TileShape, tl, br);
 
-			CustomTerrain = new CellLayer<int>(this);
+			CustomTerrain = new CellLayer<byte>(this);
 			foreach (var cell in Cells)
-				CustomTerrain[cell] = -1;
+				CustomTerrain[cell] = byte.MaxValue;
 		}
 
 		public Ruleset PreloadRules()
@@ -672,10 +672,10 @@ namespace OpenRA
 			}
 		}
 
-		public int GetTerrainIndex(CPos cell)
+		public byte GetTerrainIndex(CPos cell)
 		{
 			var custom = CustomTerrain[cell];
-			return custom != -1 ? custom : cachedTileSet.Value.GetTerrainIndex(MapTiles.Value[cell]);
+			return custom != byte.MaxValue ? custom : cachedTileSet.Value.GetTerrainIndex(MapTiles.Value[cell]);
 		}
 
 		public TerrainTypeInfo GetTerrainInfo(CPos cell)

OpenRA.Game/Map/TileSet.cs

@@ -39,9 +39,9 @@ namespace OpenRA
 		public readonly bool PickAny;
 		public readonly string Category;
 
-		int[] tiles;
+		byte[] tiles;
 
-		public TileTemplate(ushort id, string image, int2 size, int[] tiles)
+		public TileTemplate(ushort id, string image, int2 size, byte[] tiles)
 		{
 			this.Id = id;
 			this.Image = image;
@@ -56,16 +56,16 @@ namespace OpenRA
 			tiles = LoadTiles(tileSet, my);
 		}
 
-		int[] LoadTiles(TileSet tileSet, MiniYaml y)
+		byte[] LoadTiles(TileSet tileSet, MiniYaml y)
 		{
 			var nodes = y.ToDictionary()["Tiles"].Nodes;
 
 			if (!PickAny)
 			{
-				var tiles = new int[Size.X * Size.Y];
+				var tiles = new byte[Size.X * Size.Y];
 
 				for (var i = 0; i < tiles.Length; i++)
-					tiles[i] = -1;
+					tiles[i] = byte.MaxValue;
 
 				foreach (var node in nodes)
 				{
@@ -80,7 +80,7 @@ namespace OpenRA
 			}
 			else
 			{
-				var tiles = new int[nodes.Count];
+				var tiles = new byte[nodes.Count];
 				var i = 0;
 
 				foreach (var node in nodes)
@@ -98,7 +98,7 @@ namespace OpenRA
 
 		static readonly string[] Fields = { "Id", "Image", "Frames", "Size", "PickAny" };
 
-		public int this[int index]
+		public byte this[int index]
 		{
 			get { return tiles[index]; }
 		}
@@ -145,8 +145,8 @@ namespace OpenRA
 		public readonly string[] EditorTemplateOrder;
 
 		public readonly TerrainTypeInfo[] TerrainInfo;
-		readonly Dictionary<string, int> terrainIndexByType = new Dictionary<string, int>();
+		readonly Dictionary<string, byte> terrainIndexByType = new Dictionary<string, byte>();
-		readonly int defaultWalkableTerrainIndex;
+		readonly byte defaultWalkableTerrainIndex;
 
 		static readonly string[] Fields = { "Name", "Id", "SheetSize", "Palette", "Extensions" };
 
@@ -162,7 +162,9 @@ namespace OpenRA
 				.Select(y => new TerrainTypeInfo(y))
 				.OrderBy(tt => tt.Type)
 				.ToArray();
-			for (var i = 0; i < TerrainInfo.Length; i++)
+			if (TerrainInfo.Length >= byte.MaxValue)
+				throw new InvalidDataException("Too many terrain types.");
+			for (byte i = 0; i < TerrainInfo.Length; i++)
 			{
 				var tt = TerrainInfo[i].Type;
 
@@ -186,8 +188,9 @@ namespace OpenRA
 			this.Palette = palette;
 			this.Extensions = extensions;
 			this.TerrainInfo = terrainInfo;
-
+			if (TerrainInfo.Length >= byte.MaxValue)
-			for (var i = 0; i < terrainInfo.Length; i++)
+				throw new InvalidDataException("Too many terrain types.");
+			for (byte i = 0; i < terrainInfo.Length; i++)
 			{
 				var tt = terrainInfo[i].Type;
 
@@ -199,7 +202,7 @@ namespace OpenRA
 			defaultWalkableTerrainIndex = GetTerrainIndex("Clear");
 		}
 
-		public TerrainTypeInfo this[int index]
+		public TerrainTypeInfo this[byte index]
 		{
 			get { return TerrainInfo[index]; }
 		}
@@ -209,28 +212,28 @@ namespace OpenRA
 			get { return TerrainInfo.Length; }
 		}
 
-		public bool TryGetTerrainIndex(string type, out int index)
+		public bool TryGetTerrainIndex(string type, out byte index)
 		{
 			return terrainIndexByType.TryGetValue(type, out index);
 		}
 
-		public int GetTerrainIndex(string type)
+		public byte GetTerrainIndex(string type)
 		{
-			int index;
+			byte index;
 			if (terrainIndexByType.TryGetValue(type, out index))
 				return index;
 
 			throw new InvalidDataException("Tileset '{0}' lacks terrain type '{1}'".F(Id, type));
 		}
 
-		public int GetTerrainIndex(TerrainTile r)
+		public byte GetTerrainIndex(TerrainTile r)
 		{
 			var tpl = Templates[r.Type];
 
 			if (tpl.Contains(r.Index))
 			{
 				var ti = tpl[r.Index];
-				if (ti != -1)
+				if (ti != byte.MaxValue)
 					return ti;
 			}
 
@@ -263,7 +266,7 @@ namespace OpenRA
 
 		public TerrainTypeInfo GetTerrainInfo(TerrainTile r)
 		{
-			return TerrainInfo[GetTerrainIndex(r)];
+			return this[GetTerrainIndex(r)];
 		}
 	}
 }

OpenRA.Mods.RA/AI/HackyAI.cs

@@ -158,7 +158,7 @@ namespace OpenRA.Mods.RA.AI
 		bool enabled;
 		int ticks;
 
-		HashSet<int> resourceTypeIndices;
+		HashSet<byte> resourceTypeIndices;
 
 		RushFuzzy rushFuzzy = new RushFuzzy();
 
@@ -208,7 +208,7 @@ namespace OpenRA.Mods.RA.AI
 
 			random = new MersenneTwister((int)p.PlayerActor.ActorID);
 
-			resourceTypeIndices = new HashSet<int>(
+			resourceTypeIndices = new HashSet<byte>(
 				Map.Rules.Actors["world"].Traits
 				.WithInterface<ResourceTypeInfo>()
 				.Select(t => world.TileSet.GetTerrainIndex(t.TerrainType)));

OpenRA.Mods.RA/Bridge.cs

@@ -98,7 +98,7 @@ namespace OpenRA.Mods.RA
 				self.World.Map.CustomTerrain[c] = GetTerrainType(c);
 		}
 
-		int GetTerrainType(CPos cell)
+		byte GetTerrainType(CPos cell)
 		{
 			var dx = cell - self.Location;
 			var index = dx.X + self.World.TileSet.Templates[template].Size.X * dx.Y;

OpenRA.Mods.RA/Buildings/LaysTerrain.cs

@@ -57,7 +57,7 @@ namespace OpenRA.Mods.RA.Buildings
 						continue;
 
 					// Don't place under other buildings or custom terrain
-					if (bi.GetBuildingAt(c) != self || map.CustomTerrain[c] != -1)
+					if (bi.GetBuildingAt(c) != self || map.CustomTerrain[c] != byte.MaxValue)
 						continue;
 
 					var index = Game.CosmeticRandom.Next(template.TilesCount);
@@ -77,7 +77,7 @@ namespace OpenRA.Mods.RA.Buildings
 					continue;
 
 				// Don't place under other buildings or custom terrain
-				if (bi.GetBuildingAt(c) != self || map.CustomTerrain[c] != -1)
+				if (bi.GetBuildingAt(c) != self || map.CustomTerrain[c] != byte.MaxValue)
 					continue;
 
 				layer.AddTile(c, new TerrainTile(template.Id, (byte)i));

OpenRA.Mods.RA/Move/Mobile.cs

@@ -82,7 +82,7 @@ namespace OpenRA.Mods.RA.Move
 
 			foreach (var kvp in TerrainSpeeds)
 			{
-				int index;
+				byte index;
 				if (tileSet.TryGetTerrainIndex(kvp.Key, out index))
 					info[index] = kvp.Value;
 			}
@@ -125,7 +125,7 @@ namespace OpenRA.Mods.RA.Move
 				return int.MaxValue;
 
 			var index = world.Map.GetTerrainIndex(cell);
-			if (index == -1)
+			if (index == byte.MaxValue)
 				return int.MaxValue;
 
 			return TilesetTerrainInfo[world.TileSet][index].Cost;
@@ -526,7 +526,7 @@ namespace OpenRA.Mods.RA.Move
 		public int MovementSpeedForCell(Actor self, CPos cell)
 		{
 			var index = self.World.Map.GetTerrainIndex(cell);
-			if (index == -1)
+			if (index == byte.MaxValue)
 				return 0;
 
 			// TODO: Convert to integers

OpenRA.Mods.RA/World/ResourceLayer.cs

@@ -203,7 +203,7 @@ namespace OpenRA.Mods.RA
 			if (--c.Density < 0)
 			{
 				content[cell] = EmptyCell;
-				world.Map.CustomTerrain[cell] = -1;
+				world.Map.CustomTerrain[cell] = byte.MaxValue;
 			}
 			else
 				content[cell] = c;
@@ -222,7 +222,7 @@ namespace OpenRA.Mods.RA
 
 			// Clear cell
 			content[cell] = EmptyCell;
-			world.Map.CustomTerrain[cell] = -1;
+			world.Map.CustomTerrain[cell] = byte.MaxValue;
 
 			if (!dirty.Contains(cell))
 				dirty.Add(cell);

OpenRA.TilesetBuilder/FormBuilder.cs

@@ -385,7 +385,7 @@ namespace OpenRA.TilesetBuilder
 			ushort cur = 0;
 			foreach (var tp in surface1.Templates)
 			{
-				var tiles = new int[tp.Width * tp.Height];
+				var tiles = new byte[tp.Width * tp.Height];
 				foreach (var t in tp.Cells)
 				{
 					var ttype = TerrainType[surface1.TerrainTypes[t.Key.X, t.Key.Y]].Type;