Fix and optimize FindTilesInCircle

OpenRA.Game/Map/Map.cs

@@ -630,9 +630,9 @@ namespace OpenRA
 		}
 
 		public const int MaxTilesInCircleRange = 50;
-		static List<CVec>[] TilesByDistance = InitTilesByDistance(MaxTilesInCircleRange);
+		static CVec[][] TilesByDistance = InitTilesByDistance(MaxTilesInCircleRange);
 
-		static List<CVec>[] InitTilesByDistance(int max)
+		static CVec[][] InitTilesByDistance(int max)
 		{
 			var ts = new List<CVec>[max + 1];
 			for (var i = 0; i < max + 1; i++)
@@ -643,15 +643,26 @@ namespace OpenRA
 					if (max * max >= i * i + j * j)
 						ts [(int)Math.Ceiling(Math.Sqrt(i * i + j * j))].Add(new CVec(i, j));
 
-			return ts;
+			// Sort each integer-distance group by the actual distance
+			foreach (var list in ts)
+				list.Sort((a, b) => a.LengthSquared.CompareTo(b.LengthSquared));
+
+			return ts.Select(list => list.ToArray()).ToArray();
 		}
 
-		public IEnumerable<CPos> FindTilesInCircle(CPos center, int range)
+		// Both ranges are inclusive because everything that calls it is designed for maxRange being inclusive:
+		// it rounds the actual distance up to the next integer so that this call
+		// will return any cells that intersect with the requested range circle.
+		// The returned positions are sorted by distance from the center.
+		public IEnumerable<CPos> FindTilesInAnnulus(CPos center, int minRange, int maxRange)
 		{
-			if (range >= TilesByDistance.Length)
+			if (maxRange < minRange)
-				throw new InvalidOperationException("FindTilesInCircle supports queries for only <= {0}".F(MaxTilesInCircleRange));
+				throw new ArgumentOutOfRangeException("maxRange", "Maximum range is less than the minimum range.");
 
-			for (var i = 0; i <= range; i++)
+			if (maxRange > TilesByDistance.Length)
+				throw new ArgumentOutOfRangeException("maxRange", "The requested range ({0}) exceeds the maximum allowed ({1})".F(maxRange, MaxTilesInCircleRange));
+
+			for (var i = minRange; i <= maxRange; i++)
 			{
 				foreach (var offset in TilesByDistance[i])
 				{
@@ -661,5 +672,10 @@ namespace OpenRA
 				}
 			}
 		}
+
+		public IEnumerable<CPos> FindTilesInCircle(CPos center, int maxRange)
+		{
+			return FindTilesInAnnulus(center, 0, maxRange);
+		}
 	}
 }

OpenRA.Mods.RA/AI/HackyAI.cs

@@ -347,8 +347,7 @@ namespace OpenRA.Mods.RA.AI
 			{
 				for (var k = MaxBaseDistance; k >= 0; k--)
 				{
-					var tlist = Map.FindTilesInCircle(center, k)
+					var tlist = Map.FindTilesInCircle(center, k);
-						.OrderBy(a => (world.Map.CenterOfCell(a) - pos).LengthSquared);
 
 					foreach (var t in tlist)
 						if (world.CanPlaceBuilding(actorType, bi, t, null))

OpenRA.Mods.RA/Activities/MoveWithinRange.cs

@@ -45,16 +45,13 @@ namespace OpenRA.Mods.RA.Activities
 		{
 			var map = self.World.Map;
 			var maxCells = (maxRange.Range + 1023) / 1024;
-			var outerCells = map.FindTilesInCircle(targetPosition, maxCells);
-
 			var minCells = minRange.Range / 1024;
-			var innerCells = map.FindTilesInCircle(targetPosition, minCells);
 
 			var outerSq = maxRange.Range * maxRange.Range;
 			var innerSq = minRange.Range * minRange.Range;
 			var center = target.CenterPosition;
 
-			return outerCells.Except(innerCells).Where(c =>
+			return map.FindTilesInAnnulus(targetPosition, minCells + 1, maxCells).Where(c =>
 			{
 				var dxSq = (map.CenterOfCell(c) - center).HorizontalLengthSquared;
 				return dxSq >= innerSq && dxSq <= outerSq;

OpenRA.Mods.RA/Activities/Teleport.cs

@@ -99,18 +99,13 @@ namespace OpenRA.Mods.RA.Activities
 			if (pos.CanEnterCell(destination) && self.Owner.Shroud.IsExplored(destination))
 				return destination;
 
-			var searched = new List<CPos>();
+			var max = maximumDistance != null ? maximumDistance.Value : maxCellSearchRange;
-			for (var r = 1; r <= maxCellSearchRange || (maximumDistance != null && r <= maximumDistance); r++)
+			foreach (var tile in self.World.Map.FindTilesInCircle(destination, max))
-			{
-				foreach (var tile in self.World.Map.FindTilesInCircle(destination, r).Except(searched))
 			{
 				if (self.Owner.Shroud.IsExplored(tile)
 					&& (restrictTo == null || (restrictTo != null && restrictTo.Contains(tile)))
 					&& pos.CanEnterCell(tile))
 					return tile;
-
-					searched.Add(tile);
-				}
 			}
 
 			return null;

OpenRA.Mods.RA/Move/Mobile.cs

@@ -313,6 +313,7 @@ namespace OpenRA.Mods.RA.Move
 
 		public CPos NearestMoveableCell(CPos target)
 		{
+			// Limit search to a radius of 10 tiles
 			return NearestMoveableCell(target, 1, 10);
 		}
 
@@ -321,19 +322,10 @@ namespace OpenRA.Mods.RA.Move
 			if (CanEnterCell(target))
 				return target;
 
-			var searched = new List<CPos>();
+			foreach (var tile in self.World.Map.FindTilesInAnnulus(target, minRange, maxRange))
-			// Limit search to a radius of 10 tiles
-			for (var r = minRange; r < maxRange; r++)
-			{
-				foreach (var tile in self.World.Map.FindTilesInCircle(target, r).Except(searched))
-				{
 				if (CanEnterCell(tile))
 					return tile;
 
-					searched.Add(tile);
-				}
-			}
-
 			// Couldn't find a cell
 			return target;
 		}
@@ -343,18 +335,10 @@ namespace OpenRA.Mods.RA.Move
 			if (check(target))
 				return target;
 
-			var searched = new List<CPos>();
+			foreach (var tile in self.World.Map.FindTilesInAnnulus(target, minRange, maxRange))
-			for (var r = minRange; r < maxRange; r++)
-			{
-				foreach (var tile in self.World.Map.FindTilesInCircle(target, r).Except(searched))
-				{
 				if (check(tile))
 					return tile;
 
-					searched.Add(tile);
-				}
-			}
-
 			// Couldn't find a cell
 			return target;
 		}

OpenRA.Mods.RA/Player/PlayerStatistics.cs

@@ -58,7 +58,9 @@ namespace OpenRA.Mods.RA
 			var total = (double)world.Map.Bounds.Width * world.Map.Bounds.Height;
 			MapControl = world.Actors
 				.Where(a => !a.IsDead() && a.IsInWorld && a.Owner == player && a.HasTrait<RevealsShroud>())
-				.SelectMany(a => world.Map.FindTilesInCircle(a.Location, a.Trait<RevealsShroud>().Range.Clamp(WRange.Zero, WRange.FromCells(50)).Range / 1024))
+				.SelectMany(a => world.Map.FindTilesInCircle(
+					a.Location,
+					a.Trait<RevealsShroud>().Range.Clamp(WRange.Zero, WRange.FromCells(Map.MaxTilesInCircleRange)).Range / 1024))
 				.Distinct()
 				.Count() / total;
 		}

OpenRA.Mods.RA/SpawnMPUnits.cs

@@ -52,8 +52,7 @@ namespace OpenRA.Mods.RA
 				return;
 
 			// Spawn support units in an annulus around the base actor
-			var supportSpawnCells = w.Map.FindTilesInCircle(sp, unitGroup.OuterSupportRadius)
+			var supportSpawnCells = w.Map.FindTilesInAnnulus(sp, unitGroup.InnerSupportRadius + 1, unitGroup.OuterSupportRadius);
-				.Except(w.Map.FindTilesInCircle(sp, unitGroup.InnerSupportRadius));
 
 			foreach (var s in unitGroup.SupportActors)
 			{