Moves Attack, Armament, Move, Air traits and activities as well as anything required by them to Mods.Common.

Extracts Exit from Production into its own trait.

OpenRA.Mods.Common/Activities/Move/AttackMoveActivity.cs

@@ -0,0 +1,64 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System.Collections.Generic;
+using OpenRA.Activities;
+using OpenRA.Mods.Common.Traits;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Activities
+{
+	public class AttackMoveActivity : Activity
+	{
+		const int ScanInterval = 7;
+
+		Activity inner;
+		int scanTicks;
+		AutoTarget autoTarget;
+
+		public AttackMoveActivity(Actor self, Activity inner)
+		{
+			this.inner = inner;
+			autoTarget = self.TraitOrDefault<AutoTarget>();
+		}
+
+		public override Activity Tick(Actor self)
+		{
+			if (autoTarget != null && --scanTicks <= 0)
+			{
+				autoTarget.ScanAndAttack(self);
+				scanTicks = ScanInterval;
+			}
+
+			if (inner == null)
+				return NextActivity;
+
+			inner = Util.RunActivity(self, inner);
+
+			return this;
+		}
+
+		public override void Cancel(Actor self)
+		{
+			if (inner != null)
+				inner.Cancel(self);
+
+			base.Cancel(self);
+		}
+
+		public override IEnumerable<Target> GetTargets(Actor self)
+		{
+			if (inner != null)
+				return inner.GetTargets(self);
+
+			return Target.None;
+		}
+	}
+}

OpenRA.Mods.Common/Activities/Move/Follow.cs

@@ -0,0 +1,50 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using OpenRA.Activities;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Activities
+{
+	public class Follow : Activity
+	{
+		readonly Target target;
+		readonly WRange minRange;
+		readonly WRange maxRange;
+		readonly IMove move;
+
+		public Follow(Actor self, Target target, WRange minRange, WRange maxRange)
+		{
+			this.target = target;
+			this.minRange = minRange;
+			this.maxRange = maxRange;
+
+			move = self.Trait<IMove>();
+		}
+
+		public override Activity Tick(Actor self)
+		{
+			if (IsCanceled || !target.IsValidFor(self))
+				return NextActivity;
+
+			var cachedPosition = target.CenterPosition;
+			var path = move.MoveWithinRange(target, minRange, maxRange);
+
+			// We are already in range, so wait until the target moves before doing anything
+			if (target.IsInRange(self.CenterPosition, maxRange) && !target.IsInRange(self.CenterPosition, minRange))
+			{
+				var wait = new WaitFor(() => !target.IsValidFor(self) || target.CenterPosition != cachedPosition);
+				return Util.SequenceActivities(wait, path, this);
+			}
+
+			return Util.SequenceActivities(path, this);
+		}
+	}
+}

OpenRA.Mods.Common/Activities/Move/Move.cs

@@ -0,0 +1,451 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using OpenRA.Activities;
+using OpenRA.Mods.Common.Traits;
+using OpenRA.Primitives;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Activities
+{
+	public class Move : Activity
+	{
+		static readonly List<CPos> NoPath = new List<CPos>();
+
+		readonly Mobile mobile;
+		readonly IEnumerable<IDisableMove> moveDisablers;
+		readonly WRange nearEnough;
+		readonly Func<List<CPos>> getPath;
+		readonly Actor ignoredActor;
+
+		List<CPos> path;
+		CPos? destination;
+
+		// For dealing with blockers
+		bool hasWaited;
+		bool hasNotifiedBlocker;
+		int waitTicksRemaining;
+
+		// Scriptable move order
+		// Ignores lane bias and nearby units
+		public Move(Actor self, CPos destination)
+		{
+			mobile = self.Trait<Mobile>();
+			moveDisablers = self.TraitsImplementing<IDisableMove>();
+
+			getPath = () =>
+				self.World.WorldActor.Trait<PathFinder>().FindPath(
+					PathSearch.FromPoint(self.World, mobile.Info, self, mobile.toCell, destination, false)
+					.WithoutLaneBias());
+			this.destination = destination;
+			this.nearEnough = WRange.Zero;
+		}
+
+		// HACK: for legacy code
+		public Move(Actor self, CPos destination, int nearEnough)
+			: this(self, destination, WRange.FromCells(nearEnough)) { }
+
+		public Move(Actor self, CPos destination, WRange nearEnough)
+		{
+			mobile = self.Trait<Mobile>();
+			moveDisablers = self.TraitsImplementing<IDisableMove>();
+
+			getPath = () => self.World.WorldActor.Trait<PathFinder>()
+				.FindUnitPath(mobile.toCell, destination, self);
+			this.destination = destination;
+			this.nearEnough = nearEnough;
+		}
+
+		public Move(Actor self, CPos destination, SubCell subCell, WRange nearEnough)
+		{
+			mobile = self.Trait<Mobile>();
+			moveDisablers = self.TraitsImplementing<IDisableMove>();
+
+			getPath = () => self.World.WorldActor.Trait<PathFinder>()
+				.FindUnitPathToRange(mobile.fromCell, subCell, self.World.Map.CenterOfSubCell(destination, subCell), nearEnough, self);
+			this.destination = destination;
+			this.nearEnough = nearEnough;
+		}
+
+		public Move(Actor self, CPos destination, Actor ignoredActor)
+		{
+			mobile = self.Trait<Mobile>();
+			moveDisablers = self.TraitsImplementing<IDisableMove>();
+
+			getPath = () =>
+				self.World.WorldActor.Trait<PathFinder>().FindPath(
+					PathSearch.FromPoint(self.World, mobile.Info, self, mobile.toCell, destination, false)
+					.WithIgnoredActor(ignoredActor));
+
+			this.destination = destination;
+			this.nearEnough = WRange.Zero;
+			this.ignoredActor = ignoredActor;
+		}
+
+		public Move(Actor self, Target target, WRange range)
+		{
+			mobile = self.Trait<Mobile>();
+			moveDisablers = self.TraitsImplementing<IDisableMove>();
+
+			getPath = () =>
+			{
+				if (!target.IsValidFor(self))
+					return NoPath;
+
+				return self.World.WorldActor.Trait<PathFinder>().FindUnitPathToRange(
+					mobile.toCell, mobile.toSubCell, target.CenterPosition, range, self);
+			};
+
+			destination = null;
+			nearEnough = range;
+		}
+
+		public Move(Actor self, Func<List<CPos>> getPath)
+		{
+			mobile = self.Trait<Mobile>();
+			moveDisablers = self.TraitsImplementing<IDisableMove>();
+
+			this.getPath = getPath;
+
+			destination = null;
+			nearEnough = WRange.Zero;
+		}
+
+		static int HashList<T>(List<T> xs)
+		{
+			var hash = 0;
+			var n = 0;
+			foreach (var x in xs)
+				hash += n++ * x.GetHashCode();
+
+			return hash;
+		}
+
+		List<CPos> EvalPath(Actor self, Mobile mobile)
+		{
+			var path = getPath().TakeWhile(a => a != mobile.toCell).ToList();
+			mobile.PathHash = HashList(path);
+			return path;
+		}
+
+		public override Activity Tick(Actor self)
+		{
+			if (moveDisablers.Any(d => d.MoveDisabled(self)))
+				return this;
+
+			if (destination == mobile.toCell)
+				return NextActivity;
+
+			if (path == null)
+			{
+				if (mobile.ticksBeforePathing > 0)
+				{
+					--mobile.ticksBeforePathing;
+					return this;
+				}
+
+				path = EvalPath(self, mobile);
+				SanityCheckPath(mobile);
+			}
+
+			if (path.Count == 0)
+			{
+				destination = mobile.toCell;
+				return this;
+			}
+
+			destination = path[0];
+
+			var nextCell = PopPath(self, mobile);
+			if (nextCell == null)
+				return this;
+
+			var firstFacing = self.World.Map.FacingBetween(mobile.fromCell, nextCell.Value.First, mobile.Facing);
+			if (firstFacing != mobile.Facing)
+			{
+				path.Add(nextCell.Value.First);
+				return Util.SequenceActivities(new Turn(self, firstFacing), this);
+			}
+			else
+			{
+				mobile.SetLocation(mobile.fromCell, mobile.fromSubCell, nextCell.Value.First, nextCell.Value.Second);
+				var move = new MoveFirstHalf(
+					this,
+					self.World.Map.CenterOfSubCell(mobile.fromCell, mobile.fromSubCell),
+					Util.BetweenCells(self.World, mobile.fromCell, mobile.toCell) + (self.World.Map.OffsetOfSubCell(mobile.fromSubCell) + self.World.Map.OffsetOfSubCell(mobile.toSubCell)) / 2,
+					mobile.Facing,
+					mobile.Facing,
+					0);
+
+				return move;
+			}
+		}
+
+		[Conditional("SANITY_CHECKS")]
+		void SanityCheckPath(Mobile mobile)
+		{
+			if (path.Count == 0)
+				return;
+			var d = path[path.Count - 1] - mobile.toCell;
+			if (d.LengthSquared > 2)
+				throw new InvalidOperationException("(Move) Sanity check failed");
+		}
+
+		static void NotifyBlocker(Actor self, CPos nextCell)
+		{
+			foreach (var blocker in self.World.ActorMap.GetUnitsAt(nextCell))
+			{
+				// Notify the blocker that he's blocking our move:
+				foreach (var moveBlocked in blocker.TraitsImplementing<INotifyBlockingMove>())
+					moveBlocked.OnNotifyBlockingMove(blocker, self);
+			}
+		}
+
+		Pair<CPos, SubCell>? PopPath(Actor self, Mobile mobile)
+		{
+			if (path.Count == 0)
+				return null;
+
+			var nextCell = path[path.Count - 1];
+
+			// Next cell in the move is blocked by another actor
+			if (!mobile.CanEnterCell(nextCell, ignoredActor, true))
+			{
+				// Are we close enough?
+				var cellRange = nearEnough.Range / 1024;
+				if ((mobile.toCell - destination.Value).LengthSquared <= cellRange * cellRange)
+				{
+					path.Clear();
+					return null;
+				}
+
+				// See if they will move
+				if (!hasNotifiedBlocker)
+				{
+					NotifyBlocker(self, nextCell);
+					hasNotifiedBlocker = true;
+				}
+
+				// Wait a bit to see if they leave
+				if (!hasWaited)
+				{
+					var info = self.Info.Traits.Get<MobileInfo>();
+					waitTicksRemaining = info.WaitAverage + self.World.SharedRandom.Next(-info.WaitSpread, info.WaitSpread);
+					hasWaited = true;
+				}
+
+				if (--waitTicksRemaining >= 0)
+					return null;
+
+				if (mobile.ticksBeforePathing > 0)
+				{
+					--mobile.ticksBeforePathing;
+					return null;
+				}
+
+				// Calculate a new path
+				mobile.RemoveInfluence();
+				var newPath = EvalPath(self, mobile);
+				mobile.AddInfluence();
+
+				if (newPath.Count != 0)
+					path = newPath;
+
+				return null;
+			}
+
+			hasNotifiedBlocker = false;
+			hasWaited = false;
+			path.RemoveAt(path.Count - 1);
+
+			var subCell = mobile.GetAvailableSubCell(nextCell, SubCell.Any, ignoredActor);
+			return Pair.New(nextCell, subCell);
+		}
+
+		public override void Cancel(Actor self)
+		{
+			path = NoPath;
+			base.Cancel(self);
+		}
+
+		public override IEnumerable<Target> GetTargets(Actor self)
+		{
+			if (path != null)
+				return Enumerable.Reverse(path).Select(c => Target.FromCell(self.World, c));
+			if (destination != null)
+				return new Target[] { Target.FromCell(self.World, destination.Value) };
+			return Target.None;
+		}
+
+		abstract class MovePart : Activity
+		{
+			protected readonly Move move;
+			protected readonly WPos from, to;
+			protected readonly int fromFacing, toFacing;
+			protected readonly int moveFractionTotal;
+			protected int moveFraction;
+
+			public MovePart(Move move, WPos from, WPos to, int fromFacing, int toFacing, int startingFraction)
+			{
+				this.move = move;
+				this.from = from;
+				this.to = to;
+				this.fromFacing = fromFacing;
+				this.toFacing = toFacing;
+				this.moveFraction = startingFraction;
+				this.moveFractionTotal = (to - from).Length;
+			}
+
+			public override void Cancel(Actor self)
+			{
+				move.Cancel(self);
+				base.Cancel(self);
+			}
+
+			public override void Queue(Activity activity)
+			{
+				move.Queue(activity);
+			}
+
+			public override Activity Tick(Actor self)
+			{
+				var mobile = self.Trait<Mobile>();
+				var ret = InnerTick(self, move.mobile);
+				mobile.IsMoving = ret is MovePart;
+
+				if (moveFraction > moveFractionTotal)
+					moveFraction = moveFractionTotal;
+				UpdateCenterLocation(self, mobile);
+
+				return ret;
+			}
+
+			Activity InnerTick(Actor self, Mobile mobile)
+			{
+				moveFraction += mobile.MovementSpeedForCell(self, mobile.toCell);
+				if (moveFraction <= moveFractionTotal)
+					return this;
+
+				var next = OnComplete(self, mobile, move);
+				if (next != null)
+					return next;
+
+				return move;
+			}
+
+			void UpdateCenterLocation(Actor self, Mobile mobile)
+			{
+				// avoid division through zero
+				if (moveFractionTotal != 0)
+					mobile.SetVisualPosition(self, WPos.Lerp(from, to, moveFraction, moveFractionTotal));
+				else
+					mobile.SetVisualPosition(self, to);
+
+				if (moveFraction >= moveFractionTotal)
+					mobile.Facing = toFacing & 0xFF;
+				else
+					mobile.Facing = int2.Lerp(fromFacing, toFacing, moveFraction, moveFractionTotal) & 0xFF;
+			}
+
+			protected abstract MovePart OnComplete(Actor self, Mobile mobile, Move parent);
+
+			public override IEnumerable<Target> GetTargets(Actor self)
+			{
+				return move.GetTargets(self);
+			}
+		}
+
+		class MoveFirstHalf : MovePart
+		{
+			public MoveFirstHalf(Move move, WPos from, WPos to, int fromFacing, int toFacing, int startingFraction)
+				: base(move, from, to, fromFacing, toFacing, startingFraction) { }
+
+			static bool IsTurn(Mobile mobile, CPos nextCell)
+			{
+				return nextCell - mobile.toCell !=
+					mobile.toCell - mobile.fromCell;
+			}
+
+			protected override MovePart OnComplete(Actor self, Mobile mobile, Move parent)
+			{
+				var fromSubcellOffset = self.World.Map.OffsetOfSubCell(mobile.fromSubCell);
+				var toSubcellOffset = self.World.Map.OffsetOfSubCell(mobile.toSubCell);
+
+				var nextCell = parent.PopPath(self, mobile);
+				if (nextCell != null)
+				{
+					if (IsTurn(mobile, nextCell.Value.First))
+					{
+						var nextSubcellOffset = self.World.Map.OffsetOfSubCell(nextCell.Value.Second);
+						var ret = new MoveFirstHalf(
+							move,
+							Util.BetweenCells(self.World, mobile.fromCell, mobile.toCell) + (fromSubcellOffset + toSubcellOffset) / 2,
+							Util.BetweenCells(self.World, mobile.toCell, nextCell.Value.First) + (toSubcellOffset + nextSubcellOffset) / 2,
+							mobile.Facing,
+							Util.GetNearestFacing(mobile.Facing, self.World.Map.FacingBetween(mobile.toCell, nextCell.Value.First, mobile.Facing)),
+							moveFraction - moveFractionTotal);
+
+						mobile.FinishedMoving(self);
+						mobile.SetLocation(mobile.toCell, mobile.toSubCell, nextCell.Value.First, nextCell.Value.Second);
+						return ret;
+					}
+
+					parent.path.Add(nextCell.Value.First);
+				}
+
+				var ret2 = new MoveSecondHalf(
+					move,
+					Util.BetweenCells(self.World, mobile.fromCell, mobile.toCell) + (fromSubcellOffset + toSubcellOffset) / 2,
+					self.World.Map.CenterOfCell(mobile.toCell) + toSubcellOffset,
+					mobile.Facing,
+					mobile.Facing,
+					moveFraction - moveFractionTotal);
+
+				mobile.EnteringCell(self);
+				mobile.SetLocation(mobile.toCell, mobile.toSubCell, mobile.toCell, mobile.toSubCell);
+				return ret2;
+			}
+		}
+
+		class MoveSecondHalf : MovePart
+		{
+			public MoveSecondHalf(Move move, WPos from, WPos to, int fromFacing, int toFacing, int startingFraction)
+				: base(move, from, to, fromFacing, toFacing, startingFraction) { }
+
+			protected override MovePart OnComplete(Actor self, Mobile mobile, Move parent)
+			{
+				mobile.SetPosition(self, mobile.toCell);
+				return null;
+			}
+		}
+	}
+
+	public static class ActorExtensionsForMove
+	{
+		public static bool IsMoving(this Actor self)
+		{
+			var a = self.GetCurrentActivity();
+			if (a == null)
+				return false;
+
+			// HACK: Dirty, but it suffices until we do something better:
+			if (a.GetType() == typeof(Move)) return true;
+			if (a.GetType() == typeof(MoveAdjacentTo)) return true;
+			if (a.GetType() == typeof(AttackMoveActivity)) return true;
+
+			// Not a move:
+			return false;
+		}
+	}
+}

OpenRA.Mods.Common/Activities/Move/MoveAdjacentTo.cs

@@ -0,0 +1,144 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using OpenRA.Activities;
+using OpenRA.Mods.Common.Traits;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Activities
+{
+	public class MoveAdjacentTo : Activity
+	{
+		static readonly List<CPos> NoPath = new List<CPos>();
+
+		readonly Mobile mobile;
+		readonly PathFinder pathFinder;
+		readonly DomainIndex domainIndex;
+		readonly uint movementClass;
+
+		protected Target target { get; private set; }
+		protected CPos targetPosition;
+		Activity inner;
+		bool repath;
+
+		public MoveAdjacentTo(Actor self, Target target)
+		{
+			this.target = target;
+
+			mobile = self.Trait<Mobile>();
+			pathFinder = self.World.WorldActor.Trait<PathFinder>();
+			domainIndex = self.World.WorldActor.Trait<DomainIndex>();
+			movementClass = (uint)mobile.Info.GetMovementClass(self.World.TileSet);
+
+			if (target.IsValidFor(self))
+				targetPosition = self.World.Map.CellContaining(target.CenterPosition);
+
+			repath = true;
+		}
+
+		protected virtual bool ShouldStop(Actor self, CPos oldTargetPosition)
+		{
+			return false;
+		}
+
+		protected virtual bool ShouldRepath(Actor self, CPos oldTargetPosition)
+		{
+			return targetPosition != oldTargetPosition;
+		}
+
+		protected virtual IEnumerable<CPos> CandidateMovementCells(Actor self)
+		{
+			return Util.AdjacentCells(self.World, target);
+		}
+
+		public override Activity Tick(Actor self)
+		{
+			var targetIsValid = target.IsValidFor(self);
+
+			// Inner move order has completed.
+			if (inner == null)
+			{
+				// We are done here if the order was cancelled for any
+				// reason except the target moving.
+				if (IsCanceled || !repath || !targetIsValid)
+					return NextActivity;
+
+				// Target has moved, and MoveAdjacentTo is still valid.
+				inner = mobile.MoveTo(() => CalculatePathToTarget(self));
+				repath = false;
+			}
+
+			if (targetIsValid)
+			{
+				// Check if the target has moved
+				var oldTargetPosition = targetPosition;
+				targetPosition = self.World.Map.CellContaining(target.CenterPosition);
+
+				var shouldStop = ShouldStop(self, oldTargetPosition);
+				if (shouldStop || (!repath && ShouldRepath(self, oldTargetPosition)))
+				{
+					// Finish moving into the next cell and then repath.
+					if (inner != null)
+						inner.Cancel(self);
+
+					repath = !shouldStop;
+				}
+			}
+			else
+			{
+				// Target became invalid. Move to its last known position.
+				target = Target.FromCell(self.World, targetPosition);
+			}
+
+			// Ticks the inner move activity to actually move the actor.
+			inner = Util.RunActivity(self, inner);
+
+			return this;
+		}
+
+		List<CPos> CalculatePathToTarget(Actor self)
+		{
+			var targetCells = CandidateMovementCells(self);
+			var searchCells = new List<CPos>();
+			var loc = self.Location;
+
+			foreach (var cell in targetCells)
+				if (domainIndex.IsPassable(loc, cell, movementClass) && mobile.CanEnterCell(cell))
+					searchCells.Add(cell);
+
+			if (!searchCells.Any())
+				return NoPath;
+
+			var fromSrc = PathSearch.FromPoints(self.World, mobile.Info, self, searchCells, loc, true);
+			var fromDest = PathSearch.FromPoint(self.World, mobile.Info, self, loc, targetPosition, true).Reverse();
+
+			return pathFinder.FindBidiPath(fromSrc, fromDest);
+		}
+
+		public override IEnumerable<Target> GetTargets(Actor self)
+		{
+			if (inner != null)
+				return inner.GetTargets(self);
+
+			return Target.None;
+		}
+
+		public override void Cancel(Actor self)
+		{
+			if (inner != null)
+				inner.Cancel(self);
+
+			base.Cancel(self);
+		}
+	}
+}

OpenRA.Mods.Common/Activities/Move/MoveWithinRange.cs

@@ -0,0 +1,62 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System.Collections.Generic;
+using System.Linq;
+using OpenRA.Activities;
+using OpenRA.Mods.Common.Traits;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Activities
+{
+	public class MoveWithinRange : MoveAdjacentTo
+	{
+		readonly WRange maxRange;
+		readonly WRange minRange;
+
+		public MoveWithinRange(Actor self, Target target, WRange minRange, WRange maxRange)
+			: base(self, target)
+		{
+			this.minRange = minRange;
+			this.maxRange = maxRange;
+		}
+
+		protected override bool ShouldStop(Actor self, CPos oldTargetPosition)
+		{
+			// We are now in range. Don't move any further!
+			// HACK: This works around the pathfinder not returning the shortest path
+			var cp = self.CenterPosition;
+			return target.IsInRange(cp, maxRange) && !target.IsInRange(cp, minRange);
+		}
+
+		protected override bool ShouldRepath(Actor self, CPos oldTargetPosition)
+		{
+			var cp = self.CenterPosition;
+			return targetPosition != oldTargetPosition && (!target.IsInRange(cp, maxRange) || target.IsInRange(cp, minRange));
+		}
+
+		protected override IEnumerable<CPos> CandidateMovementCells(Actor self)
+		{
+			var map = self.World.Map;
+			var maxCells = (maxRange.Range + 1023) / 1024;
+			var minCells = minRange.Range / 1024;
+
+			var outerSq = maxRange.Range * maxRange.Range;
+			var innerSq = minRange.Range * minRange.Range;
+			var center = target.CenterPosition;
+
+			return map.FindTilesInAnnulus(targetPosition, minCells + 1, maxCells).Where(c =>
+			{
+				var dxSq = (map.CenterOfCell(c) - center).HorizontalLengthSquared;
+				return dxSq >= innerSq && dxSq <= outerSq;
+			});
+		}
+	}
+}