Allow units to give way when path is blocked by oncoming unit.

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -32,6 +32,16 @@ namespace OpenRA.Traits
 		Dead = 32
 	}
 
+	// NOTE: Each subsequent category is a superset of the previous categories
+	// and categories are mutually exclusive.
+	public enum BlockedByActor
+	{
+		None,
+		Immovable,
+		Stationary,
+		All
+	}
+
 	/// <summary>
 	/// Type tag for DamageTypes <see cref="Primitives.BitSet{T}"/>.
 	/// </summary>
@@ -312,16 +322,16 @@ namespace OpenRA.Traits
 
 	public interface IPositionableInfo : IOccupySpaceInfo
 	{
-		bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, bool checkTransientActors = true);
+		bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All);
 	}
 
 	public interface IPositionable : IOccupySpace
 	{
 		bool CanExistInCell(CPos location);
 		bool IsLeavingCell(CPos location, SubCell subCell = SubCell.Any);
-		bool CanEnterCell(CPos location, Actor ignoreActor = null, bool checkTransientActors = true);
+		bool CanEnterCell(CPos location, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All);
 		SubCell GetValidSubCell(SubCell preferred = SubCell.Any);
-		SubCell GetAvailableSubCell(CPos location, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, bool checkTransientActors = true);
+		SubCell GetAvailableSubCell(CPos location, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All);
 		void SetPosition(Actor self, CPos cell, SubCell subCell = SubCell.Any);
 		void SetPosition(Actor self, WPos pos);
 		void SetVisualPosition(Actor self, WPos pos);

OpenRA.Mods.Cnc/Traits/Minelayer.cs

@@ -107,7 +107,7 @@ namespace OpenRA.Mods.Cnc.Traits
 				var movement = self.Trait<IPositionable>();
 
 				var minefield = GetMinefieldCells(minefieldStart, cell, Info.MinefieldDepth)
-					.Where(c => movement.CanEnterCell(c, null, false))
+					.Where(c => movement.CanEnterCell(c, null, BlockedByActor.None))
 					.OrderBy(c => (c - minefieldStart).LengthSquared).ToList();
 
 				self.QueueActivity(order.Queued, new LayMines(self, minefield));
@@ -216,7 +216,7 @@ namespace OpenRA.Mods.Cnc.Traits
 				var pal = wr.Palette(TileSet.TerrainPaletteInternalName);
 				foreach (var c in minefield)
 				{
-					var tile = movement.CanEnterCell(c, null, false) && !world.ShroudObscures(c) ? tileOk : tileBlocked;
+					var tile = movement.CanEnterCell(c, null, BlockedByActor.None) && !world.ShroudObscures(c) ? tileOk : tileBlocked;
 					yield return new SpriteRenderable(tile, world.Map.CenterOfCell(c),
 						WVec.Zero, -511, pal, 1f, true);
 				}

OpenRA.Mods.Cnc/Traits/TDGunboat.cs

@@ -47,7 +47,7 @@ namespace OpenRA.Mods.Cnc.Traits
 		bool IOccupySpaceInfo.SharesCell { get { return false; } }
 
 		// Used to determine if actor can spawn
-		public bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, bool checkTransientActors = false)
+		public bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
 			if (!world.Map.Contains(cell))
 				return false;
@@ -158,9 +158,9 @@ namespace OpenRA.Mods.Cnc.Traits
 
 		public bool CanExistInCell(CPos cell) { return true; }
 		public bool IsLeavingCell(CPos location, SubCell subCell = SubCell.Any) { return false; }
-		public bool CanEnterCell(CPos cell, Actor ignoreActor = null, bool checkTransientActors = false) { return true; }
+		public bool CanEnterCell(CPos cell, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All) { return true; }
 		public SubCell GetValidSubCell(SubCell preferred) { return SubCell.Invalid; }
-		public SubCell GetAvailableSubCell(CPos a, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, bool checkTransientActors = true)
+		public SubCell GetAvailableSubCell(CPos a, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
 			// Does not use any subcell
 			return SubCell.Invalid;

OpenRA.Mods.Common/Activities/Attack.cs

@@ -152,7 +152,7 @@ namespace OpenRA.Mods.Common.Activities
 			if (!target.IsValidFor(self))
 				return AttackStatus.UnableToAttack;
 
-			if (attack.Info.AttackRequiresEnteringCell && !positionable.CanEnterCell(target.Actor.Location, null, false))
+			if (attack.Info.AttackRequiresEnteringCell && !positionable.CanEnterCell(target.Actor.Location, null, BlockedByActor.None))
 				return AttackStatus.UnableToAttack;
 
 			if (!attack.Info.TargetFrozenActors && !forceAttack && target.Type == TargetType.FrozenActor)

OpenRA.Mods.Common/Activities/FindAndDeliverResources.cs

@@ -194,7 +194,7 @@ namespace OpenRA.Mods.Common.Activities
 
 			// Find any harvestable resources:
 			List<CPos> path;
-			using (var search = PathSearch.Search(self.World, mobile.Locomotor, self, true, loc =>
+			using (var search = PathSearch.Search(self.World, mobile.Locomotor, self, BlockedByActor.Stationary, loc =>
 					domainIndex.IsPassable(self.Location, loc, locomotorInfo) && harv.CanHarvestCell(self, loc) && claimLayer.CanClaimCell(self, loc))
 				.WithCustomCost(loc =>
 				{

OpenRA.Mods.Common/Activities/HarvestResource.cs

@@ -62,7 +62,7 @@ namespace OpenRA.Mods.Common.Activities
 				foreach (var n in notifyHarvesterActions)
 					n.MovingToResources(self, targetCell);
 
-				QueueChild(move.MoveTo(targetCell, 2));
+				QueueChild(move.MoveTo(targetCell, 0));
 				return false;
 			}
 

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

@@ -11,7 +11,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.Linq;
 using OpenRA.Activities;
 using OpenRA.Mods.Common.Pathfinder;
@@ -27,7 +26,7 @@ namespace OpenRA.Mods.Common.Activities
 
 		readonly Mobile mobile;
 		readonly WDist nearEnough;
-		readonly Func<List<CPos>> getPath;
+		readonly Func<BlockedByActor, List<CPos>> getPath;
 		readonly Actor ignoreActor;
 		readonly Color? targetLineColor;
 
@@ -36,7 +35,6 @@ namespace OpenRA.Mods.Common.Activities
 
 		// For dealing with blockers
 		bool hasWaited;
-		bool hasNotifiedBlocker;
 		int waitTicksRemaining;
 
 		// To work around queued activity issues while minimizing changes to legacy behaviour
@@ -48,11 +46,11 @@ namespace OpenRA.Mods.Common.Activities
 		{
 			mobile = self.Trait<Mobile>();
 
-			getPath = () =>
+			getPath = check =>
 			{
 				List<CPos> path;
 				using (var search =
-					PathSearch.FromPoint(self.World, mobile.Locomotor, self, mobile.ToCell, destination, false)
+					PathSearch.FromPoint(self.World, mobile.Locomotor, self, mobile.ToCell, destination, check)
 					.WithoutLaneBias())
 					path = self.World.WorldActor.Trait<IPathFinder>().FindPath(search);
 				return path;
@@ -67,13 +65,13 @@ namespace OpenRA.Mods.Common.Activities
 		{
 			mobile = self.Trait<Mobile>();
 
-			getPath = () =>
+			getPath = check =>
 			{
 				if (!this.destination.HasValue)
 					return NoPath;
 
 				return self.World.WorldActor.Trait<IPathFinder>()
-					.FindUnitPath(mobile.ToCell, this.destination.Value, self, ignoreActor);
+					.FindUnitPath(mobile.ToCell, this.destination.Value, self, ignoreActor, check);
 			};
 
 			// Note: Will be recalculated from OnFirstRun if evaluateNearestMovableCell is true
@@ -89,8 +87,8 @@ namespace OpenRA.Mods.Common.Activities
 		{
 			mobile = self.Trait<Mobile>();
 
-			getPath = () => self.World.WorldActor.Trait<IPathFinder>()
+			getPath = check => self.World.WorldActor.Trait<IPathFinder>()
-				.FindUnitPathToRange(mobile.FromCell, subCell, self.World.Map.CenterOfSubCell(destination, subCell), nearEnough, self);
+				.FindUnitPathToRange(mobile.FromCell, subCell, self.World.Map.CenterOfSubCell(destination, subCell), nearEnough, self, check);
 			this.destination = destination;
 			this.nearEnough = nearEnough;
 			this.targetLineColor = targetLineColor;
@@ -100,13 +98,13 @@ namespace OpenRA.Mods.Common.Activities
 		{
 			mobile = self.Trait<Mobile>();
 
-			getPath = () =>
+			getPath = check =>
 			{
 				if (!target.IsValidFor(self))
 					return NoPath;
 
 				return self.World.WorldActor.Trait<IPathFinder>().FindUnitPathToRange(
-					mobile.ToCell, mobile.ToSubCell, target.CenterPosition, range, self);
+					mobile.ToCell, mobile.ToSubCell, target.CenterPosition, range, self, check);
 			};
 
 			destination = null;
@@ -114,7 +112,7 @@ namespace OpenRA.Mods.Common.Activities
 			this.targetLineColor = targetLineColor;
 		}
 
-		public Move(Actor self, Func<List<CPos>> getPath, Color? targetLineColor = null)
+		public Move(Actor self, Func<BlockedByActor, List<CPos>> getPath, Color? targetLineColor = null)
 		{
 			mobile = self.Trait<Mobile>();
 
@@ -135,9 +133,9 @@ namespace OpenRA.Mods.Common.Activities
 			return hash;
 		}
 
-		List<CPos> EvalPath()
+		List<CPos> EvalPath(BlockedByActor check)
 		{
-			var path = getPath().TakeWhile(a => a != mobile.ToCell).ToList();
+			var path = getPath(check).TakeWhile(a => a != mobile.ToCell).ToList();
 			mobile.PathHash = HashList(path);
 			return path;
 		}
@@ -149,10 +147,16 @@ namespace OpenRA.Mods.Common.Activities
 				var movableDestination = mobile.NearestMoveableCell(destination.Value);
 				destination = mobile.CanEnterCell(movableDestination) ? movableDestination : (CPos?)null;
 			}
+
+			path = EvalPath(BlockedByActor.Stationary);
+			if (path.Count == 0)
+				path = EvalPath(BlockedByActor.None);
 		}
 
 		public override bool Tick(Actor self)
 		{
+			mobile.TurnToMove = false;
+
 			// If the actor is inside a tunnel then we must let them move
 			// all the way through before moving to the next activity
 			if (IsCanceling && self.Location.Layer != CustomMovementLayerType.Tunnel)
@@ -164,9 +168,6 @@ namespace OpenRA.Mods.Common.Activities
 			if (destination == mobile.ToCell)
 				return true;
 
-			if (path == null)
-				path = EvalPath();
-
 			if (path.Count == 0)
 			{
 				destination = mobile.ToCell;
@@ -184,6 +185,7 @@ namespace OpenRA.Mods.Common.Activities
 			{
 				path.Add(nextCell.Value.First);
 				QueueChild(new Turn(self, firstFacing));
+				mobile.TurnToMove = true;
 				return false;
 			}
 
@@ -211,7 +213,7 @@ namespace OpenRA.Mods.Common.Activities
 			var containsTemporaryBlocker = WorldUtils.ContainsTemporaryBlocker(self.World, nextCell, self);
 
 			// Next cell in the move is blocked by another actor
-			if (containsTemporaryBlocker || !mobile.CanEnterCell(nextCell, ignoreActor, true))
+			if (containsTemporaryBlocker || !mobile.CanEnterCell(nextCell, ignoreActor))
 			{
 				// Are we close enough?
 				var cellRange = nearEnough.Length / 1024;
@@ -221,42 +223,116 @@ namespace OpenRA.Mods.Common.Activities
 					return null;
 				}
 
-				// See if they will move
+				// There is no point in waiting for the other actor to move if it is incapable of moving.
-				if (!hasNotifiedBlocker)
+				if (!mobile.CanEnterCell(nextCell, ignoreActor, BlockedByActor.Immovable))
 				{
-					self.NotifyBlocker(nextCell);
+					path = EvalPath(BlockedByActor.Immovable);
-					hasNotifiedBlocker = true;
+					return null;
 				}
 
+				// See if they will move
+				self.NotifyBlocker(nextCell);
+
 				// Wait a bit to see if they leave
 				if (!hasWaited)
 				{
-					waitTicksRemaining = mobile.Info.LocomotorInfo.WaitAverage
+					waitTicksRemaining = mobile.Info.LocomotorInfo.WaitAverage;
-						+ self.World.SharedRandom.Next(-mobile.Info.LocomotorInfo.WaitSpread, mobile.Info.LocomotorInfo.WaitSpread);
-
 					hasWaited = true;
+					return null;
 				}
 
 				if (--waitTicksRemaining >= 0)
 					return null;
 
+				hasWaited = false;
+
+				// If the blocking actors are already leaving, wait a little longer instead of repathing
+				if (CellIsEvacuating(self, nextCell))
+					return null;
+
 				// Calculate a new path
 				mobile.RemoveInfluence();
-				var newPath = EvalPath();
+				var newPath = EvalPath(BlockedByActor.All);
 				mobile.AddInfluence();
 
 				if (newPath.Count != 0)
+				{
 					path = newPath;
+					var newCell = path[path.Count - 1];
+					path.RemoveAt(path.Count - 1);
+
+					return Pair.New(newCell, mobile.GetAvailableSubCell(nextCell, SubCell.Any, ignoreActor));
+				}
+				else if (mobile.IsBlocking)
+				{
+					// If there is no way around the blocker and blocker will not move and we are blocking others, back up to let others pass.
+					var newCell = GetAdjacentCell(self, nextCell);
+					if (newCell != null)
+					{
+						if ((nextCell - newCell).Value.LengthSquared > 2)
+							path.Add(mobile.ToCell);
+
+						return Pair.New(newCell.Value, mobile.GetAvailableSubCell(newCell.Value, SubCell.Any, ignoreActor));
+					}
+				}
 
 				return null;
 			}
 
-			hasNotifiedBlocker = false;
 			hasWaited = false;
 			path.RemoveAt(path.Count - 1);
 
-			var subCell = mobile.GetAvailableSubCell(nextCell, SubCell.Any, ignoreActor);
+			return Pair.New(nextCell, mobile.GetAvailableSubCell(nextCell, SubCell.Any, ignoreActor));
-			return Pair.New(nextCell, subCell);
+		}
+
+		protected override void OnLastRun(Actor self)
+		{
+			path = null;
+		}
+
+		bool CellIsEvacuating(Actor self, CPos cell)
+		{
+			foreach (var actor in self.World.ActorMap.GetActorsAt(cell))
+			{
+				var move = actor.TraitOrDefault<Mobile>();
+				if (move == null || !move.IsTraitEnabled() || !move.IsLeaving())
+					return false;
+			}
+
+			return true;
+		}
+
+		CPos? GetAdjacentCell(Actor self, CPos nextCell)
+		{
+			var availCells = new List<CPos>();
+			var notStupidCells = new List<CPos>();
+			for (var i = -1; i <= 1; i++)
+			{
+				for (var j = -1; j <= 1; j++)
+				{
+					var p = mobile.ToCell + new CVec(i, j);
+					if (mobile.CanEnterCell(p))
+						availCells.Add(p);
+					else if (p != nextCell && p != mobile.ToCell)
+						notStupidCells.Add(p);
+				}
+			}
+
+			CPos? newCell = null;
+			if (availCells.Count > 0)
+				newCell = availCells.Random(self.World.SharedRandom);
+			else
+			{
+				var cellInfo = notStupidCells
+					.SelectMany(c => self.World.ActorMap.GetActorsAt(c)
+						.Where(a => a.IsIdle && a.Info.HasTraitInfo<MobileInfo>()),
+						(c, a) => new { Cell = c, Actor = a })
+					.RandomOrDefault(self.World.SharedRandom);
+				if (cellInfo != null)
+					newCell = cellInfo.Cell;
+			}
+
+			return newCell;
 		}
 
 		public override void Cancel(Actor self, bool keepQueue = false)
@@ -397,10 +473,13 @@ namespace OpenRA.Mods.Common.Activities
 			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)
+			static bool IsTurn(Mobile mobile, CPos nextCell, Map map)
 			{
-				return nextCell - mobile.ToCell !=
+				// Tight U-turns should be done in place instead of making silly looking loops.
-					mobile.ToCell - mobile.FromCell;
+				var nextFacing = map.FacingBetween(nextCell, mobile.ToCell, mobile.Facing);
+				var currentFacing = map.FacingBetween(mobile.ToCell, mobile.FromCell, mobile.Facing);
+				var delta = Util.NormalizeFacing(nextFacing - currentFacing);
+				return delta != 0 && (delta < 96 || delta > 160);
 			}
 
 			protected override MovePart OnComplete(Actor self, Mobile mobile, Move parent)
@@ -412,7 +491,7 @@ namespace OpenRA.Mods.Common.Activities
 				var nextCell = parent.PopPath(self);
 				if (nextCell != null)
 				{
-					if (IsTurn(mobile, nextCell.Value.First))
+					if (IsTurn(mobile, nextCell.Value.First, map))
 					{
 						var nextSubcellOffset = map.Grid.OffsetOfSubCell(nextCell.Value.Second);
 						var ret = new MoveFirstHalf(

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

@@ -82,7 +82,7 @@ namespace OpenRA.Mods.Common.Activities
 
 		protected override void OnFirstRun(Actor self)
 		{
-			QueueChild(Mobile.MoveTo(() => CalculatePathToTarget(self)));
+			QueueChild(Mobile.MoveTo(check => CalculatePathToTarget(self, check)));
 		}
 
 		public override bool Tick(Actor self)
@@ -112,14 +112,14 @@ namespace OpenRA.Mods.Common.Activities
 
 			// Target has moved, and MoveAdjacentTo is still valid.
 			if (!IsCanceling && shouldRepath)
-				QueueChild(Mobile.MoveTo(() => CalculatePathToTarget(self)));
+				QueueChild(Mobile.MoveTo(check => CalculatePathToTarget(self, check)));
 
 			// The last queued childactivity is guaranteed to be the inner move, so if the childactivity
 			// queue is empty it means we have reached our destination.
 			return TickChild(self);
 		}
 
-		List<CPos> CalculatePathToTarget(Actor self)
+		List<CPos> CalculatePathToTarget(Actor self, BlockedByActor check)
 		{
 			var targetCells = CandidateMovementCells(self);
 			var searchCells = new List<CPos>();
@@ -132,8 +132,8 @@ namespace OpenRA.Mods.Common.Activities
 			if (!searchCells.Any())
 				return NoPath;
 
-			using (var fromSrc = PathSearch.FromPoints(self.World, Mobile.Locomotor, self, searchCells, loc, true))
+			using (var fromSrc = PathSearch.FromPoints(self.World, Mobile.Locomotor, self, searchCells, loc, check))
-			using (var fromDest = PathSearch.FromPoint(self.World, Mobile.Locomotor, self, loc, lastVisibleTargetLocation, true).Reverse())
+			using (var fromDest = PathSearch.FromPoint(self.World, Mobile.Locomotor, self, loc, lastVisibleTargetLocation, check).Reverse())
 				return pathFinder.FindBidiPath(fromSrc, fromDest);
 		}
 

OpenRA.Mods.Common/Activities/UnloadCargo.cs

@@ -67,7 +67,7 @@ namespace OpenRA.Mods.Common.Activities
 
 			// Find the cells that are blocked by transient actors
 			return cargo.CurrentAdjacentCells
-				.Where(c => pos.CanEnterCell(c, null, true) != pos.CanEnterCell(c, null, false));
+				.Where(c => pos.CanEnterCell(c, null, BlockedByActor.All) != pos.CanEnterCell(c, null, BlockedByActor.None));
 		}
 
 		protected override void OnFirstRun(Actor self)

OpenRA.Mods.Common/Pathfinder/PathFinderUnitPathCacheDecorator.cs

@@ -30,37 +30,47 @@ namespace OpenRA.Mods.Common.Pathfinder
 			this.cacheStorage = cacheStorage;
 		}
 
-		public List<CPos> FindUnitPath(CPos source, CPos target, Actor self, Actor ignoreActor)
+		public List<CPos> FindUnitPath(CPos source, CPos target, Actor self, Actor ignoreActor, BlockedByActor check)
 		{
 			using (new PerfSample("Pathfinder"))
 			{
 				var key = "FindUnitPath" + self.ActorID + source.X + source.Y + target.X + target.Y;
-				var cachedPath = cacheStorage.Retrieve(key);
 
-				if (cachedPath != null)
+				// Only cache path when transient actors are ignored, otherwise there is no guarantee that the path
-					return cachedPath;
+				// is still valid at the next check.
+				if (check == BlockedByActor.None)
+				{
+					var cachedPath = cacheStorage.Retrieve(key);
+					if (cachedPath != null)
+						return cachedPath;
+				}
 
-				var pb = pathFinder.FindUnitPath(source, target, self, ignoreActor);
+				var pb = pathFinder.FindUnitPath(source, target, self, ignoreActor, check);
 
-				cacheStorage.Store(key, pb);
+				if (check == BlockedByActor.None)
+					cacheStorage.Store(key, pb);
 
 				return pb;
 			}
 		}
 
-		public List<CPos> FindUnitPathToRange(CPos source, SubCell srcSub, WPos target, WDist range, Actor self)
+		public List<CPos> FindUnitPathToRange(CPos source, SubCell srcSub, WPos target, WDist range, Actor self, BlockedByActor check)
 		{
 			using (new PerfSample("Pathfinder"))
 			{
 				var key = "FindUnitPathToRange" + self.ActorID + source.X + source.Y + target.X + target.Y;
-				var cachedPath = cacheStorage.Retrieve(key);
 
-				if (cachedPath != null)
+				if (check == BlockedByActor.None)
-					return cachedPath;
+				{
+					var cachedPath = cacheStorage.Retrieve(key);
+					if (cachedPath != null)
+						return cachedPath;
+				}
 
-				var pb = pathFinder.FindUnitPathToRange(source, srcSub, target, range, self);
+				var pb = pathFinder.FindUnitPathToRange(source, srcSub, target, range, self, check);
 
-				cacheStorage.Store(key, pb);
+				if (check == BlockedByActor.None)
+					cacheStorage.Store(key, pb);
 
 				return pb;
 			}

OpenRA.Mods.Common/Pathfinder/PathGraph.cs

@@ -14,6 +14,7 @@ using System.Collections.Generic;
 using System.Linq;
 using OpenRA.Mods.Common.Traits;
 using OpenRA.Primitives;
+using OpenRA.Traits;
 
 namespace OpenRA.Mods.Common.Pathfinder
 {
@@ -82,7 +83,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 		public bool InReverse { get; set; }
 		public Actor IgnoreActor { get; set; }
 
-		readonly CellConditions checkConditions;
+		readonly BlockedByActor checkConditions;
 		readonly Locomotor locomotor;
 		readonly LocomotorInfo.WorldMovementInfo worldMovementInfo;
 		readonly CellInfoLayerPool.PooledCellInfoLayer pooledLayer;
@@ -92,7 +93,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 		readonly Dictionary<byte, Pair<ICustomMovementLayer, CellLayer<CellInfo>>> customLayerInfo =
 			new Dictionary<byte, Pair<ICustomMovementLayer, CellLayer<CellInfo>>>();
 
-		public PathGraph(CellInfoLayerPool layerPool, Locomotor locomotor, Actor actor, World world, bool checkForBlocked)
+		public PathGraph(CellInfoLayerPool layerPool, Locomotor locomotor, Actor actor, World world, BlockedByActor check)
 		{
 			pooledLayer = layerPool.Get();
 			groundInfo = pooledLayer.GetLayer();
@@ -108,7 +109,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 			worldMovementInfo = locomotorInfo.GetWorldMovementInfo(world);
 			Actor = actor;
 			LaneBias = 1;
-			checkConditions = checkForBlocked ? CellConditions.TransientActors : CellConditions.None;
+			checkConditions = check;
 			checkTerrainHeight = world.Map.Grid.MaximumTerrainHeight > 0;
 		}
 
@@ -172,8 +173,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 
 		int GetCostToNode(CPos destNode, CVec direction)
 		{
-			var movementCost = locomotor.MovementCostToEnterCell(Actor, destNode, IgnoreActor, checkConditions);
+			var movementCost = locomotor.MovementCostToEnterCell(Actor, destNode, checkConditions, IgnoreActor);
-
 			if (movementCost != short.MaxValue && !(CustomBlock != null && CustomBlock(destNode)))
 				return CalculateCellCost(destNode, direction, movementCost);
 

OpenRA.Mods.Common/Pathfinder/PathSearch.cs

@@ -15,6 +15,7 @@ using System.Linq;
 using System.Runtime.CompilerServices;
 using OpenRA.Mods.Common.Traits;
 using OpenRA.Primitives;
+using OpenRA.Traits;
 
 namespace OpenRA.Mods.Common.Pathfinder
 {
@@ -45,18 +46,18 @@ namespace OpenRA.Mods.Common.Pathfinder
 			considered = new LinkedList<Pair<CPos, int>>();
 		}
 
-		public static IPathSearch Search(World world, Locomotor locomotor, Actor self, bool checkForBlocked, Func<CPos, bool> goalCondition)
+		public static IPathSearch Search(World world, Locomotor locomotor, Actor self, BlockedByActor check, Func<CPos, bool> goalCondition)
 		{
-			var graph = new PathGraph(LayerPoolForWorld(world), locomotor, self, world, checkForBlocked);
+			var graph = new PathGraph(LayerPoolForWorld(world), locomotor, self, world, check);
 			var search = new PathSearch(graph);
 			search.isGoal = goalCondition;
 			search.heuristic = loc => 0;
 			return search;
 		}
 
-		public static IPathSearch FromPoint(World world, Locomotor locomotor, Actor self, CPos @from, CPos target, bool checkForBlocked)
+		public static IPathSearch FromPoint(World world, Locomotor locomotor, Actor self, CPos @from, CPos target, BlockedByActor check)
 		{
-			var graph = new PathGraph(LayerPoolForWorld(world), locomotor, self, world, checkForBlocked);
+			var graph = new PathGraph(LayerPoolForWorld(world), locomotor, self, world, check);
 			var search = new PathSearch(graph)
 			{
 				heuristic = DefaultEstimator(target)
@@ -74,9 +75,9 @@ namespace OpenRA.Mods.Common.Pathfinder
 			return search;
 		}
 
-		public static IPathSearch FromPoints(World world, Locomotor locomotor, Actor self, IEnumerable<CPos> froms, CPos target, bool checkForBlocked)
+		public static IPathSearch FromPoints(World world, Locomotor locomotor, Actor self, IEnumerable<CPos> froms, CPos target, BlockedByActor check)
 		{
-			var graph = new PathGraph(LayerPoolForWorld(world), locomotor, self, world, checkForBlocked);
+			var graph = new PathGraph(LayerPoolForWorld(world), locomotor, self, world, check);
 			var search = new PathSearch(graph)
 			{
 				heuristic = DefaultEstimator(target)

OpenRA.Mods.Common/Traits/Air/Aircraft.cs

@@ -158,7 +158,7 @@ namespace OpenRA.Mods.Common.Traits
 		bool IOccupySpaceInfo.SharesCell { get { return false; } }
 
 		// Used to determine if an aircraft can spawn landed
-		public bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, bool checkTransientActors = true)
+		public bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
 			if (!world.Map.Contains(cell))
 				return false;
@@ -170,7 +170,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (world.WorldActor.Trait<BuildingInfluence>().GetBuildingAt(cell) != null)
 				return false;
 
-			if (!checkTransientActors)
+			if (check == BlockedByActor.None)
 				return true;
 
 			return !world.ActorMap.GetActorsAt(cell).Any(x => x != ignoreActor);
@@ -721,9 +721,9 @@ namespace OpenRA.Mods.Common.Traits
 
 		public bool CanExistInCell(CPos cell) { return true; }
 		public bool IsLeavingCell(CPos location, SubCell subCell = SubCell.Any) { return false; } // TODO: Handle landing
-		public bool CanEnterCell(CPos cell, Actor ignoreActor = null, bool checkTransientActors = true) { return true; }
+		public bool CanEnterCell(CPos cell, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All) { return true; }
 		public SubCell GetValidSubCell(SubCell preferred) { return SubCell.Invalid; }
-		public SubCell GetAvailableSubCell(CPos a, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, bool checkTransientActors = true)
+		public SubCell GetAvailableSubCell(CPos a, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
 			// Does not use any subcell
 			return SubCell.Invalid;

OpenRA.Mods.Common/Traits/Attack/AttackBase.cs

@@ -231,7 +231,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (IsTraitDisabled)
 				return false;
 
-			if (Info.AttackRequiresEnteringCell && (positionable == null || !positionable.CanEnterCell(t.Actor.Location, null, false)))
+			if (Info.AttackRequiresEnteringCell && (positionable == null || !positionable.CanEnterCell(t.Actor.Location, null, BlockedByActor.None)))
 				return false;
 
 			// PERF: Avoid LINQ.

OpenRA.Mods.Common/Traits/BotModules/HarvesterBotModule.cs

@@ -146,7 +146,7 @@ namespace OpenRA.Mods.Common.Traits
 				claimLayer.CanClaimCell(actor, cell);
 
 			var path = pathfinder.FindPath(
-				PathSearch.Search(world, harv.Locomotor, actor, true, isValidResource)
+				PathSearch.Search(world, harv.Locomotor, actor, BlockedByActor.Stationary, isValidResource)
 					.WithCustomCost(loc => world.FindActorsInCircle(world.Map.CenterOfCell(loc), Info.HarvesterEnemyAvoidanceRadius)
 						.Where(u => !u.IsDead && actor.Owner.Stances[u.Owner] == Stance.Enemy)
 						.Sum(u => Math.Max(WDist.Zero.Length, Info.HarvesterEnemyAvoidanceRadius.Length - (world.Map.CenterOfCell(loc) - u.CenterPosition).Length)))

OpenRA.Mods.Common/Traits/Buildings/TransformsIntoMobile.cs

@@ -198,7 +198,7 @@ namespace OpenRA.Mods.Common.Traits
 				if (mobile.locomotor.MovementCostForCell(cell) == short.MaxValue)
 					return false;
 
-				return mobile.locomotor.CanMoveFreelyInto(self, cell, null, CellConditions.BlockedByMovers);
+				return mobile.locomotor.CanMoveFreelyInto(self, cell, BlockedByActor.All, null);
 			}
 		}
 	}

OpenRA.Mods.Common/Traits/Cargo.cs

@@ -218,7 +218,7 @@ namespace OpenRA.Mods.Common.Traits
 			return Util.AdjacentCells(self.World, Target.FromActor(self)).Where(c => self.Location != c);
 		}
 
-		public bool CanUnload(bool immediate = false)
+		public bool CanUnload(BlockedByActor check = BlockedByActor.None)
 		{
 			if (checkTerrainType)
 			{
@@ -229,7 +229,7 @@ namespace OpenRA.Mods.Common.Traits
 			}
 
 			return !IsEmpty(self) && (aircraft == null || aircraft.CanLand(self.Location, blockedByMobile: false))
-				&& CurrentAdjacentCells != null && CurrentAdjacentCells.Any(c => Passengers.Any(p => !p.IsDead && p.Trait<IPositionable>().CanEnterCell(c, null, immediate)));
+				&& CurrentAdjacentCells != null && CurrentAdjacentCells.Any(c => Passengers.Any(p => !p.IsDead && p.Trait<IPositionable>().CanEnterCell(c, null, check)));
 		}
 
 		public bool CanLoad(Actor self, Actor a)
@@ -430,7 +430,7 @@ namespace OpenRA.Mods.Common.Traits
 		void INotifyKilled.Killed(Actor self, AttackInfo e)
 		{
 			if (Info.EjectOnDeath)
-				while (!IsEmpty(self) && CanUnload(true))
+				while (!IsEmpty(self) && CanUnload(BlockedByActor.All))
 				{
 					var passenger = Unload(self);
 					var cp = self.CenterPosition;
@@ -438,7 +438,7 @@ namespace OpenRA.Mods.Common.Traits
 					var positionable = passenger.Trait<IPositionable>();
 					positionable.SetPosition(passenger, self.Location);
 
-					if (!inAir && positionable.CanEnterCell(self.Location, self, false))
+					if (!inAir && positionable.CanEnterCell(self.Location, self, BlockedByActor.None))
 					{
 						self.World.AddFrameEndTask(w => w.Add(passenger));
 						var nbms = passenger.TraitsImplementing<INotifyBlockingMove>();

OpenRA.Mods.Common/Traits/Crates/Crate.cs

@@ -40,9 +40,9 @@ namespace OpenRA.Mods.Common.Traits
 
 		bool IOccupySpaceInfo.SharesCell { get { return false; } }
 
-		public bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, bool checkTransientActors = true)
+		public bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
-			return GetAvailableSubCell(world, cell, ignoreActor, checkTransientActors) != SubCell.Invalid;
+			return GetAvailableSubCell(world, cell, ignoreActor, check) != SubCell.Invalid;
 		}
 
 		public bool CanExistInCell(World world, CPos cell)
@@ -57,7 +57,7 @@ namespace OpenRA.Mods.Common.Traits
 			return true;
 		}
 
-		public SubCell GetAvailableSubCell(World world, CPos cell, Actor ignoreActor = null, bool checkTransientActors = true)
+		public SubCell GetAvailableSubCell(World world, CPos cell, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
 			if (!CanExistInCell(world, cell))
 				return SubCell.Invalid;
@@ -65,7 +65,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (world.WorldActor.Trait<BuildingInfluence>().GetBuildingAt(cell) != null)
 				return SubCell.Invalid;
 
-			if (!checkTransientActors)
+			if (check == BlockedByActor.None)
 				return SubCell.FullCell;
 
 			return !world.ActorMap.GetActorsAt(cell).Any(x => x != ignoreActor)
@@ -208,16 +208,16 @@ namespace OpenRA.Mods.Common.Traits
 
 		public bool IsLeavingCell(CPos location, SubCell subCell = SubCell.Any) { return self.Location == location && ticks + 1 == info.Lifetime * 25; }
 		public SubCell GetValidSubCell(SubCell preferred = SubCell.Any) { return SubCell.FullCell; }
-		public SubCell GetAvailableSubCell(CPos cell, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, bool checkTransientActors = true)
+		public SubCell GetAvailableSubCell(CPos cell, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
-			return info.GetAvailableSubCell(self.World, cell, ignoreActor, checkTransientActors);
+			return info.GetAvailableSubCell(self.World, cell, ignoreActor, check);
 		}
 
 		public bool CanExistInCell(CPos cell) { return info.CanExistInCell(self.World, cell); }
 
-		public bool CanEnterCell(CPos a, Actor ignoreActor = null, bool checkTransientActors = true)
+		public bool CanEnterCell(CPos a, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
-			return GetAvailableSubCell(a, SubCell.Any, ignoreActor, checkTransientActors) != SubCell.Invalid;
+			return GetAvailableSubCell(a, SubCell.Any, ignoreActor, check) != SubCell.Invalid;
 		}
 
 		bool ICrushable.CrushableBy(Actor self, Actor crusher, BitSet<CrushClass> crushClasses)

OpenRA.Mods.Common/Traits/Harvester.cs

@@ -184,7 +184,7 @@ namespace OpenRA.Mods.Common.Traits
 			// Start a search from each refinery's delivery location:
 			List<CPos> path;
 
-			using (var search = PathSearch.FromPoints(self.World, mobile.Locomotor, self, refs.Values.Select(r => r.Location), self.Location, false)
+			using (var search = PathSearch.FromPoints(self.World, mobile.Locomotor, self, refs.Values.Select(r => r.Location), self.Location, BlockedByActor.None)
 				.WithCustomCost(loc =>
 				{
 					if (!refs.ContainsKey(loc))

OpenRA.Mods.Common/Traits/Husk.cs

@@ -42,7 +42,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		bool IOccupySpaceInfo.SharesCell { get { return false; } }
 
-		public bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, bool checkTransientActors = true)
+		public bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
 			// IPositionable*Info*.CanEnterCell is only ever used for things like exiting production facilities,
 			// all places relevant for husks check IPositionable.CanEnterCell instead, so we can safely set this to true.
@@ -107,21 +107,21 @@ namespace OpenRA.Mods.Common.Traits
 		public Pair<CPos, SubCell>[] OccupiedCells() { return new[] { Pair.New(TopLeft, SubCell.FullCell) }; }
 		public bool IsLeavingCell(CPos location, SubCell subCell = SubCell.Any) { return false; }
 		public SubCell GetValidSubCell(SubCell preferred = SubCell.Any) { return SubCell.FullCell; }
-		public SubCell GetAvailableSubCell(CPos cell, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, bool checkTransientActors = true)
+		public SubCell GetAvailableSubCell(CPos cell, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
 			if (!CanExistInCell(cell))
 				return SubCell.Invalid;
 
-			if (!checkTransientActors)
+			if (check == BlockedByActor.None)
 				return SubCell.FullCell;
 
 			return self.World.ActorMap.GetActorsAt(cell)
 				.All(x => x == ignoreActor) ? SubCell.FullCell : SubCell.Invalid;
 		}
 
-		public bool CanEnterCell(CPos a, Actor ignoreActor = null, bool checkTransientActors = true)
+		public bool CanEnterCell(CPos a, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
-			return GetAvailableSubCell(a, SubCell.Any, ignoreActor, checkTransientActors) != SubCell.Invalid;
+			return GetAvailableSubCell(a, SubCell.Any, ignoreActor, check) != SubCell.Invalid;
 		}
 
 		public void SetPosition(Actor self, CPos cell, SubCell subCell = SubCell.Any) { SetPosition(self, self.World.Map.CenterOfCell(cell)); }

OpenRA.Mods.Common/Traits/Mobile.cs

@@ -82,7 +82,7 @@ namespace OpenRA.Mods.Common.Traits
 		// initialized and used by CanEnterCell
 		Locomotor locomotor;
 
-		public bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, bool checkTransientActors = true)
+		public bool CanEnterCell(World world, Actor self, CPos cell, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
 			// PERF: Avoid repeated trait queries on the hot path
 			if (locomotor == null)
@@ -92,8 +92,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (locomotor.MovementCostForCell(cell) == short.MaxValue)
 				return false;
 
-			var check = checkTransientActors ? CellConditions.All : CellConditions.BlockedByMovers;
+			return locomotor.CanMoveFreelyInto(self, cell, check, ignoreActor);
-			return locomotor.CanMoveFreelyInto(self, cell, ignoreActor, check);
 		}
 
 		public IReadOnlyDictionary<CPos, SubCell> OccupiedCells(ActorInfo info, CPos location, SubCell subCell = SubCell.Any)
@@ -176,6 +175,8 @@ namespace OpenRA.Mods.Common.Traits
 		INotifyFinishedMoving[] notifyFinishedMoving;
 		IWrapMove[] moveWrappers;
 		bool requireForceMove;
+		public bool TurnToMove;
+		public bool IsBlocking { get; private set; }
 
 		#region IFacing
 		[Sync]
@@ -298,15 +299,6 @@ namespace OpenRA.Mods.Common.Traits
 			if (IsTraitDisabled || IsTraitPaused)
 				return;
 
-			// Initial fairly braindead implementation.
-			// don't allow ourselves to be pushed around by the enemy!
-			if (!force && self.Owner.Stances[nudger.Owner] != Stance.Ally)
-				return;
-
-			// Don't nudge if we're busy doing something!
-			if (!force && !self.IsIdle)
-				return;
-
 			// Pick an adjacent available cell.
 			var availCells = new List<CPos>();
 			var notStupidCells = new List<CPos>();
@@ -358,6 +350,17 @@ namespace OpenRA.Mods.Common.Traits
 			}
 		}
 
+		public bool IsLeaving()
+		{
+			if (CurrentMovementTypes.HasFlag(MovementType.Horizontal))
+				return true;
+
+			if (CurrentMovementTypes.HasFlag(MovementType.Turn))
+				return TurnToMove;
+
+			return false;
+		}
+
 		public bool CanInteractWithGroundLayer(Actor self)
 		{
 			// TODO: Think about extending this to support arbitrary layer-layer checks
@@ -442,10 +445,9 @@ namespace OpenRA.Mods.Common.Traits
 				&& (subCell == SubCell.Any || FromSubCell == subCell || subCell == SubCell.FullCell || FromSubCell == SubCell.FullCell);
 		}
 
-		public SubCell GetAvailableSubCell(CPos a, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, bool checkTransientActors = true)
+		public SubCell GetAvailableSubCell(CPos a, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
-			var cellConditions = checkTransientActors ? CellConditions.All : CellConditions.None;
+			return Locomotor.GetAvailableSubCell(self, a, check, preferredSubCell, ignoreActor);
-			return Locomotor.GetAvailableSubCell(self, a, preferredSubCell, ignoreActor, cellConditions);
 		}
 
 		public bool CanExistInCell(CPos cell)
@@ -453,9 +455,9 @@ namespace OpenRA.Mods.Common.Traits
 			return Locomotor.MovementCostForCell(cell) != short.MaxValue;
 		}
 
-		public bool CanEnterCell(CPos cell, Actor ignoreActor = null, bool checkTransientActors = true)
+		public bool CanEnterCell(CPos cell, Actor ignoreActor = null, BlockedByActor check = BlockedByActor.All)
 		{
-			return Info.CanEnterCell(self.World, self, cell, ignoreActor, checkTransientActors);
+			return Info.CanEnterCell(self.World, self, cell, ignoreActor, check);
 		}
 
 		#endregion
@@ -474,6 +476,7 @@ namespace OpenRA.Mods.Common.Traits
 			FromSubCell = fromSub;
 			ToSubCell = toSub;
 			AddInfluence();
+			IsBlocking = false;
 
 			// Most custom layer conditions are added/removed when starting the transition between layers.
 			if (toCell.Layer != fromCell.Layer)
@@ -737,7 +740,7 @@ namespace OpenRA.Mods.Common.Traits
 		}
 
 		public Activity ScriptedMove(CPos cell) { return new Move(self, cell); }
-		public Activity MoveTo(Func<List<CPos>> pathFunc) { return new Move(self, pathFunc); }
+		public Activity MoveTo(Func<BlockedByActor, List<CPos>> pathFunc) { return new Move(self, pathFunc); }
 
 		Activity VisualMove(Actor self, WPos fromPos, WPos toPos, CPos cell)
 		{
@@ -758,7 +761,7 @@ namespace OpenRA.Mods.Common.Traits
 
 			var pathFinder = self.World.WorldActor.Trait<IPathFinder>();
 			List<CPos> path;
-			using (var search = PathSearch.Search(self.World, Locomotor, self, true,
+			using (var search = PathSearch.Search(self.World, Locomotor, self, BlockedByActor.All,
 					loc => loc.Layer == 0 && CanEnterCell(loc))
 				.FromPoint(self.Location))
 				path = pathFinder.FindPath(search);
@@ -782,7 +785,7 @@ namespace OpenRA.Mods.Common.Traits
 			init.Add(new FacingInit(facing));
 
 			// Allows the husk to drag to its final position
-			if (CanEnterCell(self.Location, self, false))
+			if (CanEnterCell(self.Location, self, BlockedByActor.Stationary))
 				init.Add(new HuskSpeedInit(MovementSpeedForCell(self, self.Location)));
 		}
 
@@ -804,8 +807,16 @@ namespace OpenRA.Mods.Common.Traits
 
 		void INotifyBlockingMove.OnNotifyBlockingMove(Actor self, Actor blocking)
 		{
-			if (self.IsIdle && self.AppearsFriendlyTo(blocking))
+			if (!self.AppearsFriendlyTo(blocking))
+				return;
+
+			if (self.IsIdle)
+			{
 				Nudge(self, blocking, true);
+				return;
+			}
+
+			IsBlocking = true;
 		}
 
 		public override IEnumerable<VariableObserver> GetVariableObservers()

OpenRA.Mods.Common/Traits/World/Locomotor.cs

@@ -19,33 +19,19 @@ using OpenRA.Traits;
 
 namespace OpenRA.Mods.Common.Traits
 {
-	[Flags]
-	public enum CellConditions
-	{
-		None = 0,
-		TransientActors,
-		BlockedByMovers,
-		All = TransientActors | BlockedByMovers
-	}
-
 	[Flags]
 	public enum CellFlag : byte
 	{
 		HasFreeSpace = 0,
-		HasActor = 1,
+		HasMovingActor = 1,
-		HasMovingActor = 2,
+		HasStationaryActor = 2,
-		HasCrushableActor = 4,
+		HasMovableActor = 4,
-		HasTemporaryBlocker = 8
+		HasCrushableActor = 8,
+		HasTemporaryBlocker = 16
 	}
 
 	public static class LocomoterExts
 	{
-		public static bool HasCellCondition(this CellConditions c, CellConditions cellCondition)
-		{
-			// PERF: Enum.HasFlag is slower and requires allocations.
-			return (c & cellCondition) == cellCondition;
-		}
-
 		public static bool HasCellFlag(this CellFlag c, CellFlag cellFlag)
 		{
 			// PERF: Enum.HasFlag is slower and requires allocations.
@@ -204,13 +190,13 @@ namespace OpenRA.Mods.Common.Traits
 	{
 		struct CellCache
 		{
-			public readonly LongBitSet<PlayerBitMask> Blocking;
+			public readonly LongBitSet<PlayerBitMask> Immovable;
 			public readonly LongBitSet<PlayerBitMask> Crushable;
 			public readonly CellFlag CellFlag;
 
-			public CellCache(LongBitSet<PlayerBitMask> blocking, CellFlag cellFlag, LongBitSet<PlayerBitMask> crushable = default(LongBitSet<PlayerBitMask>))
+			public CellCache(LongBitSet<PlayerBitMask> immovable, CellFlag cellFlag, LongBitSet<PlayerBitMask> crushable = default(LongBitSet<PlayerBitMask>))
 			{
-				Blocking = blocking;
+				Immovable = immovable;
 				Crushable = crushable;
 				CellFlag = cellFlag;
 			}
@@ -244,7 +230,7 @@ namespace OpenRA.Mods.Common.Traits
 			return cell.Layer == 0 ? cellsCost[cell] : customLayerCellsCost[cell.Layer][cell];
 		}
 
-		public short MovementCostToEnterCell(Actor actor, CPos destNode, Actor ignoreActor, CellConditions check)
+		public short MovementCostToEnterCell(Actor actor, CPos destNode, BlockedByActor check, Actor ignoreActor)
 		{
 			if (!world.Map.Contains(destNode))
 				return short.MaxValue;
@@ -252,19 +238,20 @@ namespace OpenRA.Mods.Common.Traits
 			var cellCost = destNode.Layer == 0 ? cellsCost[destNode] : customLayerCellsCost[destNode.Layer][destNode];
 
 			if (cellCost == short.MaxValue ||
-				!CanMoveFreelyInto(actor, destNode, ignoreActor, check))
+				!CanMoveFreelyInto(actor, destNode, check, ignoreActor))
 				return short.MaxValue;
 
 			return cellCost;
 		}
 
 		// Determines whether the actor is blocked by other Actors
-		public bool CanMoveFreelyInto(Actor actor, CPos cell, Actor ignoreActor, CellConditions check)
+		public bool CanMoveFreelyInto(Actor actor, CPos cell, BlockedByActor check, Actor ignoreActor)
 		{
 			var cellCache = GetCache(cell);
 			var cellFlag = cellCache.CellFlag;
 
-			if (!check.HasCellCondition(CellConditions.TransientActors))
+			// If the check allows: We are not blocked by transient actors.
+			if (check == BlockedByActor.None)
 				return true;
 
 			// No actor in the cell or free SubCell.
@@ -281,14 +268,31 @@ namespace OpenRA.Mods.Common.Traits
 			if (cellCache.Crushable.Overlaps(actor.Owner.PlayerMask))
 				return true;
 
+			// If the check allows: We are not blocked by moving units.
+			if (check <= BlockedByActor.Stationary && !cellFlag.HasCellFlag(CellFlag.HasStationaryActor))
+				return true;
+
+			// If the check allows: We are not blocked by units that we can force to move out of the way.
+			if (check <= BlockedByActor.Immovable && !cellCache.Immovable.Overlaps(actor.Owner.PlayerMask))
+				return true;
+
 			// Cache doesn't account for ignored actors or temporary blockers - these must use the slow path.
 			if (ignoreActor == null && !cellFlag.HasCellFlag(CellFlag.HasTemporaryBlocker))
 			{
-				// We are blocked by another actor in the cell.
+				// We already know there are uncrushable actors in the cell so we are always blocked.
-				if (cellCache.Blocking.Overlaps(actor.Owner.PlayerMask))
+				if (check == BlockedByActor.All)
 					return false;
 
-				if (check == CellConditions.BlockedByMovers && cellFlag < CellFlag.HasCrushableActor)
+				// We already know there are either immovable or stationary actors which the check does not allow.
+				if (!cellFlag.HasCellFlag(CellFlag.HasCrushableActor))
+					return false;
+
+				// All actors in the cell are immovable and some cannot be crushed.
+				if (!cellFlag.HasCellFlag(CellFlag.HasMovableActor))
+					return false;
+
+				// All actors in the cell are stationary and some cannot be crushed.
+				if (check == BlockedByActor.Stationary && !cellFlag.HasCellFlag(CellFlag.HasMovingActor))
 					return false;
 			}
 
@@ -299,12 +303,12 @@ namespace OpenRA.Mods.Common.Traits
 			return true;
 		}
 
-		public SubCell GetAvailableSubCell(Actor self, CPos cell, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, CellConditions check = CellConditions.All)
+		public SubCell GetAvailableSubCell(Actor self, CPos cell, BlockedByActor check, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null)
 		{
 			if (MovementCostForCell(cell) == short.MaxValue)
 				return SubCell.Invalid;
 
-			if (check.HasCellCondition(CellConditions.TransientActors))
+			if (check > BlockedByActor.None)
 			{
 				Func<Actor, bool> checkTransient = otherActor => IsBlockedBy(self, otherActor, ignoreActor, check, GetCache(cell).CellFlag);
 
@@ -320,15 +324,20 @@ namespace OpenRA.Mods.Common.Traits
 			return world.ActorMap.FreeSubCell(cell, preferredSubCell);
 		}
 
-		bool IsBlockedBy(Actor self, Actor otherActor, Actor ignoreActor, CellConditions check, CellFlag cellFlag)
+		bool IsBlockedBy(Actor self, Actor otherActor, Actor ignoreActor, BlockedByActor check, CellFlag cellFlag)
 		{
 			if (otherActor == ignoreActor)
 				return false;
 
-			// If the check allows: we are not blocked by allied units moving in our direction.
+			// If the check allows: We are not blocked by units that we can force to move out of the way.
-			if (!check.HasCellCondition(CellConditions.BlockedByMovers) && cellFlag.HasCellFlag(CellFlag.HasMovingActor) &&
+			if (check <= BlockedByActor.Immovable && cellFlag.HasCellFlag(CellFlag.HasMovableActor) &&
 				self.Owner.Stances[otherActor.Owner] == Stance.Ally &&
-				IsMovingInMyDirection(self, otherActor))
+				otherActor.TraitOrDefault<IMove>() != null)
+				return false;
+
+			// If the check allows: we are not blocked by moving units.
+			if (check <= BlockedByActor.Stationary && cellFlag.HasCellFlag(CellFlag.HasMovingActor) &&
+				IsMoving(self, otherActor))
 				return false;
 
 			if (cellFlag.HasCellFlag(CellFlag.HasTemporaryBlocker))
@@ -339,11 +348,8 @@ namespace OpenRA.Mods.Common.Traits
 					return false;
 			}
 
-			if (!cellFlag.HasCellFlag(CellFlag.HasCrushableActor))
-				return true;
-
 			// If we cannot crush the other actor in our way, we are blocked.
-			if (Info.Crushes.IsEmpty)
+			if (!cellFlag.HasCellFlag(CellFlag.HasCrushableActor) || Info.Crushes.IsEmpty)
 				return true;
 
 			// If the other actor in our way cannot be crushed, we are blocked.
@@ -356,7 +362,7 @@ namespace OpenRA.Mods.Common.Traits
 			return true;
 		}
 
-		static bool IsMovingInMyDirection(Actor self, Actor other)
+		static bool IsMoving(Actor self, Actor other)
 		{
 			// PERF: Because we can be sure that OccupiesSpace is Mobile here we can save some performance by avoiding querying for the trait.
 			var otherMobile = other.OccupiesSpace as Mobile;
@@ -368,9 +374,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (selfMobile == null)
 				return false;
 
-			// Moving in the same direction if the facing delta is between +/- 90 degrees
+			return true;
-			var delta = Util.NormalizeFacing(otherMobile.Facing - selfMobile.Facing);
-			return delta < 64 || delta > 192;
 		}
 
 		public void WorldLoaded(World w, WorldRenderer wr)
@@ -456,31 +460,32 @@ namespace OpenRA.Mods.Common.Traits
 				var cache = cell.Layer == 0 ? blockingCache : customLayerBlockingCache[cell.Layer];
 
 				var actors = actorMap.GetActorsAt(cell);
+				var cellFlag = CellFlag.HasFreeSpace;
 
 				if (!actors.Any())
 				{
-					cache[cell] = new CellCache(default(LongBitSet<PlayerBitMask>), CellFlag.HasFreeSpace);
+					cache[cell] = new CellCache(default(LongBitSet<PlayerBitMask>), cellFlag);
 					return;
 				}
 
 				if (sharesCell && actorMap.HasFreeSubCell(cell))
 				{
-					cache[cell] = new CellCache(default(LongBitSet<PlayerBitMask>), CellFlag.HasFreeSpace);
+					cache[cell] = new CellCache(default(LongBitSet<PlayerBitMask>), cellFlag);
 					return;
 				}
 
-				var cellFlag = CellFlag.HasActor;
+				var cellImmovablePlayers = default(LongBitSet<PlayerBitMask>);
-				var cellBlockedPlayers = default(LongBitSet<PlayerBitMask>);
 				var cellCrushablePlayers = world.AllPlayersMask;
 
 				foreach (var actor in actors)
 				{
-					var actorBlocksPlayers = world.AllPlayersMask;
+					var actorImmovablePlayers = world.AllPlayersMask;
 					var actorCrushablePlayers = world.NoPlayersMask;
 
 					var crushables = actor.TraitsImplementing<ICrushable>();
 					var mobile = actor.OccupiesSpace as Mobile;
-					var isMoving = mobile != null && mobile.CurrentMovementTypes.HasMovementType(MovementType.Horizontal);
+					var isMovable = mobile != null;
+					var isMoving = isMovable && mobile.CurrentMovementTypes.HasMovementType(MovementType.Horizontal);
 
 					if (crushables.Any())
 					{
@@ -490,9 +495,14 @@ namespace OpenRA.Mods.Common.Traits
 					}
 
 					if (isMoving)
-					{
-						actorBlocksPlayers = actorBlocksPlayers.Except(actor.Owner.AlliedPlayersMask);
 						cellFlag |= CellFlag.HasMovingActor;
+					else
+						cellFlag |= CellFlag.HasStationaryActor;
+
+					if (isMovable)
+					{
+						cellFlag |= CellFlag.HasMovableActor;
+						actorImmovablePlayers = actorImmovablePlayers.Except(actor.Owner.AlliedPlayersMask);
 					}
 
 					// PERF: Only perform ITemporaryBlocker trait look-up if mod/map rules contain any actors that are temporary blockers
@@ -504,10 +514,10 @@ namespace OpenRA.Mods.Common.Traits
 					}
 
 					cellCrushablePlayers = cellCrushablePlayers.Intersect(actorCrushablePlayers);
-					cellBlockedPlayers = cellBlockedPlayers.Union(actorBlocksPlayers);
+					cellImmovablePlayers = cellImmovablePlayers.Union(actorImmovablePlayers);
 				}
 
-				cache[cell] = new CellCache(cellBlockedPlayers, cellFlag, cellCrushablePlayers);
+				cache[cell] = new CellCache(cellImmovablePlayers, cellFlag, cellCrushablePlayers);
 			}
 		}
 	}

OpenRA.Mods.Common/Traits/World/PathFinder.cs

@@ -33,9 +33,9 @@ namespace OpenRA.Mods.Common.Traits
 		/// Calculates a path for the actor from source to destination
 		/// </summary>
 		/// <returns>A path from start to target</returns>
-		List<CPos> FindUnitPath(CPos source, CPos target, Actor self, Actor ignoreActor);
+		List<CPos> FindUnitPath(CPos source, CPos target, Actor self, Actor ignoreActor, BlockedByActor check);
 
-		List<CPos> FindUnitPathToRange(CPos source, SubCell srcSub, WPos target, WDist range, Actor self);
+		List<CPos> FindUnitPathToRange(CPos source, SubCell srcSub, WPos target, WDist range, Actor self, BlockedByActor check);
 
 		/// <summary>
 		/// Calculates a path given a search specification
@@ -62,7 +62,7 @@ namespace OpenRA.Mods.Common.Traits
 			this.world = world;
 		}
 
-		public List<CPos> FindUnitPath(CPos source, CPos target, Actor self, Actor ignoreActor)
+		public List<CPos> FindUnitPath(CPos source, CPos target, Actor self, Actor ignoreActor, BlockedByActor check)
 		{
 			var mobile = self.Trait<Mobile>();
 			var locomotor = mobile.Locomotor;
@@ -78,19 +78,23 @@ namespace OpenRA.Mods.Common.Traits
 				return EmptyPath;
 
 			var distance = source - target;
-			if (source.Layer == target.Layer && distance.LengthSquared < 3 && locomotor.CanMoveFreelyInto(self, target, null, CellConditions.All))
+			var canMoveFreely = locomotor.CanMoveFreelyInto(self, target, check, null);
+			if (distance.LengthSquared < 3 && !canMoveFreely)
+				return new List<CPos> { };
+
+			if (source.Layer == target.Layer && distance.LengthSquared < 3 && canMoveFreely)
 				return new List<CPos> { target };
 
 			List<CPos> pb;
 
-			using (var fromSrc = PathSearch.FromPoint(world, locomotor, self, target, source, true).WithIgnoredActor(ignoreActor))
+			using (var fromSrc = PathSearch.FromPoint(world, locomotor, self, target, source, check).WithIgnoredActor(ignoreActor))
-			using (var fromDest = PathSearch.FromPoint(world, locomotor, self, source, target, true).WithIgnoredActor(ignoreActor).Reverse())
+			using (var fromDest = PathSearch.FromPoint(world, locomotor, self, source, target, check).WithIgnoredActor(ignoreActor).Reverse())
 				pb = FindBidiPath(fromSrc, fromDest);
 
 			return pb;
 		}
 
-		public List<CPos> FindUnitPathToRange(CPos source, SubCell srcSub, WPos target, WDist range, Actor self)
+		public List<CPos> FindUnitPathToRange(CPos source, SubCell srcSub, WPos target, WDist range, Actor self, BlockedByActor check)
 		{
 			if (!cached)
 			{
@@ -123,8 +127,8 @@ namespace OpenRA.Mods.Common.Traits
 
 			var locomotor = mobile.Locomotor;
 
-			using (var fromSrc = PathSearch.FromPoints(world, locomotor, self, tilesInRange, source, true))
+			using (var fromSrc = PathSearch.FromPoints(world, locomotor, self, tilesInRange, source, check))
-			using (var fromDest = PathSearch.FromPoint(world, locomotor, self, source, targetCell, true).Reverse())
+			using (var fromDest = PathSearch.FromPoint(world, locomotor, self, source, targetCell, check).Reverse())
 				return FindBidiPath(fromSrc, fromDest);
 		}
 

OpenRA.Mods.D2k/Activities/SwallowActor.cs

@@ -121,7 +121,7 @@ namespace OpenRA.Mods.D2k.Activities
 					}
 
 					// The target reached solid ground
-					if (!positionable.CanEnterCell(targetLocation, null, false))
+					if (!positionable.CanEnterCell(targetLocation, null, BlockedByActor.None))
 					{
 						RevokeCondition(self);
 						return true;

OpenRA.Mods.D2k/Traits/Sandworm.cs

@@ -98,7 +98,7 @@ namespace OpenRA.Mods.D2k.Traits
 				if (!a.Info.HasTraitInfo<AttractsWormsInfo>())
 					return false;
 
-				return mobile.CanEnterCell(a.Location, null, false);
+				return mobile.CanEnterCell(a.Location, null, BlockedByActor.None);
 			};
 
 			var actorsInRange = self.World.FindActorsInCircle(self.CenterPosition, WormInfo.MaxSearchRadius)
@@ -112,7 +112,7 @@ namespace OpenRA.Mods.D2k.Traits
 
 			var moveTo = self.World.Map.CellContaining(self.CenterPosition + noiseDirection);
 
-			while (!self.World.Map.Contains(moveTo) || !mobile.CanEnterCell(moveTo, null, false))
+			while (!self.World.Map.Contains(moveTo) || !mobile.CanEnterCell(moveTo, null, BlockedByActor.None))
 			{
 				// without this check, this while can be infinity loop
 				if (moveTo == self.Location)