Merge pull request #6528 from atlimit8/DragIntoTransports

Modifies IMove & Enter and Fixes #4640 - Units teleport into transports

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -101,6 +101,7 @@ namespace OpenRA.Traits
 	public interface INotifyCapture { void OnCapture(Actor self, Actor captor, Player oldOwner, Player newOwner); }
 	public interface INotifyHarvest { void Harvested(Actor self, ResourceType resource); }
 	public interface INotifyInfiltrated { void Infiltrated(Actor self, Actor infiltrator); }
+	public interface IDisableMove { bool MoveDisabled(Actor self); }
 
 	public interface IUpgradable
 	{
@@ -206,9 +207,12 @@ namespace OpenRA.Traits
 		Activity MoveWithinRange(Target target, WRange minRange, WRange maxRange);
 		Activity MoveFollow(Actor self, Target target, WRange minRange, WRange maxRange);
 		Activity MoveIntoWorld(Actor self, CPos cell, SubCell subCell = SubCell.Any);
+		Activity MoveToTarget(Actor self, Target target);
+		Activity MoveIntoTarget(Actor self, Target target);
 		Activity VisualMove(Actor self, WPos fromPos, WPos toPos);
 		CPos NearestMoveableCell(CPos target);
 		bool IsMoving { get; set; }
+		bool CanEnterTargetNow(Actor self, Target target);
 	}
 
 	public interface INotifyBlockingMove { void OnNotifyBlockingMove(Actor self, Actor blocking); }

OpenRA.Mods.Cnc/Activities/HarvesterDockSequence.cs

@@ -47,10 +47,10 @@ namespace OpenRA.Mods.Cnc
 					return this;
 				case State.Turn:
 					state = State.DragIn;
-					return Util.SequenceActivities(new Turn(112), this);
+					return Util.SequenceActivities(new Turn(self, 112), this);
 				case State.DragIn:
 					state = State.Dock;
-					return Util.SequenceActivities(new Drag(startDock, endDock, 12), this);
+					return Util.SequenceActivities(new Drag(self, startDock, endDock, 12), this);
 				case State.Dock:
 					ru.PlayCustomAnimation(self, "dock", () => {
 						ru.PlayCustomAnimRepeating(self, "dock-loop");
@@ -73,7 +73,7 @@ namespace OpenRA.Mods.Cnc
 					state = State.Wait;
 					return this;
 				case State.DragOut:
-					return Util.SequenceActivities(new Drag(endDock, startDock, 12), NextActivity);
+					return Util.SequenceActivities(new Drag(self, endDock, startDock, 12), NextActivity);
 			}
 
 			throw new InvalidOperationException("Invalid harvester dock state");

OpenRA.Mods.Cnc/WithCargo.cs

@@ -62,7 +62,7 @@ namespace OpenRA.Mods.Cnc
 					cargoFacing.Facing = facing.Facing;
 
 				var cargoPassenger = c.Trait<Passenger>();
-				if (cargoInfo.DisplayTypes.Contains(cargoPassenger.info.CargoType))
+				if (cargoInfo.DisplayTypes.Contains(cargoPassenger.Info.CargoType))
 				{
 					var offset = pos - c.CenterPosition + body.LocalToWorld(cargoInfo.LocalOffset[i++ % cargoInfo.LocalOffset.Length].Rotate(bodyOrientation));
 					foreach (var cr in c.Render(wr))

OpenRA.Mods.RA/Activities/Attack.cs

@@ -64,7 +64,7 @@ namespace OpenRA.Mods.RA.Activities
 
 			var desiredFacing = Util.GetFacing(Target.CenterPosition - self.CenterPosition, 0);
 			if (facing.Facing != desiredFacing)
-				return Util.SequenceActivities(new Turn(desiredFacing), this);
+				return Util.SequenceActivities(new Turn(self, desiredFacing), this);
 
 			attack.DoAttack(self, Target);
 

OpenRA.Mods.RA/Activities/Enter.cs

@@ -8,41 +8,267 @@
  */
 #endregion
 
+using System;
+using System.Collections.Generic;
 using System.Linq;
+using OpenRA.Mods.RA.Move;
 using OpenRA.Traits;
 
 namespace OpenRA.Mods.RA.Activities
 {
 	public class Enter : Activity
 	{
-		readonly Target target;
+		public enum ReserveStatus { None, TooFar, Pending, Ready }
-		readonly Activity inner;
+		enum State { ApproachingOrEntering, Inside, Exiting, Done }
 
-		public Enter(Actor target, Activity inner)
+		readonly Activity inside;
+		readonly IMove move;
+		readonly int maxTries = 0;
+		Target target;
+		State nextState = State.ApproachingOrEntering; // Hint/starting point for next state
+		bool isEnteringOrInside = false; // Used to know if exiting should be used
+		WPos savedPos; // Position just before entering
+		Activity inner;
+		bool firstApproach = true;
+
+		protected Enter(Actor self, Actor target, int maxTries = 1)
+			: this(self, target, null)
 		{
+			this.maxTries = maxTries;
+		}
+
+		public Enter(Actor self, Actor target, Activity inside)
+		{
+			this.move = self.Trait<IMove>();
 			this.target = Target.FromActor(target);
-			this.inner = inner;
+			this.inside = inside;
+		}
+
+		// CanEnter(target) should to be true; othwise, Enter may abort.
+		// Tries counter starts at 1 (reset every tick)
+		protected virtual bool TryGetAlternateTarget(Actor self, int tries, ref Target target) { return false; }
+		protected virtual bool CanReserve(Actor self) { return true; }
+		protected virtual ReserveStatus Reserve(Actor self)
+		{
+			return !CanReserve(self) ? ReserveStatus.None : move.CanEnterTargetNow(self, target) ? ReserveStatus.Ready : ReserveStatus.TooFar;
+		}
+
+		protected virtual void Unreserve(Actor self, bool abort) { }
+		protected virtual void OnInside(Actor self) { }
+
+		protected bool TryGetAlternateTargetInCircle(Actor self, WRange radius, Action<Target> update, Func<Actor, bool> primaryFilter, Func<Actor, bool>[] preferenceFilters = null)
+		{
+			var radiusSquared = radius.Range * radius.Range;
+			var diff = new WVec(radius, radius, WRange.Zero);
+			var candidates = self.World.ActorMap.ActorsInBox(self.CenterPosition - diff, self.CenterPosition + diff)
+				.Where(primaryFilter).Select(a => new { Actor = a, Ls = (self.CenterPosition - a.CenterPosition).HorizontalLengthSquared })
+				.Where(p => p.Ls <= radiusSquared).OrderBy(p => p.Ls).Select(p => p.Actor);
+			if (preferenceFilters != null)
+				foreach (var filter in preferenceFilters)
+				{
+					var preferredCandidate = candidates.FirstOrDefault(filter);
+					if (preferredCandidate == null)
+						continue;
+					target = Target.FromActor(preferredCandidate);
+					update(target);
+					return true;
+				}
+
+			var candidate = candidates.FirstOrDefault();
+			if (candidate == null)
+				return false;
+			target = Target.FromActor(candidate);
+			update(target);
+			return true;
+		}
+
+		// Called when inner activity is this and returns inner activity for next tick.
+		protected virtual Activity InsideTick(Actor self) { return Util.RunActivity(self, inside); }
+
+		// Abort entering and/or leave if necessary
+		protected virtual void AbortOrExit(Actor self)
+		{
+			if (nextState == State.Done)
+				return;
+			nextState = isEnteringOrInside ? State.Exiting : State.Done;
+			if (inner == this)
+				inner = null;
+			else if (inner != null)
+				inner.Cancel(self);
+			if (isEnteringOrInside)
+				Unreserve(self, true);
+			isEnteringOrInside = false;
+		}
+
+		// Cancel inner activity and mark as done unless already leaving or done
+		protected void Done(Actor self)
+		{
+			if (nextState == State.Done)
+				return;
+			nextState = State.Done;
+			if (inner == this)
+				inner = null;
+			else if (inner != null)
+				inner.Cancel(self);
+		}
+
+		public override void Cancel(Actor self)
+		{
+			AbortOrExit(self);
+			if (nextState < State.Exiting)
+				base.Cancel(self);
+			else
+				NextActivity = null;
+		}
+
+		ReserveStatus TryReserveElseTryAlternateReserve(Actor self)
+		{
+			for (var tries = 0;;) 
+				switch (Reserve(self))
+				{
+					case ReserveStatus.None:
+						if (++tries > maxTries || !TryGetAlternateTarget(self, tries, ref target))
+							return ReserveStatus.None;
+						continue;
+					case ReserveStatus.TooFar:
+						// Always goto to transport on first approach
+						if (firstApproach)
+						{
+							firstApproach = false;
+							return ReserveStatus.TooFar;
+						}
+
+						if (++tries > maxTries)
+							return ReserveStatus.TooFar;
+						Target t = target;
+						if (!TryGetAlternateTarget(self, tries, ref t))
+							return ReserveStatus.TooFar;
+						if ((target.CenterPosition - self.CenterPosition).HorizontalLengthSquared <= (t.CenterPosition - self.CenterPosition).HorizontalLengthSquared)
+							return ReserveStatus.TooFar;
+						target = t;
+						continue;
+					case ReserveStatus.Pending:
+						return ReserveStatus.Pending;
+					case ReserveStatus.Ready:
+						return ReserveStatus.Ready;
+				}
+		}
+
+		State FindAndTransitionToNextState(Actor self)
+		{
+			switch (nextState)
+			{
+				case State.ApproachingOrEntering:
+
+					// Reserve to enter or approach
+					isEnteringOrInside = false;
+					switch (TryReserveElseTryAlternateReserve(self))
+					{
+						case ReserveStatus.None:
+							return State.Done; // No available target -> abort to next activity
+						case ReserveStatus.TooFar:
+							inner = move.MoveToTarget(self, Target.FromPos(target.CenterPosition)); // Approach
+							return State.ApproachingOrEntering;
+						case ReserveStatus.Pending:
+							return State.ApproachingOrEntering; // Retry next tick
+						case ReserveStatus.Ready:
+							break; // Reserved target -> start entering target
+					}
+
+					// Entering
+					isEnteringOrInside = true;
+					savedPos = self.CenterPosition; // Save position of self, before entering, for returning on exit
+					inner = move.MoveIntoTarget(self, target); // Enter
+
+					if (inner != null)
+					{
+						nextState = State.Inside; // Should be inside once inner activity is null
+						return State.ApproachingOrEntering;
+					}
+
+					// Can enter but there is no activity for it, so go inside without one
+					goto case State.Inside;
+
+				case State.Inside:
+					// Might as well teleport into target if there is no MoveIntoTarget activity
+					if (nextState == State.ApproachingOrEntering)
+						nextState = State.Inside;
+
+					// Otherwise, try to recover from moving target
+					else if (target.CenterPosition != self.CenterPosition)
+					{
+						nextState = State.ApproachingOrEntering;
+						Unreserve(self, false);
+						if (Reserve(self) == ReserveStatus.Ready)
+						{
+							inner = move.MoveIntoTarget(self, target); // Enter
+							if (inner != null)
+								return State.ApproachingOrEntering;
+
+							nextState = State.ApproachingOrEntering;
+							goto case State.ApproachingOrEntering;
+						}
+
+						nextState = State.ApproachingOrEntering;
+						isEnteringOrInside = false;
+						inner = move.MoveIntoWorld(self, self.World.Map.CellContaining(savedPos));
+
+						return State.ApproachingOrEntering;
+					}
+
+					OnInside(self);
+
+					// Return if Abort(Actor) or Done(self) was called from OnInside.
+					if (nextState >= State.Exiting)
+						return State.Inside;
+
+					inner = this; // Start inside activity
+					nextState = State.Exiting; // Exit once inner activity is null (unless Done(self) is called)
+					return State.Inside;
+
+				// TODO: Handle target moved while inside or always call done for movable targets and use a separate exit activity
+				case State.Exiting:
+					inner = move.MoveIntoWorld(self, self.World.Map.CellContaining(savedPos));
+
+					// If not successfully exiting, retry on next tick
+					if (inner == null)
+						return State.Exiting;
+					isEnteringOrInside = false;
+					nextState = State.Done;
+					return State.Exiting;
+
+				case State.Done:
+					return State.Done;
+			}
+
+			return State.Done; // dummy to quiet dumb compiler
+		}
+
+		Activity CanceledTick(Actor self)
+		{
+			if (inner == null)
+				return Util.RunActivity(self, NextActivity);
+			inner.Cancel(self);
+			inner.Queue(NextActivity);
+			return Util.RunActivity(self, inner);
 		}
 
 		public override Activity Tick(Actor self)
 		{
-			if (IsCanceled || !target.IsValidFor(self))
+			if (IsCanceled)
-				return NextActivity;
+				return CanceledTick(self);
 
-			if (target.Type != TargetType.Actor)
+			// Check target validity if not exiting or done
-				return NextActivity;
+			if (nextState != State.Done && (target.Type != TargetType.Actor || !target.IsValidFor(self)))
+					AbortOrExit(self);
 
-			if (!Util.AdjacentCells(self.World, target).Any(c => c == self.Location))
+			// If no current activity, tick next activity
-				return Util.SequenceActivities(new MoveAdjacentTo(self, target), this);
+			if (inner == null && FindAndTransitionToNextState(self) == State.Done)
+				return CanceledTick(self);
 
-			// Move to the middle of the target, ignoring impassable tiles
+			// Run inner activity/InsideTick
-			var move = self.Trait<IMove>();
+			inner = inner == this ? InsideTick(self) : Util.RunActivity(self, inner);
-			return Util.SequenceActivities(
+			return this;
-				move.VisualMove(self, self.CenterPosition, target.CenterPosition),
-				inner,
-				move.VisualMove(self, target.CenterPosition, self.CenterPosition),
-				NextActivity
-			);
 		}
 	}
 }

OpenRA.Mods.RA/Activities/EnterTransport.cs

@@ -8,39 +8,42 @@
  */
 #endregion
 
+using System;
 using System.Linq;
 using OpenRA.Traits;
 
 namespace OpenRA.Mods.RA.Activities
 {
-	class EnterTransport : Activity
+	class EnterTransport : Enter
 	{
 		readonly Actor transport;
-		readonly Cargo cargo;
+		readonly Passenger passenger;
+		readonly int maxTries;
+		Cargo cargo;
 
-		public EnterTransport(Actor self, Actor transport)
+		public EnterTransport(Actor self, Actor transport, int maxTries = 0)
+			: base(self, transport, maxTries)
 		{
 			this.transport = transport;
+			this.maxTries = maxTries;
 			cargo = transport.Trait<Cargo>();
+			passenger = self.Trait<Passenger>();
 		}
 
-		public override Activity Tick(Actor self)
+		protected override void Unreserve(Actor self, bool abort) { passenger.Unreserve(self); }
+		protected override bool CanReserve(Actor self) { return cargo.Unloading || cargo.CanLoad(transport, self); }
+		protected override ReserveStatus Reserve(Actor self)
 		{
-			if (IsCanceled)
+			var status = base.Reserve(self);
-				return NextActivity;
+			if (status != ReserveStatus.Ready)
-
+				return status;
-			if (transport == null || !transport.IsInWorld)
+			if (passenger.Reserve(self, cargo))
-				return NextActivity;
+				return ReserveStatus.Ready;
-
+			return ReserveStatus.Pending;
-			if (!cargo.CanLoad(transport, self))
+		}
-				return NextActivity;
-
-			// TODO: Queue a move order to the transport? need to be
-			// careful about units that can't path to the transport
-			var cells = Util.AdjacentCells(self.World, Target.FromActor(transport));
-			if (!cells.Contains(self.Location))
-				return NextActivity;
 
+		protected override void OnInside(Actor self)
+		{
 			self.World.AddFrameEndTask(w => 
 			{
 				if (self.IsDead() || transport.IsDead() || !cargo.CanLoad(transport, self))
@@ -50,7 +53,19 @@ namespace OpenRA.Mods.RA.Activities
 				w.Remove(self);
 			});
 
-			return this;
+			Done(self);
+		}
+
+		protected override bool TryGetAlternateTarget(Actor self, int tries, ref Target target)
+		{
+			if (tries > maxTries)
+				return false;
+			var type = target.Actor.Info.Name;
+			return TryGetAlternateTargetInCircle(
+				self, passenger.Info.AlternateTransportScanRange,
+				t => cargo = t.Actor.Trait<Cargo>(), // update cargo
+				a => { var c = a.TraitOrDefault<Cargo>(); return c != null && (c.Unloading || c.CanLoad(a, self)); },
+				new Func<Actor, bool>[] { a => a.Info.Name == type }); // Prefer transports of the same type
 		}
 	}
 }

OpenRA.Mods.RA/Activities/FindResources.cs

@@ -153,7 +153,7 @@ namespace OpenRA.Mods.RA.Activities
 				var facing = self.Trait<IFacing>().Facing;
 				var desired = Util.QuantizeFacing(facing, harvInfo.HarvestFacings) * (256 / harvInfo.HarvestFacings);
 				if (desired != facing)
-					return Util.SequenceActivities(new Turn(desired), this);
+					return Util.SequenceActivities(new Turn(self, desired), this);
 			}
 
 			var resLayer = self.World.WorldActor.Trait<ResourceLayer>();

OpenRA.Mods.RA/Activities/RAHarvesterDockSequence.cs

@@ -43,7 +43,7 @@ namespace OpenRA.Mods.RA
 					return this;
 				case State.Turn:
 					state = State.Dock;
-					return Util.SequenceActivities(new Turn(angle), this);
+					return Util.SequenceActivities(new Turn(self, angle), this);
 				case State.Dock:
 					ru.PlayCustomAnimation(self, "dock", () => {
 						ru.PlayCustomAnimRepeating(self, "dock-loop");

OpenRA.Mods.RA/Activities/Turn.cs

@@ -8,22 +8,30 @@
  */
 #endregion
 
+using System.Collections.Generic;
+using System.Linq;
 using OpenRA.Traits;
 
 namespace OpenRA.Mods.RA.Activities
 {
 	public class Turn : Activity
 	{
-		int desiredFacing;
+		readonly IEnumerable<IDisableMove> moveDisablers;
+		readonly int desiredFacing;
 
-		public Turn( int desiredFacing )
+		public Turn(Actor self, int desiredFacing)
 		{
+			moveDisablers = self.TraitsImplementing<IDisableMove>();
 			this.desiredFacing = desiredFacing;
 		}
 
 		public override Activity Tick( Actor self )
 		{
-			if (IsCanceled) return NextActivity;
+			if (IsCanceled)
+				return NextActivity;
+			if (moveDisablers.Any(d => d.MoveDisabled(self)))
+				return this;
+
 			var facing = self.Trait<IFacing>();
 
 			if( desiredFacing == facing.Facing )

OpenRA.Mods.RA/Activities/UnloadCargo.cs

@@ -54,6 +54,7 @@ namespace OpenRA.Mods.RA.Activities
 
 		public override Activity Tick(Actor self)
 		{
+			cargo.Unloading = false;
 			if (IsCanceled || cargo.IsEmpty(self))
 				return NextActivity;
 
@@ -93,6 +94,7 @@ namespace OpenRA.Mods.RA.Activities
 			if (!unloadAll || cargo.IsEmpty(self))
 				return NextActivity;
 
+			cargo.Unloading = true;
 			return this;
 		}
 	}

OpenRA.Mods.RA/Air/Aircraft.cs

@@ -135,7 +135,7 @@ namespace OpenRA.Mods.RA.Air
 			if (afld == null)
 				return;
 
-			var res = afld.Trait<Reservable>();
+			var res = afld.TraitOrDefault<Reservable>();
 
 			if (res != null)
 			{
@@ -204,6 +204,18 @@ namespace OpenRA.Mods.RA.Air
 		public SubCell GetAvailableSubCell(CPos a, SubCell preferredSubCell = SubCell.Any, Actor ignoreActor = null, bool checkTransientActors = true) { return SubCell.Invalid; } // Does not use any subcell
 		public bool CanEnterCell(CPos cell, Actor ignoreActor = null, bool checkTransientActors = true) { return true; }
 
+		public bool CanEnterTargetNow(Actor self, Target target)
+		{
+			if (target.Positions.Any(p => self.World.ActorMap.GetUnitsAt(self.World.Map.CellContaining(p)).Any(a => a != self && a != target.Actor)))
+				return false;
+			var res = target.Actor.TraitOrDefault<Reservable>();
+			if (res == null)
+				return true;
+			UnReserve();
+			Reservation = res.Reserve(target.Actor, self, this);
+			return true;
+		}
+
 		public int MovementSpeed
 		{
 			get

OpenRA.Mods.RA/Air/HeliReturn.cs

@@ -40,7 +40,7 @@ namespace OpenRA.Mods.RA.Air
 									.ClosestTo(self);
 
 				if (nearestHpad == null)
-					return Util.SequenceActivities(new Turn(initialFacing), new HeliLand(true), NextActivity);
+					return Util.SequenceActivities(new Turn(self, initialFacing), new HeliLand(true), NextActivity);
 				else
 					return Util.SequenceActivities(new HeliFly(self, Target.FromActor(nearestHpad)));
 			}
@@ -58,7 +58,7 @@ namespace OpenRA.Mods.RA.Air
 
 			return Util.SequenceActivities(
 				new HeliFly(self, Target.FromPos(dest.CenterPosition + offset)),
-				new Turn(initialFacing),
+				new Turn(self, initialFacing),
 				new HeliLand(false),
 				new ResupplyAircraft());
 		}

OpenRA.Mods.RA/Air/Helicopter.cs

@@ -8,6 +8,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
@@ -70,7 +71,7 @@ namespace OpenRA.Mods.RA.Air
 				if (Info.LandWhenIdle)
 				{
 					if (Info.TurnToLand)
-						self.QueueActivity(new Turn(Info.InitialFacing));
+						self.QueueActivity(new Turn(self, Info.InitialFacing));
 
 					self.QueueActivity(new HeliLand(true));
 				}
@@ -96,7 +97,7 @@ namespace OpenRA.Mods.RA.Air
 
 					self.CancelActivity();
 					self.QueueActivity(new HeliFly(self, Target.FromPos(order.TargetActor.CenterPosition + offset)));
-					self.QueueActivity(new Turn(Info.InitialFacing));
+					self.QueueActivity(new Turn(self, Info.InitialFacing));
 					self.QueueActivity(new HeliLand(false));
 					self.QueueActivity(new ResupplyAircraft());
 					self.QueueActivity(new TakeOff());
@@ -116,7 +117,7 @@ namespace OpenRA.Mods.RA.Air
 				if (Info.LandWhenIdle)
 				{
 					if (Info.TurnToLand)
-						self.QueueActivity(new Turn(Info.InitialFacing));
+						self.QueueActivity(new Turn(self, Info.InitialFacing));
 
 					self.QueueActivity(new HeliLand(true));
 				}
@@ -153,6 +154,12 @@ namespace OpenRA.Mods.RA.Air
 			return new HeliFly(self, Target.FromCell(self.World, cell, subCell));
 		}
 
+		public Activity MoveIntoTarget(Actor self, Target target) { return new HeliLand(false); }
+		public Activity MoveToTarget(Actor self, Target target)
+		{
+			return Util.SequenceActivities(new HeliFly(self, target), new Turn(self, Info.InitialFacing));
+		}
+
 		public Activity VisualMove(Actor self, WPos fromPos, WPos toPos)
 		{
 			// TODO: Ignore repulsion when moving

OpenRA.Mods.RA/Air/Plane.cs

@@ -8,6 +8,7 @@
  */
 #endregion
 
+using System;
 using System.Drawing;
 using OpenRA.Mods.RA.Activities;
 using OpenRA.Traits;
@@ -129,5 +130,7 @@ namespace OpenRA.Mods.RA.Air
 
 		public Activity MoveIntoWorld(Actor self, CPos cell, SubCell subCell = SubCell.Any) { return new Fly(self, Target.FromCell(self.World, cell)); }
 		public Activity VisualMove(Actor self, WPos fromPos, WPos toPos) { return Util.SequenceActivities(new CallFunc(() => SetVisualPosition(self, fromPos)), new Fly(self, Target.FromPos(toPos))); }
+		public Activity MoveToTarget(Actor self, Target target)	{ return new Fly(self, target, WRange.FromCells(3), WRange.FromCells(5)); }
+		public Activity MoveIntoTarget(Actor self, Target target) { return new Land(target); }
 	}
 }

OpenRA.Mods.RA/C4Demolition.cs

@@ -76,7 +76,7 @@ namespace OpenRA.Mods.RA
 				self.CancelActivity();
 
 			self.SetTargetLine(target, Color.Red);
-			self.QueueActivity(new Enter(target.Actor, new Demolish(
+			self.QueueActivity(new Enter(self, target.Actor, new Demolish(
 				target.Actor, info.C4Delay, info.Flashes, info.FlashesDelay, info.FlashInterval, info.FlashDuration)));
 		}
 

OpenRA.Mods.RA/Captures.cs

@@ -75,7 +75,7 @@ namespace OpenRA.Mods.RA
 				self.CancelActivity();
 
 			self.SetTargetLine(target, Color.Red);
-			self.QueueActivity(new Enter(target.Actor, new CaptureActor(target)));
+			self.QueueActivity(new Enter(self, target.Actor, new CaptureActor(target)));
 		}
 
 		class CaptureOrderTargeter : UnitOrderTargeter

OpenRA.Mods.RA/Cargo.cs

@@ -29,13 +29,16 @@ namespace OpenRA.Mods.RA
 		public object Create(ActorInitializer init) { return new Cargo(init, this); }
 	}
 
-	public class Cargo : IPips, IIssueOrder, IResolveOrder, IOrderVoice, INotifyKilled, INotifyCapture, ITick, INotifySold
+	public class Cargo : IPips, IIssueOrder, IResolveOrder, IOrderVoice, INotifyKilled, INotifyCapture, ITick, INotifySold, IDisableMove
 	{
-		readonly Actor self;
 		public readonly CargoInfo Info;
+		readonly Actor self;
 
+		public bool Unloading { get; internal set; }
 		int totalWeight = 0;
+		int reservedWeight = 0;
 		List<Actor> cargo = new List<Actor>();
+		HashSet<Actor> reserves = new HashSet<Actor>();
 		public IEnumerable<Actor> Passengers { get { return cargo; } }
 
 		CPos currentCell;
@@ -45,6 +48,7 @@ namespace OpenRA.Mods.RA
 		{
 			self = init.self;
 			Info = info;
+			Unloading = false;
 
 			if (init.Contains<RuntimeCargoInit>())
 			{
@@ -97,6 +101,7 @@ namespace OpenRA.Mods.RA
 				if (!CanUnload())
 					return;
 
+				Unloading = true;
 				self.CancelActivity();
 				self.QueueActivity(new UnloadCargo(self, true));
 			}
@@ -115,7 +120,27 @@ namespace OpenRA.Mods.RA
 
 		public bool CanLoad(Actor self, Actor a)
 		{
-			return HasSpace(GetWeight(a)) && self.CenterPosition.Z == 0;
+			return (reserves.Contains(a) || HasSpace(GetWeight(a))) && self.CenterPosition.Z == 0;
+		}
+
+		internal bool ReserveSpace(Actor a)
+		{
+			if (reserves.Contains(a))
+				return true;
+			var w = GetWeight(a);
+			if (!HasSpace(w))
+				return false;
+			reserves.Add(a);
+			reservedWeight += w;
+			return true;
+		}
+
+		internal void UnreserveSpace(Actor a)
+		{
+			if (!reserves.Contains(a))
+				return;
+			reservedWeight -= GetWeight(a);
+			reserves.Remove(a);
 		}
 
 		public string CursorForOrder(Actor self, Order order)
@@ -130,7 +155,8 @@ namespace OpenRA.Mods.RA
 			return self.HasVoice("Unload") ? "Unload" : "Move";
 		}
 
-		public bool HasSpace(int weight) { return totalWeight + weight <= Info.MaxWeight; }
+		public bool MoveDisabled(Actor self) { return reserves.Any(); }
+		public bool HasSpace(int weight) { return totalWeight + reservedWeight + weight <= Info.MaxWeight; }
 		public bool IsEmpty(Actor self) { return cargo.Count == 0; }
 
 		public Actor Peek(Actor self) { return cargo[0]; }
@@ -177,7 +203,13 @@ namespace OpenRA.Mods.RA
 		public void Load(Actor self, Actor a)
 		{
 			cargo.Add(a);
-			totalWeight += GetWeight(a);
+			var w = GetWeight(a);
+			totalWeight += w;
+			if (reserves.Contains(a))
+			{
+				reservedWeight -= w;
+				reserves.Remove(a);
+			}
 
 			foreach (var npe in self.TraitsImplementing<INotifyPassengerEntered>())
 				npe.PassengerEntered(self, a);

OpenRA.Mods.RA/EngineerRepair.cs

@@ -78,7 +78,7 @@ namespace OpenRA.Mods.RA
 				self.CancelActivity();
 
 			self.SetTargetLine(target, Color.Yellow);
-			self.QueueActivity(new Enter(target.Actor, new RepairBuilding(target.Actor)));
+			self.QueueActivity(new Enter(self, target.Actor, new RepairBuilding(target.Actor)));
 		}
 
 		class EngineerRepairOrderTargeter : UnitOrderTargeter

OpenRA.Mods.RA/Husk.cs

@@ -49,7 +49,7 @@ namespace OpenRA.Mods.RA
 			var finalPos = init.world.Map.CenterOfCell(TopLeft);
 			var distance = (finalPos - CenterPosition).Length;
 			if (speed > 0 && distance > 0)
-				self.QueueActivity(new Drag(CenterPosition, finalPos, distance / speed));
+				self.QueueActivity(new Drag(init.self, CenterPosition, finalPos, distance / speed));
 		}
 
 		public IEnumerable<Pair<CPos, SubCell>> OccupiedCells() { yield return Pair.New(TopLeft, SubCell.FullCell); }

OpenRA.Mods.RA/Infiltration/Infiltrates.cs

@@ -96,7 +96,7 @@ namespace OpenRA.Mods.RA.Infiltration
 				self.CancelActivity();
 
 			self.SetTargetLine(target, Color.Red);
-			self.QueueActivity(new Enter(target.Actor, new Infiltrate(target.Actor)));
+			self.QueueActivity(new Enter(self, target.Actor, new Infiltrate(target.Actor)));
 		}
 	}
 }

OpenRA.Mods.RA/Move/Drag.cs

@@ -9,18 +9,25 @@
 #endregion
 
 using System.Collections.Generic;
+using System.Linq;
 using OpenRA.Traits;
 
 namespace OpenRA.Mods.RA.Move
 {
 	public class Drag : Activity
 	{
+		readonly IPositionable positionable;
+		readonly IMove movement;
+		readonly IEnumerable<IDisableMove> moveDisablers;
 		WPos start, end;
 		int length;
 		int ticks = 0;
 
-		public Drag(WPos start, WPos end, int length)
+		public Drag(Actor self, WPos start, WPos end, int length)
 		{
+			positionable = self.Trait<IPositionable>();
+			movement = self.TraitOrDefault<IMove>();
+			moveDisablers = self.TraitsImplementing<IDisableMove>();
 			this.start = start;
 			this.end = end;
 			this.length = length;
@@ -28,8 +35,8 @@ namespace OpenRA.Mods.RA.Move
 
 		public override Activity Tick(Actor self)
 		{
-			var positionable = self.Trait<IPositionable>();
+			if (moveDisablers.Any(d => d.MoveDisabled(self)))
-			var movement = self.TraitOrDefault<IMove>();
+				return this;
 
 			var pos = length > 1
 				? WPos.Lerp(start, end, ticks, length - 1)

OpenRA.Mods.RA/Move/Mobile.cs

@@ -660,22 +660,42 @@ namespace OpenRA.Mods.RA.Move
 			SetPosition(self, cell, subCell);
 			SetVisualPosition(self, pos);
 
-			// Animate transition
+			return VisualMove(self, pos, self.World.Map.CenterOfSubCell(cell, subCell), cell);
-			var to = self.World.Map.CenterOfSubCell(cell, subCell);
+		}
-			var speed = MovementSpeedForCell(self, cell);
-			var length = speed > 0 ? (to - pos).Length / speed : 0;
 
-			var facing = Util.GetFacing(to - pos, Facing);
+		public Activity MoveToTarget(Actor self, Target target)
-			return Util.SequenceActivities(new Turn(facing), new Drag(pos, to, length));
+		{
+			if (target.Type == TargetType.Invalid)
+				return null;
+
+			return new MoveAdjacentTo(self, target);
+		}
+
+		public Activity MoveIntoTarget(Actor self, Target target)
+		{
+			if (target.Type == TargetType.Invalid)
+				return null;
+
+			return VisualMove(self, self.CenterPosition, target.CenterPosition);
+		}
+
+		public bool CanEnterTargetNow(Actor self, Target target)
+		{
+			return self.Location == self.World.Map.CellContaining(target.CenterPosition) || Util.AdjacentCells(self.World, target).Any(c => c == self.Location);
 		}
 
 		public Activity VisualMove(Actor self, WPos fromPos, WPos toPos)
 		{
-			var speed = MovementSpeedForCell(self, self.Location);
+			return VisualMove(self, fromPos, toPos, self.Location);
+		}
+
+		public Activity VisualMove(Actor self, WPos fromPos, WPos toPos, CPos cell)
+		{
+			var speed = MovementSpeedForCell(self, cell);
 			var length = speed > 0 ? (toPos - fromPos).Length / speed : 0;
 
 			var facing = Util.GetFacing(toPos - fromPos, Facing);
-			return Util.SequenceActivities(new Turn(facing), new Drag(fromPos, toPos, length));
+			return Util.SequenceActivities(new Turn(self, facing), new Drag(self, fromPos, toPos, length));
 		}
 	}
 }

OpenRA.Mods.RA/Move/Move.cs

@@ -151,7 +151,7 @@ namespace OpenRA.Mods.RA.Move
 			if (firstFacing != mobile.Facing)
 			{
 				path.Add(nextCell.Value.First);
-				return Util.SequenceActivities(new Turn(firstFacing), this);
+				return Util.SequenceActivities(new Turn(self, firstFacing), this);
 			}
 			else
 			{

OpenRA.Mods.RA/Passenger.cs

@@ -8,6 +8,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
@@ -17,34 +18,113 @@ using OpenRA.Traits;
 
 namespace OpenRA.Mods.RA
 {
+	public enum AlternateTransportsMode { None, Force, Default, Always }
+
+	public class EnterTransportTargeter : EnterAlliedActorTargeter<Cargo>
+	{
+		readonly AlternateTransportsMode mode;
+
+		public EnterTransportTargeter(string order, int priority,
+			Func<Actor, bool> canTarget, Func<Actor, bool> useEnterCursor,
+			AlternateTransportsMode mode)
+			: base (order, priority, canTarget, useEnterCursor) { this.mode = mode; }
+
+		public override bool CanTargetActor(Actor self, Actor target, TargetModifiers modifiers, ref string cursor)
+		{
+			switch (mode)
+			{
+				case AlternateTransportsMode.None:
+					break;
+				case AlternateTransportsMode.Force:
+					if (modifiers.HasModifier(TargetModifiers.ForceMove))
+						return false;
+					break;
+				case AlternateTransportsMode.Default:
+					if (!modifiers.HasModifier(TargetModifiers.ForceMove))
+						return false;
+					break;
+				case AlternateTransportsMode.Always:
+					return false;
+			}
+
+			return base.CanTargetActor(self, target, modifiers, ref cursor);
+		}
+	}
+
+	public class EnterTransportsTargeter : EnterAlliedActorTargeter<Cargo>
+	{
+		readonly AlternateTransportsMode mode;
+
+		public EnterTransportsTargeter(string order, int priority,
+			Func<Actor, bool> canTarget, Func<Actor, bool> useEnterCursor,
+			AlternateTransportsMode mode)
+			: base (order, priority, canTarget, useEnterCursor) { this.mode = mode; }
+
+		public override bool CanTargetActor(Actor self, Actor target, TargetModifiers modifiers, ref string cursor)
+		{
+			switch (mode)
+			{
+				case AlternateTransportsMode.None:
+					return false;
+				case AlternateTransportsMode.Force:
+					if (!modifiers.HasModifier(TargetModifiers.ForceMove))
+						return false;
+					break;
+				case AlternateTransportsMode.Default:
+					if (modifiers.HasModifier(TargetModifiers.ForceMove))
+						return false;
+					break;
+				case AlternateTransportsMode.Always:
+					break;
+			}
+			return base.CanTargetActor(self, target, modifiers, ref cursor);
+		}
+	}
+
 	[Desc("This actor can enter Cargo actors.")]
 	public class PassengerInfo : ITraitInfo
 	{
 		public readonly string CargoType = null;
 		public readonly PipType PipType = PipType.Green;
-		public int Weight = 1;
+		public readonly int Weight = 1;
+
+		[Desc("Use to set when to use alternate transports (Never, Force, Default, Always).",
+			"Force - use force move modifier (Alt) to enable.",
+			"Default - use force move modifier (Alt) to disable.")]
+		public readonly AlternateTransportsMode AlternateTransportsMode = AlternateTransportsMode.Force;
+
+		[Desc("Number of retries using alternate transports.")]
+		public readonly int MaxAlternateTransportAttempts = 1;
+
+		[Desc("Range from self for looking for an alternate transport (default: 5.5 cells).")]
+		public readonly WRange AlternateTransportScanRange = WRange.FromCells(11) / 2;
 
 		public object Create(ActorInitializer init) { return new Passenger(this); }
 	}
 
-	public class Passenger : IIssueOrder, IResolveOrder, IOrderVoice
+	public class Passenger : IIssueOrder, IResolveOrder, IOrderVoice, INotifyRemovedFromWorld
 	{
-		public readonly PassengerInfo info;
+		public readonly PassengerInfo Info;
-		public Passenger(PassengerInfo info) { this.info = info; }
+		public Passenger(PassengerInfo info) { Info = info; }
 		public Actor Transport;
+		public Cargo ReservedCargo { get; private set; }
 
 		public IEnumerable<IOrderTargeter> Orders
 		{
 			get
 			{
-				yield return new EnterAlliedActorTargeter<Cargo>("EnterTransport", 6,
+				yield return new EnterTransportTargeter("EnterTransport", 6,
-					target => IsCorrectCargoType(target), target => CanEnter(target));
+					target => IsCorrectCargoType(target), target => CanEnter(target),
+					Info.AlternateTransportsMode);
+				yield return new EnterTransportsTargeter("EnterTransports", 6,
+					target => IsCorrectCargoType(target), target => CanEnter(target),
+					Info.AlternateTransportsMode);
 			}
 		}
 
 		public Order IssueOrder(Actor self, IOrderTargeter order, Target target, bool queued)
 		{
-			if (order.OrderID == "EnterTransport")
+			if (order.OrderID == "EnterTransport" || order.OrderID == "EnterTransports")
 				return new Order(order.OrderID, self, queued) { TargetActor = target.Actor };
 
 			return null;
@@ -53,25 +133,29 @@ namespace OpenRA.Mods.RA
 		bool IsCorrectCargoType(Actor target)
 		{
 			var ci = target.Info.Traits.Get<CargoInfo>();
-			return ci.Types.Contains(info.CargoType);
+			return ci.Types.Contains(Info.CargoType);
+		}
+
+		bool CanEnter(Cargo cargo)
+		{
+			return cargo != null && cargo.HasSpace(Info.Weight);
 		}
 
 		bool CanEnter(Actor target)
 		{
-			var cargo = target.TraitOrDefault<Cargo>();
+			return CanEnter(target.TraitOrDefault<Cargo>());
-			return cargo != null && cargo.HasSpace(info.Weight);
 		}
 
 		public string VoicePhraseForOrder(Actor self, Order order)
 		{
-			if (order.OrderString != "EnterTransport" ||
+			if ((order.OrderString != "EnterTransport" && order.OrderString != "EnterTransports") ||
 				!CanEnter(order.TargetActor)) return null;
 			return "Move";
 		}
 
 		public void ResolveOrder(Actor self, Order order)
 		{
-			if (order.OrderString == "EnterTransport")
+			if (order.OrderString == "EnterTransport" || order.OrderString == "EnterTransports")
 			{
 				if (order.TargetActor == null) return;
 				if (!CanEnter(order.TargetActor)) return;
@@ -81,9 +165,26 @@ namespace OpenRA.Mods.RA
 				self.SetTargetLine(target, Color.Green);
 
 				self.CancelActivity();
-				self.QueueActivity(new MoveAdjacentTo(self, target));
+				self.QueueActivity(new EnterTransport(self, order.TargetActor, order.OrderString == "EnterTransport" ? 0 : Info.MaxAlternateTransportAttempts));
-				self.QueueActivity(new EnterTransport(self, order.TargetActor));
 			}
 		}
+
+		public bool Reserve(Actor self, Cargo cargo)
+		{
+			Unreserve(self);
+			if (!cargo.ReserveSpace(self))
+				return false;
+			ReservedCargo = cargo;
+			return true;
+		}
+
+		public void RemovedFromWorld(Actor self) { Unreserve(self); }
+		public void Unreserve(Actor self)
+		{
+			if (ReservedCargo == null)
+				return;
+			ReservedCargo.UnreserveSpace(self);
+			ReservedCargo = null;
+		}
 	}
 }

OpenRA.Mods.RA/RepairsBridges.cs

@@ -59,7 +59,7 @@ namespace OpenRA.Mods.RA
 				self.SetTargetLine(Target.FromOrder(self.World, order), Color.Yellow);
 
 				self.CancelActivity();
-				self.QueueActivity(new Enter(order.TargetActor, new RepairBridge(order.TargetActor)));
+				self.QueueActivity(new Enter(self, order.TargetActor, new RepairBridge(order.TargetActor)));
 			}
 		}
 

OpenRA.Mods.RA/Scripting/Global/ReinforcementsGlobal.cs

@@ -177,7 +177,7 @@ namespace OpenRA.Mods.RA.Scripting
 				var heli = transport.TraitOrDefault<Helicopter>();
 				if (heli != null)
 				{
-					transport.QueueActivity(new Turn(heli.Info.InitialFacing));
+					transport.QueueActivity(new Turn(transport, heli.Info.InitialFacing));
 					transport.QueueActivity(new HeliLand(true));
 					transport.QueueActivity(new Wait(15));
 				}

OpenRA.Mods.RA/SupplyTruck.cs

@@ -67,7 +67,7 @@ namespace OpenRA.Mods.RA
 				self.CancelActivity();
 
 			self.SetTargetLine(target, Color.Yellow);
-			self.QueueActivity(new Enter(target.Actor, new DonateSupplies(target.Actor, info.Payload)));
+			self.QueueActivity(new Enter(self, target.Actor, new DonateSupplies(target.Actor, info.Payload)));
 		}
 
 		class SupplyTruckOrderTargeter : UnitOrderTargeter

OpenRA.Mods.RA/Transforms.cs

@@ -87,7 +87,7 @@ namespace OpenRA.Mods.RA
 				self.CancelActivity();
 
 			if (self.HasTrait<IFacing>())
-				self.QueueActivity(new Turn(info.Facing));
+				self.QueueActivity(new Turn(self, info.Facing));
 
 			foreach (var nt in self.TraitsImplementing<INotifyTransform>())
 				nt.BeforeTransform(self);

OpenRA.Mods.TS/Activities/VoxelHarvesterDockSequence.cs

@@ -41,7 +41,7 @@ namespace OpenRA.Mods.TS
 			{
 				case State.Turn:
 					state = State.Dock;
-					return Util.SequenceActivities(new Turn(160), this);
+					return Util.SequenceActivities(new Turn(self, 160), this);
 				case State.Dock:
 					if (proc.IsInWorld && !proc.IsDead())
 						foreach (var nd in proc.TraitsImplementing<INotifyDocking>())