Rework paradrop logic to be more robust.

OpenRA.Mods.Common/Activities/Parachute.cs

@@ -18,72 +18,45 @@ namespace OpenRA.Mods.Common.Activities
 	public class Parachute : Activity
 	{
 		readonly IPositionable pos;
-		readonly ParachutableInfo para;
 		readonly WVec fallVector;
 		readonly Actor ignore;
 
-		WPos dropPosition;
+		int groundLevel;
-		WPos currentPosition;
-		bool triggered = false;
 
-		public Parachute(Actor self, WPos dropPosition, Actor ignoreActor = null)
+		public Parachute(Actor self, Actor ignoreActor = null)
 		{
 			pos = self.TraitOrDefault<IPositionable>();
 			ignore = ignoreActor;
 
-			// Parachutable trait is a prerequisite for running this activity
+			fallVector = new WVec(0, 0, self.Info.TraitInfo<ParachutableInfo>().FallRate);
-			para = self.Info.TraitInfo<ParachutableInfo>();
-			fallVector = new WVec(0, 0, para.FallRate);
-			this.dropPosition = dropPosition;
 			IsInterruptible = false;
 		}
 
-		Activity FirstTick(Actor self)
+		protected override void OnFirstRun(Actor self)
 		{
-			triggered = true;
+			groundLevel = self.World.Map.CenterOfCell(self.Location).Z;
-
 			foreach (var np in self.TraitsImplementing<INotifyParachute>())
 				np.OnParachute(self);
-
-			// Place the actor and retrieve its visual position (CenterPosition)
-			pos.SetPosition(self, dropPosition);
-			currentPosition = self.CenterPosition;
-
-			return this;
-		}
-
-		Activity LastTick(Actor self)
-		{
-			var dat = self.World.Map.DistanceAboveTerrain(currentPosition);
-			pos.SetPosition(self, currentPosition - new WVec(WDist.Zero, WDist.Zero, dat));
-
-			foreach (var np in self.TraitsImplementing<INotifyParachute>())
-				np.OnLanded(self, ignore);
-
-			return NextActivity;
 		}
 
 		public override Activity Tick(Actor self)
 		{
-			// If this is the first tick
+			var nextPosition = self.CenterPosition - fallVector;
-			if (!triggered)
+			if (nextPosition.Z < groundLevel)
-				return FirstTick(self);
+				return NextActivity;
 
-			currentPosition -= fallVector;
+			pos.SetVisualPosition(self, nextPosition);
-
-			// If the unit has landed, this will be the last tick
-			if (self.World.Map.DistanceAboveTerrain(currentPosition).Length <= 0)
-				return LastTick(self);
-
-			pos.SetVisualPosition(self, currentPosition);
 
 			return this;
 		}
 
-		// Only the last queued activity (given order) is kept
+		protected override void OnLastRun(Actor self)
-		public override void Queue(Actor self, Activity activity)
 		{
-			NextActivity = activity;
+			var centerPosition = self.CenterPosition;
+			pos.SetPosition(self, centerPosition - new WVec(0, 0, groundLevel - centerPosition.Z));
+
+			foreach (var np in self.TraitsImplementing<INotifyParachute>())
+				np.OnLanded(self, ignore);
 		}
 	}
 }

OpenRA.Mods.Common/Traits/EjectOnDeath.cs

@@ -63,32 +63,46 @@ namespace OpenRA.Mods.Common.Traits
 			var pilot = self.World.CreateActor(false, Info.PilotActor.ToLowerInvariant(),
 				new TypeDictionary { new OwnerInit(self.Owner), new LocationInit(self.Location) });
 
-			if (Info.AllowUnsuitableCell || IsSuitableCell(self, pilot))
+			var pilotPositionable = pilot.TraitOrDefault<IPositionable>();
+			var pilotCell = self.Location;
+			var pilotSubCell = pilotPositionable.GetAvailableSubCell(pilotCell);
+			if (pilotSubCell == SubCell.Invalid)
 			{
-				if (inAir)
+				if (!Info.AllowUnsuitableCell)
 				{
-					self.World.AddFrameEndTask(w =>
+					pilot.Dispose();
-					{
+					return;
-						w.Add(pilot);
-						pilot.QueueActivity(new Parachute(pilot, cp));
-					});
-					Game.Sound.Play(SoundType.World, Info.ChuteSound, cp);
 				}
-				else
+
+				pilotSubCell = SubCell.Any;
+			}
+
+			if (inAir)
+			{
+				self.World.AddFrameEndTask(w =>
 				{
-					self.World.AddFrameEndTask(w => w.Add(pilot));
+					pilotPositionable.SetPosition(pilot, pilotCell, pilotSubCell);
+					w.Add(pilot);
+
+					var dropPosition = pilot.CenterPosition + new WVec(0, 0, self.CenterPosition.Z - pilot.CenterPosition.Z);
+					pilotPositionable.SetVisualPosition(pilot, dropPosition);
+					pilot.QueueActivity(new Parachute(pilot));
+				});
+
+				Game.Sound.Play(SoundType.World, Info.ChuteSound, cp);
+			}
+			else
+			{
+				self.World.AddFrameEndTask(w =>
+				{
+					w.Add(pilot);
+					pilotPositionable.SetPosition(pilot, pilotCell, pilotSubCell);
+
 					var pilotMobile = pilot.TraitOrDefault<Mobile>();
 					if (pilotMobile != null)
 						pilotMobile.Nudge(pilot, pilot, true);
-				}
+				});
 			}
-			else
-				pilot.Dispose();
-		}
-
-		static bool IsSuitableCell(Actor self, Actor actorToDrop)
-		{
-			return actorToDrop.Trait<IPositionable>().CanEnterCell(self.Location, self, true);
 		}
 	}
 }

OpenRA.Mods.Common/Traits/ParaDrop.cs

@@ -22,6 +22,9 @@ namespace OpenRA.Mods.Common.Traits
 		[Desc("Distance around the drop-point to unload troops.")]
 		public readonly WDist DropRange = WDist.FromCells(4);
 
+		[Desc("Wait at least this many ticks between each drop.")]
+		public readonly int DropInterval = 5;
+
 		[Desc("Sound to play when dropping.")]
 		public readonly string ChuteSound = null;
 
@@ -33,7 +36,6 @@ namespace OpenRA.Mods.Common.Traits
 		readonly ParaDropInfo info;
 		readonly Actor self;
 		readonly Cargo cargo;
-		readonly HashSet<CPos> droppedAt = new HashSet<CPos>();
 
 		public event Action<Actor> OnRemovedFromWorld = self => { };
 		public event Action<Actor> OnEnteredDropRange = self => { };
@@ -45,6 +47,9 @@ namespace OpenRA.Mods.Common.Traits
 		[Sync]
 		Target target;
 
+		[Sync]
+		int dropDelay;
+
 		bool checkForSuitableCell;
 
 		public ParaDrop(Actor self, ParaDropInfo info)
@@ -56,13 +61,18 @@ namespace OpenRA.Mods.Common.Traits
 
 		public void SetLZ(CPos lz, bool checkLandingCell)
 		{
-			droppedAt.Clear();
 			target = Target.FromCell(self.World, lz);
 			checkForSuitableCell = checkLandingCell;
 		}
 
 		void ITick.Tick(Actor self)
 		{
+			if (dropDelay > 0)
+			{
+				dropDelay--;
+				return;
+			}
+
 			var wasInDropRange = inDropRange;
 			inDropRange = target.IsInRange(self.CenterPosition, info.DropRange);
 
@@ -73,30 +83,38 @@ namespace OpenRA.Mods.Common.Traits
 				OnExitedDropRange(self);
 
 			// Are we able to drop the next trooper?
-			if (!inDropRange || cargo.IsEmpty(self))
+			if (!inDropRange || cargo.IsEmpty(self) || !self.World.Map.Contains(self.Location))
 				return;
 
-			if (droppedAt.Contains(self.Location) || (checkForSuitableCell && !IsSuitableCell(cargo.Peek(self), self.Location)))
+			var dropActor = cargo.Peek(self);
-				return;
+			var dropPositionable = dropActor.Trait<IPositionable>();
+			var dropCell = self.Location;
+			var dropSubCell = dropPositionable.GetAvailableSubCell(dropCell);
+			if (dropSubCell == SubCell.Invalid)
+			{
+				if (checkForSuitableCell)
+					return;
 
-			if (!self.World.Map.Contains(self.Location))
+				dropSubCell = SubCell.Any;
-				return;
+			}
 
-			// unload a dude here
+			// Unload here
-			droppedAt.Add(self.Location);
+			if (cargo.Unload(self) != dropActor)
+				throw new InvalidOperationException("Peeked cargo was not unloaded!");
 
-			var a = cargo.Unload(self);
 			self.World.AddFrameEndTask(w =>
 			{
-				w.Add(a);
+				dropPositionable.SetPosition(dropActor, dropCell, dropSubCell);
-				a.QueueActivity(new Parachute(a, self.CenterPosition));
+				w.Add(dropActor);
-			});
-			Game.Sound.Play(SoundType.World, info.ChuteSound, self.CenterPosition);
-		}
 
-		static bool IsSuitableCell(Actor actorToDrop, CPos p)
+				var dropPosition = dropActor.CenterPosition + new WVec(0, 0, self.CenterPosition.Z - dropActor.CenterPosition.Z);
-		{
+				dropPositionable.SetVisualPosition(dropActor, dropPosition);
-			return actorToDrop.Trait<IPositionable>().CanEnterCell(p);
+
+				dropActor.QueueActivity(new Parachute(dropActor));
+			});
+
+			Game.Sound.Play(SoundType.World, info.ChuteSound, self.CenterPosition);
+			dropDelay = info.DropInterval;
 		}
 
 		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)

OpenRA.Mods.Common/Traits/ProductionParadrop.cs

@@ -135,7 +135,7 @@ namespace OpenRA.Mods.Common.Traits
 			{
 				var newUnit = self.World.CreateActor(producee.Name, td);
 
-				newUnit.QueueActivity(new Parachute(newUnit, newUnit.CenterPosition, self));
+				newUnit.QueueActivity(new Parachute(newUnit, self));
 				var move = newUnit.TraitOrDefault<IMove>();
 				if (move != null)
 				{

OpenRA.Mods.Common/Traits/SupportPowers/ParatroopersPower.cs

@@ -175,14 +175,6 @@ namespace OpenRA.Mods.Common.Traits
 				}
 			};
 
-			foreach (var p in info.DropItems)
-			{
-				var unit = self.World.CreateActor(false, p.ToLowerInvariant(),
-					new TypeDictionary { new OwnerInit(self.Owner) });
-
-				units.Add(unit);
-			}
-
 			self.World.AddFrameEndTask(w =>
 			{
 				PlayLaunchSounds();
@@ -216,11 +208,17 @@ namespace OpenRA.Mods.Common.Traits
 					drop.OnRemovedFromWorld += onRemovedFromWorld;
 
 					var cargo = a.Trait<Cargo>();
-					var passengers = units.Skip(added).Take(passengersPerPlane);
+					foreach (var p in info.DropItems.Skip(added).Take(passengersPerPlane))
-					added += passengersPerPlane;
+					{
+						var unit = self.World.CreateActor(false, p.ToLowerInvariant(), new TypeDictionary
+						{
+							new OwnerInit(self.Owner)
+						});
 
-					foreach (var p in passengers)
+						cargo.Load(a, unit);
-						cargo.Load(a, p);
+						units.Add(unit);
+						added++;
+					}
 
 					a.QueueActivity(new Fly(a, Target.FromPos(target + spawnOffset)));
 					a.QueueActivity(new Fly(a, Target.FromPos(finishEdge + spawnOffset)));