Rewrite Leap activity to be more robust.

The dog will now always leap to the target
subcell (even if the target dies or moves),
and will kill whatever happens to be in the
target cell when it lands.

OpenRA.Mods.RA/Activities/Leap.cs

@@ -8,6 +8,7 @@
  */
 #endregion
 
+using System;
 using System.Linq;
 using OpenRA.Mods.RA.Move;
 using OpenRA.Mods.RA.Render;
@@ -17,16 +18,29 @@ namespace OpenRA.Mods.RA.Activities
 {
 	class Leap : Activity
 	{
-		Target target;
-		PPos initialLocation;
+		Mobile mobile;
+
+		PPos from;
+		PPos to;
 
 		int moveFraction;
-		const int delay = 6;
+		const int length = 6;
 
 		public Leap(Actor self, Target target)
 		{
-			this.target = target;
-			initialLocation = (PPos) self.Trait<Mobile>().PxPosition;
+			if (!target.IsActor)
+				throw new InvalidOperationException("Leap requires a target actor");
+
+			var targetMobile = target.Actor.TraitOrDefault<Mobile>();
+			if (targetMobile == null)
+				throw new InvalidOperationException("Leap requires a target actor with the Mobile trait");
+
+			mobile = self.Trait<Mobile>();
+			mobile.SetLocation(mobile.fromCell, mobile.fromSubCell, targetMobile.fromCell, targetMobile.fromSubCell);
+			mobile.IsMoving = true;
+
+			from = self.CenterLocation;
+			to = Util.CenterOfCell(targetMobile.fromCell) + MobileInfo.SubCellOffsets[targetMobile.fromSubCell];
 
 			self.Trait<RenderInfantry>().Attacking(self, target);
 			Sound.Play("dogg5p.aud", self.CenterLocation);
@@ -34,23 +48,18 @@ namespace OpenRA.Mods.RA.Activities
 
 		public override Activity Tick(Actor self)
 		{
-			if( moveFraction == 0 && IsCanceled ) return NextActivity;
-			if (!target.IsValid) return NextActivity;
+			if (moveFraction == 0 && IsCanceled)
+				return NextActivity;
 
-			self.Trait<AttackLeap>().IsLeaping = true;
-			var mobile = self.Trait<Mobile>();
-			++moveFraction;
-
-			mobile.PxPosition = PPos.Lerp(initialLocation, target.PxPosition, moveFraction, delay);
-
-			if (moveFraction >= delay)
+			mobile.AdjustPxPosition(self, PPos.Lerp(from, to, moveFraction++, length - 1));
+			if (moveFraction >= length)
 			{
-				self.TraitsImplementing<IMove>().FirstOrDefault()
-					.SetPosition(self, target.CenterLocation.ToCPos());
+				mobile.SetLocation(mobile.toCell, mobile.toSubCell, mobile.toCell, mobile.toSubCell);
+				mobile.FinishedMoving(self);
+				mobile.IsMoving = false;
 
-				if (target.IsActor)
-					target.Actor.Kill(self);
-				self.Trait<AttackLeap>().IsLeaping = false;
+				// Kill whatever else is in our new cell
+				self.World.ActorMap.GetUnitsAt(mobile.toCell, mobile.toSubCell).Except(new []{self}).Do(a => a.Kill(self));
 				return NextActivity;
 			}
 

OpenRA.Mods.RA/Attack/AttackLeap.cs

@@ -22,8 +22,6 @@ namespace OpenRA.Mods.RA
 
 	class AttackLeap : AttackFrontal, ISync
 	{
-		[Sync] internal bool IsLeaping;
-
 		public AttackLeap(Actor self, AttackLeapInfo info)
 			: base(self, info) {}
 

OpenRA.Mods.RA/Move/Mobile.cs

@@ -170,7 +170,9 @@ namespace OpenRA.Mods.RA.Move
 
 		public void SetLocation(CPos from, SubCell fromSub, CPos to, SubCell toSub)
 		{
-			if (fromCell == from && toCell == to) return;
+			if (fromCell == from && toCell == to && fromSubCell == fromSub && toSubCell == toSub)
+				return;
+
 			RemoveInfluence();
 			__fromCell = from;
 			__toCell = to;