Allow turreted units to acquire targets of opportunity while moving

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

@@ -20,6 +20,9 @@ namespace OpenRA.Mods.Common.Traits
 	[Desc("Actor will follow units until in range to attack them.")]
 	public class AttackFollowInfo : AttackBaseInfo
 	{
+		[Desc("Automatically acquire and fire on targets of opportunity when not actively attacking.")]
+		public readonly bool OpportunityFire = true;
+
 		public override object Create(ActorInitializer init) { return new AttackFollow(init.Self, this); }
 	}
 
@@ -28,14 +31,18 @@ public class AttackFollow : AttackBase, INotifyOwnerChanged
 		protected Target requestedTarget;
 		protected bool requestedForceAttack;
 		protected int requestedTargetLastTick;
+		protected Target opportunityTarget;
+		protected bool opportunityForceAttack;
 		Mobile mobile;
+		AutoTarget autoTarget;
 
 		public AttackFollow(Actor self, AttackFollowInfo info)
 			: base(self, info) { }
 
 		protected override void Created(Actor self)
 		{
 			mobile = self.TraitOrDefault<Mobile>();
+			autoTarget = self.TraitOrDefault<AutoTarget>();
 			base.Created(self);
 		}
 
@@ -59,7 +66,7 @@ protected bool CanAimAtTarget(Actor self, Target target, bool forceAttack)
 		protected override void Tick(Actor self)
 		{
 			if (IsTraitDisabled)
-				requestedTarget = Target.Invalid;
+				requestedTarget = opportunityTarget = Target.Invalid;
 
 			if (requestedTargetLastTick != self.World.WorldTick)
 			{
@@ -80,8 +87,26 @@ protected override void Tick(Actor self)
 					DoAttack(self, requestedTarget);
 			}
 			else
+			{
 				IsAiming = false;
 
+				if (opportunityTarget.Type != TargetType.Invalid)
+					IsAiming = CanAimAtTarget(self, opportunityTarget, opportunityForceAttack);
+
+				if (!IsAiming && ((AttackFollowInfo)Info).OpportunityFire && autoTarget != null &&
+				    !autoTarget.IsTraitDisabled && autoTarget.Stance >= UnitStance.Defend)
+				{
+					opportunityTarget = autoTarget.ScanForTarget(self, false);
+					opportunityForceAttack = false;
+
+					if (opportunityTarget.Type != TargetType.Invalid)
+						IsAiming = CanAimAtTarget(self, opportunityTarget, opportunityForceAttack);
+				}
+
+				if (IsAiming)
+					DoAttack(self, opportunityTarget);
+			}
+
 			base.Tick(self);
 		}
 
@@ -105,18 +130,13 @@ public override void OnQueueAttackActivity(Actor self, Target target, bool queue
 
 		public override void OnStopOrder(Actor self)
 		{
-			requestedTarget = Target.Invalid;
+			requestedTarget = opportunityTarget = Target.Invalid;
 			base.OnStopOrder(self);
 		}
 
-		public bool HasReachableTarget(bool allowMove)
-		{
-			return IsReachableTarget(requestedTarget, allowMove);
-		}
-
 		void INotifyOwnerChanged.OnOwnerChanged(Actor self, Player oldOwner, Player newOwner)
 		{
-			requestedTarget = Target.Invalid;
+			requestedTarget = opportunityTarget = Target.Invalid;
 		}
 
 		class AttackActivity : Activity
@@ -157,7 +177,13 @@ public AttackActivity(Actor self, Target target, bool allowMove, bool forceAttac
 			public override Activity Tick(Actor self)
 			{
 				if (IsCanceled)
+				{
+					// Cancel the requested target, but keep firing on it while in range
+					attack.opportunityTarget = attack.requestedTarget;
+					attack.opportunityForceAttack = attack.requestedForceAttack;
+					attack.requestedTarget = Target.Invalid;
 					return NextActivity;
+				}
 
 				// Check that AttackFollow hasn't cancelled the target by modifying attack.Target
 				// Having both this and AttackFollow modify that field is a horrible hack.

OpenRA.Mods.Common/Traits/AutoTarget.cs

@@ -112,7 +112,6 @@ IEnumerable<EditorActorOption> IEditorActorOptions.ActorOptions(ActorInfo ai, Wo
 	public class AutoTarget : ConditionalTrait<AutoTargetInfo>, INotifyIdle, INotifyDamage, ITick, IResolveOrder, ISync, INotifyCreated
 	{
 		readonly IEnumerable<AttackBase> activeAttackBases;
-		readonly AttackFollow[] attackFollows;
 		[Sync] int nextScanTime = 0;
 
 		public UnitStance Stance { get { return stance; } }
@@ -161,7 +160,6 @@ public AutoTarget(ActorInitializer init, AutoTargetInfo info)
 				stance = self.Owner.IsBot || !self.Owner.Playable ? info.InitialStanceAI : info.InitialStance;
 
 			PredictedStance = stance;
-			attackFollows = self.TraitsImplementing<AttackFollow>().ToArray();
 		}
 
 		void INotifyCreated.Created(Actor self)
@@ -215,31 +213,17 @@ void INotifyDamage.Damaged(Actor self, AttackInfo e)
 
 			Aggressor = attacker;
 
-			bool allowMove;
-			if (ShouldAttack(out allowMove))
-				Attack(self, Target.FromActor(Aggressor), allowMove);
+			var allowMove = Info.AllowMovement && Stance > UnitStance.Defend;
+			Attack(self, Target.FromActor(Aggressor), allowMove);
 		}
 
 		void INotifyIdle.TickIdle(Actor self)
 		{
 			if (IsTraitDisabled || Stance < UnitStance.Defend)
 				return;
 
-			bool allowMove;
-			if (ShouldAttack(out allowMove))
-				ScanAndAttack(self, allowMove);
-		}
-
-		bool ShouldAttack(out bool allowMove)
-		{
-			allowMove = Info.AllowMovement && Stance > UnitStance.Defend;
-
-			// PERF: Avoid LINQ.
-			foreach (var attackFollow in attackFollows)
-				if (!attackFollow.IsTraitDisabled && attackFollow.HasReachableTarget(allowMove))
-					return false;
-
-			return true;
+			var allowMove = Info.AllowMovement && Stance > UnitStance.Defend;
+			ScanAndAttack(self, allowMove);
 		}
 
 		void ITick.Tick(Actor self)

mods/ts/rules/gdi-vehicles.yaml

@@ -288,6 +288,7 @@ SONIC:
 	AttackTurreted:
 		Voice: Attack
 		PauseOnCondition: empdisable
+		OpportunityFire: False
 	Turreted:
 		TurnSpeed: 5
 		Offset: -170,0,0