Add plumbing for targeting of target center instead of closest targetable position

Note: Projectiles that can track their target need minor additional changes, but for InstantHit (which already implemented support for this) and unguided projectiles (Bullet, GravityBomb) this commit is already sufficient.

OpenRA.Mods.Common/Activities/Attack.cs

@@ -114,7 +114,7 @@ namespace OpenRA.Mods.Common.Activities
 				return NextActivity;
 			}
 
-			var targetedPosition = Target.Positions.PositionClosestTo(pos);
+			var targetedPosition = attack.Info.AttackTargetCenter ? Target.CenterPosition : Target.Positions.PositionClosestTo(pos);
 			var desiredFacing = (targetedPosition - pos).Yaw.Facing;
 			if (facing.Facing != desiredFacing)
 			{

OpenRA.Mods.Common/Traits/Armament.cs

@@ -102,6 +102,8 @@ namespace OpenRA.Mods.Common.Traits
 		public readonly Barrel[] Barrels;
 
 		readonly Actor self;
+		readonly AttackBase[] attackTraits;
+		AttackBase attack;
 		Turreted turret;
 		AmmoPool ammoPool;
 		BodyOrientation coords;
@@ -134,6 +136,7 @@ namespace OpenRA.Mods.Common.Traits
 				barrels.Add(new Barrel { Offset = WVec.Zero, Yaw = WAngle.Zero });
 
 			Barrels = barrels.ToArray();
+			attackTraits = self.TraitsImplementing<AttackBase>().Where(a => a.Info.Armaments.Contains(Info.Name)).ToArray();
 		}
 
 		public virtual WDist MaxRange()
@@ -190,6 +193,10 @@ namespace OpenRA.Mods.Common.Traits
 		// The world coordinate model uses Actor.Orientation
 		public virtual Barrel CheckFire(Actor self, IFacing facing, Target target)
 		{
+			attack = attackTraits.FirstOrDefault(Exts.IsTraitEnabled);
+			if (attack == null)
+				return null;
+
 			if (IsReloading)
 				return null;
 
@@ -229,7 +236,7 @@ namespace OpenRA.Mods.Common.Traits
 				Source = muzzlePosition(),
 				CurrentSource = muzzlePosition,
 				SourceActor = self,
-				PassiveTarget = target.Positions.PositionClosestTo(muzzlePosition()),
+				PassiveTarget = attack.Info.AttackTargetCenter ? target.CenterPosition : target.Positions.PositionClosestTo(muzzlePosition()),
 				GuidedTarget = target
 			};
 

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

@@ -24,6 +24,9 @@ namespace OpenRA.Mods.Common.Traits
 		[Desc("Armament names")]
 		public readonly string[] Armaments = { "primary", "secondary" };
 
+		[Desc("Attack the target's center, instead of the closest targetable offset.")]
+		public readonly bool AttackTargetCenter = false;
+
 		public readonly string Cursor = null;
 
 		public readonly string OutsideRangeCursor = null;

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

@@ -40,7 +40,7 @@ namespace OpenRA.Mods.Common.Traits
 
 			var f = facing.Facing;
 			var pos = self.CenterPosition;
-			var targetedPosition = target.Positions.PositionClosestTo(pos);
+			var targetedPosition = Info.AttackTargetCenter ? target.CenterPosition : target.Positions.PositionClosestTo(pos);
 			var delta = targetedPosition - pos;
 			var facingToTarget = delta.HorizontalLengthSquared != 0 ? delta.Yaw.Facing : f;
 

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

@@ -146,7 +146,7 @@ namespace OpenRA.Mods.Common.Traits
 				return;
 
 			var pos = self.CenterPosition;
-			var targetedPosition = target.Positions.PositionClosestTo(pos);
+			var targetedPosition = Info.AttackTargetCenter ? target.CenterPosition : target.Positions.PositionClosestTo(pos);
 			var targetYaw = (targetedPosition - pos).Yaw;
 
 			foreach (var a in Armaments)

OpenRA.Mods.Common/Traits/Turreted.cs

@@ -131,7 +131,8 @@ namespace OpenRA.Mods.Common.Traits
 				return false;
 
 			var pos = self.CenterPosition;
-			var delta = target.Positions.PositionClosestTo(pos) - pos;
+			var targetPos = attack != null && attack.Info.AttackTargetCenter ? target.CenterPosition : target.Positions.PositionClosestTo(pos);
+			var delta = targetPos - pos;
 			DesiredFacing = delta.HorizontalLengthSquared != 0 ? delta.Yaw.Facing : TurretFacing;
 			MoveTurret();
 			return HasAchievedDesiredFacing;