Implemented: Stances

Added: Basic stances (Aggressive, Guard (Hold Ground), Hold Fire, None (dummy), Return Fire)
Added: WorldCommandWidget (to be able to set said stances)
Added: WorldCommandWidget to ra (cnc will follow, later on)
Changed: Added support to AttackBase for firing with movement disabled + utility method ScanForTarget (used by stances)
Added: AssignUnitStance (attach this to unit-producing actors, together with what stances can be picked as 'default')

OpenRA.Mods.RA/UnitStances/UnitStance.cs

@@ -0,0 +1,218 @@
+using System;
+using System.Linq;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA
+{
+	public interface IUnitStance
+	{
+		bool Active { get; set; }
+		bool IsDefault { get; }
+		void Activate(Actor self);
+		void Deactivate(Actor self);
+	}
+
+	public class UnitStanceInfo : ITraitInfo
+	{
+		public readonly bool Default;
+
+		#region ITraitInfo Members
+
+		public virtual object Create(ActorInitializer init)
+		{
+			throw new Exception("Do not use UnitStance at the rules!");
+		}
+
+		#endregion
+	}
+
+	public abstract class UnitStance : IUnitStance, ITick
+	{
+		public int NextScantime;
+		public int ScanDelay = 12; // 2x - second
+		private bool _unsetFirstTick;
+
+		public UnitStanceInfo Info { get; protected set; }
+
+		public bool IsFirstTick { get; private set; }
+
+		public bool IsScanAvailable
+		{
+			get
+			{
+				NextScantime--;
+				if (NextScantime <= 0)
+				{
+					NextScantime = ScanDelay;
+					return true;
+				}
+
+				return false;
+			}
+		}
+
+		#region ITick Members
+
+		public virtual void Tick(Actor self)
+		{
+			if (!Active) return;
+
+			if (IsFirstTick && _unsetFirstTick)
+			{
+				IsFirstTick = false;
+				_unsetFirstTick = false;
+			}
+			else if (IsFirstTick)
+			{
+				_unsetFirstTick = true;
+				OnFirstTick(self);
+			}
+
+			if (IsScanAvailable)
+			{
+				OnScan(self);
+			}
+		}
+
+		#endregion
+
+		#region IUnitStance Members
+
+		public bool Active { get; set; }
+
+		public virtual bool IsDefault
+		{
+			get { return Info.Default; }
+		}
+
+		public virtual void Activate(Actor self)
+		{
+			if (Active) return;
+
+			Active = true;
+			IsFirstTick = true;
+			NextScantime = 0;
+			_unsetFirstTick = false;
+
+			DeactivateOthers(self);
+		}
+
+		public virtual void Deactivate(Actor self)
+		{
+			if (Active)
+			{
+				Active = false;
+			}
+		}
+
+		#endregion
+
+		public virtual void DeactivateOthers(Actor self)
+		{
+			DeactivateOthers(self, this);
+		}
+
+		public static bool IsActive<T>(Actor self) where T : UnitStance
+		{
+			var stance = self.TraitOrDefault<T>();
+
+			return stance != null && stance.Active;
+		}
+
+		public static void ActivateDefault(Actor self)
+		{
+			if (!self.TraitsImplementing<IUnitStance>().Where(t => t.IsDefault).Any())
+			{
+				// deactive all of them as a default if nobody has a default
+				DeactivateOthers(self, null);
+				return;
+			}
+
+			self.TraitsImplementing<IUnitStance>().Where(t => t.IsDefault).First().Activate(self);
+		}
+
+		public static void DeactivateOthers(Actor self, IUnitStance stance)
+		{
+			self.TraitsImplementing<IUnitStance>().Where(t => t != stance).Do(t => t.Deactivate(self));
+		}
+
+		public static bool ReturnFire(Actor self, AttackInfo e, bool allowActivity, bool allowTargetSwitch, bool holdStill)
+		{
+			if (!self.IsIdle && !allowActivity) return false;
+			if (e.Attacker.Destroyed) return false;
+
+			var attack = self.TraitOrDefault<AttackBase>();
+
+			// this unit cannot fight back at all (no guns)
+			if (attack == null) return false;
+
+			// if attacking already and force was used, return (ie to respond to attacks while moving around)
+			if (attack.IsAttacking && (!allowTargetSwitch)) return false;
+
+			// don't fight back if we dont have the guns to do so
+			if (!attack.HasAnyValidWeapons(Target.FromActor(e.Attacker))) return false;
+
+			// don't retaliate against allies
+			if (self.Owner.Stances[e.Attacker.Owner] == Stance.Ally) return false;
+
+			// don't retaliate against healers
+			if (e.Damage < 0) return false;
+
+			// perform the attack
+			AttackTarget(self, e.Attacker, holdStill);
+
+			return true;
+		}
+
+		public static bool ReturnFire(Actor self, AttackInfo e, bool allowActivity, bool allowTargetSwitch)
+		{
+			return ReturnFire(self, e, allowActivity, allowTargetSwitch, false);
+		}
+
+		public static bool ReturnFire(Actor self, AttackInfo e, bool allowActivity)
+		{
+			return ReturnFire(self, e, allowActivity, false);
+		}
+
+		public static UnitStance GetActive(Actor self)
+		{
+			return self.TraitsImplementing<UnitStance>().Where(t => t.Active).FirstOrDefault();
+		}
+
+		public static void AttackTarget(Actor self, Actor target, bool holdStill)
+		{
+			var attack = self.Trait<AttackBase>();
+
+			if (attack != null && target != null)
+			{
+				self.World.IssueOrder(new Order((holdStill) ? "AttackHold" : "Attack", self, target, false));
+			}
+		}
+
+		public static void StopAttack(Actor self)
+		{
+			self.World.IssueOrder(new Order("StopAttack", self, self, false));
+		}
+
+		/// <summary>
+		/// Called when on the first tick after the stance has been activated
+		/// </summary>
+		/// <param name="self"></param>
+		protected virtual void OnScan(Actor self)
+		{
+		}
+
+		/// <summary>
+		/// Called when on the first tick after the stance has been activated
+		/// </summary>
+		/// <param name="self"></param>
+		protected virtual void OnFirstTick(Actor self)
+		{
+		}
+
+		public static Actor ScanForTarget(Actor self)
+		{
+			return self.Trait<AttackBase>().ScanForTarget(self);
+		}
+	}
+}