Core/Creatures: Implemented CREATURE_STATIC_FLAG_4_NO_MELEE_APPROACH and fixed CREATURE_STATIC_FLAG_NO_MELEE_FLEE implementation (should cause fleeing from melee range)

Port From (https://github.com/TrinityCore/TrinityCore/commit/a748fddfa47216e1f516303e3bca9b5a86823748)

Source/Framework/Constants/CreatureConst.cs

@@ -290,7 +290,7 @@ namespace Framework.Constants
         CombatPing = 0x00020000,
         Aquatic = 0x00040000, // Aka Water Only, CreatureTemplateMovement.Ground = 0
         Amphibious = 0x00080000, // CreatureTemplateMovement.Swim = 1
-        NoMelee = 0x00100000, // Prevents Melee(Does Not Prevent Chasing, Does Not Make Creature Passive). Not Sure What 'Flee' Means But Another Flag Is Named NoMeleeApproach
+        NoMeleeFlee = 0x00100000, // "No Melee (Flee)" Prevents melee (moves as-if feared, does not make creature passive)
         VisibleToGhosts = 0x00200000, // CreatureTypeFlagVisibleToGhosts
         PvpEnabling = 0x00400000, // Old UnitFlagPvpEnabling, Now UnitBytes2OffsetPvpFlag From UnitFieldBytes2
         DoNotPlayWoundAnim = 0x00800000, // CreatureTypeFlagDoNotPlayWoundAnim
@@ -390,7 +390,7 @@ namespace Framework.Constants
         DealsTripleDamageToPcControlledPets = 0x00000040,
         NoNpcDamageBelow85ptc = 0x00000080,
         ObeysTauntDiminishingReturns = 0x00000100, // CreatureFlagExtraObeysTauntDiminishingReturns
-        NoMeleeApproach = 0x00000200,
+        NoMeleeApproach = 0x00000200, // "No Melee (Approach)" Prevents melee (chases into melee range, does not make creature passive)
         UpdateCreatureRecordWhenInstanceChangesDifficulty = 0x00000400, // Used Only By Snobold Vassal
         CannotDaze = 0x00000800, // "Cannot Daze (Combat Stun)"
         FlatHonorAward = 0x00001000,

Source/Game/AI/CoreAI/CreatureAI.cs

@@ -27,9 +27,9 @@ namespace Game.AI
         protected TaskScheduler _scheduler = new();
         protected InstanceScript _instanceScript;
 
-        public CreatureAI(Creature _creature) : base(_creature)
+        public CreatureAI(Creature creature) : base(creature)
         {
-            me = _creature;
+            me = creature;
             _moveInLOSLocked = false;
         }
 
@@ -514,6 +514,21 @@ namespace Game.AI
         // called when the corpse of this creature gets removed
         public virtual void CorpseRemoved(long respawnDelay) { }
 
+        public override void AttackStart(Unit victim)
+        {
+            if (victim != null && me.Attack(victim, true))
+            {
+                // Clear distracted state on attacking
+                if (me.HasUnitState(UnitState.Distracted))
+                {
+                    me.ClearUnitState(UnitState.Distracted);
+                    me.GetMotionMaster().Clear();
+                }
+
+                me.StartDefaultCombatMovement(victim);
+            }
+        }
+
         /// == Gossip system ================================
 
         // Called when the dialog status between a player and the creature is requested.

Source/Game/AI/CoreAI/PassiveAI.cs

@@ -4,6 +4,7 @@
 using Framework.Constants;
 using Game.Entities;
 using Game.Spells;
+using System;
 
 namespace Game.AI
 {
@@ -92,28 +93,34 @@ namespace Game.AI
 
     public class CritterAI : PassiveAI
     {
-        public CritterAI(Creature c) : base(c)
+        TimeTracker _evadeTimer;
+
+        public CritterAI(Creature creature) : base(creature)
         {
-            me.SetReactState(ReactStates.Passive);
+            _evadeTimer = new();
+            me.SetCanMelee(false, true);
         }
 
         public override void JustEngagedWith(Unit who)
         {
-            if (!me.HasUnitState(UnitState.Fleeing))
+            me.StartDefaultCombatMovement(who);            
-                me.SetControlled(true, UnitState.Fleeing);
+            _evadeTimer.Reset(TimeSpan.FromMilliseconds(WorldConfig.GetIntValue(WorldCfg.CreatureFamilyFleeDelay)));
         }
 
-        public override void MovementInform(MovementGeneratorType type, uint id)
+        public override void UpdateAI(uint diff)
         {
-            if (type == MovementGeneratorType.TimedFleeing)
+            if (me.IsEngaged())
-                EnterEvadeMode(EvadeReason.Other);
+            {
-        }
+                if (!me.IsInCombat())
+                {
+                    EnterEvadeMode(EvadeReason.NoHostiles);
+                    return;
+                }
 
-        public override void EnterEvadeMode(EvadeReason why)
+                _evadeTimer.Update(diff);
-        {
+                if (_evadeTimer.Passed())
-            if (me.HasUnitState(UnitState.Fleeing))
+                    EnterEvadeMode(EvadeReason.Other);
-                me.SetControlled(false, UnitState.Fleeing);
+            }
-            base.EnterEvadeMode(why);
         }
     }
 

Source/Game/AI/ScriptedAI/ScriptedAI.cs

@@ -52,7 +52,7 @@ namespace Game.AI
         public void DoStartMovement(Unit target, float distance = 0.0f, float angle = 0.0f)
         {
             if (target != null)
-                me.GetMotionMaster().MoveChase(target, distance, angle);
+                me.StartDefaultCombatMovement(target, distance, angle);
         }
 
         //Start no movement on victim

Source/Game/AI/SmartScripts/SmartAI.cs

@@ -618,7 +618,7 @@ namespace Game.AI
                 if (_canCombatMove)
                 {
                     SetRun(_run);
-                    me.GetMotionMaster().MoveChase(who);
+                    me.StartDefaultCombatMovement(who);
                 }
             }
         }
@@ -830,7 +830,7 @@ namespace Game.AI
                     }))
                     {
                         SetRun(_run);
-                        me.GetMotionMaster().MoveChase(me.GetVictim());
+                        me.StartDefaultCombatMovement(me.GetVictim());
                     }
                 }
                 else

Source/Game/AI/SmartScripts/SmartScript.cs

@@ -1515,7 +1515,7 @@ namespace Game.AI
                         if (creature != null)
                             if (IsSmart(creature) && creature.GetVictim() != null)
                                 if (((SmartAI)creature.GetAI()).CanCombatMove())
-                                    creature.GetMotionMaster().MoveChase(creature.GetVictim(), attackDistance, attackAngle);
+                                    creature.StartDefaultCombatMovement(creature.GetVictim(), attackDistance, attackAngle);
                     }
                     break;
                 }

Source/Game/Entities/Creature/Creature.cs

@@ -2602,6 +2602,47 @@ namespace Game.Entities
             Global.WorldMgr.SendGlobalMessage(packet, null, (enemy_team == Team.Alliance ? Team.Horde : Team.Alliance));
         }
 
+        public void SetCanMelee(bool canMelee, bool fleeFromMelee = false)
+        {
+            bool wasFleeingFromMelee = HasFlag(CreatureStaticFlags.NoMeleeFlee);
+
+            _staticFlags.ApplyFlag(CreatureStaticFlags.NoMeleeFlee, !canMelee && fleeFromMelee);
+            _staticFlags.ApplyFlag(CreatureStaticFlags4.NoMeleeApproach, !canMelee && !fleeFromMelee);
+
+            if (wasFleeingFromMelee == HasFlag(CreatureStaticFlags.NoMeleeFlee))
+                return;
+
+            Unit victim = GetVictim();
+            if (victim == null)
+                return;
+
+            var currentMovement = GetMotionMaster().GetCurrentMovementGenerator();
+            if (currentMovement == null)
+                return;
+
+            var canChangeMovement = new Func<bool>(() =>
+            {
+                if (wasFleeingFromMelee)
+                    return currentMovement.GetMovementGeneratorType() == MovementGeneratorType.Fleeing && !HasUnitFlag(UnitFlags.Fleeing);
+
+                return currentMovement.GetMovementGeneratorType() == MovementGeneratorType.Chase;
+            })();
+
+            if (!canChangeMovement)
+                return;
+
+            GetMotionMaster().Remove(currentMovement);
+            StartDefaultCombatMovement(victim);
+        }
+
+        public void StartDefaultCombatMovement(Unit victim, float? range = null, float? angle = null)
+        {
+            if (!HasFlag(CreatureStaticFlags.NoMeleeFlee) || IsSummon())
+                GetMotionMaster().MoveChase(victim, range.GetValueOrDefault(0), angle.GetValueOrDefault(0));
+            else
+                GetMotionMaster().MoveFleeing(victim);
+        }
+
         public override bool HasSpell(uint spellId)
         {
             return m_spells.Contains(spellId);
@@ -3376,9 +3417,7 @@ namespace Game.Entities
         public override SpellSchoolMask GetMeleeDamageSchoolMask(WeaponAttackType attackType = WeaponAttackType.BaseAttack) { return m_meleeDamageSchoolMask; }
         public void SetMeleeDamageSchool(SpellSchools school) { m_meleeDamageSchoolMask = (SpellSchoolMask)(1 << (int)school); }
 
-        public bool CanMelee() { return !_staticFlags.HasFlag(CreatureStaticFlags.NoMelee); }
+        public bool CanMelee() { return !_staticFlags.HasFlag(CreatureStaticFlags.NoMeleeFlee) && !_staticFlags.HasFlag(CreatureStaticFlags4.NoMeleeApproach); }
-
-        public void SetCanMelee(bool canMelee) { _staticFlags.ApplyFlag(CreatureStaticFlags.NoMelee, !canMelee); }
 
         public bool CanIgnoreLineOfSightWhenCastingOnMe() { return _staticFlags.HasFlag(CreatureStaticFlags4.IgnoreLosWhenCastingOnMe); }
 

Source/Game/Entities/Unit/Unit.Movement.cs

@@ -1391,14 +1391,17 @@ namespace Game.Entities
                 if (caster == null)
                     caster = GetAttackerForHelper();
                 GetMotionMaster().MoveFleeing(caster, TimeSpan.FromMilliseconds(fearAuras.Empty() ? WorldConfig.GetIntValue(WorldCfg.CreatureFamilyFleeDelay) : 0)); // caster == NULL processed in MoveFleeing
+                SetUnitFlag(UnitFlags.Fleeing);
             }
             else
             {
+                RemoveUnitFlag(UnitFlags.Fleeing);
                 if (IsAlive())
                 {
                     GetMotionMaster().Remove(MovementGeneratorType.Fleeing);
-                    if (GetVictim() != null)
+                    Unit victim = GetVictim();
-                        SetTarget(GetVictim().GetGUID());
+                    if (victim != null)
+                        SetTarget(victim.GetGUID());
                     if (!IsPlayer() && !IsInCombat())
                         GetMotionMaster().MoveTargetedHome();
                 }

Source/Game/Movement/Generators/FleeingMovementGenerator.cs

@@ -32,8 +32,6 @@ namespace Game.Movement
             if (owner == null || !owner.IsAlive())
                 return;
 
-            // TODO: UNIT_FIELD_FLAGS should not be handled by generators
-            owner.SetUnitFlag(UnitFlags.Fleeing);
             _path = null;
             SetTargetLocation(owner);
         }
@@ -83,16 +81,15 @@ namespace Game.Movement
             {
                 if (owner.IsPlayer())
                 {
-                    owner.RemoveUnitFlag(UnitFlags.Fleeing);
                     owner.ClearUnitState(UnitState.FleeingMove);
                     owner.StopMoving();
                 }
                 else
                 {
-                    owner.RemoveUnitFlag(UnitFlags.Fleeing);
                     owner.ClearUnitState(UnitState.FleeingMove);
-                    if (owner.GetVictim() != null)
+                    Unit victim = owner.GetVictim();
-                        owner.SetTarget(owner.GetVictim().GetGUID());
+                    if (victim != null)
+                        owner.SetTarget(victim.GetGUID());
                 }
             }
         }
@@ -220,7 +217,6 @@ namespace Game.Movement
             if (!active)
                 return;
 
-            owner.RemoveUnitFlag(UnitFlags.Fleeing);
             Unit victim = owner.GetVictim();
             if (victim != null)
             {

Source/Game/Movement/MotionMaster.cs

@@ -563,7 +563,6 @@ namespace Game.Movement
         }
 
         public void MoveChase(Unit target, float dist, float angle = 0.0f) { MoveChase(target, new ChaseRange(dist), new ChaseAngle(angle)); }
-        public void MoveChase(Unit target, float dist) { MoveChase(target, new ChaseRange(dist)); }
         public void MoveChase(Unit target, ChaseRange? dist = null, ChaseAngle? angle = null)
         {
             // Ignore movement request if target not exist