feat(Core/CreatureAI): improve npc position during the combat (#3369)

+ tangent equation to find correct angle and distance when moving

+ implemented proper backward

* Improved performance + random angle margin

* chore: add tollerance calculation in instance

* improved LOS checks with movements

* implemented collisions using raycast (imported by TC)

+ improved collision detection for CanReachPositionAndGetCoords

+ improved collision check

+ set correct flags for the backward movement

+ first implementation of slope angle (to improve)

Co-authored-by: Yehonal <yehonal.azeroth@gmail.com>

src/server/game/Entities/Unit/Unit.h

@@ -1255,6 +1255,26 @@ private:
     GlobalCooldownMgr _GlobalCooldownMgr;
 };
 
+struct AttackPosition {
+    AttackPosition(Position pos) : _pos(pos), _taken(false) {}
+    bool operator==(const int val)
+    {
+        return !val;
+    };
+    int operator=(const int val)
+    {
+        if (!val)
+        {
+            // _pos = NULL;
+            _taken = false;
+            return 0; // NULL
+        }
+        return 0; // NULL
+    };
+    Position _pos;
+    bool _taken;
+};
+
 // for clearing special attacks
 #define REACTIVE_TIMER_START 5000
 
@@ -1405,6 +1425,7 @@ public:
     virtual void SetCanDualWield(bool value) { m_canDualWield = value; }
     [[nodiscard]] float GetCombatReach() const override { return m_floatValues[UNIT_FIELD_COMBATREACH]; }
     [[nodiscard]] float GetMeleeReach() const { float reach = m_floatValues[UNIT_FIELD_COMBATREACH]; return reach > MIN_MELEE_REACH ? reach : MIN_MELEE_REACH; }
+    [[nodiscard]] bool IsWithinRange(Unit const* obj, float dist) const;
     bool IsWithinCombatRange(const Unit* obj, float dist2compare) const;
     bool IsWithinMeleeRange(const Unit* obj, float dist = MELEE_RANGE) const;
     bool GetRandomContactPoint(const Unit* target, float& x, float& y, float& z, bool force = false) const;
@@ -1434,6 +1455,7 @@ public:
     bool AttackStop();
     void RemoveAllAttackers();
     [[nodiscard]] AttackerSet const& getAttackers() const { return m_attackers; }
+    [[nodiscard]] Position* GetMeleeAttackPoint(Unit* attacker);
     [[nodiscard]] bool isAttackingPlayer() const;
     [[nodiscard]] Unit* GetVictim() const { return m_attacking; }
 
@@ -2174,7 +2196,7 @@ public:
 
     uint32 GetDisplayId() { return GetUInt32Value(UNIT_FIELD_DISPLAYID); }
     virtual void SetDisplayId(uint32 modelId);
-    uint32 GetNativeDisplayId() { return GetUInt32Value(UNIT_FIELD_NATIVEDISPLAYID); }
+    [[nodiscard]] uint32 GetNativeDisplayId() const { return GetUInt32Value(UNIT_FIELD_NATIVEDISPLAYID); }
     void RestoreDisplayId();
     void SetNativeDisplayId(uint32 modelId) { SetUInt32Value(UNIT_FIELD_NATIVEDISPLAYID, modelId); }
     void setTransForm(uint32 spellid) { m_transform = spellid;}
@@ -2451,6 +2473,8 @@ public:
     // Movement info
     Movement::MoveSpline* movespline;
 
+    [[nodiscard]] float GetCollisionHeight() const override;
+
 protected:
     explicit Unit (bool isWorldObject);
 
@@ -2566,6 +2590,7 @@ private:
     HostileRefManager m_HostileRefManager;
 
     FollowerRefManager m_FollowingRefManager;
+    Unit* m_comboTarget;
 
     ComboPointHolderSet m_ComboPointHolders;