Refactor Creature::SelectNearestTarget(float dist)

This function is used in many scripts to find the nearest enemy within the given distance.
However, it had an implicit limit to the ATTACK_DISTANCE. so in many case the "dist" was in fact just ignored.
In other case, the ATTACK_DISTANCE is required. So 2 functions are necessary to avoid ambiguities.

The refactoring is the split of the function in 2: SelectNearestTarget and SelectNearestTargetInAttackDistance.

--HG--
branch : trunk

src/game/Creature.cpp

@@ -1783,6 +1783,8 @@ bool Creature::IsVisibleInGridForPlayer(Player const* pl) const
     return false;
 }
 
+
+// select nearest hostile unit within the given distance (regardless of threat list).
 Unit* Creature::SelectNearestTarget(float dist) const
 {
     CellPair p(Trinity::ComputeCellPair(GetPositionX(), GetPositionY()));
@@ -1792,6 +1794,36 @@ Unit* Creature::SelectNearestTarget(float dist) const
 
     Unit *target = NULL;
 
+    {
+        if (dist == 0.0f || dist > MAX_VISIBILITY_DISTANCE)
+            dist = MAX_VISIBILITY_DISTANCE;
+
+        Trinity::NearestHostileUnitCheck u_check(this, dist);
+        Trinity::UnitLastSearcher<Trinity::NearestHostileUnitCheck> searcher(this, target, u_check);
+
+        TypeContainerVisitor<Trinity::UnitLastSearcher<Trinity::NearestHostileUnitCheck>, WorldTypeMapContainer > world_unit_searcher(searcher);
+        TypeContainerVisitor<Trinity::UnitLastSearcher<Trinity::NearestHostileUnitCheck>, GridTypeMapContainer >  grid_unit_searcher(searcher);
+
+        cell.Visit(p, world_unit_searcher, *GetMap(), *this, dist);
+        cell.Visit(p, grid_unit_searcher, *GetMap(), *this, dist);
+    }
+
+    return target;
+}
+
+// select nearest hostile unit within the given attack distance (i.e. distance is ignored if > than ATTACK_DISTANCE), regardless of threat list.
+Unit* Creature::SelectNearestTargetInAttackDistance(float dist) const
+{
+    CellPair p(Trinity::ComputeCellPair(GetPositionX(), GetPositionY()));
+    Cell cell(p);
+    cell.data.Part.reserved = ALL_DISTRICT;
+    cell.SetNoCreate();
+
+    Unit *target = NULL;
+
+    if (dist > ATTACK_DISTANCE)
+        sLog.outError("Creature (GUID: %u Entry: %u) SelectNearestTargetInAttackDistance called with dist > ATTACK_DISTANCE. Extra distance ignored.",GetGUIDLow(),GetEntry());
+
     {
         Trinity::NearestHostileUnitInAttackDistanceCheck u_check(this, dist);
         Trinity::UnitLastSearcher<Trinity::NearestHostileUnitInAttackDistanceCheck> searcher(this, target, u_check);

src/game/Creature.h

@@ -557,6 +557,8 @@ class Creature : public Unit, public GridObject<Creature>
         void SendAIReaction(AiReaction reactionType);
 
         Unit* SelectNearestTarget(float dist = 0) const;
+        Unit* SelectNearestTargetInAttackDistance(float dist = 0) const;
+
         void DoFleeToGetAssistance();
         void CallForHelp(float fRadius);
         void CallAssistance();

src/game/CreatureAI.cpp

@@ -131,15 +131,6 @@ void CreatureAI::MoveInLineOfSight(Unit *who)
     //    me->GetMotionMaster()->MoveChase(who->getVictim());
 }
 
-void CreatureAI::SelectNearestTarget(Unit *who)
-{
-    if (me->getVictim() && me->GetDistanceOrder(who, me->getVictim()) && me->canAttack(who))
-    {
-        me->getThreatManager().modifyThreatPercent(me->getVictim(), -100);
-        me->AddThreat(who, 1000000.0f);
-    }
-}
-
 void CreatureAI::EnterEvadeMode()
 {
     if (!_EnterEvadeMode())

src/game/CreatureAI.h

@@ -73,8 +73,6 @@ class CreatureAI : public UnitAI
         bool UpdateVictimWithGaze();
         bool UpdateCombatState();
 
-        void SelectNearestTarget(Unit *who);
-
         void SetGazeOn(Unit *target);
 
         Creature *DoSummon(uint32 uiEntry, const Position &pos, uint32 uiDespawntime = 30000, TempSummonType uiType = TEMPSUMMON_CORPSE_TIMED_DESPAWN);

src/game/GridNotifiers.h

@@ -940,6 +940,31 @@ namespace Trinity
 
     // Creature checks
 
+    class NearestHostileUnitCheck
+    {
+        public:
+            explicit NearestHostileUnitCheck(Creature const* creature, float dist = 0) : me(creature)
+            {
+                m_range = (dist == 0 ? 9999 : dist);
+            }
+            bool operator()(Unit* u)
+            {
+                if (!me->IsWithinDistInMap(u, m_range))
+                    return false;
+
+                if (!me->canAttack(u))
+                    return false;
+
+                m_range = me->GetDistance(u);   // use found unit range as new range limit for next check
+                return true;
+            }
+
+    private:
+            Creature const *me;
+            float m_range;
+            NearestHostileUnitCheck(NearestHostileUnitCheck const&);
+    };
+
     class NearestHostileUnitInAttackDistanceCheck
     {
         public:
@@ -950,7 +975,6 @@ namespace Trinity
             }
             bool operator()(Unit* u)
             {
-                // TODO: addthreat for every enemy in range?
                 if (!me->IsWithinDistInMap(u, m_range))
                     return false;
 
@@ -965,7 +989,7 @@ namespace Trinity
                         return false;
                 }
 
-                m_range = me->GetDistance(u);
+                m_range = me->GetDistance(u);   // use found unit range as new range limit for next check
                 return true;
             }
             float GetLastRange() const { return m_range; }

src/game/Unit.cpp

@@ -12200,7 +12200,7 @@ Unit* Creature::SelectVictim()
     // search nearby enemy before enter evade mode
     if (HasReactState(REACT_AGGRESSIVE))
     {
-        target = SelectNearestTarget();
+        target = SelectNearestTargetInAttackDistance();
         if (target && _IsTargetAcceptable(target))
                 return target;
     }

src/game/UnitAI.cpp

@@ -323,5 +323,5 @@ void SimpleCharmedAI::UpdateAI(const uint32 /*diff*/)
 
     Unit *target = me->getVictim();
     if (!target || !charmer->canAttack(target))
-        AttackStart(charmer->SelectNearestTarget());
+        AttackStart(charmer->SelectNearestTargetInAttackDistance());
 }

src/scripts/kalimdor/temple_of_ahnqiraj/boss_twinemperors.cpp

@@ -258,12 +258,11 @@ struct boss_twinemperorsAI : public ScriptedAI
             {
                 AfterTeleport = false;
                 me->clearUnitState(UNIT_STAT_STUNNED);
-                Unit *nearu = me->SelectNearestTarget(100);
-                //DoYell(nearu->GetName(), LANG_UNIVERSAL, 0);
-                if (nearu)
+                if (Unit *nearu = me->SelectNearestTarget(100))
                 {
+                    //DoYell(nearu->GetName(), LANG_UNIVERSAL, 0);
                     AttackStart(nearu);
-                    me->getThreatManager().addThreat(nearu, 10000);
+                    me->AddThreat(nearu, 10000);
                 }
                 return true;
             }

src/scripts/northrend/naxxramas/boss_four_horsemen.cpp

@@ -236,6 +236,16 @@ struct boss_four_horsemenAI : public BossAI
         nextWP = id + 1;
     }
 
+    // switch to "who" if nearer than current target.
+    void SelectNearestTarget(Unit *who)
+    {
+        if (me->getVictim() && me->GetDistanceOrder(who, me->getVictim()) && me->canAttack(who))
+        {
+            me->getThreatManager().modifyThreatPercent(me->getVictim(), -100);
+            me->AddThreat(who, 1000000.0f);
+        }
+    }
+
     void MoveInLineOfSight(Unit *who)
     {
         BossAI::MoveInLineOfSight(who);

src/scripts/outland/tempest_keep/the_eye/boss_alar.cpp

@@ -408,7 +408,7 @@ struct boss_alarAI : public ScriptedAI
             else
             {
                 Unit *pTarget = NULL;
-                pTarget = me->SelectNearestTarget(5);
+                pTarget = me->SelectNearestTargetInAttackDistance(5);
                 if (pTarget)
                     me->AI()->AttackStart(pTarget);
                 else