Core/Spells: Update nearby visible objects for new viewpoints, fix spells with Far Sight and Bind Sight effects.

src/server/game/Entities/Object/Object.cpp

@@ -1668,7 +1668,11 @@ bool WorldObject::canSeeOrDetect(WorldObject const* obj, bool ignoreStealth, boo
             }
         }
 
-        if (!corpseCheck && !IsWithinDist(obj, GetSightRange(obj), false))
+        WorldObject const* viewpoint = this;
+        if (Player const* player = this->ToPlayer())
+            viewpoint = player->GetViewpoint();
+
+        if (!corpseCheck && !viewpoint->IsWithinDist(obj, GetSightRange(obj), false))
             return false;
     }
 

src/server/game/Entities/Player/Player.cpp

@@ -22974,7 +22974,7 @@ WorldObject* Player::GetViewpoint() const
 {
     if (uint64 guid = GetUInt64Value(PLAYER_FARSIGHT))
         return (WorldObject*)ObjectAccessor::GetObjectByTypeMask(*this, guid, TYPEMASK_SEER);
-    return NULL;
+    return (WorldObject*) this;
 }
 
 bool Player::CanUseBattlegroundObject()