Core/Movement: delay movement update in MotionMaster until its owner signals AddToWorld

ref #23199
closes #23876

(cherry picked from commit d033032d33cff5dae76000f8432d78746cda9e06)

3 files changed, 38 insertions, 14 deletions

diff --git a/src/server/game/Entities/Unit/Unit.cpp b/src/server/game/Entities/Unit/Unit.cpp
index 3821c974849..d7d4fe80531 100644
--- a/src/server/game/Entities/Unit/Unit.cpp
+++ b/src/server/game/Entities/Unit/Unit.cpp
@@ -9098,6 +9098,7 @@ void Unit::RestoreDisabledAI()
 void Unit::AddToWorld()
 {
     WorldObject::AddToWorld();
+    i_motionMaster->AddToWorld();
 
     RemoveAurasWithInterruptFlags(SpellAuraInterruptFlags::EnterWorld);
 }
diff --git a/src/server/game/Movement/MotionMaster.cpp b/src/server/game/Movement/MotionMaster.cpp
index 9c6ae257ec1..cdfe8144868 100644
--- a/src/server/game/Movement/MotionMaster.cpp
+++ b/src/server/game/Movement/MotionMaster.cpp
@@ -95,7 +95,7 @@ MotionMaster::~MotionMaster()
 
 void MotionMaster::Initialize()
 {
-    if (HasFlag(MOTIONMASTER_FLAG_UPDATE))
+    if (HasFlag(MOTIONMASTER_FLAG_DELAYED))
     {
         DelayedActionDefine action = [this]()
         {
@@ -113,6 +113,16 @@ void MotionMaster::InitializeDefault()
     Add(FactorySelector::SelectMovementGenerator(_owner), MOTION_SLOT_DEFAULT);
 }
 
+void MotionMaster::AddToWorld()
+{
+    if (!HasFlag(MOTIONMASTER_FLAG_INITIALIZATION_PENDING))
+        return;
+
+    ResolveDelayedActions();
+
+    RemoveFlag(MOTIONMASTER_FLAG_INITIALIZATION_PENDING);
+}
+
 bool MotionMaster::Empty() const
 {
     return !_defaultGenerator && _generators.empty();
@@ -277,6 +287,9 @@ void MotionMaster::Update(uint32 diff)
     if (!_owner)
         return;
 
+    if (HasFlag(MOTIONMASTER_FLAG_INITIALIZATION_PENDING))
+        return;
+
     ASSERT(!Empty(), "MotionMaster:Update: update called without Initializing! (%s)", _owner->GetGUID().ToString().c_str());
 
     AddFlag(MOTIONMASTER_FLAG_UPDATE);
@@ -304,11 +317,7 @@ void MotionMaster::Update(uint32 diff)
 
     RemoveFlag(MOTIONMASTER_FLAG_UPDATE);
 
-    while (!_delayedActions.empty())
-    {
-        _delayedActions.front().Resolve();
-        _delayedActions.pop_front();
-    }
+    ResolveDelayedActions();
 }
 
 void MotionMaster::Add(MovementGenerator* movement, MovementSlot slot/* = MOTION_SLOT_ACTIVE*/)
@@ -322,7 +331,7 @@ void MotionMaster::Add(MovementGenerator* movement, MovementSlot slot/* = MOTION
         return;
     }
 
-    if (HasFlag(MOTIONMASTER_FLAG_UPDATE))
+    if (HasFlag(MOTIONMASTER_FLAG_DELAYED))
     {
         DelayedActionDefine action = [this, movement, slot]()
         {
@@ -339,7 +348,7 @@ void MotionMaster::Remove(MovementGenerator* movement, MovementSlot slot/* = MOT
     if (!movement || IsInvalidMovementSlot(slot))
         return;
 
-    if (HasFlag(MOTIONMASTER_FLAG_UPDATE))
+    if (HasFlag(MOTIONMASTER_FLAG_DELAYED))
     {
         DelayedActionDefine action = [this, movement, slot]()
         {
@@ -377,7 +386,7 @@ void MotionMaster::Remove(MovementGeneratorType type, MovementSlot slot/* = MOTI
     if (IsInvalidMovementGeneratorType(type) || IsInvalidMovementSlot(slot))
         return;
 
-    if (HasFlag(MOTIONMASTER_FLAG_UPDATE))
+    if (HasFlag(MOTIONMASTER_FLAG_DELAYED))
     {
         DelayedActionDefine action = [this, type, slot]()
         {
@@ -415,7 +424,7 @@ void MotionMaster::Remove(MovementGeneratorType type, MovementSlot slot/* = MOTI
 
 void MotionMaster::Clear()
 {
-    if (HasFlag(MOTIONMASTER_FLAG_UPDATE))
+    if (HasFlag(MOTIONMASTER_FLAG_DELAYED))
     {
         DelayedActionDefine action = [this]()
         {
@@ -434,7 +443,7 @@ void MotionMaster::Clear(MovementSlot slot)
     if (IsInvalidMovementSlot(slot))
         return;
 
-    if (HasFlag(MOTIONMASTER_FLAG_UPDATE))
+    if (HasFlag(MOTIONMASTER_FLAG_DELAYED))
     {
         DelayedActionDefine action = [this, slot]()
         {
@@ -462,7 +471,7 @@ void MotionMaster::Clear(MovementSlot slot)
 
 void MotionMaster::Clear(MovementGeneratorMode mode)
 {
-    if (HasFlag(MOTIONMASTER_FLAG_UPDATE))
+    if (HasFlag(MOTIONMASTER_FLAG_DELAYED))
     {
         DelayedActionDefine action = [this, mode]()
         {
@@ -484,7 +493,7 @@ void MotionMaster::Clear(MovementGeneratorMode mode)
 
 void MotionMaster::Clear(MovementGeneratorPriority priority)
 {
-    if (HasFlag(MOTIONMASTER_FLAG_UPDATE))
+    if (HasFlag(MOTIONMASTER_FLAG_DELAYED))
     {
         DelayedActionDefine action = [this, priority]()
         {
@@ -1074,6 +1083,15 @@ void MotionMaster::LaunchMoveSpline(Movement::MoveSplineInit&& init, uint32 id/*
 
 /******************** Private methods ********************/
 
+void MotionMaster::ResolveDelayedActions()
+{
+    while (!_delayedActions.empty())
+    {
+        _delayedActions.front().Resolve();
+        _delayedActions.pop_front();
+    }
+}
+
 void MotionMaster::Remove(MotionMasterContainer::iterator iterator, bool active, bool movementInform)
 {
     MovementGenerator* pointer = *iterator;
diff --git a/src/server/game/Movement/MotionMaster.h b/src/server/game/Movement/MotionMaster.h
index 65f4dcbc540..61069cf4cf4 100644
--- a/src/server/game/Movement/MotionMaster.h
+++ b/src/server/game/Movement/MotionMaster.h
@@ -47,7 +47,10 @@ enum MotionMasterFlags : uint8
 {
     MOTIONMASTER_FLAG_NONE                          = 0x0,
     MOTIONMASTER_FLAG_UPDATE                        = 0x1, // Update in progress
-    MOTIONMASTER_FLAG_STATIC_INITIALIZATION_PENDING = 0x2
+    MOTIONMASTER_FLAG_STATIC_INITIALIZATION_PENDING = 0x2, // Static movement (MOTION_SLOT_DEFAULT) hasn't been initialized
+    MOTIONMASTER_FLAG_INITIALIZATION_PENDING        = 0x4, // MotionMaster is stalled until signaled
+
+    MOTIONMASTER_FLAG_DELAYED = MOTIONMASTER_FLAG_STATIC_INITIALIZATION_PENDING | MOTIONMASTER_FLAG_INITIALIZATION_PENDING
 };
 
 enum MotionMasterDelayedActionType : uint8
@@ -112,6 +115,7 @@ class TC_GAME_API MotionMaster
 
         void Initialize();
         void InitializeDefault();
+        void AddToWorld();
 
         bool Empty() const;
         uint32 Size() const;
@@ -199,6 +203,7 @@ class TC_GAME_API MotionMaster
         bool HasFlag(uint8 const flag) const { return (_flags & flag) != 0; }
         void RemoveFlag(uint8 const flag) { _flags &= ~flag; }
 
+        void ResolveDelayedActions();
         void Remove(MotionMasterContainer::iterator iterator, bool active, bool movementInform);
         void Pop(bool active, bool movementInform);
         void DirectInitialize();