Core/Movement: Add new flag MOVEMENTGENERATOR_FLAG_PERSIST_ON_DEATH (#26549)

* Core/Movement: Add new flag MOVEMENTGENERATOR_FLAG_PERSIST_ON_DEATH

Add new flag MOVEMENTGENERATOR_FLAG_PERSIST_ON_DEATH to keep movement generators even after death.

Fixes #23095
Could replace ff26027453

* Core/Movement: reorder new method MotionMaster::StopOnDeath

* Core/Movement: reorder new method MotionMaster::StopOnDeath

* Keep MoveJump movement generator after death

Co-authored-by: ccrs <ccrs@users.noreply.github.com>

src/server/game/Entities/Unit/Unit.cpp

@@ -8722,19 +8722,8 @@ void Unit::setDeathState(DeathState s)
         // Don't clear the movement if the Unit was on a vehicle as we are exiting now
         if (!isOnVehicle)
         {
-            if (IsInWorld())
-            {
-                // Only clear MotionMaster for entities that exists in world
-                // Avoids crashes in the following conditions :
-                //  * Using 'call pet' on dead pets
-                //  * Using 'call stabled pet'
-                //  * Logging in with dead pets
-                GetMotionMaster()->Clear();
-                GetMotionMaster()->MoveIdle();
-            }
-
-            StopMoving();
-            DisableSpline();
+            if (GetMotionMaster()->StopOnDeath())
+                DisableSpline();
         }
 
         // without this when removing IncreaseMaxHealth aura player may stuck with 1 hp

src/server/game/Movement/MotionMaster.cpp

@@ -543,6 +543,28 @@ bool MotionMaster::GetDestination(float &x, float &y, float &z)
     return true;
 }
 
+bool MotionMaster::StopOnDeath()
+{
+    if (MovementGenerator* movementGenerator = GetCurrentMovementGenerator())
+        if (movementGenerator->HasFlag(MOVEMENTGENERATOR_FLAG_PERSIST_ON_DEATH))
+            return false;
+
+    if (_owner->IsInWorld())
+    {
+        // Only clear MotionMaster for entities that exists in world
+        // Avoids crashes in the following conditions :
+        //  * Using 'call pet' on dead pets
+        //  * Using 'call stabled pet'
+        //  * Logging in with dead pets
+        Clear();
+        MoveIdle();
+    }
+
+    _owner->StopMoving();
+
+    return true;
+}
+
 void MotionMaster::MoveIdle()
 {
     Add(GetIdleMovementGenerator(), MOTION_SLOT_DEFAULT);
@@ -757,6 +779,7 @@ void MotionMaster::MoveKnockbackFrom(float srcX, float srcY, float speedXY, floa
 
     GenericMovementGenerator* movement = new GenericMovementGenerator(std::move(init), EFFECT_MOTION_TYPE, 0);
     movement->Priority = MOTION_PRIORITY_HIGHEST;
+    movement->AddFlag(MOVEMENTGENERATOR_FLAG_PERSIST_ON_DEATH);
     Add(movement);
 }
 
@@ -801,6 +824,7 @@ void MotionMaster::MoveJump(float x, float y, float z, float o, float speedXY, f
     GenericMovementGenerator* movement = new GenericMovementGenerator(std::move(init), EFFECT_MOTION_TYPE, id);
     movement->Priority = MOTION_PRIORITY_HIGHEST;
     movement->BaseUnitState = UNIT_STATE_JUMPING;
+    movement->AddFlag(MOVEMENTGENERATOR_FLAG_PERSIST_ON_DEATH);
     Add(movement);
 }
 

src/server/game/Movement/MotionMaster.h

@@ -149,6 +149,7 @@ class TC_GAME_API MotionMaster
         void Clear(MovementGeneratorPriority priority);
         void PropagateSpeedChange();
         bool GetDestination(float &x, float &y, float &z);
+        bool StopOnDeath();
 
         void MoveIdle();
         void MoveTargetedHome();

src/server/game/Movement/MovementGenerator.h

@@ -39,6 +39,7 @@ enum MovementGeneratorFlags : uint16
     MOVEMENTGENERATOR_FLAG_DEACTIVATED            = 0x040,
     MOVEMENTGENERATOR_FLAG_INFORM_ENABLED         = 0x080,
     MOVEMENTGENERATOR_FLAG_FINALIZED              = 0x100,
+    MOVEMENTGENERATOR_FLAG_PERSIST_ON_DEATH       = 0x200,
 
     MOVEMENTGENERATOR_FLAG_TRANSITORY = MOVEMENTGENERATOR_FLAG_SPEED_UPDATE_PENDING | MOVEMENTGENERATOR_FLAG_INTERRUPTED
 };