[10431] Correcting issues with flying creatures falling to ground at death.

Simplified the way FallGround works and death states are set in a more logical way when a mob is in fact DEAD_FALLING.
Visual will in some cases not be correct. Notes in code for details.

Thanks to Lynx fixing Map::GetHeight
It now return mapHeight as last resort, making FallGround work as expected.
This fix reveal one (known) bug, and therefore a temp hack is added in TargetedMovegen, to be sure Z is not the ground Z for a creature that are able to fly.
Other creatures will follow by the ground level Z (in other words, they will no longer follow in the air).

src/game/Creature.cpp

@@ -561,15 +561,13 @@ void Creature::Update(uint32 diff)
         }
         case DEAD_FALLING:
         {
-            if (!FallGround())
-                setDeathState(JUST_DIED);
+            setDeathState(CORPSE);
         }
         default:
             break;
     }
 }
 
-
 void Creature::StartGroupLoot( Group* group, uint32 timer )
 {
     m_groupLootId = group->GetId();
@@ -1379,13 +1377,8 @@ void Creature::setDeathState(DeathState s)
         // always save boss respawn time at death to prevent crash cheating
         if (sWorld.getConfig(CONFIG_BOOL_SAVE_RESPAWN_TIME_IMMEDIATLY) || isWorldBoss())
             SaveRespawnTime();
-
-        if (canFly() && FallGround())
-            return;
-
-        if (!IsStopped())
-            StopMoving();
     }
+
     Unit::setDeathState(s);
 
     if (s == JUST_DIED)
@@ -1393,17 +1386,19 @@ void Creature::setDeathState(DeathState s)
         SetTargetGUID(0);                                   // remove target selection in any cases (can be set at aura remove in Unit::setDeathState)
         SetUInt32Value(UNIT_NPC_FLAGS, UNIT_NPC_FLAG_NONE);
 
-        if (canFly() && FallGround())
-            return;
-
         if (HasSearchedAssistance())
         {
             SetNoSearchAssistance(false);
             UpdateSpeed(MOVE_RUN, false);
         }
 
+        // return, since we promote to DEAD_FALLING. DEAD_FALLING is promoted to CORPSE at next update.
+        if (canFly() && FallGround())
+            return;
+
         Unit::setDeathState(CORPSE);
     }
+
     if (s == JUST_ALIVED)
     {
         SetHealth(GetMaxHealth());
@@ -1423,20 +1418,44 @@ void Creature::setDeathState(DeathState s)
 
 bool Creature::FallGround()
 {
-    // Let's abort after we called this function one time
-    if (getDeathState() == DEAD_FALLING)
+    // Only if state is JUST_DIED. DEAD_FALLING is set below and promoted to CORPSE later
+    if (getDeathState() != JUST_DIED)
         return false;
 
     // use larger distance for vmap height search than in most other cases
     float tz = GetMap()->GetHeight(GetPositionX(), GetPositionY(), GetPositionZ(), true, MAX_FALL_DISTANCE);
 
+    if (tz < INVALID_HEIGHT)
+    {
+        DEBUG_LOG("FallGround: creature %u at map %u (x: %f, y: %f, z: %f), not able to retrive a proper GetHeight (z: %f).",
+            GetEntry(), GetMap()->GetId(), GetPositionX(), GetPositionX(), GetPositionZ(), tz);
+    }
+
     // Abort too if the ground is very near
     if (fabs(GetPositionZ() - tz) < 0.1f)
         return false;
 
     Unit::setDeathState(DEAD_FALLING);
-    GetMotionMaster()->MovePoint(0, GetPositionX(), GetPositionY(), tz);
-    Relocate(GetPositionX(), GetPositionY(), tz);
+
+    float dz = tz - GetPositionZ();
+    float distance = sqrt(dz*dz);
+
+    // flight speed * 2 explicit, not verified though but result looks proper
+    double speed = GetSpeed(MOVE_FLIGHT) * 2;
+
+    speed *= 0.001;                                         // to milliseconds
+
+    uint32 travelTime = uint32(distance/speed);
+
+    DEBUG_LOG("FallGround: traveltime: %u, distance: %f, speed: %f, from %f to %f", travelTime, distance, speed, GetPositionZ(), tz);
+
+    // For creatures that are moving towards target and dies, the visual effect is not nice.
+    // It is possibly caused by a xyz mismatch in DestinationHolder's GetLocationNow and the location
+    // of the mob in client. For mob that are already reached target or dies while not moving
+    // the visual appear to be fairly close to the expected.
+
+    GetMap()->CreatureRelocation(this, GetPositionX(), GetPositionY(), tz, GetOrientation());
+    SendMonsterMove(GetPositionX(), GetPositionY(), tz, SPLINETYPE_NORMAL, SPLINEFLAG_FALLING, travelTime);
     return true;
 }
 

src/game/Map.cpp

@@ -1063,15 +1063,8 @@ float Map::GetHeight(float x, float y, float z, bool pUseVmaps, float maxSearchD
         else
             return vmapHeight;                              // we have only vmapHeight (if have)
     }
-    else
-    {
-        if(!pUseVmaps)
-            return mapHeight;                               // explicitly use map data (if have)
-        else if(mapHeight > INVALID_HEIGHT && (z < mapHeight + 2 || z == MAX_HEIGHT))
-            return mapHeight;                               // explicitly use map data if original z < mapHeight but map found (z+2 > mapHeight)
-        else
-            return VMAP_INVALID_HEIGHT_VALUE;               // we not have any height
-    }
+
+    return mapHeight;
 }
 
 inline bool IsOutdoorWMO(uint32 mogpFlags, int32 adtId, int32 rootId, int32 groupId,

src/game/TargetedMovementGenerator.cpp

@@ -74,6 +74,12 @@ void TargetedMovementGeneratorMedium<T,D>::_setTargetLocation(T &owner)
         if( i_destinationHolder.HasDestination() && i_destinationHolder.GetDestinationDiff(x,y,z) < bothObjectSize )
             return;
     */
+
+    // Just a temp hack, GetContactPoint/GetClosePoint in above code use UpdateGroundPositionZ (in GetNearPoint)
+    // and then has the wrong z to use when creature try follow unit in the air.
+    if (owner.GetTypeId() == TYPEID_UNIT && ((Creature*)&owner)->canFly())
+        z = i_target->GetPositionZ();
+
     Traveller<T> traveller(owner);
     i_destinationHolder.SetDestination(traveller, x, y, z);
 

src/game/Traveller.h

@@ -92,7 +92,7 @@ inline float Traveller<Creature>::GetMoveDestinationTo(float x, float y, float z
     float dx = x - GetPositionX();
     float dy = y - GetPositionY();
 
-    if(i_traveller.hasUnitState(UNIT_STAT_TAXI_FLIGHT))
+    if (i_traveller.canFly())
     {
         float dz = z - GetPositionZ();
         return sqrt((dx*dx) + (dy*dy) + (dz*dz));

src/game/Unit.cpp

@@ -8217,7 +8217,18 @@ void Unit::setDeathState(DeathState s)
 
         // after removing a Fearaura (in RemoveAllAurasOnDeath)
         // Unit::SetFeared is called and makes that creatures attack player again
-        StopMoving();
+        if (GetTypeId() == TYPEID_UNIT)
+        {
+            clearUnitState(UNIT_STAT_MOVING);
+
+            GetMap()->CreatureRelocation((Creature*)this, GetPositionX(), GetPositionY(), GetPositionZ(), GetOrientation());
+            SendMonsterMove(GetPositionX(), GetPositionY(), GetPositionZ(), SPLINETYPE_NORMAL, SPLINEFLAG_WALKMODE, 0);
+        }
+        else
+        {
+            if (!IsStopped())
+                StopMoving();
+        }
 
         ModifyAuraState(AURA_STATE_HEALTHLESS_20_PERCENT, false);
         ModifyAuraState(AURA_STATE_HEALTHLESS_35_PERCENT, false);

src/shared/revision_nr.h

@@ -1,4 +1,4 @@
 #ifndef __REVISION_NR_H__
 #define __REVISION_NR_H__
- #define REVISION_NR "10430"
+ #define REVISION_NR "10431"
 #endif // __REVISION_NR_H__