fix(Core/Unit): Add melee leeway for auto attacks (#22566)

src/server/game/Entities/Object/ObjectDefines.h

@@ -48,6 +48,8 @@
 #define NOMINAL_MELEE_RANGE         5.0f
 #define MELEE_RANGE                 (NOMINAL_MELEE_RANGE - MIN_MELEE_REACH * 2) //center to center for players
 #define DEFAULT_COLLISION_HEIGHT    2.03128f                // Most common value in dbc
+#define LEEWAY_MIN_MOVE_SPEED       4.97f                   // NYI
+#define LEEWAY_BONUS_RANGE          2.66f
 
 // used for creating values for respawn for example
 inline uint32 PAIR64_HIPART(uint64 x);

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

@@ -674,6 +674,9 @@ bool Unit::IsWithinMeleeRange(Unit const* obj, float dist) const
 
     float maxdist = dist + GetMeleeRange(obj);
 
+    if ((IsPlayer() || obj->IsPlayer()) && HasLeewayMovement() && obj->HasLeewayMovement())
+        maxdist += LEEWAY_BONUS_RANGE;
+
     return distsq < maxdist * maxdist;
 }
 

src/server/game/Entities/Unit/Unit.h

@@ -1639,6 +1639,12 @@ public:
                              UNIT_STATE_ROOT | UNIT_STATE_STUNNED | UNIT_STATE_DISTRACTED) && !GetOwnerGUID();
     }
 
+    [[nodiscard]] bool HasLeewayMovement() const
+    {
+         return m_movementInfo.HasMovementFlag(MOVEMENTFLAG_FORWARD | MOVEMENTFLAG_STRAFE_LEFT | MOVEMENTFLAG_STRAFE_RIGHT | MOVEMENTFLAG_FALLING)
+                && !IsWalking();
+    }
+
     void KnockbackFrom(float x, float y, float speedXY, float speedZ);
     void JumpTo(float speedXY, float speedZ, bool forward = true);
     void JumpTo(WorldObject* obj, float speedZ);

src/server/game/Spells/Spell.cpp

@@ -7109,7 +7109,7 @@ SpellCastResult Spell::CheckRange(bool strict)
             if (range_type == SPELL_RANGE_MELEE)
             {
                 float real_max_range = max_range;
-                if (!m_caster->IsCreature() && m_caster->isMoving() && target->isMoving() && !m_caster->IsWalking() && !target->IsWalking())
+                if (!m_caster->IsCreature() && m_caster->HasLeewayMovement() && target->HasLeewayMovement())
                     real_max_range -= MIN_MELEE_REACH; // Because of lag, we can not check too strictly here (is only used if both caster and target are moving)
                 else
                     real_max_range -= 2 * MIN_MELEE_REACH;