From 2e1f848f09e14a81e469909f4507a37d218adfcb Mon Sep 17 00:00:00 2001
From: Jelle Meeus <sogladev@gmail.com>
Date: Tue, 29 Jul 2025 05:58:30 -0700
Subject: [PATCH] fix(Core/Unit): Add melee leeway for auto attacks (#22566)

---
 src/server/game/Entities/Object/ObjectDefines.h | 2 ++
 src/server/game/Entities/Unit/Unit.cpp          | 3 +++
 src/server/game/Entities/Unit/Unit.h            | 6 ++++++
 src/server/game/Spells/Spell.cpp                | 2 +-
 4 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/server/game/Entities/Object/ObjectDefines.h b/src/server/game/Entities/Object/ObjectDefines.h
index 2913e587b..bfae02203 100644
--- a/src/server/game/Entities/Object/ObjectDefines.h
+++ b/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);
diff --git a/src/server/game/Entities/Unit/Unit.cpp b/src/server/game/Entities/Unit/Unit.cpp
index 96a10b1c7..e1cd1735c 100644
--- a/src/server/game/Entities/Unit/Unit.cpp
+++ b/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;
 }
 
diff --git a/src/server/game/Entities/Unit/Unit.h b/src/server/game/Entities/Unit/Unit.h
index f83e2a623..4dc7cb585 100644
--- a/src/server/game/Entities/Unit/Unit.h
+++ b/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);
diff --git a/src/server/game/Spells/Spell.cpp b/src/server/game/Spells/Spell.cpp
index ca543c804..439713ee7 100644
--- a/src/server/game/Spells/Spell.cpp
+++ b/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;