From 2431b077cd2d99c7bf1fde4d3c93f937acef0cce Mon Sep 17 00:00:00 2001
From: Bond-009 <bond.009@outlook.com>
Date: Fri, 13 Jul 2018 00:10:15 +0200
Subject: Add unbreaking for armor (#4220)

Ref: minecraft.gamepedia.com/Enchanting#Unbreaking

#915
---
 src/Entities/Player.cpp | 55 +++++++++++++++++++++++++++++--------------------
 src/Entities/Player.h   |  4 ++++
 2 files changed, 37 insertions(+), 22 deletions(-)

diff --git a/src/Entities/Player.cpp b/src/Entities/Player.cpp
index c674f4620..e984534a5 100644
--- a/src/Entities/Player.cpp
+++ b/src/Entities/Player.cpp
@@ -934,17 +934,14 @@ void cPlayer::SetFlying(bool a_IsFlying)
 
 
 
-void cPlayer::ApplyArmorDamage(int DamageBlocked)
+void cPlayer::ApplyArmorDamage(int a_DamageBlocked)
 {
-	short ArmorDamage = static_cast<short>(DamageBlocked / 4);
-	if (ArmorDamage == 0)
+	short ArmorDamage = static_cast<short>(std::max(a_DamageBlocked / 4, 1));
+
+	for (int i = 0; i < 4; i++)
 	{
-		ArmorDamage = 1;
+		UseItem(cInventory::invArmorOffset + i, ArmorDamage);
 	}
-	m_Inventory.DamageItem(cInventory::invArmorOffset + 0, ArmorDamage);
-	m_Inventory.DamageItem(cInventory::invArmorOffset + 1, ArmorDamage);
-	m_Inventory.DamageItem(cInventory::invArmorOffset + 2, ArmorDamage);
-	m_Inventory.DamageItem(cInventory::invArmorOffset + 3, ArmorDamage);
 }
 
 
@@ -2334,20 +2331,7 @@ void cPlayer::UseEquippedItem(short a_Damage)
 		return;
 	}
 
-	// If the item has an unbreaking enchantment, give it a chance of escaping damage:
-	// Ref: https://minecraft.gamepedia.com/Enchanting#Unbreaking
-	cItem Item = GetEquippedItem();
-	int UnbreakingLevel = static_cast<int>(Item.m_Enchantments.GetLevel(cEnchantments::enchUnbreaking));
-	double chance = 1 - (1.0 / (UnbreakingLevel + 1));
-	if (GetRandomProvider().RandBool(chance))
-	{
-		return;
-	}
-
-	if (GetInventory().DamageEquippedItem(a_Damage))
-	{
-		m_World->BroadcastSoundEffect("entity.item.break", GetPosition(), 0.5f, static_cast<float>(0.75 + (static_cast<float>((GetUniqueID() * 23) % 32)) / 64));
-	}
+	UseItem(cInventory::invHotbarOffset + m_Inventory.GetEquippedSlotNum(), a_Damage);
 }
 
 
@@ -2369,6 +2353,33 @@ void cPlayer::UseEquippedItem(cItemHandler::eDurabilityLostAction a_Action)
 
 
 
+void cPlayer::UseItem(int a_SlotNumber, short a_Damage)
+{
+	const cItem & Item = m_Inventory.GetSlot(a_SlotNumber);
+	if (Item.IsEmpty())
+	{
+		return;
+	}
+
+	// Ref: https://minecraft.gamepedia.com/Enchanting#Unbreaking
+	unsigned int UnbreakingLevel = Item.m_Enchantments.GetLevel(cEnchantments::enchUnbreaking);
+	double chance = ItemCategory::IsArmor(Item.m_ItemType)
+		? (0.6 + (0.4 / (UnbreakingLevel + 1))) : (1.0 / (UnbreakingLevel + 1));
+
+	// When durability is reduced by multiple points
+	// Unbreaking is applied for each point of reduction.
+	std::binomial_distribution<short> Dist(a_Damage, chance);
+	short ReducedDamage = Dist(GetRandomProvider().Engine());
+	if (m_Inventory.DamageItem(a_SlotNumber, ReducedDamage))
+	{
+		m_World->BroadcastSoundEffect("entity.item.break", GetPosition(), 0.5f, static_cast<float>(0.75 + (static_cast<float>((GetUniqueID() * 23) % 32)) / 64));
+	}
+}
+
+
+
+
+
 void cPlayer::HandleFood(void)
 {
 	// Ref.: https://minecraft.gamepedia.com/Hunger
diff --git a/src/Entities/Player.h b/src/Entities/Player.h
index f04f90a2b..8fa463c5a 100644
--- a/src/Entities/Player.h
+++ b/src/Entities/Player.h
@@ -425,6 +425,10 @@ public:
 	is damaged by when used for a_Action */
 	void UseEquippedItem(cItemHandler::eDurabilityLostAction a_Action);
 
+	/** Damage the item in a_SlotNumber by a_Damage, possibly less if the
+	equipped item is enchanted. */
+	void UseItem(int a_SlotNumber, short a_Damage = 1);
+
 	void SendHealth(void);
 
 	void SendExperience(void);
-- 
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