6 files changed, 62 insertions, 53 deletions

diff --git a/src/Entities/Entity.cpp b/src/Entities/Entity.cpp
index 039c58ee4..c8df6b4b1 100644
--- a/src/Entities/Entity.cpp
+++ b/src/Entities/Entity.cpp
@@ -18,49 +18,50 @@
 
 
 
-int cEntity::m_EntityCount = 0;
+UInt32 cEntity::m_EntityCount = 0;
 cCriticalSection cEntity::m_CSCount;
 
 
 
 
 
-cEntity::cEntity(eEntityType a_EntityType, double a_X, double a_Y, double a_Z, double a_Width, double a_Height)
-	: m_UniqueID(0)
-	, m_Health(1)
-	, m_MaxHealth(1)
-	, m_AttachedTo(nullptr)
-	, m_Attachee(nullptr)
-	, m_bDirtyHead(true)
-	, m_bDirtyOrientation(true)
-	, m_bHasSentNoSpeed(true)
-	, m_bOnGround(false)
-	, m_Gravity(-9.81f)
-	, m_LastPos(a_X, a_Y, a_Z)
-	, m_IsInitialized(false)
-	, m_WorldTravellingFrom(nullptr)
-	, m_EntityType(a_EntityType)
-	, m_World(nullptr)
-	, m_IsFireproof(false)
-	, m_TicksSinceLastBurnDamage(0)
-	, m_TicksSinceLastLavaDamage(0)
-	, m_TicksSinceLastFireDamage(0)
-	, m_TicksLeftBurning(0)
-	, m_TicksSinceLastVoidDamage(0)
-	, m_IsSwimming(false)
-	, m_IsSubmerged(false)
-	, m_AirLevel(0)
-	, m_AirTickTimer(0)
-	, m_TicksAlive(0)
-	, m_HeadYaw(0.0)
-	, m_Rot(0.0, 0.0, 0.0)
-	, m_Pos(a_X, a_Y, a_Z)
-	, m_WaterSpeed(0, 0, 0)
-	, m_Mass (0.001)  // Default 1g
-	, m_Width(a_Width)
-	, m_Height(a_Height)
-	, m_InvulnerableTicks(0)
-{
+cEntity::cEntity(eEntityType a_EntityType, double a_X, double a_Y, double a_Z, double a_Width, double a_Height):
+	m_UniqueID(INVALID_ID),  // Proper ID will be assigned later in the constructor code
+	m_Health(1),
+	m_MaxHealth(1),
+	m_AttachedTo(nullptr),
+	m_Attachee(nullptr),
+	m_bDirtyHead(true),
+	m_bDirtyOrientation(true),
+	m_bHasSentNoSpeed(true),
+	m_bOnGround(false),
+	m_Gravity(-9.81f),
+	m_LastPos(a_X, a_Y, a_Z),
+	m_IsInitialized(false),
+	m_WorldTravellingFrom(nullptr),
+	m_EntityType(a_EntityType),
+	m_World(nullptr),
+	m_IsFireproof(false),
+	m_TicksSinceLastBurnDamage(0),
+	m_TicksSinceLastLavaDamage(0),
+	m_TicksSinceLastFireDamage(0),
+	m_TicksLeftBurning(0),
+	m_TicksSinceLastVoidDamage(0),
+	m_IsSwimming(false),
+	m_IsSubmerged(false),
+	m_AirLevel(0),
+	m_AirTickTimer(0),
+	m_TicksAlive(0),
+	m_HeadYaw(0.0),
+	m_Rot(0.0, 0.0, 0.0),
+	m_Pos(a_X, a_Y, a_Z),
+	m_WaterSpeed(0, 0, 0),
+	m_Mass (0.001),  // Default 1g
+	m_Width(a_Width),
+	m_Height(a_Height),
+	m_InvulnerableTicks(0)
+{
+	// Assign a proper ID:
 	cCSLock Lock(m_CSCount);
 	m_EntityCount++;
 	m_UniqueID = m_EntityCount;
diff --git a/src/Entities/Entity.h b/src/Entities/Entity.h
index 809e974d2..9bb1837f1 100644
--- a/src/Entities/Entity.h
+++ b/src/Entities/Entity.h
@@ -142,6 +142,10 @@ public:
 	
 	static const int VOID_BOUNDARY         = -46;  ///< Y position to begin applying void damage
 	static const int FALL_DAMAGE_HEIGHT    = 4;    ///< Y difference after which fall damage is applied
+
+	/** Special ID that is considered an "invalid value", signifying no entity. */
+	static const UInt32 INVALID_ID = 0;  // Exported to Lua in ManualBindings.cpp, ToLua doesn't parse initialized constants.
+
 	
 	cEntity(eEntityType a_EntityType, double a_X, double a_Y, double a_Z, double a_Width, double a_Height);
 	virtual ~cEntity();
@@ -248,7 +252,7 @@ public:
 	virtual void HandleSpeedFromAttachee(float a_Forward, float a_Sideways);
 	void SteerVehicle(float a_Forward, float a_Sideways);
 
-	inline int  GetUniqueID(void) const { return m_UniqueID; }
+	inline UInt32 GetUniqueID(void) const { return m_UniqueID; }
 	inline bool IsDestroyed(void) const { return !m_IsInitialized; }
 
 	/// Schedules the entity for destroying; if a_ShouldBroadcast is set to true, broadcasts the DestroyEntity packet
@@ -464,12 +468,15 @@ public:
 
 protected:
 	static cCriticalSection m_CSCount;
-	static int m_EntityCount;
+	static UInt32 m_EntityCount;
 	
 	/** Measured in meter/second (m/s) */
 	Vector3d m_Speed;
 
-	int m_UniqueID;
+	/** The ID of the entity that is guaranteed to be unique within a single run of the server.
+	Always nonzero (a zero UniqueID (cEntity::INVALID_ID) is used for error reporting).
+	Note that the UniqueID is not persisted through storage. */
+	UInt32 m_UniqueID;
 	
 	int m_Health;
 	int m_MaxHealth;
diff --git a/src/Entities/ItemFrame.h b/src/Entities/ItemFrame.h
index 2444b26a3..ff43e5ee1 100644
--- a/src/Entities/ItemFrame.h
+++ b/src/Entities/ItemFrame.h
@@ -24,7 +24,7 @@ public:
 	// tolua_begin
 
 	/** Returns the item in the frame */
-	const cItem & GetItem(void) { return m_Item; }
+	const cItem & GetItem(void) const { return m_Item; }
 
 	/** Set the item in the frame */
 	void SetItem(cItem & a_Item) { m_Item = a_Item; }
diff --git a/src/Entities/Minecart.cpp b/src/Entities/Minecart.cpp
index a32926838..ee10cf6b3 100644
--- a/src/Entities/Minecart.cpp
+++ b/src/Entities/Minecart.cpp
@@ -24,7 +24,7 @@ class cMinecartCollisionCallback :
 	public cEntityCallback
 {
 public:
-	cMinecartCollisionCallback(Vector3d a_Pos, double a_Height, double a_Width, int a_UniqueID, int a_AttacheeUniqueID) :
+	cMinecartCollisionCallback(Vector3d a_Pos, double a_Height, double a_Width, UInt32 a_UniqueID, UInt32 a_AttacheeUniqueID) :
 		m_DoesInteserct(false),
 		m_CollidedEntityPos(0, 0, 0),
 		m_Pos(a_Pos),
@@ -77,8 +77,8 @@ protected:
 
 	Vector3d m_Pos;
 	double m_Height, m_Width;
-	int m_UniqueID;
-	int m_AttacheeUniqueID;
+	UInt32 m_UniqueID;
+	UInt32 m_AttacheeUniqueID;
 };
 
 
@@ -824,7 +824,10 @@ bool cMinecart::TestBlockCollision(NIBBLETYPE a_RailMeta)
 
 bool cMinecart::TestEntityCollision(NIBBLETYPE a_RailMeta)
 {
-	cMinecartCollisionCallback MinecartCollisionCallback(GetPosition(), GetHeight(), GetWidth(), GetUniqueID(), ((m_Attachee == nullptr) ? -1 : m_Attachee->GetUniqueID()));
+	cMinecartCollisionCallback MinecartCollisionCallback(
+		GetPosition(), GetHeight(), GetWidth(), GetUniqueID(),
+		((m_Attachee == nullptr) ? cEntity::INVALID_ID : m_Attachee->GetUniqueID())
+	);
 	int ChunkX, ChunkZ;
 	cChunkDef::BlockToChunk(POSX_TOINT, POSZ_TOINT, ChunkX, ChunkZ);
 	m_World->ForEachEntityInChunk(ChunkX, ChunkZ, MinecartCollisionCallback);
diff --git a/src/Entities/ProjectileEntity.cpp b/src/Entities/ProjectileEntity.cpp
index 21ec4e63a..4684e3e09 100644
--- a/src/Entities/ProjectileEntity.cpp
+++ b/src/Entities/ProjectileEntity.cpp
@@ -221,7 +221,7 @@ cProjectileEntity::cProjectileEntity(eKind a_Kind, cEntity * a_Creator, double a
 	super(etProjectile, a_X, a_Y, a_Z, a_Width, a_Height),
 	m_ProjectileKind(a_Kind),
 	m_CreatorData(
-		((a_Creator != nullptr) ? a_Creator->GetUniqueID() : -1),
+		((a_Creator != nullptr) ? a_Creator->GetUniqueID() : cEntity::INVALID_ID),
 		((a_Creator != nullptr) ? (a_Creator->IsPlayer() ? ((cPlayer *)a_Creator)->GetName() : "") : ""),
 		((a_Creator != nullptr) ? a_Creator->GetEquippedWeapon().m_Enchantments : cEnchantments())
 	),
diff --git a/src/Entities/ProjectileEntity.h b/src/Entities/ProjectileEntity.h
index 93e442d8c..de460a8ad 100644
--- a/src/Entities/ProjectileEntity.h
+++ b/src/Entities/ProjectileEntity.h
@@ -69,7 +69,7 @@ public:
 	/** Returns the unique ID of the entity who created this projectile
 	May return an ID <0
 	*/
-	int GetCreatorUniqueID(void) { return m_CreatorData.m_UniqueID; }
+	UInt32 GetCreatorUniqueID(void) { return m_CreatorData.m_UniqueID; }
 
 	/** Returns the name of the player that created the projectile
 	Will be empty for non-player creators
@@ -90,18 +90,17 @@ public:
 protected:
 
 	/** A structure that stores the Entity ID and Playername of the projectile's creator
-	Used to migitate invalid pointers caused by the creator being destroyed
-	*/
+	Used to migitate invalid pointers caused by the creator being destroyed. */
 	struct CreatorData
 	{
-		CreatorData(int a_UniqueID, const AString & a_Name, const cEnchantments & a_Enchantments) :
+		CreatorData(UInt32 a_UniqueID, const AString & a_Name, const cEnchantments & a_Enchantments) :
 			m_UniqueID(a_UniqueID),
 			m_Name(a_Name),
 			m_Enchantments(a_Enchantments)
 		{
 		}
 
-		const int m_UniqueID;
+		const UInt32 m_UniqueID;
 		AString m_Name;
 		cEnchantments m_Enchantments;
 	};
@@ -110,8 +109,7 @@ protected:
 	eKind m_ProjectileKind;
 	
 	/** The structure for containing the entity ID and name who has created this projectile
-	The ID and/or name may be nullptr (e.g. for dispensers/mobs)
-	*/
+	The ID and/or name may be nullptr (e.g. for dispensers/mobs). */
 	CreatorData m_CreatorData;
 	
 	/** True if the projectile has hit the ground and is stuck there */