New API for assigning unique network ids to objects

src/common/objects/dobject.cpp

@@ -218,6 +218,8 @@ CCMD (dumpclasses)
 //
 //==========================================================================
 
+#include "d_net.h"
+
 void DObject::InPlaceConstructor (void *mem)
 {
 	new ((EInPlace *)mem) DObject;
@@ -317,6 +319,8 @@ void DObject::Release()
 
 void DObject::Destroy ()
 {
+	NetworkEntityManager::RemoveNetworkEntity(this);
+
 	// We cannot call the VM during shutdown because all the needed data has been or is in the process of being deleted.
 	if (PClass::bVMOperational)
 	{
@@ -504,8 +508,15 @@ void DObject::Serialize(FSerializer &arc)
 
 	SerializeFlag("justspawned", OF_JustSpawned);
 	SerializeFlag("spawned", OF_Spawned);
-
+	SerializeFlag("networked", OF_Networked);
+
 	ObjectFlags |= OF_SerialSuccess;
+
+	if (arc.isReading() && (ObjectFlags & OF_Networked))
+	{
+		ClearNetworkID();
+		EnableNetworking(true);
+	}
 }
 
 void DObject::CheckIfSerialized () const
@@ -520,6 +531,73 @@ void DObject::CheckIfSerialized () const
 	}
 }
 
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
+void DObject::SetNetworkID(const uint32_t id)
+{
+	if (!IsNetworked())
+	{
+		ObjectFlags |= OF_Networked;
+		_networkID = id;
+	}
+}
+
+void DObject::ClearNetworkID()
+{
+	ObjectFlags &= ~OF_Networked;
+	_networkID = NetworkEntityManager::WorldNetID;
+}
+
+void DObject::EnableNetworking(const bool enable)
+{
+	if (enable)
+		NetworkEntityManager::AddNetworkEntity(this);
+	else
+		NetworkEntityManager::RemoveNetworkEntity(this);
+}
+
+static unsigned int GetNetworkID(DObject* const self)
+{
+	return self->GetNetworkID();
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(DObject, GetNetworkID, GetNetworkID)
+{
+	PARAM_SELF_PROLOGUE(DObject);
+
+	ACTION_RETURN_INT(self->GetNetworkID());
+}
+
+static void EnableNetworking(DObject* const self, const bool enable)
+{
+	self->EnableNetworking(enable);
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(DObject, EnableNetworking, EnableNetworking)
+{
+	PARAM_SELF_PROLOGUE(DObject);
+	PARAM_BOOL(enable);
+
+	self->EnableNetworking(enable);
+	return 0;
+}
+
+static DObject* GetNetworkEntity(const unsigned int id)
+{
+	return NetworkEntityManager::GetNetworkEntity(id);
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(DObject, GetNetworkEntity, GetNetworkEntity)
+{
+	PARAM_PROLOGUE;
+	PARAM_UINT(id);
+
+	ACTION_RETURN_OBJECT(NetworkEntityManager::GetNetworkEntity(id));
+}
 
 DEFINE_ACTION_FUNCTION(DObject, MSTime)
 {

src/common/objects/dobject.h

@@ -351,6 +351,17 @@ class DObject
 		friend T* Create(Args&&... args);
 
 	friend class JitCompiler;
+
+private:
+	// This is intentionally left unserialized.
+	uint32_t _networkID;
+
+public:
+	inline bool IsNetworked() const { return (ObjectFlags & OF_Networked); }
+	inline uint32_t GetNetworkID() const { return _networkID; }
+	void SetNetworkID(const uint32_t id);
+	void ClearNetworkID();
+	virtual void EnableNetworking(const bool enable);
 };
 
 // This is the only method aside from calling CreateNew that should be used for creating DObjects

src/common/objects/dobjgc.h

@@ -26,6 +26,7 @@ enum EObjectFlags
 	OF_Transient		= 1 << 11,		// Object should not be archived (references to it will be nulled on disk)
 	OF_Spawned			= 1 << 12,      // Thinker was spawned at all (some thinkers get deleted before spawning)
 	OF_Released			= 1 << 13,		// Object was released from the GC system and should not be processed by GC function
+	OF_Networked		= 1 << 14,		// Object has a unique network identifier that makes it synchronizable between all clients.
 };
 
 template<class T> class TObjPtr;

src/d_main.cpp

@@ -3100,6 +3100,8 @@ static int FileSystemPrintf(FSMessageLevel level, const char* fmt, ...)
 
 static int D_InitGame(const FIWADInfo* iwad_info, std::vector<std::string>& allwads, std::vector<std::string>& pwads)
 {
+	NetworkEntityManager::InitializeNetworkEntities();
+
 	if (!restart)
 	{
 		V_InitScreenSize();

src/d_net.cpp

@@ -2965,6 +2965,89 @@ int Net_GetLatency(int *ld, int *ad)
 	return severity;
 }
 
+void NetworkEntityManager::InitializeNetworkEntities()
+{
+	if (!s_netEntities.Size())
+		s_netEntities.AppendFill(nullptr, NetIDStart); // Allocate the first 0-8 slots for the world and clients.
+}
+
+// Clients need special handling since they always go in slots 1 - MAXPLAYERS.
+void NetworkEntityManager::SetClientNetworkEntity(player_t* const client)
+{
+	AActor* const mo = client->mo;
+	const uint32_t id = ClientNetIDStart + mo->Level->PlayerNum(client);
+
+	// If resurrecting, we need to swap the corpse's position with the new pawn's
+	// position so it's no longer considered the client's body.
+	DObject* const oldBody = s_netEntities[id];
+	if (oldBody != nullptr)
+	{
+		if (oldBody == mo)
+			return;
+
+		const uint32_t curID = mo->GetNetworkID();
+
+		s_netEntities[curID] = oldBody;
+		oldBody->ClearNetworkID();
+		oldBody->SetNetworkID(curID);
+
+		mo->ClearNetworkID();
+	}
+	else
+	{
+		RemoveNetworkEntity(mo); // Free up its current id.
+	}
+
+	s_netEntities[id] = mo;
+	mo->SetNetworkID(id);
+}
+
+void NetworkEntityManager::AddNetworkEntity(DObject* const ent)
+{
+	if (ent->IsNetworked())
+		return;
+
+	// Slot 0 is reserved for the world.
+	// Clients go in the first 1 - MAXPLAYERS slots
+	// Everything else is first come first serve.
+	uint32_t id = WorldNetID;
+	if (s_openNetIDs.Size())
+	{
+		s_openNetIDs.Pop(id);
+		s_netEntities[id] = ent;
+	}
+	else
+	{
+		id = s_netEntities.Push(ent);
+	}
+
+	ent->SetNetworkID(id);
+}
+
+void NetworkEntityManager::RemoveNetworkEntity(DObject* const ent)
+{
+	if (!ent->IsNetworked())
+		return;
+
+	const uint32_t id = ent->GetNetworkID();
+	if (id == WorldNetID)
+		return;
+
+	assert(s_netEntities[id] == ent);
+	if (id >= NetIDStart)
+		s_openNetIDs.Push(id);
+	s_netEntities[id] = nullptr;
+	ent->ClearNetworkID();
+}
+
+DObject* NetworkEntityManager::GetNetworkEntity(const uint32_t id)
+{
+	if (id == WorldNetID || id >= s_netEntities.Size())
+		return nullptr;
+
+	return s_netEntities[id];
+}
+
 // [RH] List "ping" times
 CCMD (pings)
 {

src/d_net.h

@@ -95,6 +95,29 @@ extern	int 			nodeforplayer[MAXPLAYERS];
 extern	ticcmd_t		netcmds[MAXPLAYERS][BACKUPTICS];
 extern	int 			ticdup;
 
+class player_t;
+class DObject;
+
+class NetworkEntityManager
+{
+private:
+	inline static TArray<DObject*> s_netEntities = {};
+	inline static TArray<uint32_t> s_openNetIDs = {};
+
+public:
+	NetworkEntityManager() = delete;
+
+	inline static uint32_t WorldNetID = 0u;
+	inline static uint32_t ClientNetIDStart = 1u;
+	inline static uint32_t NetIDStart = MAXPLAYERS + 1u;
+
+	static void InitializeNetworkEntities();
+	static void SetClientNetworkEntity(player_t* const client);
+	static void AddNetworkEntity(DObject* const ent);
+	static void RemoveNetworkEntity(DObject* const ent);
+	static DObject* GetNetworkEntity(const uint32_t id);
+};
+
 // [RH]
 // New generic packet structure:
 //

src/g_game.cpp

@@ -1424,6 +1424,7 @@ void FLevelLocals::PlayerReborn (int player)
 	p->oldbuttons = ~0, p->attackdown = true; p->usedown = true;	// don't do anything immediately
 	p->original_oldbuttons = ~0;
 	p->playerstate = PST_LIVE;
+	NetworkEntityManager::SetClientNetworkEntity(p);
 
 	if (gamestate != GS_TITLELEVEL)
 	{

src/p_saveg.cpp

@@ -62,6 +62,7 @@
 #include "fragglescript/t_script.h"
 #include "s_music.h"
 #include "model.h"
+#include "d_net.h"
 
 EXTERN_CVAR(Bool, save_formatted)
 
@@ -653,6 +654,15 @@ void FLevelLocals::SerializePlayers(FSerializer &arc, bool skipload)
 				ReadMultiplePlayers(arc, numPlayers, numPlayersNow, skipload);
 			}
 			arc.EndArray();
+
+			if (!skipload)
+			{
+				for (unsigned int i = 0u; i < MAXPLAYERS; ++i)
+				{
+					if (PlayerInGame(i) && Players[i]->mo != nullptr)
+						NetworkEntityManager::SetClientNetworkEntity(Players[i]);
+				}
+			}
 		}
 		if (!skipload && numPlayersNow > numPlayers)
 		{

src/playsim/actor.h

@@ -794,6 +794,7 @@ class AActor final : public DThinker
 	virtual void PostSerialize() override;
 	virtual void PostBeginPlay() override;		// Called immediately before the actor's first tick
 	virtual void Tick() override;
+	void EnableNetworking(const bool enable) override;
 
 	static AActor *StaticSpawn (FLevelLocals *Level, PClassActor *type, const DVector3 &pos, replace_t allowreplacement, bool SpawningMapThing = false);
 

src/playsim/p_mobj.cpp

@@ -100,6 +100,7 @@
 #include "a_dynlight.h"
 #include "fragglescript/t_fs.h"
 #include "shadowinlines.h"
+#include "d_net.h"
 
 // MACROS ------------------------------------------------------------------
 
@@ -178,6 +179,23 @@ IMPLEMENT_POINTERS_START(AActor)
 	IMPLEMENT_POINTER(boneComponentData)
 IMPLEMENT_POINTERS_END
 
+//==========================================================================
+//
+// Make sure Actors can never have their networking disabled.
+//
+//==========================================================================
+
+void AActor::EnableNetworking(const bool enable)
+{
+	if (!enable)
+	{
+		ThrowAbortException(X_OTHER, "Cannot disable networking on Actors. Consider a Thinker instead.");
+		return;
+	}
+
+	Super::EnableNetworking(true);
+}
+
 //==========================================================================
 //
 // AActor :: Serialize
@@ -4775,6 +4793,7 @@ AActor *AActor::StaticSpawn(FLevelLocals *Level, PClassActor *type, const DVecto
 	AActor *actor;
 
 	actor = static_cast<AActor *>(Level->CreateThinker(type));
+	actor->EnableNetworking(true);
 
 	ConstructActor(actor, pos, SpawningMapThing);
 	return actor;

wadsrc/static/zscript/doombase.zs

@@ -137,6 +137,9 @@ extend class Object
 	native static void MarkSound(Sound snd);
 	native static uint BAM(double angle);
 	native static void SetMusicVolume(float vol);
+	native clearscope static Object GetNetworkEntity(uint id);
+	native play void EnableNetworking(bool enable);
+	native clearscope uint GetNetworkID() const;
 }
 
 class Thinker : Object native play