Vkm::Engine::NetSession Class Reference

One end of a game, whether it is the authority or a guest. More...

#include <net_session.h>

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	Holds the outstanding correction in the scene for one scope. More...
class	Rewind
	Puts every other player back where a shooter saw them, for one scope. More...

Public Member Functions
void	setWorld (uint64_t fingerprint)
	Say which world this end loaded, so both can agree they match.
bool	host (uint16_t port, uint32_t maxPlayers, uint32_t tickRate)
	Take players on port.
bool	connect (const NetAddress &server, uint32_t tickRate)
	Join the game at server.
void	close ()
	Say goodbye and go back to Offline. Safe to call when already offline.
void	onSpawn (NetServer::SpawnPlayer spawn, NetServer::DespawnPlayer despawn)
	What the game does when a player joins and leaves. Set before host().
bool	isDisconnected () const
	True when a session was open and the other end has gone.
bool	isPlaying () const
	True once this end can play: always for a server, and for a client from the Welcome until the connection ends.
const std::string &	lastError () const
	Why the last attempt to join ended, or an empty string.
NetAddress	localAddress () const
	The address this end is bound to; the real port after hosting on zero.
EntityId	localEntity () const
	The entity this end drives; null on a server.
float	roundTrip () const
	Round trip to the server, in seconds. Zero on a server or offline.
size_t	playerCount () const
	How many players this end knows of.
bool	simulates (EntityId entity) const
	Whether this end decides what happens to entity.
void	lease (const std::vector< EntityId > &entities)
	Also simulate entities, for a while.
size_t	leaseCount () const
	How many bodies this end is simulating on top of its own.
bool	isMine (EntityId entity) const
	Whether entity belongs to the player at this end.
const InputCommand &	commandFor (EntityId entity) const
	The input driving entity on the tick about to run.
void	receive (Scene &scene, ResourceManager &resources)
	Apply everything that has arrived.
const std::vector< InputCommand > &	replayCommands () const
	The ticks a correction wants run again, oldest first.
void	beginReplayTick (const InputCommand &command)
	Take command for a tick being run a second time.
void	endReplay (Scene &scene)
	Finish the replay and clear the request.
bool	replaying () const
	True while a tick that already happened is being run again.
void	endTick (Scene &scene, uint32_t tick)
	Record what this end predicted for the tick that just ran.
void	beginTick (uint32_t tick, const InputCommand &command, uint32_t actionCount, uint64_t actionNames=0)
	Take the command this tick runs under.
void	send (Scene &scene, uint32_t tick)
	Send what this frame produced. Called once a frame, after the ticks.
EntityId	spawn (Scene &scene, ResourceManager &resources, const std::string &prefab, const Transform &at)
	Build prefab at at, here and on every client.
void	advance (float seconds)
	Wall-clock time passing, for the timers that must run while the simulation does not - a paused editor still notices a peer leaving.
void	interpolate (Scene &scene, float deltaTime)
	Draw what this end is only told about where it was a moment ago.
float	renderDelay () const
	How far behind the server this end is drawing, in ticks; zero when it holds the present.
float	pacing () const
	How much faster than the wall clock this end should run its ticks.
float	predictionError () const
	How far this end's prediction of its own entity was out, last time the server said.
std::string	describe () const
	One line describing the session, for a log or a readout.

Detailed Description

One end of a game, whether it is the authority or a guest.

Not a System: it brackets the frame - what arrived is applied before the ticks that consume it, what happened is sent after them.

Offline is a real state: a single-player game's session answers every question as it would with no networking at all.

Member Function Documentation

setWorld()

void Vkm::Engine::NetSession::setWorld ( uint64_t fingerprint )

inline

Say which world this end loaded, so both can agree they match.

Slots name entities on the wire, so different scenes would agree on every name and mean different things. Zero means no file behind this world and is compared against nothing.

Parameters

fingerprint

What fingerprintScene said of the entry scene.

host()

bool Vkm::Engine::NetSession::host	(	uint16_t	port,
		uint32_t	maxPlayers,
		uint32_t	tickRate )

Take players on port.

A host referees and does not play; to play too, run a server and join it.

Parameters

port	UDP port to bind; zero takes whatever is free.
maxPlayers	Seats; a connection past the last is refused, and zero is refused.
tickRate	The clock's ticks a second; at most NET_MAX_TICK_RATE.

Returns

False when the port could not be bound, maxPlayers is zero, or tickRate is too fast.

connect()

bool Vkm::Engine::NetSession::connect	(	const NetAddress &	server,
		uint32_t	tickRate )

Join the game at server.

Parameters

server	Where the game is.
tickRate	The clock's ticks a second; at most NET_MAX_TICK_RATE.

Returns

False when the socket cannot be opened or tickRate is too fast. A refusal arrives later, as a state change.

isPlaying()

bool Vkm::Engine::NetSession::isPlaying

(

)

const

True once this end can play: always for a server, and for a client from the Welcome until the connection ends.

Returns

Whether this end can play.

localAddress()

NetAddress Vkm::Engine::NetSession::localAddress ( ) const

inline

The address this end is bound to; the real port after hosting on zero.

Returns

The bound address.

localEntity()

EntityId Vkm::Engine::NetSession::localEntity ( ) const

inline

The entity this end drives; null on a server.

Returns

The entity, or a null id.

playerCount()

size_t Vkm::Engine::NetSession::playerCount

(

)

const

How many players this end knows of.

Every seat on a server; only its own on a client, since who the others are never crosses the wire - a scoreboard replicates its own component keyed by PlayerId.

Returns

Seats known to this end.

simulates()

bool Vkm::Engine::NetSession::simulates

(

EntityId

entity

)

const

Whether this end decides what happens to entity.

A server says yes to everything, offline too; a client only to what it owns or leases. A client that loses or is refused by its server ends Disconnected and answers no to everything. Ask the role, not isPlaying(), which is false for both Disconnected and Offline.

Parameters

entity

The entity asked about; a null id is never simulated by a client.

Returns

Whether this end decides what happens to entity.

lease()

void Vkm::Engine::NetSession::lease ( const std::vector< EntityId > & entities )

inline

Also simulate entities, for a while.

For the pile this end's character is touching (see PhysicsSystem::leaseContacts); without it a pushed crate is predicted as a wall. A lease lapses a fixed number of ticks after its last report, not when contact breaks, so a bouncing body is not handed back and forth. Re-reporting refreshes, so pass the whole island every tick.

Parameters

entities

Bodies to simulate; null ids and this end's own entity are skipped.

leaseCount()

size_t Vkm::Engine::NetSession::leaseCount ( ) const

inline

How many bodies this end is simulating on top of its own.

Returns

The number of live leases.

isMine()

bool Vkm::Engine::NetSession::isMine

(

EntityId

entity

)

const

Whether entity belongs to the player at this end.

Parameters

entity

The entity asked about.

Returns

True for everything offline, for this end's own entity on a client, and for nothing on a server.

commandFor()

const InputCommand & Vkm::Engine::NetSession::commandFor

(

EntityId

entity

)

const

The input driving entity on the tick about to run.

Offline and on the owning client, the local command; on a server, the one that entity's player sent, consumed once. An entity no player owns gets a zeroed command.

Parameters

entity

The entity about to be driven.

Returns

The command it runs under this tick.

receive()

void Vkm::Engine::NetSession::receive	(	Scene &	scene,
		ResourceManager &	resources )

Apply everything that has arrived.

Once a frame, before the ticks. A join spawns a player on a server and a client builds spawned prefabs, hence the resource manager.

Parameters

scene	The world what arrived is applied to.
resources	Loads a spawned player's or prefab's assets.

replayCommands()

const std::vector< InputCommand > & Vkm::Engine::NetSession::replayCommands ( ) const

inline

The ticks a correction wants run again, oldest first.

Empty except in the frame a snapshot disagreed with the prediction. The caller drives them; the session cannot run a System.

Returns

The commands to run again, oldest first.

beginReplayTick()

void Vkm::Engine::NetSession::beginReplayTick

(

const InputCommand &

command

)

Take command for a tick being run a second time.

Not beginTick, which would queue it for sending again.

Parameters

command

The command that tick first ran under, from replayCommands().

replaying()

bool Vkm::Engine::NetSession::replaying ( ) const

inline

True while a tick that already happened is being run again.

Returns

Whether a replay is in progress.

endTick()

void Vkm::Engine::NetSession::endTick	(	Scene &	scene,
		uint32_t	tick )

Record what this end predicted for the tick that just ran.

Inside the fixed step, after the systems. Kept to compare against a later snapshot, which describes a moment this end has moved past.

Parameters

scene	The world as this tick left it.
tick	The tick that ran.

beginTick()

void Vkm::Engine::NetSession::beginTick	(	uint32_t	tick,
		const InputCommand &	command,
		uint32_t	actionCount,
		uint64_t	actionNames = 0 )

Take the command this tick runs under.

Inside the fixed step, after InputMap::beginTick. Both ends must agree on the action count (it sizes the encoding) and on which action has which slot (the fingerprint).

Parameters

tick	The tick about to run.
command	What the local player did on it.
actionCount	Action slots the project defines.
actionNames	InputMap::actionFingerprint, or zero to be compared against nothing.

spawn()

EntityId Vkm::Engine::NetSession::spawn	(	Scene &	scene,
		ResourceManager &	resources,
		const std::string &	prefab,
		const Transform &	at )

Build prefab at at, here and on every client.

On a server the root gets a NetSpawn, which replicates so every client, and every later joiner, builds the same file into it. Offline it is an ordinary instantiate. Undone by destroying the root's subtree (HierarchyOperations::destroyHierarchy or Behavior::destroy). Authority only: a client-only entity would be corrected out of existence.

Parameters

scene	World to build into.
resources	Resolves the prefab's asset names.
prefab	Project-relative path; on a server, one that names nothing outside the project - see isSayable.
at	Root pose; on a server, finite, with a rotation of some length and a bounded scale.

Returns

The instance root, or a null id when nothing was built.

advance()

void Vkm::Engine::NetSession::advance

(

float

seconds

)

Wall-clock time passing, for the timers that must run while the simulation does not - a paused editor still notices a peer leaving.

Parameters

seconds

Real seconds since the last call.

interpolate()

void Vkm::Engine::NetSession::interpolate	(	Scene &	scene,
		float	deltaTime )

Draw what this end is only told about where it was a moment ago.

Once a frame; a no-op except on a client. Also works off the step a body takes when its lease lapses and it drops back to being drawn.

Parameters

scene	World to smooth.
deltaTime	Real seconds since the last frame.

renderDelay()

float Vkm::Engine::NetSession::renderDelay

(

)

const

How far behind the server this end is drawing, in ticks; zero when it holds the present.

Returns

The delay, in ticks.

pacing()

float Vkm::Engine::NetSession::pacing

(

)

const

How much faster than the wall clock this end should run its ticks.

A playing client's answer from NetPacing; exactly one in every other role and state. See Clock::setPacing.

Returns

The rate scale; one outside a playing client.

predictionError()

float Vkm::Engine::NetSession::predictionError ( ) const

inline

How far this end's prediction of its own entity was out, last time the server said.

Returns

The error in metres; zero on a server and offline.

describe()

std::string Vkm::Engine::NetSession::describe

(

)

const

One line describing the session, for a log or a readout.

Connection, peers, their distance and prediction health; built on demand.

Returns

The line.

---

The documentation for this class was generated from the following file:

• net/net_session.h