ENTITY COMPONENT SYSTEM

ARCHITECTUREClean, fast and simple with Entitas and Unity

ARCHITECTUREwhy it matters

Simon SchmidEngineer

GAME DEVELOPMENTis hard

GAME ENGINE

ARCHITECTUREstill?

DESIGN PATTERNS

WHY SHOULD Icare

WHY SHOULD Icare

ENTITY COMPONENT SYSTEMARCHITECTURE

ENTITAS#1 ECS ON GITHUB

ENTITAS

cleanfast

simple

ENTITASINTRODUCTION

UNITY COMPONENTS:Data + Behaviour

ENTITAS COMPONENTSData only

public class Archer : Troop {

public int health; public float speed; // ...

void Awake() { // ... }

void Start() { // ... }

void Update() { // ... }}

public class Archer : Troop { // Inheritance

public int health; public float speed; // Data // ...

void Awake() { // ... } // Initialization

void Start() { // ... }

void Update() { // ... // Update }}

// Data only - no behaviour

public class PositionComponent : IComponent { public Vector3 value;}

public class MovableComponent : IComponent {}

+------------------+ | Pool | |------------------| | e e | +-----------+ | e e---|----> | Entity | | e e | |-----------| | e e e | | Component | | e e | | | +-----------+ | e e | | Component-|----> | Component | | e e e | | | |-----------| | e e e | | Component | | Data | +------------------+ +-----------+ +-----------+ | | | +-------------+ | | e | Groups | | e e | +---> | +------------+ | e | | | | e | e | e | +--------|----+ e | | e | | e e | +------------+

LOGIC?

Games are interactive simulations— Maxim Zaks

public class MovementSystem : IExecuteSystem {

public void Execute() {

var movables = Pools.pool.GetGroup( Matcher.AllOf( Matcher.Velocity, Matcher.Position ));

foreach (var e in movables.GetEntities()) { var pos = e.position.value; e.ReplacePosition(pos + e.velocity.value); } }}

SINGLE RESPONSIBILITYprinciple

SYSTEMSChain of Responsibility

+------------+ +------------+ +------------+ +------------+| | | | | | | || System | +---> | System | +---> | System | +---> | System || | | | | | | |+------------+ +------------+ +------------+ +------------+

SYSTEMSChain of Responsibility

|-------------------------------- Game Loop --------------------------------|

+------------+ +------------+ +------------+ +------------+| | | | | | | || System | +---> | System | +---> | System | +---> | System || | | | | | | |+------------+ +------------+ +------------+ +------------+

SYSTEMS IN ENTITAS- Initialize System- Execute System- Reactive System

DEMOMatch One

ENTITAS

▸ cleanfast

simple

CLEANSeparation of concerns

Composition over InheritanceSingle responsibility principle

Consistency

SEPARATION OFCONCERNS

Composition overINHERITANCE

SINGLE RESPONSIBILITYprinciple

public class MovementSystem : IExecuteSystem {

public void Execute() {

var movables = Pools.pool.GetGroup( Matcher.AllOf( Matcher.Velocity, Matcher.Position ));

foreach (var e in movables.GetEntities()) { var pos = e.position.value; e.ReplacePosition(pos + e.velocity.value); } }}

it["adds velocity to position"] = () => {

// given var pool = Pools.sharedInstance.core; var entity = pool.CreateEntity() .AddPosition(Vector3.one) .AddVelocity(Vector3.one);

var system = pool.CreateSystem(new MovementSystem());

// when system.Execute();

// then entity.position.value.should_be(new Vector3(2, 2, 2));};

CONSISTENCY

CLEANSeparation of concerns

Composition over InheritanceSingle responsibility principle

Consistency

ENTITAS

clean▸ fastsimple

UNITY VS ENTITAS: Objects1000 objects with 2 components

Memory: 9x (2.9 MB vs 0.32 MB)CPU: 17x (105 ms vs 6 ms)

ENTITAS VS UNITY: Logicupdate 25000 objects

Memory: 5x (36.4 MB vs 7.6 MB)CPU: 2x (20.5 ms vs 9.6 ms)

UNITY BLOG10000 Update() calls by Valentin Simonov

ENTITAS

cleanfast

▸ simple

SIMPLEsimilar to Unity

simple conventionseasy to add features

Visual DebuggingReusing code

SYSTEMSChain of Responsibility

+------------+ +------------+ +------------+ +------------+| | | | | | | || System | +---> | System | +---> | System | +---> | System || | | | | | | |+------------+ +------------+ +------------+ +------------+

SYSTEMSChain of Responsibility

+------------+ +------------+ +------------+| | | | | || System | +---> | System | +------------------------> | System || | | | | |+------------+ +------------+ +------------+

SYSTEMSChain of Responsibility

+------------+ +------------+ +------------+ +------------+| | | | | | | || System | +---> | System | +---> | System | +---> | System || | | | | | | |+------------+ +------------+ +------------+ +------------+

SIMPLEsimilar to Unity

simple conventionseasy to add features

Visual DebuggingReusing code

ENTITAS ISopen source

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WOOGA.COM/JOBS

QUESTIONS?#ENTITAS

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