1. О докладчике
Якимец Максим
C# на сервере

2. Использование
Entity Component System
при разработке игр.

4. Структура доклада
•
•
•
•
•
•
•
•
Что предлагает ООП
Различные Entity Component Systems
Выбор Artemis
Описание игрового мира. Примеры
AI, Scripting
Физика
Сеть
Tips & Tricks

5. Что предлагает ООП?
•
•
•
•
•
•
Множественное наследование
Множество классов
Композиция
Типажи (traits)
АОП
Паттерн “Стратегия”
Множественное поведение

6. Entity Component Systems
Unity
Ash
Ember
Artemis
Apollo

7. Artemis
Entity System Framework

8. Entity Component System
Artemis
•
•
•
•
Entity
- ID.
Components - данные
Systems
- логика, поведение
Managers - управление данными, запросы
Data Oriented Design

9. Artemis
var world = new EntityWorld(initializeAll: true);
Entity entity = world.CreateEntity();
entity.Add(new Transform(100, 100));
entity.Add(new Velocity(1, 1));

10. Artemis
var frameTime = watch.Elapsed - currentTime;
accumulator += frameTime;
while (accumulator >= minDelta)
{
entityWorld.Update(minDelta);
accumulator -= minDelta;
}
currentTime = watch.Elapsed;

11. MovementSystem
[ArtemisEntitySystem]
public class MovementSystem : EntityProcessingSystem
{
public MovementSystem()
: base(Aspect.All(typeof(Transform), typeof(Velocity)))
{
}
...
}

12. MovementSystem
public override void Process(Entity entity)
{
var velocity = entity.Get<Velocity>();
var transform = entity.Get<Transform>();
var seconds = this.EntityWorld.Delta.TotalSeconds;
transform.X += velocity.X * seconds;
transform.Y += velocity.Y * seconds;
}

13. [ArtemisEntitySystem]
public class AfterlifeSystem : EntityProcessingSystem
{
public event Action<Entity> EntityVanishing;
public AfterlifeSystem()
: base(Aspect.All(typeof(KilledComponent)))
{
}
public override void Process(Entity entity)
{
var expiresComponent = entity.Get<ExpiresComponent>();
if (expiresComponent == null || expiresComponent.IsExpired)
{
this.OnEntityVanishing(entity);
entity.Delete();
}
}
private void OnEntityVanishing(Entity entity)
{
var handler = this.EntityVanishing;
if (handler != null)
{
handler(entity);
}
}

14. Описание игрового мира
Position (Transform)
Velocity (Movement)
Lifetime (Expires)
Health (Destroyable)
Attack (Damager)
Dead (Killed)
Gold
BountyReward
Bonus
InputController
Animation
Collider
Physics
MovementSystem
ExpirationSystem
AttackSystem
AfterlifeSystem
BonusSystem
BountyRewardSystem
AnimationSystem
RenderSystem
PhysicsSystem

15. Описание игрового мира
CellPosition
ScreenPosition
Damager
TimedEffect
Spreadable
Destroyable
Collidable
BombLayer
Powerup

16. Описание игрового мира
EnemyComponent
ExpiresComponent
HealthComponent
WeaponComponent
TransformComponent
VelocityComponent
SpatialFormComponent

17. Описание игрового мира
EnemyComponent
ExpiresComponent
HealthComponent
WeaponComponent
TransformComponent
VelocityComponent
SpatialFormComponent
EnemyShipMovementSystem
ExpirationSystem
EnemyShooterSystem
PlayerShipControlSystem
CollisionSystem
MovementSystem
RenderSystem
HudRenderSystem
EnemySpawnSystem

18. Scripting
public class ScriptComponent: IComponent
{
public IScript Script { get; set; }
}
public interface IScript
{
void Init(EntityWorld world, Entity entity);
void Update();
}

19. Scripting
ScriptComponent (IScript) + ScriptSystem
vs
BehaviorXComponent + BehaviorXSystem
BehaviorYComponent + BehaviorYSystem

20. AI: BehaviorLibrary
public class AIComponent: IComponent
{
public Behavior Behavior { get; set; }
}
public class AISystem : EntityProcessingSystem
{
public override void Process(Entity entity)
{
entity.Get<AIComponent>().Behavior.Behave();
}
}

21. Физика
PhysicsComponent:
Body
PhysicsSystem:
OnAdded
-> physicsWorld.Add(body)
OnRemoved -> physicsWorld.Remove(body)
ProcessEntities -> physicsWorld.Step();

22. Физика: Position
PositionComponent
PhysicsComponent:
Body (Position + Form)

23. Сеть
• ECS на сервере и на клиенте
• ECS на сервере, ООП на клиенте

24. Сеть
foreach (Entity player in this.players)
{
float gold = player.Get<Gold>().Value;
if (this.playersGold[player.Id] != gold)
{
this.playersGold[player.Id] = gold;
this.RaiseGoldChangedEvent(gold, player);
}
}

25. Tips & tricks
Взаимодействие
между частями Entity System
Entity-Entity
Component-Component
Entity-Component
System-System

26. Tips & tricks
• Порядок срабатывания систем
• Удаление/добавление Component
• Удаление Entity

27. Tips & tricks
Pooling
•
•
entity pool
component pool
Проблема с переиспользованием Entity.Id

28. Tips & tricks
Карта - это Entity? Component?

29. Tips & tricks
Связи между Entity:
references
IDs
Managers
System data
•
•
•
•

30. Пример: инвентарь
public class InventoryComponent: IComponent
{
public List<Entity> Items { get; set; }
}
public class InventoryItemComponent: IComponent
{
public Entity Inventory { get; set; }
}
public class InventoryManager
{
private Dictionary<Entity, List<Entity>> inventories;
}

31. Пример: Заклинания
•
•
•
•
•
•
Удар молнии = Position + Damage + Attacking
Камнепад
= Position + Damage + AoE + Attacking
Мина
= Position + Damage + AoE
Бомба с фитилем = Position + Damage + AoE +
Expires + AttackOnExpires
Болото
= Position + AoE + Expires + BuffSource
Усиление = Position + AoE + Expires(0) + BuffSource

32. Пример: неуязвимость
Неуязвимость
HealthComponent
DefenseComponent

33. “Build games, not engines”
“A game is just a real-time
database with a pretty
graphical front end.”
“Entity Systems are the
future of MMOs”
“Do not try and bend the spoon
- that's impossible. Instead, only
try to realize the truth… There is
no spoon.”
“Build games, not elaborate component systems!”
maximusya@tut.by