search

denniskaselow / dartemis

A Dart port of the Artemis Entity System Framework
BSD 2-Clause "Simplified" License
47 stars 6 forks source link

readme

dartemis

Build Status Coverage Status Pub

Content

About

dartemis is a Dart port of the Entity System Framework Artemis.

The original has been written in Java by Arni Arent and Tiago Costa and can be found here: https://gamadu.com/artemis/ (archived) with the source available here: https://code.google.com/p/artemis-framework/

Ports for other languages are also available:

Some useful links about what an Entity System/Entity Component System is:

Getting started

  1. Add dartemis to your project by adding it to your pubspec.yaml:

    dependencies:
 dartemis: any

  2. Import it in your project:

    import 'package:dartemis/dartemis.dart';

  3. Create a world:

    final world = World();

  4. Create an entity from a list of components. Entities with different components will be processed by different systems:

    world.createEntity([
 Position(0, 0), 
 Velocity(1, 1),
]);

    A Component is a pretty simple structure and should not contain any logic:

    class Position extends Component {
 num x, y;
 Position(this.x, this.y);
}

    Or if you want to use a PooledComponent:

    class Position extends PooledComponent {
 late num x, y;

 Position._();
 factory Position(num x, num y) {
   final position = Pooled.of<Position>(() => Position._())
     ..x = x
     ..y = y;
   return position;
 }
}

    By using a factory constructor and calling the static function Pooled.of, dartemis is able to reuse destroyed components and they will not be garbage collected.

  5. Define a systems that should process your entities. The Aspect defines which components an entity needs to have in order to be processed by the system:

    class MovementSystem extends EntityProcessingSystem {
 late Mapper<Position> positionMapper;
 late Mapper<Velocity> velocityMapper;

 MovementSystem() : super(Aspect.forAllOf([Position, Velocity]));

 void initialize() {
   // initialize your system
   // Mappers, Systems and Managers have to be assigned here
   // see dartemis_builder if you don't want to write this code
   positionMapper = Mapper<Position>(world);
   velocityMapper = Mapper<Velocity>(world);
 }

 void processEntity(Entity entity) {
   Position position = positionMapper[entity];
   Velocity vel = velocityMapper[entity];
   position
     ..x += vel.x * world.delta
     ..y += vel.y * world.delta;
 }
}

    Or using dartemis_builder 

    part 'filename.g.part';

@Generate(
 EntityProcessingSystem,
 allOf: [
   Position,
   Velocity,
 ],
)
class SimpleMovementSystem extends _$SimpleMovementSystem {
 @override
 void processEntity(Entity entity, Position position, Velocity velocity) {    
   position
     ..x += velocity.x * world.delta
     ..y += velocity.y * world.delta;
 }
}

  6. Add your system to the world:

    world.addSystem(MovementSystem());

  7. Initialize the world:

    world.initialize();

  8. Usually your logic requires a delta, so you need to set it in your game loop:

    world.delta = delta;

  9. In your game loop you then process your systems:

    world.process();

Documentation

API

Reference Manual

Example Games using dartemis