- Improve game performance: By decoupling game logic from the representation of game objects, ECS can significantly enhance performance through efficient data organization and optimized component updates. Increase code reusability: Components can be easily reused across different entities, promoting modularity and reducing code duplication.
- Simplify game development: The ECS architecture makes it easier to manage and maintain complex game systems, as game logic is organized in a more structured and predictable way.
- Entity Creation: Easily create entities and attach components to them.
- Event Handling: Implement event-driven architecture with custom events and event handlers.
- Coroutines: Create a coroutine to be executed at specific intervals or delays.
- Queries: Efficiently query entities based on their components.
- Systems: Implement game logic and behaviors through systems that process entities based on queries.
- Extensions: Extend the functionality of the ECS with custom extensions.
- Chained Building: World could be create by a chain of methods.
Demonstrates how to use the Prometheus library to create an Entity Component System (ECS) in Swift. The example includes creating components, querying entities, and setting up systems to interact xqwith those components.
First, add the PrometheusECS dependency to your Package.swift:
For this example the necessary imports:
import PrometheusECSDefine your components. Components are data associated with entities.
class Position : Component {
public var x: Int
public var y: Int
init(x: Int, y: Int) {
self.x = x
self.y = y
}
}Define systems to operate on entities that have specific components. Systems are functions that process entities.
func mutateCompoentInsideSystem(entityManager: EntityManager) throws {
try entityManager.addEntity(components: Position(x: 2, y: 2))
}
func mutateComponentSystem(query: Query<Position>) {
for position in query {
position.x += 1
}
}Define events that can be published and subscribed to within the world.
class SpawnEvent : Event {
public let entity: Entity
init(entity: Entity) {
self.entity = entity
}
}
func spawn(entityManager: EntityManager,eventManager: EventManager, query: Query<Entity, Health, Position>) {
print("Spawn")
for q in query{
try? entityManager.addComponentToEntity(entity: q.0, component: Velocity(dx: 0, dy: 0))
print(q.0)
}
eventManager.subscribe(SpawnEvent.self) { (world: World, ev: SpawnEvent) in
print("Ev: \(ev.entity)")
}
}Define resources that are globally accessible by systems.
class GameState : Component{
public enum State {
case playing
case paused
}
var state: State = .playing
}
func initResource(resourceManager: ResourceManager) {
resourceManager.createResource(GameState())
}
func getResource(gameState: Resource<GameState>) {
print(gameState.data.state)
}
Define easy extensions to your world.
class ExtensionExample: PluginBuilder {
func build(_ world: PrometheusECS.World) throws {
try world.addEntity(components: Velocity(dx: 0, dy: 0))
}
}Set up the world, create entities, add systems, and run the ECS.
import PrometheusECS
final class Health: Component {
var health: Int = 0
init(health: Int) {
self.health = health
}
}
extension Health : CustomStringConvertible {
var description: String {
"Health: \(health)"
}
}
class Position: Component {
var x: Int = 0
var y: Int = 0
init(x: Int, y: Int) {
self.x = x
self.y = y
}
}
extension Position: CustomStringConvertible{
var description: String {
"Position: (\(x),\(y))"
}
}
class Velocity: Component {
var dx: Int = 0
var dy: Int = 0
init(dx: Int, dy: Int) {
self.dx = dx
self.dy = dy
}
}
class GameState : Component{
public enum State {
case playing
case paused
}
var state: State = .playing
}
class SpawnEvent : Event {
public let entity: Entity
init(entity: Entity) {
self.entity = entity
}
}
extension Velocity: CustomStringConvertible {
var description: String {
"Velocity: (\(dx),\(dy))"
}
}
var world = World()
try world.addEntity(components: Health(health: 100), Position(x: 0, y: 0))
try world.addEntity(components: Health(health: 200))
try world.addEntity(components: Velocity(dx: 20, dy: 0), Health(health: 70))
let q = world.query(requiredAll: Health.self, Position.self)
for (e, p) in q {
print(p, e.health)
}
func spawn(entityManager: EntityManager,eventManager: EventManager, query: Query<Entity, Health, Position>) {
print("Spawn")
for q in query{
try? entityManager.addComponentToEntity(entity: q.0, component: Velocity(dx: 0, dy: 0))
print(q.0)
}
eventManager.subscribe(SpawnEvent.self) { (world: World, ev: SpawnEvent) in
print("Ev: \(ev.entity)")
}
}
func checkWithAddComponent(entityManager: EntityManager,eventManager: EventManager, query: Query<Entity, Health, Position, Velocity>) {
print("Check")
for q in query{
_ = try? entityManager.removeComponentFromEntity(entity: q.0) as Velocity.Type
print("Second \(q.0)")
eventManager.publish( SpawnEvent(entity: q.0))
}
}
func removeEntity(entityManager: EntityManager, query: QueryWithFilter<QueryBuilder<Entity, Health>, QueryBuilderExclude<Position>>) {
for (entity,_ ) in query {
try? entityManager.removeEntity(entity)
print("Remove entity \(entity)")
}
}
func initResource(resourceManager: ResourceManager) {
resourceManager.createResource(GameState())
}
func getResource(gameState: Resource<GameState>) {
print(gameState.data.state)
}
func coroutineManagerTest(coroutineManager: CoroutineManager){
coroutineManager.addCoroutine(name: "CoroutineTest", action: [
(10.0, {(World) in print("CoroutineTest is playing1")}),
(10.0, {(World) in print("CoroutineTest is playing2")})
])
}
_ = Query<Health, Position>.getParam(world)
world.addSystemFunction(schedule: .start, spawn)
world.addSystemFunction(schedule: .start, checkWithAddComponent)
world.addSystemFunction(schedule: .start, removeEntity)
world.addSystemFunction(schedule: .start, initResource)
world.addSystemFunction(schedule: .start, getResource)
world.addSystemFunction(schedule: .start, coroutineManagerTest)
world.executeSystems()
world.entityManager.printAllArchetypes()To run the project:
swift runThis will compile and run your ECS example, demonstrating how to create and manage entities, components, systems, events, and resources using PrometheusECS library.
This project is licensed under the MIT License. See the LICENSE file for details.
MIT License
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.