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import { System, SystemType } from "./system";
import { Entity } from "./entity";
import { ComponentType } from "./component";
export class Game {
private running: boolean;
private last_update: number;
private readonly entities: Map<string, Entity> = new Map();
private readonly component_entities: Map<ComponentType, Set<string>> =
new Map();
private readonly systems: Map<SystemType, System> = new Map();
private readonly system_order: SystemType[];
constructor(
public readonly client_id: string,
systems: System[],
) {
this.last_update = performance.now();
this.running = false;
systems.forEach((system) => this.systems.set(system.system_type, system));
this.system_order = systems.map(({ system_type }) => system_type);
}
public start() {
if (this.running) return;
console.log("starting game");
this.running = true;
this.last_update = performance.now();
const game_loop = (timestamp: number) => {
if (!this.running) return;
// rebuild component -> { entity } map
this.component_entities.clear();
Array.from(this.entities.values()).forEach((entity) =>
Object.values(entity.components).forEach((component) => {
const set =
this.component_entities.get(component.name) ?? new Set<string>();
set.add(entity.id);
this.component_entities.set(component.name, set);
}),
);
const dt = timestamp - this.last_update;
this.system_order.forEach((system_type) =>
this.systems.get(system_type)!.update(dt, this),
);
this.last_update = timestamp;
requestAnimationFrame(game_loop); // tail call recursion! /s
};
requestAnimationFrame(game_loop);
}
public stop() {
if (!this.running) return;
this.running = false;
}
public for_each_entity_with_component(
component: ComponentType,
callback: (entity: Entity) => void,
) {
this.component_entities.get(component)?.forEach((entity_id) => {
const entity = this.entities.get(entity_id);
if (!entity) return;
callback(entity);
});
}
public get_entity(id: string) {
return this.entities.get(id);
}
public put_entity(entity: Entity) {
const old_entity = this.entities.get(entity.id);
if (old_entity) this.clear_entity_components(old_entity);
Object.values(entity.components).forEach((component) => {
const set =
this.component_entities.get(component.name) ?? new Set<string>();
set.add(entity.id);
this.component_entities.set(component.name, set);
});
this.entities.set(entity.id, entity);
}
public remove_entity(id: string) {
const entity = this.entities.get(id);
if (typeof entity === "undefined") return;
this.clear_entity_components(entity);
this.entities.delete(id);
}
private clear_entity_components(entity: Entity) {
Object.values(entity.components).forEach((component) => {
const set = this.component_entities.get(component.name);
if (typeof set === "undefined") return;
set.delete(entity.id);
});
}
public get_system<T extends System>(system_type: SystemType): T | undefined {
return this.systems.get(system_type) as T;
}
}
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