silphius/app/ecs/systems/maintain-collider-hash.js

import {System} from '@/ecs/index.js';
import SpatialHash from '@/util/spatial-hash.js';

export default class MaintainColliderHash extends System {

  hash;

  deindex(entities) {
    super.deindex(entities);
    for (const id of entities) {
      this.hash.remove(id);
    }
  }

  static get priority() {
    return {
      after: 'IntegratePhysics',
    };
  }

  reindex(entities) {
    for (const id of entities) {
      if (1 === id) {
        const {AreaSize} = this.ecs.get(1);
        if (AreaSize) {
          this.hash = new SpatialHash(AreaSize);
        }
      }
    }
    super.reindex(entities);
    for (const id of entities) {
      this.updateHash(this.ecs.get(id));
    }
  }

  updateHash(entity) {
    if (!entity.Collider || !this.hash) {
      return;
    }
    this.hash.update(entity.Collider.aabb, entity.id);
  }

  tick() {
    for (const entity of this.ecs.changed(['Direction'])) {
      if (!entity.Collider) {
        continue;
      }
      entity.Collider.updateAabbs();
    }
    for (const entity of this.ecs.changed(['Position'])) {
      this.updateHash(entity);
    }
  }

  within(query) {
    const within = new Set();
    for (const id of this.hash.within(query)) {
      within.add(this.ecs.get(id));
    }
    return within;
  }

}