game_cocos_2c/assets/scripts/modules/launch/states/PreloadLobbyState.ts

import { math } from 'cc';
import { SceneId } from '../../../framework/scene/SceneNavigator';
import { LaunchContext, LaunchState, LaunchStateId } from './LaunchState';

export class PreloadLobbyState implements LaunchState {
  readonly id = LaunchStateId.PreloadLobby;

  private _context: LaunchContext;

  async enter(context: LaunchContext): Promise<LaunchStateId> {
    this._context = context;
    const i18n = context.kernel.i18n;

    let last_percent = 0;
    this.setProgress(0, i18n.t('launch.preload_res'));
    const kernel = context.kernel;
    try {
      await Promise.all([
        await kernel.sound.preload(),
        await kernel.scenes.preload(SceneId.Lobby, {
          onProgress: (percent) => {
            /// web preload 进度会回退
            if (percent < last_percent) return;
            last_percent = percent;
            this.setProgress(percent);
          }
        }),
      ]);
    } catch (error) {
      context.error = error;
      const retry = await context.dialog({
        title: "",
        message: i18n.t('launch.res_load_fail'),
        lblOK: i18n.t('launch.retry'),
      });
      if (retry) {
        return LaunchStateId.CheckVersion;
      }
      throw error;
    }
    this.setProgress(1);
    return LaunchStateId.EnterLobby;
  }

  private setProgress(percent: number, title?: string) {
    const from = this._context.totalProgress;
    const progress = math.lerp(from, 1, percent);
    this._context.progress({ state: this.id, title, progress })
  }
}