public static AssetBundleLoadOperation LoadLevelAsync(string assetBundleName, string levelName, bool isAdditive)
{
AssetBundleManager.LoadAssetBundle(assetBundleName, false);
AssetBundleLoadOperation assetBundleLoadOperation = new AssetBundleLoadLevelOperation(assetBundleName, levelName, isAdditive);
AssetBundleManager.m_InProgressOperations.Add(assetBundleLoadOperation);
return assetBundleLoadOperation;
}