【UE4/5】UE工程资产降级器 – Asset Downgrader

This plugin will downgrade assets for compatibility with 5.0.3 or 4.27 . It works by first upgrading the assets to Source Version (5.3-5.4), and then applying various patches to the .uasset files in order to make them compatible with the TargetVersion (5.0 or 4.27). Do note that features of the newer unreal versions (like nanite on masked materials or new material nodes) can’t be ported to the old versions.
该插件将降级资产以与 5.0.3 或 4.27 兼容。它的工作原理是首先将资产升级到源版本（5.3-5.4），然后对.uasset 文件应用各种补丁，以使它们与目标版本（5.0 或 4.27）兼容。请注意，新版本的虚幻引擎功能（如掩模材质上的纳米技术或新材质节点）无法移植到旧版本中。

How it works : 工作原理：

– First, backup all your assets as this plugin is highly experimental and in certain situations it may corrupt assets or crash the editor if something goes wrong.
– 首先，备份所有资产，因为此插件是高度实验性的，在某些情况下，如果出现问题，可能会损坏资产或使编辑器崩溃。

– Either have 2 projects, one the SourceVersion and the other with the TargetVersion, or just switch versions for the project you’re working with. Integrate the plugin in both projects.
– 要么有两个项目，一个是 SourceVersion，另一个是 TargetVersion，要么只需切换要处理的项目的版本。在两个项目中集成插件。

– In the SourceVersion project, select the assets you wish to downgrade.
– 在 SourceVersion 项目中，选择要降级的资产。

– From the Downgrader menu choose DowngradeSelectedAssets.
– 从降级菜单中选择 DowngradeSelectedAssets。

– Either migrate the assets by copy pasting affected files or entire folders with the assets or selecting say a level file, choosing migrate and then choosing a destination Content folder where the project on TargetVersion should reside. Alternatively, switch the version of the project to the TargetVersion
– 通过复制粘贴受影响的文件或整个文件夹中的资产，或选择一个关卡文件，选择迁移，然后选择目标 Content 文件夹，项目应该驻留在 TargetVersion 上。或者，将项目的版本切换到 TargetVersion。

– If TargetVersion is a 5.0.3 project add
– 如果 TargetVersion 是一个 5.0.3 项目，则添加。

[Core.System] [核心.系统]

UsePackageTrailer=True

to Config/DefaultEngine.ini
到 Config/DefaultEngine.ini

You will get a warning if this is not enabled.
如果未启用此功能，您将收到警告。

– Open the TargetVersion project and then the downgraded assets. If there were no errors, the assets should open correctly. To be able to migrate these assets to other TargetVersion projects that don’t have the Downgrader plugin, the assets need to be resaved (Just select all the assets and use the plugin’s SaveSelectedAssets option )
– 打开 TargetVersion 项目，然后打开降级的资产。如果没有错误，资产应该能够正确打开。要将这些资产迁移到其他没有 Downgrader 插件的 TargetVersion 项目，需要重新保存这些资产（只需选择所有资产并使用插件的 SaveSelectedAssets 选项）

What if I need to downgrade to just 5.2 or 5.1 ?
如果我只需要降级到 5.2 或 5.1 呢？

The flow is identical, but instead of opening the assets in saw 5.0.3 you can open them in 5.1 or 5.2. Do note that in certain situations resaving the assets is still required before opening them in a project without the plugin. You can use the provided “SaveSelectedAssets” option from the plugin to save everything and remove the plugin dependency.
流程相同，但是不是在 saw 5.0.3 中打开资产，而是在 5.1 或 5.2 中打开它们。请注意，在某些情况下，在不带插件的项目中打开资产之前仍然需要重新保存这些资产。您可以使用插件提供的“SaveSelectedAssets”选项保存所有内容并删除插件依赖。

Included with the plugin there are diff files for the SourceVersions (5.3 and 5.4) that you can install with a single click that will apply modifications to the engine sources in order to fix downgrading more asset type (see tutorial)
与插件一起提供了 SourceVersions（5.3 和 5.4）的 diff 文件，您可以通过单击安装它们，这将对引擎源代码进行修改，以修复降级更多资产类型（请参阅教程）

Can it be downgraded lower than 4.27 ?
它可以降级到低于 4.27 吗？

Not currently but with enough research & engine modifications definetely possible. Contact me if you have specific needs.
目前不行，但通过足够的研究和引擎修改，肯定是可能的。如果您有特定需求，请与我联系。

My asset is not supported, can you add support ?
我的资产不受支持，您能添加支持吗？

Let me know what kind of assets you’re interested. Any asset is implementable but it requires a lot of work.
请告诉我您感兴趣的资产类型。任何资产都可以实现，但需要大量工作。

Known Issues: 已知问题：

– If assets don’t appear in packaged builds you forgot to resave the assets ( use the plugin’s SaveSelectedAssets option )
– 如果资产在打包构建中不显示，您可能忘记重新保存资产（使用插件的 SaveSelectedAssets 选项）。

– some downgraded scenes’ lighting may look too bright in 5.0. You may need to tune ReflectionProbes/Skylight/Directional light intensity and/or rebuild lighting
– 一些降级场景的光照在 5.0 版本中可能看起来太亮了。您可能需要调整 ReflectionProbes/Skylight/Directional light 的强度和/或重新构建光照

– if downgrading entire projects, a lot of assets will be loaded into memory, so you may need a lot of RAM sometimes up to 128GB
– 如果降级整个项目，会加载大量资源到内存中，因此有时可能需要大量的 RAM，甚至高达 128GB

– if encountering unknown startup crashes due do downgrading a lot of assets, try and downgrade assets one by one, or exclude/delete the offending asset.
如果遇到由于降级大量资产而导致的未知启动崩溃，请尝试逐个降级资产，或排除/删除有问题的资产。

– textures with formats like RGBA32F are not downgraded because those formats don’t exist in 5.0.
– 使用 RGBA32F 等格式的纹理不会降级，因为这些格式在 5.0 中不存在。

– opening certain maps will sometimes crash. This might be due to masked materials with nanite which are not allowed in 5.0. Try first to open assets individually or remove nanite entirely and then open the map
– 打开某些地图有时会崩溃。这可能是由于具有 nanite 的蒙版材质在 5.0 中不允许。首先尝试单独打开资产或完全删除 nanite，然后再打开地图。

If you have any issues, errors or crashes don’t hesitate to contact me at relativegames7@gmail.com as this plugin is highly experimental.
如果您遇到任何问题、错误或崩溃，请随时通过 relativegames7@gmail.com 与我联系，因为这个插件是高度实验性的。

Please include your editor log found in ProjectName/Saved/Logs/ProjectName.log.
请包括您在 ProjectName/Saved/Logs/ProjectName.log 中找到的编辑器日志。