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本页面为虚幻用户介绍了如何从 虚幻引擎（UE） 的GitHub仓库下载源代码，以及如何利用源代码快速上手。
如要访问https://github.com/EpicGames/UnrealEngine上的仓库，你必须满足以下条件：
已经是虚幻引擎的订阅用户。
已经拥有GitHub账号。
已经根据GitHub上的UE4一文中的所述步骤，将GitHub账号与你的虚幻引擎账号关联。
你 无需 下载源代码就能使用虚幻引擎4。如果你想通过下载可执行文件的方式来安装虚幻引擎，请参阅
你将获得Epic工程师每天（实际上是每一分钟）完成的最新功能和漏洞修复。
如果你发现了一个尚未被我们修复，但对你的项目来说影响很大的漏洞，你可以自己在源代码中进行修复并重新生成二进制文件，以便项目能够正常运行。
通过将你的修复工作提交给Epic，你可以改进引擎并为整个虚幻社区提供帮助。
如果你是虚幻引擎的授权用户，你可以通过我们的Perforce服务器访问源代码，而无需通过GitHub的公开仓库访问代码。
源代码分支
你应该已经注意到，我们已将UE5源代码发布在若干个分支中。
Branches whose names contain dev, staging, and test are typically for internal Epic processes, and are rarely useful for end-users Other short-lived branches may appear from time to time as we stabilize new releases or hotfixes.
Release Branch
The Release branch always reflects the current official release. These are extensively tested by our QA team, so they make a great starting point for learning Unreal Engine and for making your own projects. We work hard to make releases stable and reliable, and aim to publish a new release every few months.
Main Branch
Most active development on UE5 happens in the ue5-main branch. This branch reflects the latest release of the engine and may be buggy or it may not compile. We make it available for developers who are eager to test new features or work in lock-step development with us.
If you choose to work in this branch, be aware that it is likely to be ahead of the branches for the current official release and the next upcoming release. Therefore, content and code that you create to work with the ue5-main branch may not be compatible with public releases until we create a new branch directly from ue5-main for a future official release.
下载源代码
请按照如下说明下载虚幻引擎的源代码。
Additional target platforms
Android support will be downloaded by the setup script if you have the Android NDK installed. See the Android Quick Start guide.
iOS development requires a Mac. Instructions are in the iOS Quick Start guide.
Development for consoles and other platforms with restricted access, like Sony PlayStation, Microsoft Xbox, and Nintendo Switch, is only possible if you have a registered developer account with those third-party vendors.
Depending on the platform, additional documentation or guidance may be available in the Unreal Developer Network support site, or as a downloadable archive in the section of the Unreal Engine Forums that is dedicated to your platform.
If you don't have access to these resources, first register a developer account with the third party vendor. Then contact your Epic Games account manager if you have one, or fill out and submit the Console Development Request form for Unreal Engine if you don't. Epic will contact you with a formal agreement to digitally sign. Once this is approved, you will receive instructions on how to access source code, binaries, and additional instructions for your platform.
许可和贡献
你对GitHub上的Unreal Engine的访问和使用受虚幻引擎最终用户许可协议的约束。如果你不同意这些条款（我们会不时对它们加以修订），你将不会被获准访问或使用虚幻引擎。
我们欢迎你通过GitHub上的拉取请求，为虚幻引擎的开发做出贡献。我们大部分的积极开发都在 主 分支中进行，所以我们更喜欢在那里接受拉取请求（对于新功能而言尤其如此）。我们尽力确保所有新代码都遵守Epic编码标准。所有贡献均受EULA条款的约束。
后续步骤
现在你已经下载并设置了虚幻引擎，你可以随时
注意事项
当你首次编译源代码并启动编辑器时，加载时间可能会比较长。 引擎会针对你的平台优化内容并将信息保存为 派生数据缓存（derived data cache），这种优化应该只会进行一次。
你为虚幻引擎代码设置的Fork分支会与你的GitHub账号权限关联。 如果你取消了订阅或切换了GitHub用户名，则需要重新创建Fork分支并从本地副本上传改动内容。