md.Nuke.Unreal 2.1.4

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Nuke.Unreal

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Simplistic workflow for automating Unreal Engine project tasks embracing Nuke, providing a consistent way to use UE4/5 tools and reducing chores they come with.

• Nuke.Unreal
• Usage
  • Install via remote script
  • Install manually
• Features:
• Setting up for a project
• Setting up for plugin development
  • Additional Plugin Targets
• Generators
  • C# code generators for Unreal tools
  • Using third-party C++ libraries
    • Use library from xrepo
    • Use library via CMake
    • Use header only library
  • Unreal boilerplate templates
    • Use your own templates
• Custom UBT or UAT arguments from command line

Usage

[!WARNING] dotnet is required to be installed first.

Install via remote script

Navigate to your project with powershell and do

Set-ExecutionPolicy Unrestricted -Scope Process -Force; iex (iwr 'https://raw.githubusercontent.com/microdee/Nuke.Unreal/refs/heads/main/install/install.ps1').ToString()

1. (optional) Inherit IPackageTargets interface if you want to package the associated Unreal project
2. (optional) Inherit IPluginTargets interface for automating plugin development related steps.

Install manually

Nuke.Unreal is available as a Nuget package and you can just add it to your build project as usual (package ID is md.Nuke.Unreal)

1. <details><summary>Install Nuke for an Unreal project</summary>

   > dotnet tool install Nuke.GlobalTool --global
   
   > nuke :setup
     select None for solution
     build project inside Nuke.Targets folder
   
   > nuke :add-package md.Nuke.Unreal
   

   </details>

2. Inherit your Build class from UnrealBuild instead of NukeBuild and make it public

3. Use Main () => Plugins.Execute<Build>(Execute); instead of Main () => Execute();

4. No further boilerplate required, run nuke --plan to test Nuke.Unreal

5. (optional) Inherit IPackageTargets interface if you want to package the associated Unreal project

6. (optional) Inherit IPluginTargets interface for automating plugin development related steps.

Your bare-bones minimal Build.cs which will provide the default features of Nuke.Unreal should look like this:

// Build.cs
using Nuke.Common;
using Nuke.Unreal;
using Nuke.Cola.BuildPlugins;

public class Build : UnrealBuild
{
    public static int Main () => Plugins.Execute<Build>(Execute);
}

Features:

• All what the great Nuke can offer
• Common Unreal build tasks (generate project files, build editor, cook, package, etc)

  > nuke generate
  > nuke build-editor
  > nuke cook
  > nuke package
  > nuke build --config Shipping
  > nuke build --config DebugGame Development --target-type Game --platform Android
  

• Prepare plugins for release in Marketplace

  > nuke make-release --for-marketplace
  

• Install C++ libraries (using xrepo)

  > nuke use-xrepo --spec "imgui 1.91.1 freetype=true" "vcpkg::ryml[dbg]" "conan::zlib/1.2.11"
  > nuke generate
  

• Generate boilerplate code and scaffolding from Scriban templates so no editor needs to be opened

  > nuke new-actor --name MyActor
  > nuke new-plugin --name MyPlugin
  > nuke new-module --name MyModule
  > nuke use-cmake --spec MyLibrary
  etc...
  

• Generated C# configurators for Unreal tools with gathered documentation. (UBT and UAT)
• Pluggable way to define targets for reusable plugins and modules

Setting up for a project

Nuke.Unreal targets looks for the *.uproject file automatically and it will use the first one it finds. A *.uproject is required to be present even for plugin development (more on plugins below). Automatically found project files can be in the sub-folder tree of Nuke's root (which is the folder containing the .nuke temporary folder) or in parent folders of Nuke's root. If for any reason there are more than one or no *.uproject files in that area, the developer can specify an explicit location of the associated *.uproject file.

public override AbsolutePath ProjectPath => RootDirectory / ".." / "MyProject" / "MyProject.uproject";

Only one Unreal project is supported per Nuke.Unreal instance.

Setting up for plugin development

Same is applicable when Nuke.Unreal is used for developing an Unreal Plugin for release. Of course Nuke.Unreal can work with multiple plugins in a project, but the IPluginTargets interface focuses only on one plugin. Again if the plugin is not trivially locatable then the developer can specify its location explicitly.

public AbsolutePath PluginPath => UnrealPluginsFolder / "MyPlugin" / "MyPlugin.uplugin";

Additional Plugin Targets

However plugins which require some pre-processing might benefit from the "Build plugins" pattern from Nuke.Cola. Simplest method of which is standalone *.nuke.cs files which are compiled with the build project. Let's have this scaffolding as an example:

<project root>
│   MyUnrealProject.uproject
├── .nuke
├── Content, Build, etc...
├── Nuke.Targets
│       Build.cs
│       Nuke.Targets.csproj (main build script)
├── Plugins
│   └── MyPlugin
│       │   MyPlugin.nuke.cs
│       └── <regular plugin files>
└── Source
    └── MyModule
        │   MyModule.nuke.cs
        └── <source files>

Build interfaces (or in Nuke vocabulary "Build Components") decorated with [ImplicitBuildInterface] inside these *.nuke.cs files will automatically contribute to the build graph without further boilerplate.

// MyModule.nuke.cs
using Nuke.Common;
using Nuke.Cola;
using Nuke.Cola.BuildPlugins;
using Nuke.Unreal;

namespace Nuke.MyModule;

[ImplicitBuildInterface]
public interface IMyModuleTargets : INukeBuild
{
    Target Foo => _ => _
        .DependsOn<IPackageTargets>()
        .Executes(() {...});
}

// MyPlugin.nuke.cs
using Nuke.Common;
using Nuke.Cola;
using Nuke.Cola.BuildPlugins;
using Nuke.Unreal;
namespace Nuke.MyPlugin;

[ImplicitBuildInterface]
public interface IMyPluginTargets : INukeBuild
{
    Target Foo => _ => _
        .Before<UnrealBuild>(u => u.Generate, u => u.Build, u => u.BuildEditor)
        .Executes(() {...});
}

Generators

C# code generators for Unreal tools

Nuke.Unreal provides builder pattern Unreal tool configurators in C# which yield a command line for the specified tool. TLDR: the syntax looks like this:

// For UBT:
Unreal.BuildTool(this, _ => _
    .Target(UnrealTargetType.Server)
    .Platform(UnrealPlatform.LinuxArm64)
    .Configuration(UnrealConfig.Development)
    .Project(ProjectPath)
    .Append(MyExplicitArguments)
)(workingDirectory: MyEnginePath);

// For UAT:
Unreal.AutomationTool(this, _ => _
    .BuildPlugin(_ => _
        .Plugin(PluginPath)
        .Package(targetDir)
        .StrictIncludes()
        .Unversioned()
    )
    .Append(self.UatArgs.AsArguments())
)(workingDirectory: MyEnginePath);

As the reader can see from the GIF this introduces a greater discoveribility to the vast functionality of both UAT and UBT which simply was not there before unless the developer followed some trails inside the source code of these tools. In fact the UAT configurator is generated from the actual source code using static code analysis and relying on semantical heuristics as the command line interpretation of UAT is very organic and inconsistent to say the least.

UBT on the other hand had a more disciplined and consistent approach for interpreting the command line, that allowed to rely on purely reflection while gathering arguments with the added feature of typed parameter value input (like numbers, strings and enums). As of time of writing detecting parameter types in a reliable and meaningful way is not possible for UAT.

Using third-party C++ libraries

Nuke.Unreal allows you to set up boilerplate for C++ libraries, or fetch them via a package manager. In all cases the artifacts it generates are placed in the working directory (the current location of your terminal). There are three methods available:

Use library from xrepo

Tt can be as simple as

> nuke use-xrepo --spec "zlib"

or fully specified with version and library options

> nuke use-xrepo --spec "imgui 1.91.1 freetype=true,dx11=true,dx12=true,vulkan=true"

and multiple libraries can be set up in one go

nuke use-xrepo --spec "imgui 1.91.1 freetype=true" "conan::zlib/1.2.11" "vcpkg::spdlog[wchar]" <etc...>

As you can see xrepo also can act like a meta-package-manager for libraries which may not yet been added to the xrepo repository. However their support is more limited than xrepo "native" packages.

use-xrepo will not fetch the specified libraries immediately but rather generate build plugins for them, which define Prepare-<library> targets. These are all dependent for Prepare target of UnrealBuild which is then dependent for Generate. So after nuke use-xrepo running nuke prepare or nuke generate will fetch and install properly all libraries used in this way. Having an extra build plugin allows the developer to further customize how the library is used, or add extra necessary operations.

--spec follows this syntax:

provider::name[comma,separated,features] 1.2.3 comma='separated',options=true

[!NOTE] Conan packages use / to delimit version (conan::zlib/1.2.3) instead of space. VCPKG through xrepo cannot set specific version so attempting to do vcpkg::zlib 1.2.3 will result in failing installation, but vcpkg::zlib is fine.

[!NOTE] Since Unreal requires MD C runtime linkage runtimes='MD' is implicitly added by Nuke.Unreal.

The Prepare and the individual Prepare-<library> targets will generate partial module rule classes for the platforms they were invoked for. This is done because libraries may have different requirements based on which platform they're used on / compiled on. The main MyLibrary.Build.cs module rule is the place for the developer to add custom logic if that's necessary for the library. Individual MyLibrary.Platform.Build.cs partial rules set up includes and libs.

[!IMPORTANT] During installation only one platform is considered, and only one platform worth of module rule class will be generated. This means the library should be prepared with all supported platforms or cross-compiled to be able to deploy in a truly cross-platform fashion.

The main benefit of this design is that libraries prepared this way can be further distributed with source but without the need for Nuke.Unreal, or without the need to execute complex behavior from the module rule files. This ensures for example Marketplace/Fab compliance of plugins.

Use library via CMake

nuke use-cmake --spec MyLibrary

This generates build plugins allowing the developer to prepare libraries via CMake. Fetching and storing the library is the responsibility of the developer. The build plugin is prepared for the most trivial use case when compiling a library via CMake but one may need to modify that depending on the design decisions of the library being used.

Use header only library

nuke use-header-only --spec MyLibrary

This will directly generate only the module rule file without the need for extra preparations like with the xrepo or the CMake methods.

Unreal boilerplate templates

Nuke.Unreal provides some targets which creates boilerplate code for common Unreal entities, such as

• Plugins
• Modules
• Unreal Object/Actor/Structs/Interfaces

without the need for opening the Unreal editor or extend heavy weight IDE's. These boilerplate targets work with Scriban templates. The path to these templates can be overridden in the actual Nuke build class in case a project requires further boilerplate. Example:

In any folder in your project do

> nuke new-actor --name MyPreciousActor

This will generate MyPreciousActor.h and ~.cpp at their respective places (taking public and private folders into account) and the minimal actor class boilerplate for unreal.

Use your own templates

Optional Custom templates folders are required to contain generator specific subfolders. If a subfolder doesn't exist for a generator the default will be used. Example:

Given directory scaffolding:

<project root>
├── ...
├── MyTemplates
│   ├── Actor
│   └── Object
└── Nuke.Targets
        Build.cs
        ...

In Nuke.Targets/Build.cs override TemplatesPath property

public override AbsolutePath TemplatesPath { get; set; } = RootDirectory / "MyTemplates";

This way Actor and Object generators will have their project specific Scriban templates but the remaining generator types will use the default templates of Nuke.Unreal.

Custom UBT or UAT arguments from command line

Nuke.Unreal supports passing custom arguments to UBT or UAT via --ubt-args or --uat-args. These are regular array properties exposed as Nuke target parameters. This means however that doing --ubt-args -DisableUnity wouldn't actually add -DisableUnity to the argument list. This happens because Nuke stops parsing the array argument when it hits a - character. For this reason Nuke.Unreal has a special escape mechanism where ~- is replaced with -, or if the argument starts with ~ then that's also replaced with a -.

So doing --ubt-args ~DisableUnity ~2022 will correctly pass arguments -DisableUnity -2022 to UBT.

This is especially useful for doing temporary debugging with UBT and the compiler: (not an actual usecase)

> nuke build ... --ubt-args "~CompilerArguments='/diagnostics:caret /P /C'" ~DisableUnity
> nuke build ... --ubt-args ~LinkerArguments=/VERBOSE
> nuke build ... --ubt-args ~Preprocess