Kotlin MultiLoader Template

This project provides a Gradle project template that can compile Minecraft mods written in Kotlin for multiple modloaders using a common project for the sources. This project does not require any third party libraries or dependencies.

This Kotlin version is a fork of the original Multiloader Template.

I also backported this template to 1.20.1 with Forge and Fabric using Neo's MDG Legacy Plugin. You can find it on the 1.20.1 branch.

Getting Started

IntelliJ IDEA

This guide will show how to import the MultiLoader Template into IntelliJ IDEA. The setup process is roughly equivalent to setting up the modloaders independently and should be very familiar to anyone who has worked with their MDKs.

1. Clone or download this repository to your computer.
2. Configure the project by setting the properties in the gradle.properties file. You will also need to change the rootProject.name property in settings.gradle, this should match the folder name of your project, or else IDEA may complain.
3. Configure dependency versions in the libs.versions.toml file.
4. Open the template's root folder as a new project in IDEA. This is the folder that contains this README.md file and the gradlew executable.
5. If your default JVM/JDK is not Java 21 you will encounter an error when opening the project. This error is fixed by going to File > Settings > Build, Execution, Deployment > Build Tools > Gradle > Gradle JVM and changing the value to a valid Java 21 JVM. You will also need to set the Project SDK to Java 21. This can be done by going to File > Project Structure > Project SDK. Once both have been set open the Gradle tab in IDEA and click the refresh button to reload the project.
6. Open your Run/Debug Configurations. Under the Application category there should now be options to run Fabric and NeoForge projects. Select one of the client options and try to run it.
7. Assuming you were able to run the game in step 6. your workspace should now be set up.

Eclipse

Note

The support for Kotlin in Eclipse is subpar at best and nonfunctional at worst. While the original mod loaders' plugins may support it, the original Multiloader template has made efforts to resolve this problem, this template is also not supported in Eclipse and there is not currently anything I could do to get it to work in Eclipse any better.

The original template's stance on Eclipse:

While it is possible to use this template in Eclipse it is not recommended. During the development of this template multiple critical bugs and quirks related to Eclipse were found at nearly every level of the required build tools. While we continue to work with these tools to report and resolve issues support for projects like these are not there yet. For now Eclipse is considered unsupported by this project. The development cycle for build tools is notoriously slow so there are no ETAs available.

Development Guide

When using this template the majority of your mod should be developed in the common project. The common project is compiled against the vanilla game and is used to hold code that is shared between the different loader-specific versions of your mod. The common project has no knowledge or access to ModLoader specific code, apis, or concepts. Code that requires something from a specific loader must be done through the project that is specific to that loader, such as the fabric or neoforge projects.

Loader specific projects such as the fabric and neoforge project are used to load the common project into the game. These projects also define code that is specific to that loader. Loader specific projects can access all the code in the common project. It is important to remember that the common project can not access code from loader specific projects.

Additionally, Mixins can should not be written in Kotlin and instead remain written in Java. The provided code shows how to access things implemented in Kotlin from Mixins in Java.

Removing Platforms and Loaders

While this template has support for many modloaders, new loaders may appear in the future, and existing loaders may become less relevant.

Removing loader specific projects is as easy as deleting the folder, and removing the include("projectname") line from the settings.gradle file. For example if you wanted to remove support for forge you would follow the following steps:

1. Delete the subproject folder. For example, delete MultiLoader-Template/forge.
2. Remove the project from settings.gradle. For example, remove include("forge").

Note on the fork

I've taken the following liberties when porting this template to Kotlin:

1. Rewrote the bulk of the build script in Gradle's Kotlin DSL, for better or for worse it's here to stay and if you want to write your mod in Kotlin you should know how to handle Kotlin's syntax for the build script.
2. Use Gradle's Version Catalog system to manage dependencies and libraries, this allows specifying versions and artifacts of dependencies in one place, which can then be used in every subproject and even the buildSrc project.
3. Use JetBrains' Dokka Gradle plugin to generate full javadoc jars containing the documentation for both, the Kotlin sources and the Java sources.