Development

Introduction
Everyone can contribute to GTNH in one way or another. One possible way is to improve or expand the source code of the mods.

To get started, you first need a vision for what you want to do. If you don't have it yet, you can look through issues and try to address some. If you do have a vision but want to hear more opinions on it, you can discuss it in a new Github issue or in Discord.

Getting started
If you found a mod that you want to edit, then create a fork of it by pressing the Fork button on its GitHub page. After that, you can clone your fork to a local repository, import it to your IDE, and get started on development. If you are not sure how to do something, try to look up how things similar to it were done before.

Starting from an existing repository

 * 1) Clone the repository.
 * 2) Update the buildscript automatically through   or if it doesn't work, manually with this guide.

Starting from scratch

 * 1) Create a new GitHub repository and clone it.
 * 2) Choose and download a Forge MDK, extract the ZIP-archive to the directory where you cloned your repository. If you are developing for GTNH, then use our fork of ExampleMod as a template.
 * 3) Edit your project details such as its name, version, dependencies, and so on.

Next steps

 * 1) Run   to update the Gradle build-script for the repository.
 * 2) Run   to build the project. The flag `--build-cache` makes builds faster. For more info, see documentation.
 * 3) If the build fails, check what was printed in console. Usually it fails because of outdated dependencies. You can fix it with.
 * 4) In Eclipse / IntelliJ IDEA, import your workspace as an existing Gradle project. If the import fails, you may need to adjust the Gradle version and/or the buildscript. If you are developing for Minecraft 1.7.10, read this guide.
 * 5) After you made changes, test them:
 * 6) Build the project with  . You will find several jars in  . What you need is the one without affixes like   or.
 * 7) Download the last stable release from our installing guide and import it in the launcher of your choice.
 * 8) Replace the target mod with your version or add if it's a new one.
 * 9) Launch the pack and check that things work as they should.

Common issues

 * If your IDE tells you that stuff is missing even after you executed, then try to reload Gradle.
 * You need a 64-bit Java for development. Most mods work with any Java 8-20. However, some mods now use in gradle.properties. In that case you need at least Java 11 to compile them. If you have multiple Java versions on your machine, then you may need to set the   environment variable to the location of your desired Java installation and also configure it in your IDE.

Git Configuration
If you want to avoid signing commits with your real name, then please refer to the page Managing Git Identities.

Contribution Procedure
Please do not make multiple changes/features in a single PR, make a separate PR for each. If they depend on each other, you can leave a note in the PR's description.
 * 1) Find something to contribute.
 * 2) Fork the needed repos.
 * 3) Push code into your fork.
 * 4) Open a pull request and provide a description on what it changes/adds/removes. Include pictures/graphs if necessary. If there is a related issue, link it. Ask for review from
 * 5) * DreamMasterXXL if it's about quest or recipe changes.
 * 6) * GTNewHorizons/developers team if it's some java/scala/kotlin code change.
 * 7) * mitchej123 if it's NEI.
 * 8) * Original mod developer if you are contributing to their mod and they are still around. For example, glease for TC4Tweaks, SinTh0r4s for VisualProspecting, GlodBlock for GoodGenerators.
 * 9) Address review problems. Resolve merge conflicts. Wait for final merge. DO NOT merge the PR yourself, even if approved! This is a task of GTNewHorizons/admin members.

If you are not sure how to fork and open pull requests, read this gist by Chaser324.

GTNH-specific Contribution Guides

 * You can find the Code of Conduct of the GTNH dev community here.
 * See which GTNH mods are supported outside of the modpack and see an overview of licenses in this spreadsheet.
 * For the GTNH Code Style guidelines please see the dedicated page Code Style.
 * For quest development, read the Quests Development Guide.
 * The StructureLib documentation can be found here. Use this for your multiblock structures.
 * To understand how chemical formulas are balanced in recipes, read Chemical Balance.

Tools
All applications that are grouped together can do about the same. This does not mean that you can pick any one of them, as they differ in functionality, style, performance and customizability. It is recommended you look at what they can do and try each one out, so you can decide which application you want to use for which use case.

Code Editors

 * Notepad++
 * Visual Studio Code
 * Sublime Text
 * Atom

Integrated Development Environments

 * Eclipse Note: as of version 2020-09, using Java 8 became more difficult. 2020-06 is the last version with official support for Java 8.
 * IntelliJ IDEA

Image Editors

 * GIMP
 * Paint.NET
 * Krita
 * LibreSprite
 * Aseprite Paid
 * Photoshop Paid

Modeling

 * Blockbench
 * MagicaVoxel
 * Blender

Animation

 * Block Model Animator
 * Animated Textures Editor
 * LibreSprite

Miscellaneous

 * JSONLint
 * Palette Library
 * Resource Pack Workbench
 * Bearded-Octo-Nemesis 2 (BON2)
 * FernFlower
 * Java Decompiler
 * MCP Mapping Viewer
 * WinMerge

Resources
Not every wiki/tutorial/article/... listed here contains information about Minecraft version 1.7.10 but some topics haven't changed much and often the general methodology is the same. The newer the version, the less comparable the inner workings of Minecraft/Forge are to 1.7.10.

You can look at the source-code of most mods included in GTNH here.

If you look for something specific, use the search-function of your browser!

You can find an extensive list of modding resources, made by the MMD-Team, here.

Help

 * Mathematics on StackExchange: Forum for everything related to Mathematics
 * StackOverflow: Forum for everything related to Programming
 * #mod-dev ( GTNH Discord)
 * #mc-dev-other ( Minecraft Mod Development Discord)
 * #moddev ( Minecraft Pack Development Discord)
 * #mc-dev ( CurseForge Discord)
 * #help-modded-java ( Blockbench Discord)

Using DCEVM
For better hot-reload support in intellij you can use DCEVM. Instructions for linux:


 * Unpack Trava JDK 8 DCEVM on your machine.
 * Go into the unpacked JVM. In, make a copy of   called  . After that, copy the entire   folder and name it  . This tricks the IntelliJ plugin into thinking that the DCEVM install is valid as installed by the old 2018 installer.
 * Install HotSwapAgent plugin in IntelliJ.
 * Add the DCEVM JDK as an SDK in IntelliJ, it should autodetect most stuff but I had to manually copy over the javadoc path from my other java8 JDK.
 * Set DCEVM JDK as default for the project and Gradle.
 * Set the non-DCE JDK in Build, Exec & Deployment -> Compiler -> Scala Compiler -> Scala Compile Server.
 * In Build tools -> Gradle, set both build-and-run and run tests to using IntelliJ IDEA instead of Gradle.
 * In Tools -> HotSwapAgent, enable it for all configurations, and set the agent path to  in your DCEVM installation.
 * Make sure to use the Minecraft Client/Server IntelliJ configurations with the square frame icons instead of the runClient/etc. configurations with Gradle icons.
 * Debugging that config should show up loading the hot swap agent at the beginning of the logs.
 * If you have custom JVM args in the configs, make sure to remove all garbage-collection options as DCEVM works only with the default garbage collector.

Dependency types
The following table shows if a source dependency - later called the Source - you included in Your Mod is visible to Your Mod and the mods that depend on Your Mod. For instance,  makes the Source visible to Your Mod at compile and runtime, but only at runtime to the Dependent mods, meaning that the Dependent mods are not able to use a class from Your Mod if it implements an interface from the Source. You can also read document on ExampleMod repository for details.

Useful Options

 * # Enable Mixin Debug
 * # Verbose Debug Messages
 * # Export classes after mixins have been applied. If you include fernflower in your classpath, or copy org.jetbrains.fernflower into your mixin jar the exported classes will be decompiled
 * # Throw an error if the injection count doesn't match expectations
 * # Class Load Debugging
 * # Dump classes to `.minecraft/CLASSLOADER_TEMP`

Remote debugging

 * to wait for a debugger to be attached to the game before running code, put this in launcher args to debug the full pack
 * In IntelliJ, use Run->Attach to process to attach the debugger to the running instance.