@opys/neoforge

NeoForge for opys. neoforge() adds the game and a NeoForge build, for Minecraft 1.20.2 and later. Use it instead of minecraft().

npm install -D @opys/dev @opys/neoforge @opys/java

Example

// opys.config.mjs
import { defineConfig } from '@opys/dev';
import { java } from '@opys/java';
import { neoforge } from '@opys/neoforge';

export default defineConfig({
  output: 'game.opys',
  plugins: [neoforge({ version: '1.21.1' }), java({ version: '21' })],
  manifest: {
    command: '@neoforge.command',
    args: ['@neoforge.jvmArgs', '@neoforge.mainClass', '@neoforge.gameArgs'],
    workdir: '${game_directory}',
  },
});

Options

Option	What it does
version	'1.21.1' (recommended build), '1.21.1-latest', or an exact '21.1.172'.
source	A mirror of the build index.
manifestBase	A mirror of Mojang's version list.
libraries	Libraries to add or replace, each { name, artifact }.

version is resolved when you build, so anything but an exact build can change between two builds.

What it adds

Everything @opys/minecraft-vanilla adds (the game, its variables), with these differences.

Files · NeoForge libraries

NeoForge's own jars.

// in the manifest
{
  "path": "${library_directory}/cpw/mods/modlauncher/11.0.5/modlauncher-11.0.5.jar",
  "source": { "url": "https://maven.neoforged.net/releases/cpw/mods/modlauncher/11.0.5/modlauncher-11.0.5.jar" },
  "size": 116486,
  "integrity": { "sha1": "b8f0d49294f733fdb6173931b263553e943dc950" }
}

Launch

The vanilla command line, started through horno: a small helper that finishes the loader's install on the player's machine, then starts the game.

// in the manifest
"launch": {
  // '@neoforge.command'
  "command": "${java_bin}",
  "args": [
    // '@neoforge.jvmArgs'
    // … the vanilla JVM arguments, then:
    "-cp",
    "${classpath}",
    "-Dhorno.librariesDir=${library_directory}",
    "-Dhorno.installer=${library_directory}/net/neoforged/neoforge/21.1.256/neoforge-21.1.256-installer.jar",
    "-Dhorno.installerUrl=https://maven.neoforged.net/releases/…/neoforge-21.1.256-installer.jar",
    "-Dhorno.installerSha1=9d85f6e652996e83f05ead32120317e1ef056590",
    "-Dhorno.minecraft=${library_directory}/com/mojang/minecraft/1.21.1/minecraft-1.21.1-client.jar",
    // '@neoforge.mainClass'
    "net.harmoniya.horno.Main",
    // '@neoforge.gameArgs'
    "--username", "${auth_player_name}",
    // … the vanilla game arguments, then:
    "--fml.neoForgeVersion", "21.1.256",
    "--fml.mcVersion", "1.21.1",
    "--launchTarget", "forgeclient"
  ],
  "workdir": "${game_directory}"
}

Variables

The same names as vanilla. classpath has the loader's libraries ahead of the game's.

// in the manifest
"vars": {
  "classpath": [/* the loader's libraries, the game's, then the game jar */]
  // … the rest, as in vanilla
}

The first launch is slower, because horno does its work then.

Every option

Each option, in each way it is used.

// the recommended build for a Minecraft version, or the newest if none is
neoforge({ version: '1.21.1' });
neoforge({ version: '1.21.1-recommended' });

// the newest build
neoforge({ version: '1.21.1-latest' });

// one exact build: the same in every build of the pack
neoforge({ version: '21.1.172' });

// a library the game does not ship, or a patched copy of one it does
neoforge({
  version: '1.21.1',
  libraries: [
    // a jar next to the config: it travels inside the bundle
    {
      name: 'com.google.code.gson:gson:2.11.0',
      artifact: {
        path: 'com/google/code/gson/gson/2.11.0/gson-2.11.0.jar',
        source: { file: 'libs/gson-2.11.0.jar' },
      },
    },
    // a jar by link, for one OS only
    {
      name: 'com.example:native-helper:1.0',
      artifact: {
        path: 'com/example/native-helper/1.0/native-helper-1.0.jar',
        source: { url: 'https://example.com/native-helper-1.0.jar' },
        integrity: { sha1: 'da39a3ee5e6b4b0d3255bfef95601890afd80709' },
        rules: 'allow.os.windows',
      },
    },
  ],
});

// mirrors, for a network that cannot reach the defaults
neoforge({
  version: '1.21.1',
  source: 'https://mirror.example.com/neoforge',
  manifestBase: 'https://mirror.example.com/mc/game/version_manifest_v2.json',
});

Documentation

• The full page: every option, and why it works this way
• The format: what a manifest is made of

Part of opys. Also exported by @opys/minecraft.