lwjgl3ify

The lwjgl3ify plugin, from @opys/minecraft.

lwjgl3ify: Forge 1.7.10 mods on a modern Java.

// opys.config.mjs
export default defineConfig({
  plugins: [
    lwjgl3ify({ version: '1.7.10' }),
    java({ version: '25' }),
  ],
  manifest: {
    command: '@lwjgl3ify.command',
    args: [
      '@lwjgl3ify.jvmArgs',
      '@lwjgl3ify.mainClass',
      '@lwjgl3ify.gameArgs',
    ],
    workdir: '${game_directory}',
  },
});

Use it instead of minecraft. A loader brings the game with it.

Options

Option	What it does
version	Which build. See below.
source	A mirror of the build index.
unimixins	false to leave UniMixins out, or { version, repo } to pick another.
repo	The GitHub repository the mod jar comes from.
token	A GitHub token, for the rate limit.
apiBase	A GitHub API mirror.
libraries	Libraries to add or replace.

version

You write	You get
'1.7.10'	The recommended release, or the newest if none is recommended.
'1.7.10-latest'	The newest release.
'1.7.10-recommended'	The recommended release.
'3.0.37'	Exactly that release.

The version is resolved when you build. '1.7.10' today and in six months can be different releases. For a pack that never moves, write the exact one.

What it adds

Everything Vanilla Minecraft adds, with these differences.

Kind	What
Files	The 1.7.10 game with lwjgl3ify's libraries, and two mods.
Launch	command, jvmArgs, mainClass, gameArgs.
Variables	The same as vanilla.
Environment	None.

Each one below: what it is, and how it ends up in the manifest.

Files · two mods in mods/

The lwjgl3ify mod, and UniMixins, which it cannot start without. Both come from GitHub releases, pinned by sha256.

// opys.config.mjs
export default defineConfig({
  plugins: [
    lwjgl3ify({ version: '1.7.10' }),
    java({ version: '25' }),
  ],
  manifest: {
    command: '@lwjgl3ify.command',
    args: [
      '@lwjgl3ify.jvmArgs',
      '@lwjgl3ify.mainClass',
      '@lwjgl3ify.gameArgs',
    ],
    workdir: '${game_directory}',
  },
});

// in the manifest
{
  "path": "${game_directory}/mods/lwjgl3ify-3.0.37.jar",
  "source": { "url": "https://github.com/GTNewHorizons/lwjgl3ify/releases/download/3.0.37/lwjgl3ify-3.0.37.jar" },
  "size": 8266971,
  "integrity": { "sha256": "3c5af555d62eb9b7f4196adea94cb4cbd4c8efe3e1d512f83537aa88d9d5211e" }
},
{
  "path": "${game_directory}/mods/+unimixins-all-1.7.10-0.3.2.jar",
  "source": { "url": "https://github.com/LegacyModdingMC/UniMixins/releases/download/0.3.2/%2Bunimixins-all-1.7.10-0.3.2.jar" },
  "size": 5520080,
  "integrity": { "sha256": "2687b776c8503e0b60cd8413cf70eaabb836c19f9fc726280ef61d6612257034" }
}

Launch

A long one. A 2014 game on a modern Java needs many doors opened by hand.

// opys.config.mjs
export default defineConfig({
  plugins: [
    lwjgl3ify({ version: '1.7.10' }),
    java({ version: '25' }),
  ],
  manifest: {
    command: '@lwjgl3ify.command',
    args: [
      '@lwjgl3ify.jvmArgs',
      '@lwjgl3ify.mainClass',
      '@lwjgl3ify.gameArgs',
    ],
    workdir: '${game_directory}',
  },
});

// in the manifest
"launch": {
  // '@lwjgl3ify.command'
  "command": "${java_bin}",
  "args": [
    // '@lwjgl3ify.jvmArgs'
    "-Djava.library.path=${natives_directory}",
    "-cp",
    "${classpath}",
    "-Djava.system.class.loader=com.gtnewhorizons.retrofuturabootstrap.RfbSystemClassLoader",
    "--add-opens", "java.base/java.io=ALL-UNNAMED",
    "--add-opens", "java.base/java.lang=ALL-UNNAMED"
    // … about forty more --add-opens
    // '@lwjgl3ify.mainClass'
    "com.gtnewhorizons.retrofuturabootstrap.MainStartOnFirstThread",
    // '@lwjgl3ify.gameArgs'
    "--username", "${auth_player_name}",
    // … the rest of the 1.7.10 game arguments, then:
    "--tweakClass", "cpw.mods.fml.common.launcher.FMLTweaker"
  ],
  "workdir": "${game_directory}"
}

You write	Becomes
'@lwjgl3ify.command'	The program to run: whatever Java the pack has.
'@lwjgl3ify.jvmArgs'	Arguments for Java itself, ending with the classpath.
'@lwjgl3ify.mainClass'	The class to start. One argument.
'@lwjgl3ify.gameArgs'	Arguments for the game: who is playing, and where things are.

Variables

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

// opys.config.mjs
export default defineConfig({
  plugins: [
    lwjgl3ify({ version: '1.7.10' }),
    java({ version: '25' }),
  ],
  manifest: {
    command: '@lwjgl3ify.command',
    args: [
      '@lwjgl3ify.jvmArgs',
      '@lwjgl3ify.mainClass',
      '@lwjgl3ify.gameArgs',
    ],
    workdir: '${game_directory}',
  },
});

// in the manifest
"vars": {
  "game_directory": "${root}/",
  "library_directory": "${root}/libraries",
  // … the rest, as in vanilla
}

Why the mods are added for you: forgetting either gives a game that does not start, with an error that does not say why.

Good to know

• It replaces both minecraft and forge.
• Pass unimixins: false only if your pack ships its own mixin runtime.
• Both mods come from GitHub. Pass token if a build hits the rate limit.
• Pair it with java({ version: '25' }).