Discrete GPU

The dgpuj plugin, from @opys/minecraft.

Runs the game on the fast graphics card.

// opys.config.mjs
export default defineConfig({
  plugins: [
    minecraft({ version: '1.21.1' }),
    java({ version: '21' }),
    dgpuj(),
  ],
  manifest: {
    command: '@dgpuj.bin',
    args: [
      '@minecraft.command',
      '@minecraft.jvmArgs',
      '@minecraft.mainClass',
      '@minecraft.gameArgs',
    ],
    workdir: '${game_directory}',
  },
});

On a laptop with two GPUs, Windows and Linux choose one per program, and often choose the slow one for Java.

Why a launcher cannot fix that from outside: the choice belongs to the process that opens the window. So dgpuj becomes that process. It asks for the fast card, then runs Java inside itself.

Options

Option	What it does
version	Left out, the release this version of opys was written for. Or 'latest', 'prerelease', or a tag ('v0.6.0').
platforms	Which platforms get it.
repo, token, apiBase	Where it is downloaded from, and a GitHub token.

What it adds

Kind	What
Files	One small archive per platform.
Launch	bin.
Variables	dgpuj_dir, dgpuj_bin.
Environment	None.

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

Files · one archive per platform

Five archives. rules pick the one for the player's machine, and extract takes the single executable out of it.

// opys.config.mjs
export default defineConfig({
  plugins: [
    minecraft({ version: '1.21.1' }),
    java({ version: '21' }),
    dgpuj(),
  ],
  manifest: {
    command: '@dgpuj.bin',
    args: [
      '@minecraft.command',
      '@minecraft.jvmArgs',
      '@minecraft.mainClass',
      '@minecraft.gameArgs',
    ],
    workdir: '${game_directory}',
  },
});

// in the manifest
{
  "path": "${dgpuj_dir}/dgpuj-x86_64-pc-windows-msvc.zip",
  "source": { "url": "https://github.com/harmoniya-net/dgpuj/releases/download/v0.6.0/dgpuj-x86_64-pc-windows-msvc.zip" },
  "size": 947,
  "rules": ["allow.os.windows", "allow.arch.x86_64"],
  "integrity": { "sha256": "d90a21ccc99625b450b897b10ac34bd4e36b7fbf03cbd7172133160f2d794fa4" },
  "extract": { "file": "dgpuj.exe", "into": "${dgpuj_dir}/dgpuj.exe" }
}

Variables

Where the executable is, per OS.

// opys.config.mjs
export default defineConfig({
  plugins: [
    minecraft({ version: '1.21.1' }),
    java({ version: '21' }),
    dgpuj(),
  ],
  manifest: {
    command: '@dgpuj.bin',
    args: [
      '@minecraft.command',
      '@minecraft.jvmArgs',
      '@minecraft.mainClass',
      '@minecraft.gameArgs',
    ],
    workdir: '${game_directory}',
  },
});

// in the manifest
"vars": {
  "dgpuj_dir": "${root}/dgpuj",
  "dgpuj_bin": [
    { "value": "${dgpuj_dir}/dgpuj.exe", "rules": "allow.os.windows" },
    { "value": "${dgpuj_dir}/dgpuj", "rules": "allow.os.linux" },
    { "value": "${dgpuj_dir}/dgpuj", "rules": "allow.os.osx" }
  ]
}

Launch · @dgpuj.bin

The dgpuj executable. It goes in command, because it has to be the program that starts.

// opys.config.mjs
export default defineConfig({
  plugins: [
    minecraft({ version: '1.21.1' }),
    java({ version: '21' }),
    dgpuj(),
  ],
  manifest: {
    command: '@dgpuj.bin',
    args: [
      '@minecraft.command',
      '@minecraft.jvmArgs',
      '@minecraft.mainClass',
      '@minecraft.gameArgs',
    ],
    workdir: '${game_directory}',
  },
});

// in the manifest
"command": "${dgpuj_bin}"

This is the one case where command does not come from the loader.

Why the version is not the newest by default: what you write in args is dgpuj's own command line, and it has changed between releases. Each version of opys names the release its docs describe, so a pack gets that one, and the same one in every build.

Telling it which Java to run

args: ['@forge.command', '@forge.jvmArgs', …],

dgpuj goes in front of an ordinary launch line. The first argument is the java it is to run, and that is what the loader's command already is, so the loader's command moves from command to the head of args.

It may be a path or the bare word java, so java({ system: true }) works here too.

Why dgpuj does not provide this itself: which Java runs the game is the loader's to say. Named this way, a config without a loader fails at build time instead of starting with a broken path.

Java 8 on Windows is the exception. It finds its own files from where its launcher is, so dgpuj has to be installed beside java.exe, in the JDK's bin, and given the bare word java.

Good to know

• It ships for Windows and macOS on x86_64 and ARM, and for Linux on x86_64. There is no Linux ARM build.
• On macOS there is nothing to force, so it only starts Java.
• On Linux it acts only when the proprietary NVIDIA driver is present.