jhmod

jhmod

A tool to work with Jupiter Hell game files.

Features

• Create and extract .nvc archives
• Scan for interesting .nvc archive paths referenced in the JH program
• Get information from save files

Install

Manually

Refer to https://go.dev/doc/tutorial/compile-install for more information on how to install golang packages manually.

# For those who don't have it already defined.
export GOPATH="$HOME/go"
export PATH="$PATH:$GOPATH/bin"

go install github.com/sector-f/jhmod

Nix

A flake is offered in this repository. You can add it to your own flake as a input, then add it to your environment.systemPackages. See example usage here.

You can develop using the flake via nix develop or setting up direnv so it auto-loads the flake. Add use flake to your .envrc then run direnv allow.

Usage

Conventions

• Lines beginning with $ are commends you type.
• Lines beginining with ... SNIP ... indicate lines that were removed for brevity.
• Other lines are program output.

Build a list of interesting paths

1) obtain a core file using ./scripts/get-core.

$ ./scripts/get-core
core.324962

2) build the pathlist using jhmod pathlist scan

$ jhmod pathlist scan core.324962 | tee pathlist.txt
data/font/terminal8x9_c64i.png
data/lang/de.csv
data/lang/pl.csv
... SNIP ...
data/lua/jh/gfx/tilesets/ts01/ts01.lua
data/lua/jh/gfx/tilesets/ts01/ts01_A.lua
data/lua/jh/gfx/tilesets/ts01/ts01_B.lua

Extract .nvc files

Note: You should consider generating your own pathlist.txt to ensure jhmod knows about all of the paths. Using an old pathlist.txt may result in many unknown paths that need to be extracted with -u.

$ jhmod extract -f core.nvc -p samples/pathlist.txt
Extracted 266 files
$ ls data/
font  lang  lua

Q: Where are my assets?

You may need a more complete pathlist.txt. The one provided is reproducible by using jhmod pathlist scan, however, it doesn't find graphics data (TODO).

Jupiter Hell Modding cheatsheet

1. Find your game directory that contains .nvc files. There should be assets.nvc and core.nvc. Note down these paths.
2. Use jhmod extract -f core.nvc -p samples/pathlist.txt to extract the files into the current directory. Most (all?) files should be located in a data subdirectory.
3. Create a folder in your JH game directory called mods
4. Create a subfolder in your JH game directory that will contain your mod, say coolestmod
5. Put some mod lua code into mods/coolestmod/main.lua. This will run when the game loads.
6. Use the files created via jhmod extract ... to determine what lua tables to manipulate to achieve your desired effect.
7. You can now test your mod.

See Modding on the Jupiter Hell Wiki for more information.

License

BSD 3-Clause (BSD-3-Clause). See LICENSE.