Valheim Mods

Several mods for the game Valheim, by me.

Mods can be found on Valheim ThunderStore

Development Environment Setup

How to setup the development enviroment for this project:

1. Install Visual Studio 2022 and add the C# workload.
2. Update Environment.props in the projects base path, and update the property VALHEIM_INSTALL to point to the path of your installed copy of Valheim.
3. Install the required dependencies by running the script ./scripts/Download-Dependencies.ps1 in Powershell
4. Open ValheimMods.sln with Visual Studio, and build the project at least once.
5. Close Visual Studio, and reopen ValheimMods.sln. For whatever reason Visual Studio will not detect the publicized assemblies unless this is done.

Post Build automations

Included in this repo is a PowerShell script publish.ps1. The script is referenced in the project file as a post-build event. Depending on the chosen configuration in Visual Studio the script executes the following actions.

Building Debug

1. Build the project with target Debug. The publish.ps1 PowerShell script from this repo...
   • The compiled dll file for this project is copied to <ValheimDir>\BepInEx\plugins.
   • A .mdb file is generated for the compiled project dll and copied to <ValheimDir>\BepInEx\plugins.
   • automatically generates a .dll.mdb file, which is needed for Unity/mono debugging. It should be in <ValheimDir>\BepInEx\plugins, too.
   • <JotunnModStub>\libraries\Debug\mono-2.0-bdwgc.dll is copied to <ValheimDir>\MonoBleedingEdge\EmbedRuntime replacing the original file (a backup is created before).

Building Release

• A compressed file with the binaries is created in <JotunnModStub>\Packagesready for upload to ThunderStore. Dont forget to include your information in the manifest.json and to change the project's readme file.

Unity Editor Setup

1. Download UnityHub directly from Unity or install it with the Visual Studio Installer via Individual Components -> Visual Studio Tools for Unity.
2. You will need an Unity account to register your PC and get a free licence. Create the account, login with it in Unity Hub and get your licence via Settings -> Licence Management.
3. Install Unity Editor version v2020.3.44f1.
4. Copy all assembly_*.dll from <ValheimDir>\valheim_Data\Managed into <JotunnModStub>\JotunnModUnity\Assets\Assemblies. Do this directly in the filesystem - don't open Unity first or import the dlls directly in Unity.
5. Warning: These assembly files are copyrighted material and you can theoretically get into trouble when you distribute them in your github repository. To avoid that there is a .gitignore file in the Unity project folder. Keep that when you clone or copy this repository.

Debugging

You can enable remote debugging of your mod code at runtime via dnSpy or Visual Studio. Before being able to attach a remote debugger you will have to prepare your game install and turn it into a "Development Build" once:

1. Locate your Unity Editor installation from the previous step and navigate to <UnityInstall>\Editor\Data\PlaybackEngines\windowsstandalonesupport\Variations\win64_development_mono
2. Copy UnityPlayer.dll and WinPixEventRuntime.dll from that folder into your game installation folder. Overwrite existing files.
3. Open the <Valheim>\valheim_Data\boot.config with a text editor (Notepad++ for example) and add a new line player-connection-debug=1 to it.
4. When starting up Valheim you should see a Development Build text at the lower-right corner of the screen.

Debugging with Visual Studio

Your own code can be debugged in source with Visual Studio itself. You cannot debug game disassemblies as with dnSpy, though.

1. Install Visual Studio Tools for Unity (can be done in Visual Studio installer via Individual Components -> Visual Studio Tools for Unity)
2. Build the project with target Debug.
3. Start Valheim (either directly from Steam or hit F5 in Visual Studio when Steam is running)
4. Go to Debug -> Attach Unity debugger
5. Since the patched mono dll does not open the same port as Unity Dev builds, you have to click on Input IP. It should fill in your local IP automatically. you just have to change the port to 55555and the debugger should connect.

Debugging with dnSpy

Thanks to mono and unity-mono being open source, we patched and compiled our own mono runtime to enable actual live debugging of the game and the mod itself with dnSpy.

1. Download dnSpy-net-win64 and extract the exe.
2. Load all assemblies from <ValheimDir>\unstripped_corlib into dnSpy (just drag&drop the folder onto it).
3. Load all assembly_* from <ValheimDir>\valheim_Data\Managed into dnSpy (do not load the publicized ones, they will not be loaded into the process and therefore can not be debugged).
4. Load JotunnModStub.dll from <ValheimDir>\BepInEx\plugins into dnSpy.
5. Copy <JotunnModStub>\libraries\Debug\mono-2.0-bdwgc.dll into <ValheimDir>\MonoBleedingEdge\EmbedRuntime and overwrite the existing file.
6. Now go to Debug -> Start Debugging and select Unity debug engine. Select your valheim.exe as the executable and hit OK.
7. If you did set some breakpoints, the game will halt when it hits the breakpoint in memory and dnSpy will show you the objects in memory and much more useful stuff.

Mod Development Resources

Description	Link
Template used to create this project	https://github.com/Valheim-Modding/JotunnModStub
Jötunn's in depth setup guide	https://valheim-modding.github.io/Jotunn/guides/overview.html
Jötunn Mod Library Tutorials	https://valheim-modding.github.io/Jotunn/tutorials/overview.html
Logging with BepinEx	https://docs.bepinex.dev/v5.4.11/articles/dev_guide/plugin_tutorial/4_logging.html
Helpful development mod, launches game automatically and picks world	https://valheim.thunderstore.io/package/abearcodes/Simple_Auto_Game_Start/