Editing Modding Tutorials/Decompiling source code

{{BackToTutorials}}

The base game provides a bunch of code snippets in ''../Source/'', relative to your Rimworld installation. Since this isn't a lot, one might want to take a look at the game's full source code. RimWorld's [https://rimworldgame.com/eula/ EULA] allows you to decompile the game for personal use. It's recommended to read it.

The following programs are used and recommended by modders:<br/><br/>

=Decompiling source code=

===ILSpy===

ILSpy is generally recommended as it is the best-maintained and most reliable decompiler. The core project only has binaries for Windows, but there is an [https://github.com/icsharpcode/AvaloniaILSpy Avalonia-based port] as well as a [https://github.com/icsharpcode/ILSpy#unix--mac CLI application for Mono framework] for OS X and Linux.<br/>

# Download [http://ilspy.net/ ILSpy] ([https://github.com/icsharpcode/ILSpy/releases Download latest release]) and extract it to a directory of your choosing. Optionally create a desktop shortcut;
# '''Either''': associate the .dll extension with ILSpy:
## Navigate to ''Assembly-CSharp.dll'' in ''../Rimworld***_Data/Managed/'', relative to your Rimworld installation and with *** being a version number (See Note on MacOS below);
## Right-click "Open with" and select a standard program. Navigate to your ILSpy installation and double-click ''ILSpy.exe'', tick the checkbox and accept;
## Double-click ''Assembly-CSharp.dll'',
# '''Or''': open ILSpy and open a .dll:
## Open ILSpy;
## Go to File -> Open or press Ctrl+O, navigate to ''../Rimworld***_Data/Managed/'', relative to your Rimworld installation and with *** being a version number (See Note on MacOS below);
## Select ''Assembly-CSharp.dll'' and confirm,
# Click the "+" next to ''Assembly-CSharp (***)'', you will now see a list including the items ''Rimworld'' and ''Verse'';
# Take your time to look through the source code, to make yourself familiar. If you ever need the source code, open ILSpy again:
## Ctrl+Shift+F or Ctrl+E opens the search bar which can be used to search through all loaded assemblies;
## Ctrl+F opens a search bar for the currently opened decompiled class.<br/><br/>

If using CLI application:
# Despite the instructions saying .NET 5.0 SDK is needed, you may also need [https://dotnet.microsoft.com/download/dotnet/3.1 .NET Core 3.1];
# It seems that it's possible to simply build from a [https://github.com/icsharpcode/ILSpy/releases release tarball], even if the instructions suggest to use a git checkout;
# After you've built ILSpy, find the ''ilspycmd'' tool (should be located at ''ICSharpCode.Decompiler.Console/bin/Release/netcoreapp3.1'');
# Run a command like ''ilspycmd RimWorld/RimWorld*_Data/Managed/Assembly-CSharp.dll -p -o <output directory>'' (use proper paths to RimWorld and for the output directory);
# The given output directory now contains decompiled sources.

===dnSpy===

dnSpy is an alternative with a Visual Studio editor feel. At the time of this writing, however, the original project has been archived for more than two years and none of its forks have reached a similar level of adoption. Decompilation glitches can occur.<br/>

# Download [https://github.com/0xd4d/dnSpy/releases dnSpy] and extract it somewhere.
# Open dnSpy.exe. Once it's open, click "open" on the top ribbon (or press Ctrl+O).
# Navigate to ''../Rimworld***_Data/Managed/'', relative to your Rimworld installation and with *** being a version number.
# Ctrl+Shift+K to open the search bar.
# Explore the assembly and look through the source code to your heart's desire.

===Rider / dotPeek===

Rider is a cross-platform IDE with a built-in decompiler. If you're using Rider as your IDE ([[Modding_Tutorials/Setting_up_a_solution#Rider_.28good_for_Mac.29|Setup Instructions]]), you can view the source of any RimWorld class or method by right-clicking its name and clicking Go To > Definition.

The developer of Rider also offers a free standalone decompiler in the form of [https://www.jetbrains.com/decompiler/ dotPeek]. dotPeek is preferred by some for reading IL Code for the purpose of Harmony transpilers, but suffers similar glitches and inconsistency as dnSpy when decompiling back to C# code.

===MonoDevelop===

MonoDevelop is capable of decompiling DLLs, albeit using clumsy initial settings. It is Linux only, otherwise you have to download Xamarin Studio which doesn't have a decompiler.<br/>

# Download [http://www.monodevelop.com/download/ MonoDevelop] and install it;
# '''Either''': associate the .dll extension with MonoDevelop:
## Navigate to ''Assembly-CSharp.dll'' in ''../Rimworld***_Data/Managed/'', relative to your Rimworld installation and with *** being a version number (See Note on MacOS below);
## Right-click "Open with" and select MonoDevelop as standard program;
## Double-click ''Assembly-CSharp.dll'',
# '''Or''': open MonoDevelop and open a .dll:
## Open MonoDevelop;
## Go to File -> Open, navigate to ''../Rimworld***_Data/Managed/'', relative to your Rimworld installation and with *** being a version number (See Note on MacOS below);
## Select ''Assembly-CSharp.dll'' and confirm,
# '''Very important''': search for a dropdown called "Visibility" and change it from "Only public members" to "All members";
# '''Very important''': search for a dropdown called "Language" and change it from "Summary" to "C#";
# Click the "+" next to ''Assembly-CSharp (***)'', you will now see a list including the items ''Rimworld'' and ''Verse'';
# Take your time to look through the source code, to make yourself familiar. If you ever need the source code, open ''Assembly-CSharp.dll'' again.<br/><br/>

===MacOS Directories===

For Macs, directories are similar but in: ../RimWorldMac.app/Contents/Resources/Data/Managed. 

For Steam installed RimWorld, find your app here: ~/Library/Application Support/Steam/steamapps/common/RimWorld/RimWorldMac.app.

=How to make use of a decompiler=
{{Main|Modding_Tutorials/ThingDef}}

=Tips when decompiling=
# Right-click any Type or Method and hit "analyse" to obtain more context on that item. 'Used by' and 'Uses' provide a lot of contextual clues which is required to know how things work.
# RimWorld often uses reflection to instantiate Workers and MakeThings. This means no decompiler will cleanly find what/where an instance of a class is created. Hint: if you find yourself using 'new Pawn()', you're doing it wrong.
# If you're going in circles trying to find things like "where is X assigned", odds are you'll need to look at the XML for it. The XML contains the data, C# does things with it.

=See also=

* [[Modding Tutorials/Writing custom code|Writing custom code]] shows a broad overview of C# coding.<br/>

[[Category:Modding tutorials]]