Difference between revisions of "Modding Tutorials/Decompiling source code"

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(Notes about building ILSpy)
(Updating up the decompiler recommendations to be more in line with what #mod-development actually recommends.)
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=Decompiling source code=
 
=Decompiling source code=
 
===dnSpy===
 
dnSpy is a great application for decompiling or debugging and has a Visual Studio editor feel to it. It's currently only for Windows.<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.
 
  
 
===ILSpy===
 
===ILSpy===
  
One method is to use ILSpy. This software is recommended because its settings are correct on a clean install. It provides binaries only for Windows, but you can compile it yourself as a CLI application for Mono framework on OS X and Linux, see its [https://github.com/icsharpcode/ILSpy#unix--mac "How to build" instructions] on GitHub for more info.<br/>
+
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] (Download latest release) and extract it to a directory of your choosing. Optionally create a desktop shortcut;
 
# Download [http://ilspy.net/ ILSpy] (Download latest release) and extract it to a directory of your choosing. Optionally create a desktop shortcut;
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# 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);
 
# 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.
 
# 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===
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# Click the "+" next to ''Assembly-CSharp (***)'', you will now see a list including the items ''Rimworld'' and ''Verse'';
 
# 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/>
 
# 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/>
 
 
===Rider===
 
 
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.
 
 
  
 
===MacOS Directories===
 
===MacOS Directories===

Revision as of 17:40, 8 April 2023

Modding Tutorials

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 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:

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 Avalonia-based port as well as a CLI application for Mono framework for OS X and Linux.

  1. Download ILSpy (Download latest release) and extract it to a directory of your choosing. Optionally create a desktop shortcut;
  2. Either: associate the .dll extension with ILSpy:
    1. 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);
    2. Right-click "Open with" and select a standard program. Navigate to your ILSpy installation and double-click ILSpy.exe, tick the checkbox and accept;
    3. Double-click Assembly-CSharp.dll,
  3. Or: open ILSpy and open a .dll:
    1. Open ILSpy;
    2. 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);
    3. Select Assembly-CSharp.dll and confirm,
  4. Click the "+" next to Assembly-CSharp (***), you will now see a list including the items Rimworld and Verse;
  5. Take your time to look through the source code, to make yourself familiar. If you ever need the source code, open ILSpy again:
    1. Ctrl+Shift+F or Ctrl+E opens the search bar which can be used to search through all loaded assemblies;
    2. Ctrl+F opens a search bar for the currently opened decompiled class.

If using CLI application:

  1. Despite the instructions saying .NET 5.0 SDK is needed, you may also need .NET Core 3.1;
  2. It seems that it's possible to simply build from a release tarball, even if the instructions suggest to use a git checkout;
  3. After you've built ILSpy, find the ilspycmd tool (should be located at ICSharpCode.Decompiler.Console/bin/Release/netcoreapp3.1);
  4. 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);
  5. 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.

  1. Download dnSpy and extract it somewhere.
  2. Open dnSpy.exe. Once it's open, click "open" on the top ribbon (or press Ctrl+O).
  3. Navigate to ../Rimworld***_Data/Managed/, relative to your Rimworld installation and with *** being a version number.
  4. Ctrl+Shift+K to open the search bar.
  5. 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 (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 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.

  1. Download MonoDevelop and install it;
  2. Either: associate the .dll extension with MonoDevelop:
    1. 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);
    2. Right-click "Open with" and select MonoDevelop as standard program;
    3. Double-click Assembly-CSharp.dll,
  3. Or: open MonoDevelop and open a .dll:
    1. Open MonoDevelop;
    2. 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);
    3. Select Assembly-CSharp.dll and confirm,
  4. Very important: search for a dropdown called "Visibility" and change it from "Only public members" to "All members";
  5. Very important: search for a dropdown called "Language" and change it from "Summary" to "C#";
  6. Click the "+" next to Assembly-CSharp (***), you will now see a list including the items Rimworld and Verse;
  7. 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.

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

Tips when decompiling

  1. 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.
  2. 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.
  3. 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