Modding Tutorials/Writing custom code

< Modding Tutorials

In addition to creating data for the game to use, you can also write code. You could probably write in any .NET language, but I’ve only tested C#.

1. Create a new class library project in your IDE of choice;
   1. Go to File -> New -> Solution;
   2. Go to C# or .NET -> Library or Class Library (NOT portable);
   3. Enter a project name (solution name automatically updated);
   4. Choose a location, preferably:
      

      (RimWorldInstallFolder)/Mods/(YourModName)/Source

   5. Untick "Create a directory for solution"/"Create a project within the solution directory",
2. In your project, add references to Assembly-CSharp.dll and UnityEngine.dll:
   1. Copy these files:
      

      (RimWorldInstallFolder)/RimWorld_Data/Managed/Assembly-CSharp.dll
      (RimWorldInstallFolder)/RimWorld_Data/Managed/UnityEngine.dll

   2. Place them in your project:
      

      (RimWorldInstallFolder)/Mods/(YourModName)/Source/(YourSolutionName)/Source-DLLs

   3. In your IDE project file browser, right-click the "References" folder and "Add reference";
   4. Choose the ".NET Assembly Browser" tab and "Browse", go to the folder you placed the copied DLLs;
   5. Choose both DLLs and click OK,
3. In your project properties, change the target framework to .NET 3.5:
   1. In your IDE project file browser, right-click Solution (YourSolutionName);
   2. Choose Properties;
   3. Go to the "Compiling" tab, "Output", "Target framework", "Change" and choose ".NET Framework 3.5",
4. Create a new class in a new code file:
   1. In your IDE project file browser, right-click (YourProjectName), Add -> New item -> C# or .NET -> Class;
   2. Rename the class to what you want the class name to be, e.g DamageWorker_FlameExtension,
5. You’ll want to add these namespace to the top of each of your .cs source files as necessary;
   

   using UnityEngine;  	//For all Unity functionality, rendering, resource management
   using AI;		//RimWorld AI
   using Sound;	        //RimWorld sound subsystem
   using UI;		//RimWorld GUI
   

6. Write your class;
   1. Decompile source code to take a look at the game's existing code;
   2. If you still get stuck on anything, any modding questions can be asked on the subforum,
7. Compile your class into a .dll;
   1. Make sure your project's output type is "class library";
   2. Note: by default, Visual Studio will compile all the references of the project as well, so you’ll get a copy of UnityEngine.dll and Assembly-CSharp.dll and some others. You don’t need these. Just take YourModName.dll,
8. Place the .dll in the YourModName/Assemblies folder of your mod;
9. Reference the classes in your .dll from the xml data in the YourModName/Defs folder;
   1. Example: Create a new ThingDef with a <thingClass> that points to a class in your .dll,
10. The game should load your class now;
11. Optional: Release your source code.
    1. Most mods include a YourModName/Source folder with the full C# project in it for other modders to check out;
    2. Some mods include a Dropbox download link to their source code in the mod's topic. This is also a possibility.
       
       

See also

• You can find a small tutorial project here: Modding Tutorials/Assembly Modding Example