Finally. Finally. Let’s make our first mod.

Article Goals

• Create a working mod using tdesc.lot51.cc and S4E
• Learn to link resources together

Prerequisites

This article assumes you know the tuning basics and how to use Lot51’s Tuning Builder.

Preview

The final mod will create a new CAS trait called Radical.

Making the Tuning

Open tdesc.lot51.cc and create a new Trait tuning. Set the name of your tuning, which for me will be ZMilla:RadicalTrait.

Now let’s add the minimum required fields to get our trait to show up in CAS.

1. display_name - The name of the trait. Use 0x2D8777C7 for Awesome!
2. trait_description - Tooltip description. Use 0x89F40002 for I trust in my awesomeness.
3. ages - List of ages that can have the trait. Required for CAS.
   • I’ll add YOUNG_ADULT, ADULT, and ELDER
4. species - Species that can have this trait. Required for CAS. Add HUMAN.
5. occults - Occults that can have the trait. Required for CAS. Add HUMAN.
6. icon - The icon. Use 2f7d0004:00000000:cfc547bc4742a87a for trait_CoolGuy.png.
7. tags - There are hundreds of tags for different things. We need to one to define the CAS trait category. Add one of the following:
   • TraitGroup_Emotional, TraitGroup_Hobbies, TraitGroup_Lifestyle, or TraitGroup_Social
   • TraitGroup_Emotional is first, so it’s easiest to test with

Here’s a look at the final XML:

<?xml version="1.0" encoding="utf-8"?>
<I c="Trait" i="trait" m="traits.traits" n="ZMilla:Radical" s="4166051917">
  <L n="ages">
      <E>YOUNGADULT</E>
      <E>ADULT</E>
      <E>ELDER</E>
  </L>
  <T n="display_name">0x2D8777C7<!--Awesome!--></T>
  <T n="icon" p="InGame\UI\Icons\CAS\Traits\trait_CoolGuy.png">2f7d0004:00000000:cfc547bc4742a87a</T>
  <L n="occults">
      <E>HUMAN</E>
  </L>
  <L n="species">
      <E>HUMAN</E>
  </L>
  <L n="tags">
      <E>TraitGroup_Emotional</E>
  </L>
  <T n="trait_description">0x89F40002<!--I trust in my awesomeness.--></T>
</I>

Making the Mod

Now we need to add the tuning files to a .package file.

1. In lot51.tdesc.cc, click Download Tuning AND Download SimData
2. (Optional) In Sims 4 Editor, you can create a new empty environment for easier testing.
3. In Sims 4 Editor, open the package editor, enable editing, then create a new package
   • Make sure the new package is in your Mods folder
4. Click Import and import both files from step 1, then save
   • You can also drag & drop files into S4E!

That’s it! A working mod! Our package contains tuning XML that defines a new trait, points to existing game resources, and is backed by SimData.

Troubleshooting

If you have any issues up to this point, here are some things to try.

• Your mod must be in the mods folder
• In Sims 4, select Game Options > Other > View Custom Content. Make sure your mod appears in the custom content list
• Make sure you are looking in the right CAS trait category
• Make sure your XML matches the example above
• SimData fields must match their corresponding XML fields

Modding the Mod

Having a working mod is awesome, and you should feel proud if you’ve made it this far. Congratulations!

There’s a small problem though… this mod just points to existing game data. That’s boring. Let’s fix it!

String Tables

Let’s customize the trait’s name and description using string tables.

1. In the S4E package editor, click Create and change the type to String Table.
2. (Optional) When making a mod you plan to release, use the All Languages option to create linked tables for all languages.
3. Select the English (or your native language) table, and click the + button to create new entires. New entries are added to all linked tables.
4. Create two entries, one for the trait name, one for the description.
5. In both the XML and SimData resources, update the display_name and trait_description fields with the keys you just created. You can copy keys from the string table editor.

   • <T n="display_name">0xADFD2D36</T>
     <T n="trait_description">0x02AEC635</T>

Language Sync

When creating a new string table entry using S4E, an entry will automatically be created for every language.

Because traits are sorted alphabetically, your trait will likely have moved in the list.

Test

Test, test, test some more. While it may be tempting to jump straight to the next step, it is good to test often. The more change you make between tests, the harder it is to know what change caused something to break.

DDS Images

Images referenced by tuning use DDS format, but S4E also supports converting to and from other image types. We’ll export the image we’ve already been referencing, edit it, then reimport it with a new resource key.

1. On the S4E homepage, open the Game File Browser, select the Icon Browser tab.
2. While any icon should work, search trait_CoolGuy to find the one we’ve been using.
3. Right click the image and export to a DDS or PNG.
4. Edit the image with an editor like GIMP or photoshop.

Generating an Instance

The exported file was named trait_CoolGuy-0xCFC547BC4742A87A.dds. When importing files with S4E, the instance will be taken from the file name, and the type will be inferred from the file extension. Use this feature if ever want to manually set instances.

For images, you can exclude an instance entirely, and one will be generated using the file name. Internally, it uses the FNV hash of CreatorName:PackageName:FileName. I’ll rename my image to trait_Radical.dds.

Importing and Referencing

Now we need to import the image into our package and tell our tuning files to use it.

1. Click Import and select your edited DDS file (or drag and drop).
2. Right click the new DDS resource and select Copy > Copy Instance
3. In the tuning XML AND SimData, update the icon field with the new DDS resource key.
   • Only the instance changed, so just editing the last part of the key is enough.

<T n="icon">0x2f7d0004:0x00000000:0x835ACA909C22EAEA</T>

Finally, a fully customized tuning mod!

Example Mod

Radical Trait Mod

• ZMilla-RadicalTrait.package

The Takeaway

While the mod we made is very simple, it shows some very important concepts.

• Resources can reference other resources using Resource Keys
• Some resource types, like string tables, use a resource specific key.

These concepts hold true for more complex mods. Tuning files can reference other tuning using tuning IDs, or reference things like sound and animation using resource keys.

There’s thousands of tuning descriptions, and hundreds of thousands of tuning files. In the next article, we’ll look more at exploring this massive dataset in a manageable way.