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Theme Catchup2018 - posted on 1st May 2018 at 1:50 PM
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Delphy's CAS Texture Unitool v1.7


The following is simply a guide/handbook/manual (however you want to look at it) for the CAS Texture Unitool (CTU). This is not a creation tutorial, so do not expect to specifically learn how to edit, modify or design textures from reading this.

RightArrow.gif Refer to CTU Tutorials for a list of tutorials. Or, poke around the MTS Sims 3 Creation Forum.

CAS Parts

A .caspart file itself can be thought of as a "placeholder" in Create-A-Sim. By linking meshes, textures and other details to the .caspart, you create what is commonly know as a CAS Part. CAS Parts are what a the game actually displays on the sim (i.e. shirts, shoes, watches, etc); this includes the mesh, shape, color, lighting, transparency or anything else that affects the look of the design.

DDS Files

A DDS file is a type of raster image, commonly used by many games, including both Sims 2 and Sims 3. DDS files can be saved in a variety of formats, both compressed and uncompressed. You will need to save your images in DDS format for use in the CTU.

RightArrow.gif Image Editor
Your everyday run of the mill image editor like MS Paint or Paintbrush will not suffice for TS3 skinning. Instead you'll need a program that at least has these basic features:

  • RGB Mode
  • Channel View
  • Layers
  • Image Adjusters (i.e. desaturate, colorize, etc.)

Most people use Adobe Photoshop or Paint Shop Pro. However, there are free alternatives like GIMP or Paint.NET.

RightArrow.gif Plugin
Many imaging programs do not initially know how to save/handle DDS files, so you'll have to install a plugin for them. Here are two of the most common ones.

DXT Compression Chart

When working with CAS Part textures the compression type most commonly used is DXT. There are several different DXT compressions available so refer to the chart below to see which one to use for each specific part.

Texture/File Acceptable Compression(s) Alpha Channel
Base Texture DXT5 Yes
Clothing Specular DXT1 No
Clothing Ambient DXT1 No
Mask DXT1 No*
Overlay DXT1, DXT3, DXT5 Yes
Part Mask DXT1 No*
Stencil DXT1, DXT3, DXT5 Yes
Skin Specular DXT1 No
Skin Ambient DXT1 No

* If the mask has 4 pattern regions, then you'll need to include the alpha channel.


The CTU saves your finished creations as .packages, similar to what was used with The Sims 2.

RightArrow.gif For help with installing .packages, see Installing Sims 3 Package Files

Creating A New .Package