Tutorial:Understanding CAS Modding/Textures/DDS Files and Alphas

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DDS Files and Alphas

All textures in TS3 - for CAS content but also objects - are in the DDS format. This is a fairly uncommon format, so you will have to set up your graphics program to be able to use it. However, we're getting ahead of ourselves, there's no point in being able to edit DDS files if you don't have any files to edit!

Step 1: Extracting Textures

First off, open CTU. The first thing you see will be a grid containing thumbnails; this is a "list" of all the basegame outfits, ready for cloning.

In order to create custom content you always have to start with game content - and it's always better to start with basegame content if you can, to ensure that your custom item doesn't end up still using EP textures and so on, since if it does then people without that EP can't use it. Of course, sometimes you specifically want to retexture an EP mesh, or somesuch - you can do that, of course, it just takes a couple of extra steps. Let's not worry about that for now: it's not important. :)

Cloning is exactly what it sounds like: making an exact copy of an item, ready for you to change however you like. Once you have cloned something, it's totally separate from the original: you can change the meshes, textures, whatever you like, and there won't be any effect on the original EA item.

In CTU, cloning is easy: you just pick an item in the grid, and go change something. First, of course, we need to find the right item to change. Using the dropdown filter menus above the grid, pick Adult, Female, and Top. Now scroll down the grid - use the mouse, not the scroll wheel, or you'll change the filters by accident - until you find the jacket with three-quarter length sleeves, and a striped shirt underneath it.

Go into the Designs tab, and click "Add New Design". Now you see three options: "Add all from base" adds all of the designs - the colour variations - that the original outfit has in CAS. "Add new blank" just adds the first design, and "Copy last" copies the last design you added, which of course is greyed out since you haven't added any designs. Click "Add new blank".

Give it a moment, and the 3D preview will load, showing the outfit with the currently selected design. You can zoom in and out, rotate, and move the preview - play around with holding down different mouse buttons and seeing what happens when you drag. This is a very useful part of CTU, since it means that you can see how your item will look in-game without having to actually load Sims 3. However, remember that it won't look exactly the same in CAS or in-game, so you should always check in-game occasionally when you're working on something.

Underneath the designs box you'll see several tabs; they all do various interesting things, but the only one we're interested in right now is the Textures tab, so click it.

You'll now see a load of what looks like random numbers and letters: these are called reskeys, short for resource keys, and they're a shorthand way of referring to all the different textures that the outfit is using - the long section after the third colon is called the instance, and this is a unique ID given to that texture, like a file name (if you modded TS2, the instance is very similar to the GUID). You can doubleclick the various reskeys to see the texture image in a popup window: if you have a look at them all, you'll see that they're all very different, and there's a reason for this.

When making clothes, you'll usually need to know about the following textures. Double-click them in CTU as you read the descriptions so you can see what I'm talking about.

  • Base texture - This is also sometimes called the multiplier. It's the main bit of the texture, which gets the CASt colours painted over the top of it: if you want to add buttons, pockets, folds, or anything else which should always be there no matter what colour the outfit is, you usually add them on the base texture. The base texture is always grey, so that you can add CASt colours over the top without them looking weird - if the base texture was coloured, then the CASt colours would get mixed with the base texture colours, so the clothes would always be the wrong colour.
The base texture also contains an alpha, which decides which parts of the mesh are covered by the clothes, and which parts are just skin.
  • Specular - The specular is usually a very dark version of the base texture, and it controls how shiny the clothes are. Lighter bits of the specular are more shiny ingame, darker bits are duller. It has to be very dark because if you make it as light as the base texture, you'll be able to see your own reflection in the clothes. ;)
  • Mask - This controls what's called the RGB channels - that is, the different parts which you can recolour using CASt. You might sometimes find that this texture is just a tiny little red square: this means that the whole outfit just has one recolourable channel. Masks sometimes also have an alpha channel, but it works differently from the alpha channels in base textures - there'll be more on that later. :)
  • Overlay - Think of the overlay like a sticker: you can stick an overlay onto clothes, and it will go on top of the base texture, CASt colours and all that. Overlays are mostly used for complicated details which can't be recoloured: for example zips, metal buttons, belt studs and so on. Overlays have an alpha which decides which parts of the overlay are visible: like the alpha on a base texture, except it only affects the overlay, not the whole outfit.
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