How Do I Indirectly Create Shading On Clothes?

How can I add shading to clothes without directly shading the texture?

I don't think you can, what makes you think it's possible? Is someone saying they're doing it?

Nope. You can't. Folds, wrinkles, and any other shadows are all drawn into the texture as you create it in Photoshop or whatever your favorite graphics design program is. This is perhaps the most difficult part of creating believable clothing ... getting the shadows to look right. Take a look at a couple of recent threads in this forum ..

and especially,

If you're asking whether or not SL can render dynamic shading on clothing (like folds), the answer is NO. Clothing is nothing more than a flat texture. It is the same as skin, hair, or any other pixel data rendered on the surface of the avatar's polygons. There is no getting around that fact unless you create your clothing out of sculpted prims, which will not conform to a moving avatar the way draped clothing would.

If you're asking about preserving the layers you might already have in Photoshop, or similar application, the answer is YES... BUT... This gets into the use of multiple clothing items for overlay effects. I suppose you could create a shirt on the undershirt layer and then apply an additional layer of shading (for folds or whatnot) on the shirt layer. You may even take this a step further and put highlights on the jacket layer, but the compromise would be significant. You would lose the ability to use any of those other clothing layers for other textures, AND also lose the ability to create many of the special layering effects that SL's transparency alone can not support (i.e. Burn and Dodge, Overlay, Color Burn, etc.).

It's best to do as much as you can within the image editior and then upload it as a single texture representing a specific clothing item. It's easier to wear, easier to sell (if that is what you plan to do), and much easier to layer with other clothing (we still do not have a generalized texture layer feature within SL).

If you REALLY need some sort of dynamic way of altering the shading on clothing folds and such, the only way to do that without touching the original texture is to modify the polymesh in a 3D application like ZBrush or Maya, apply the texture to the modified polymesh, set up a light source, and bake the lighting into a new rendered version of that texture, then upload it into SL as a single texture. That's a LOT of work (especially modifying the polymesh), and a lot of steps just to get some folds on clothing. Personally, I would rather draw them, or start with angled reference photos of real clothing to begin with, and let reality handle the lighting while I project the clothing onto the avatar in one of those 3D applications.