My recommendation to make this better, is to truly make the Actors multiple layers. From one of my friends who uses this a lot more than me, one of the issue of doing clothing is you have to do clothing for each skin tone if you want a shirt to be truly universal.

I personally come from making a few clothes in SecondLife like environments, and I think their solution could work here as well. Make the Actor say layer 0, everything else is on top of layer 0.

So this would help in that when you make a shirt lets say your shirt would be layer 1, if it had a spot that was transparent then the Actor would go through, or if you were making something a second layer then the first layer would come through etc.

I realize this would probably mean recreating the actors completely, but I think it would make the limits much further out for what you could do with this software.

CloneCloth and the various Cloths developed by third-party developers are double or even multi-layer, so that already exists. The same item of clothing can therefore be applied to different characters, regardless of skin tone. The only distinction made is between physique, so clothing is separate for male and female characters and yet again for heavy-set characters. 

Without collision detection, however, it has hard to make it work right under all circumstances.

IC6 will have an new clothing system, that includes dynamic clothing that can actually drape, so it has some form of physics interaction. We don't know all details yet of IC6 clothing, but it will be an improvement. We also don't know how universal the clothing system will be.

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Welcome to the forum!

What you describe is how most iClone avatars are. Chuck and Gwynn are just one layer, but you can adjust the texture separately, as the clothing and skin are separate UV's

CloneCloth is what Reallusion calls there multi-layer clothing option. You will also find many third party avatars that are multiple layer. Often many more than two.

You can also import DAZ (or other) multi-layer avatars if you have 3DXchange 5 Pro.

We have yet to see if the upcoming iClone 6 avatars have full skins under their clothes or not.

iClone 6 will be able to utilize all types (single and multiple layer) and generations of avatars.

My apologies I posted this to the wrong subsection.