I think that's happening because you have triangles there that share an edge. I believe that little bit of clipping there is unavoidable. You can either change the mesh, or camouflage the clipping with texture.

Right now, you have this:

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The up and down line is the tummy, the diagonal line is the skirt, see how they meet at the top? That can be a good thing. If you match the normals, you can create a seamless look with matching skirts and tops. But it also means, you can sometimes get a little bit of clipping there. So what I do is put the skirt texture on the tummy. Not just blue undies, but actual blue skirt texture.

Here's a different way you could mesh the skirt at the waist:
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See how there's a 3D ridge at the waist in that picture? The good thing about this is you shouldn't get that clipping. The bad thing is, well, now you have a 3D ridge. That makes it harder to fit untucked shirts over it (which may or may not be a concern for some folks). It also means you can't have a seamless look, again, that may or may not be a concern, depending on what look you're going for.

We are trying to simulate the look and motion of real life fabric skirts with discrete, polygonal meshes. We're also trying to mesh a body inside a skirt without any mesh self-intersection. It is simply not possible to do this perfectly. Every approach and technique we can try has tradeoffs. Just do the best you can.

Thanks... I'll have to try changing the texture.

I changed the mesh because it originally had a 3D ridge (like in your second diagram), and I thought that that was what was causing the problem! So now it's like the first diagram, and it's still happening.

I'm confused as to why it shows up in Body Shop and the game but not in MilkShape, though...

Edited to add:

Changing the texture didn't work. The mesh doesn't line up the bits properly, so it's still very visible.

Okay, this is very weird. I've got two alpha meshes. The alpha skirt parts are identical, but I made one with boots and one with shoes. The one with boots doesn't have this clipping problem... but the one with shoes does. The thing is, I made the second mesh from the first by substituting the different shoes. The rest of it (including the legs, tummy, and butt) should be exactly the same.

Please excuse me while I scream.

Okay, here's what I did. I looked at the bottom layer (the legs) for each alpha mesh. The normals weren't the same, so I changed them to match with the alpha mesh that does work. But I still had the same problem.

So I went in and used the MilkShape shape for the alpha skirt with boots (which works fine), and changed nothing except the shoes. And there's still clipping at the waist!



The one on the left is the skirt with shoes; the one on the right is the skirt with the boots. I don't get it. From the knees up, they are exactly the same. I wonder if SimPE is actually accepting my changes...

Are the bone weights the same too?
Do they add up to 100%?
If not, you will get wierd effects, and clipping is one of them.

Remember when you were making a shirt or maybe pants and it looked fine in BodyShop but not the game? They don't render things the same way. Things looking fine in BodyShop is no guarantee they will look fine in game. But if it was easy, would it be as fun? Yes, yes it would. Much more fun in fact. Hm. Forget I said that.

Ah. My skirt's uv map matches the leg uv map in the waist area, so that works for me. But if you already have textures made at this point, it would be much too annoying to go back and change the uv map.

They should have the same bone weights. Unless MilkShape changed them on me. As I said, I imported the working alpha mesh, changed only the shoes, and then replaced the resulting shape into the correct mesh file in SimPE. So if the bone weights at the waist got changed, I wasn't the one who changed them!

This is making my brain hurt. Darn gremlins.

Edited to add:

I just tried something. I replaced the GMDC for the borked alpha mesh with the GMDC for the working alpha mesh. And it's still borked (it does change, though... I can tell by the shoes).

Can something within the mesh itself (other than the shape) get corrupted? Because this is making no sense, otherwise. Two identical shapes that don't display identically? Ugh...

I really don't know, sorry. *Something* somewhere isn't identical, but it might be something like a bounding box optimization being done by the graphics engine, that we can't do a thing about. I don't even know if that's what it is. All I can think of right now is tweak it this way or that way and see if that does anything. :/

Or change the waist texture on that skirt, for the "with shoes" mesh. That mesh doesn't like the elastic waist, then give it a different waist or belt or something.

And remember, don't drive yourself crazy with this.

The pockets are full of cute, BTW.

Ugh. It was the alpha texture on the legs. I thought all the alphas were the same up in the waist area, but I guess they weren't.

Too bad I already went crazy...