It’s not possible to wear on a mesh body tow or more texture semi transparent! (like lace texture or tattoo)

our video-card become crazy and don’t know what she must show use and she don’t know hate texture are first and what texture are the second one 😦

for this reason we use the masking mode ( Masking is like a black and white image for our texture.The white represents the transparent part of our texture. The black represents the solid part of our texture)

Actually EVE rare configured by default like this :

Layer Tattoo = blending
Layer Underwear = Masking
Layer Fashion = Masking

If you wear tow texture in same time in blending mode you can see the first one but not the second one (you must wear the first one in MASKING mod and the second one in Blending)

Some Example:

Masking / Masking / Masking = it’s ok
Blending / Masking / Masking = it’s ok
Masking / Blending / Masking = it’s ok
Masking / Masking / Blending = it’s ok
Masking / Blending / Blending = it’s NOT ok
Blending / Blending / Blending = it’s NOT ok
Blending / Masking / Blending = it’s NOT ok
Blending / Blending / Masking = it’s NOT ok

So when you buy a fashion applier (style semi-transparency) and if this fashion are send on the underwear or fashion layer you fashion look like this:

For have the good look result you must active your layer in the Blending mod!

And now your fashion look like this:

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SL WIKI source:

Alpha blending

Alpha blending is a technique commonly used to “blend” multiple semi-transparent polygons (or in Second Life’s context, “faces”) to resemble real-world semi-transparent surfaces. The rendering of alpha blended objects is not trivial, and puts more stress on the rendering pipeline to:

Reorder the order of which every single semi-transparent object in the world gets rendered
Render each face in back to front ordering
Blend each rendered face with the previously rendered face

There are also a number of problems that semi-transparent objects cause on the hardware, such as not being able to discard fragments (or “potential” pixels) that are blocked from view before the renderer attempts to render them due to the nature of alpha blending. It’s also difficult to apply per-pixel lighting to these surfaces within the lighting & shadows renderer, instead requiring workarounds to apply the correct lighting to these surfaces.

As such, alpha blending should be used very sparingly, and avoided wherever possible.

Alpha masking

Alpha masking (or alpha testing for those of you familiar with the more technical term!) is a technique wherein each pixel in a texture map is “tested” for if it’s above a specific threshold or not. If the test passes, then that pixel is rendered as if it were fully opaque. If the test fails, then that pixel is discarded, or otherwise considered to be fully transparent.

Alpha masking allows us to take advantages of many of the optimization techniques available to us on most graphics hardware, and these surfaces can receive full lighting and shadows with no need for any workarounds. They perform very well, but at the cost of having much sharper edges where pixels are transparent. Since alpha masking relies on a simple test for if a pixel’s alpha channel falls above or below a given value, varying transparency values are not possible with this technique.

Alpha masking is also not subject to many of the flaws of alpha blending, such as different sorting errors that can arise due to overlapping faces and objects. It’s handled much like any other opaque surface, either the pixel is opaque, or it’s not; there is no inbetween.

So which should I use?

Although alpha masking may be much faster than alpha blending, you must consider how badly your surface needs varying transparency values. If you can make due with a surface that has sections that are either fully opaque or fully transparent, then always opt for alpha masking. If you can’t live without varying transparency values, then opt (very sparingly) for alpha blending.

Remember, your choice can have a significant impact on performance and quality of your content!