Saturday, March 7, 2015

Things you need to know about mesh bodies (Part 2)

This article was published in Fusion Magazine, March 2015. Click for the magazine!

Greetings everybody! In the previous issue of Fusion, we started defining what a mesh body is, what the UVs of the mesh body are, and why this means a lot more work for skin and clothes creators... Particularly when some parts do not conform to the SL avatar UVs.

In this issue, we're going to talk about alpha zones.

Similarly to when we wear clothes over our SL avatar, some clothes will completely cover the avatar in the areas they occupy, and some other clothes won't, resulting in the effect that the mesh body pokes out of the clothes. When using the SL avatar, the solution consists of using a special clothing layer called the alpha layer. These alpha layers, as we know, will make the indicated areas of the SL avatar transparent. In the process of rebaking, the server shows the avatar's skin, minus the alpha areas indicated in the alpha layer.

We might think that the same process could be translated to mesh bodies: Have a texture as an alpha layer, and apply it to the body. The bad news: Currently, we cannot do this to prims (Remember that mesh items, in the end, are also prims.)

That's why creators of mesh bodies adopt this approach: They decide where to create slices of the body (alpha cuts, or alpha zones), and then, by using a HUD, a script makes those alpha zones hide or show, as needed.

Maitreya's HUD
Belleza's HUD
Slink's HUD, v1 (the updated body was released after this article was ready to publish)

Now, keep this in mind: Each mesh prim may have a maximum of eight texturable faces. This means that for every eight alpha cuts, maximum, a new prim will be required, to be able to have more alpha cuts. It's not something that affects the final user, but when you ask to a creator to make more alpha cuts in their body HUDs... remember that this creates more technical issues for them. They can be overcome, but thank them for taking all the hassle.

We'll finish this issue with a note: If you're wearing a mesh body, and you have to alpha all of it, to wear your mesh clothes... just take the mesh body off! Your graphics card will thank you for it, and the graphics cards of those around you will, too.

The reason? Transparent or not, that geometry is still there, and so, is still transmitted. We don't want to add extra stress to servers and our own computer (and those of people around). Living in SL is also living in a community; be the nice neighbour and try to minimize the impact you cause on others' machines.

That's it for this issue! We'll finish the mini series in the next one, talking about appliers and the Omega system. Enjoy your SL.

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