Everything you need to know About Alpha Layers in Second Life – Part 2

In the previous article, I talked about some of the history of creating in Second Life and the challenges we faced as creators and as customers in hiding the avatar body to prevent clipping of our skin through the clothing. Or even just hiding the body to wear a cute dragon avatar! In this article I will talk about the current state of things. Starting with…

Bakes on Mesh

In March or so of 2018, Linden Lab made the announcement that they would be implementing this new feature called “Bakes on Mesh“. Bakes on Mesh would take whatever textures were baked into the hidden, base SL avatar, and display it to whatever worn mesh items had the “Bake” flag applied to them.

A peek into our working folders

When Bakes on Mesh was announced, we at the Slink workshop had already started, and were several months into, our “More Alpha Cuts” project. Our scripts were groaning under the weight of what we had already, and adding the many requested new alpha cuts was a very daunting task, but nevertheless, we had started to break up our body and HUD into more pieces and faces, and explore what was required for the new setup.

Of course, being early adopters, and always keen to keep up with new technology, we jumped on Bakes on Mesh as soon as the project viewer became available. I read everything I could find about it. I explored all of the available options in the new viewer. I experimented, and became actively involved in development, since I was one of a few creators I knew about at the time who were using the project viewer and developing for it. I logged a number of bugs through the SL Jira. I even found a nasty little bug that caused LL to take the project viewer offline while they fixed it!

I blogged about Bakes on Mesh in April of 2018, because I felt that this was something that we couldn’t just throw out there. It needed time for SL residents to adopt and accept so I wanted to start that process as early as I could. And I knew it would really be a game changer, so I wanted to do my part in preparing SL residents for the adjustment.

An early BOM test wearing my beloved Tuli skin on my mesh head!

Bakes on Mesh has been a creative boon on a number of fronts. I strongly believe that when Linden Lab gave us the ability to upload and wear mesh items, Bakes on Mesh should perhaps have happened at the same time. It would have pushed the mesh implementation project back a few months, but it would have answered a lot of questions that never needed to be asked.

Anyhoo I digress. I settled into that project viewer like it was my new home and used it exclusively for the almost year and a half or so that it took for the Bakes on Mesh project to go from initial announcement to release.

Alpha Modes

SL has had the ability to change the way textures with alpha channels display on prim faces for some years now, and we had written into Slink’s code to always set the skin layer to mode “none”, as alpha channels on skin textures can cause some strange lighting glitches to happen. So one day I was messing about with my BOM prototype body, with the skin layer set to the alpha mode “none” as always, when it occurred to me that if a skin layer could bake to the avatar, and a shirt layer could bake to the avatar, maybe an alpha layer could bake to the avatar.

An example of how alpha masking with a mask cutoff looks while editing.

We no longer used alpha layers to hide our bodies for Bakes on Mesh enabled bodies, as that is done by BOM magic 🙂 So I put on a random alpha layer that I had floating about in my inventory and… nothing happened, other than disappointment. But then I thought “wait a minute, what if I set the alpha mode to Alpha Masking instead of None” (one of the other options available in the alpha mode mode menu) To my absolute delight, my body disappeared exactly where the alpha layer said it should, with a nice sharp edge, and no lighting glitches!

I experimented some more and worked out that changing the “Mask Cutoff” value could also make the edge of the alpha’ed section move, provided the texture was blurry! I made a new alpha layer that was a big old blurry semi transparent gradient from waist to ankles and found that I could change the alpha’ed section from *most of the legs* right up to *none of the legs* with one single alpha layer, just by changing that mask cutoff value!

This was my big aha moment. I excitedly showed it to my scripter (my very patient husband Caine), archived everything we had been working on up to that point, and started a new project called “No Alpha Cuts”

How one alpha layer can change depending on the Mask Cutoff Value

As it turns out, Bakes on Mesh has almost completely eliminated the need for HUD controlled alpha zones. There is an important exception which I will go into in a moment.

Alpha Mask/Alpha Layers

With Bakes on Mesh, we are back to using our brilliant, reliable, low avatar rendering cost, easy to create, inexpensive avatar alpha layers. All you do is wear them and your mesh body will disappear wherever the texture says it should, the same way your SL avatar body would prior to mesh implementation, prior to alpha zone HUDs and all that extra complexity.

An important change that has come along with Bakes on Mesh is the ability to wear up to 60 system layers of whatever kind you want. We are no longer limited to 5 tattoo layers, 5 alpha layers etc. We can wear any number of any kind of layer that we like. This means that if you have an alpha layer for your jeans, one for your shoes, one for your gloves, one for your shirt, one for your scalp, one for your hands, you can wear all of them at once, and they will combine in rendering on your avatar into one big, beautiful alpha layer!

Editing an alpha layer

Creating Alpha Layers

Alpha layers are also very easy to create. Everyone in SL has the tools to create a basic alpha layer, just like everyone has the tools to create a basic shirt or a basic pair of pants. All you do is right click on any folder in your inventory, select “New Clothes”, mouse on down to “New Alpha Mask” and click it! Give it a name and voila, a new alpha layer is born! You can now wear it, edit it and add your own texture to it.

I have created a couple of tutorials on how to create a texture suitable to be used as an alpha layer in Photoshop and G.I.M.P.

I will add to these tutorials with a step by step in blog format in the future.

*important caveat with GIMP alpha creation – If your erase brush is drawing with colour instead of making the pixels transparent – select “Layer – Transparency — Add Alpha Channel and it should work properly.*

Asymmetry

Now onto that important exception that I mentioned earlier. Before mesh bodies were even a thing we could imagine, we had the SL avatar. The SL avatar has a UV template that is… less than ideal. It has a great face and head layout, good torso and legs, terrible arms, hands and feet. For some reason, known only to the original creators of the SL avatar, the arms and feet are 2 islands in one, laid upon each other so that whatever is on one is automatically baked into the other. This was something we at Slink wanted to address with the Slink Physique body system, pre Bakes on Mesh, so we wrote the missing asymmetry into our bodies and 3rd party applier scripts. With Slink Physique, you could create a tattoo applier that would send different textures to the left and right arms and/or feet, and they would display properly. You could also make your arms and feet invisible, left and right, independent of the other side.

With Bakes on Mesh, unfortunately we would have to take a step backwards by going back to that forced symmetry from the SL avatar, so we thought very long and hard about what to do to keep the asymmetry that our customers have enjoyed and came up with our Asymmetry Harness.

Join me in the next installment where I go into the last remaining bastion of HUD controlled alpha cuts for the Slink Physique and Redux body systems 🙂

♥ Siddean

 

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