Bakes on Mesh – a basic primer

Updated with an overview of “Bakes on Mesh appliers” for Mesh bodies and head yet to be updated to support BoM.

Monday, August 26th, 2019 saw the formal release of Bakes on Mesh (BoM) for Second Life, and with it, an attempt to make system wearables (skins, tattoo and clothing layers) usable on modern mesh avatar bodies, utilising the avatar Bake Service and without the need for a dedicated applier system.

While Bakes on Mesh has been in development for over years, and much of it is known to many users, this article has been written to provide something of an introduction / overview of BoM, covering things like system wearables, the Bake Service, that changes that have been made, where to find information on using BoM, and what it may mean for Second Life users in the future, depending upon how well the capability is received by creators.

Some Basics

System Wearables and the Bake Service

System wearables as they appear in inventory

Without going too deeply into specifics for those unfamiliar with them, system wearables are a special kind of inventory asset (some of which are shown on the right) that can be directly worn / added to the system avatar to produce a “dressed” look.

These wearables come in a number of “layers”- skin (which must always be worn on the system avatar), tattoo, undershirt, shirt, and jacket.

The naming of the layers isn’t that important – a creator could be assign a bra or a shirt or a pair of pants to any one of the tattoo, undershirt, shirt and jacket layers, depending on how flexible they want their clothing to be. What is important is that the always follow an hierarchy: skin is always at the bottom and so “covered” by the other layers, which are in turn “covered” by the next (so undershirt wearables always apply “over” tattoo wearables; “shirt layers “over” undershirt wearables, etc), with the avatar able to wear up to 62 wearables in any combination of layers at one time.

This might sound very complex, but for those familiar with the system, it is very easy to grasp; however, what is important is what comes next. When an avatar’s look is complete, the information about all these wearables are sent to the simulator and then to a back-end set of servers called the Bake Service over a series of channels called the “bake channels”, which define where the layers appear on the avatar. These channels are:

  • BAKE_HEAD, which defines all the wearable elements that have been applied to the head (e.g. skin, and tattoo layers used for make-up)
  • BAKE_UPPER, which defines all the wearable elements – skin plus any tattoo, undershirt, shirt and / or jacket layer(s) that have been applied to the avatar body above the waist and below the neck (with the left arm mirrored from the right).
  • BAKE_LOWER, which defines all the wearable elements – skin plus any tattoo, undershirt, shirt and / or jacket layer(s) that have been applied to the avatar body from the waist to the feet (with the left leg mirrored from the right).
  • BAKE_EYES and BAKE_HAIR (both pretty self-explanatory).
  • BAKE_SKIRT, which defines skirt / dress style wearables.

The Bake Service then composites (bakes) the layers received on each of these bake channels into a single texture, and sends the results out to every viewer able to “see” the avatar. So, for example, facial / head skin and any make-up tattoo(s) received via the BAKE_HEAD channel are baked to become a texture seen on the avatar’s head, while the layers received over the Bake_Upper channel are baked into a texture seen on the avatar’s upper body, and so on, ensuring the avatar consistently appears to everyone dressed at the user intended, while also removing the need for individual viewers to manage the complex layering and rendering of all the individual wearable layers on other people’s avatars.

Mesh Bodies and Complexity

Since their introduction, mesh bodies have not been able to leverage this approach. Instead, they require a dedicated “applier” mechanism to achieve the same ends, together with the use of an alpha layer to hide the system avatar.

Further, to enable clothing items to be layered – so you can have an applied shirt / blouse appearing to be “under” a jacket, for a example, mesh bodies have had to be constructed in a complex manner, with several layers closely packed together (colloquially called “onion layers”) that effectively mimic the system wearable layers. This actually makes the avatar a lot more complex than they otherwise might be, resulting in their relatively high rendering costs.

Enter Bakes on Mesh

So, Bakes on Mesh has been developed to allow system wearable to be applied directly from inventory to worn mesh faces (e.g. avatar bodies and wearables) that have been correctly flagged by the creator to support Bakes on Mesh. Through Bakes on Mesh, Linden Lab hopes:

  • Users can avoid the need to use appliers, but can add wearables to their mesh avatar directly from inventory.
  • Creators will be able to simplify avatar mesh bodies and heads by removing the need for some of the “onion” layers. This should – if done – reduce the rendering complexity for bodies and heads, thus hopefully improving people’s SL experience (as avatars won’t be quite so resource intensive or require quite so much “assembly time” when encountering them on logging-on or after teleporting somewhere).


  • As with all new features, use of Bakes on Mesh will only be apparent to those actually using viewers running the Bakes on Mesh code; anyone not on such a viewer will likely see something of a mess.And as with new features, it will take time for the Bakes on Mesh code to be implemented by all TPVs.
  • Bakes on Mesh does not mean user “have” to go back to using system wearables nor does it mean that applier systems can no longer be used. It is simply a means of making system wearables work with mesh bodies and heads, hopefully with the benefits given above. Those who wish to can continue to use applier-based clothing as they always have.
Bakes on Mesh adds new options for applying suitable textures to the baking channels for application on a mesh body by the Bake Service

An introduction to using BoM can be found in the Bakes on Mesh Knowledge Base article. This includes information on trying BOM using a test mesh body – the best way to do this is to use Aditi, the beta grid. I’m not going to go into specifics here, simply because there are multiple resources available to assist users and creators – some of which are noted at the end of this article, and I want to keep this as a more general, easy-to-understand primer.

When considering Bakes on Mesh it is important to remember it is not necessarily intended as an outright replacement for appliers and current mesh bodies from the get-go. Rather, it is initially an alternative – although if the popularity / take-up among creators and users are sufficient, then over time it could obviously become the system of choice over appliers and more complex mesh bodies. However, existing mesh bodies / heads and applier systems will continue to work as they always have.

Key Points of Bakes on Mesh

This list is not exhaustive, but is intended to give a feel for Bakes on Mesh and its use:

  • System skin layers, tattoo layers, clothing layers and alpha layers all work – the mesh just needs to be flagged by its creator as supporting Bakes on Mesh and correctly set-up for alpha layers to work as intended.
    • As an alternative, there are assorted “BoM appliers” designed to work with mesh bodies  / heads that have not (yet) been updated with Bakes on Mesh support – see below for more.
  • You do not need a full body alpha to wear a Bakes on Mesh flagged mesh. If the flag is present when you wear the mesh, the body section it is flagged for disappears. So, if you wear a lower body “Bakes on Mesh ready” avatar part, then entire lower body of the system avatar will disappear.
  • The Bake Service has been updated to support 1024×1024 resolution textures, so it offers the same texture resolution for wearables as offered through applier systems (prior to Bakes on Mesh the maximum resolution for wearables was 512×512).
    • Obviously, the wearable must be made at this resolution in order to utilise it; a 512×512 wearable will not magically appear to be 1024×1024 resolution when applied.
  • In order to be fully effective, mesh bodies using BoM and BoM wearables should match the system avatar UV map as closely as possible.
    • Fortunately, most of the current range of avatar bodies sold under brands such as Maitreya, Slink etc., do tend to stay close to the system avatar UV map. So any new BoM-specific versions / updates should continue to do so.
  • Alpha support means that  layers means that mesh bodies should no longer need to be split into multiple pieces for individual alpha-masking to prevent a body clipping through clothes. Alpha requirements are back in the hands of the clothing creator, and should be made alongside the clothing, so that when used and providing the body is correctly set-up they should just “work”. In addition, clothing makers may not longer need to include auto alpha scripts.
  • Changing mesh body parts should be easier, providing both bodies are flagged to use Bakes on Mesh. The body takes whatever is worn on the system body – skin and make-up instantly appear on each change of head, for example.
  • Skin makers will be able to offer more options by including tattoos with their skins, allowing for a variety of make-up options, whilst there will no longer be any limitation on the use of tattoos (one per zone).
  • Applier support will still be required for the following: nails; eyelashes; standalone ears, hands, feet, lips, bust implants, etc.; lip gloss; materials finishes (see Some Possible Points of Contention, below); neck blenders, anything not intended to look “painted” on.

New with Bakes On Mesh

To provide full “wearables” support, Bakes on Mesh introduces some new elements that will be of key import to creators:

  • The introduction of 5 new bake channels – LEFT_ARM_BAKED, LEFT_LEG_BAKED, AUX1_BAKED, AUX2_BAKED, AUX3_BAKED:
    • These can only be used with Bakes on Mesh, and are not available to the system avatar.
    • LEFT_ARM_BAKED and LEFT_LEG_BAKED are intended to help with making mesh avatars where the left and right limbs have different textures (and so can be asymmetric, as can currently be achieved with applier systems).
    • The AUX channels are general purpose, and could be used for body regions not possessed by system avatars (such as wings) or for other purposes.
    • This means BoM has 11 possible channels for wearables to use for textures, and for the baking service to produce.
    • However, the new channels listed above do not have alpha support like the other channels, and so cannot have “holes” cutting through the mesh face they are worn against.
  • BOM also adds a new wearable type called Universal.
    • While specifically added to allow the wearing items that use the new  channels described above, the Universal wearable has slots corresponding to all 11 of the bake channels, offering extensive flexibility of use. In layering order, universal wearables go between the tattoo and body layers.

Note that for others to see your avatar correctly when you are using Bakes on Mesh they must also be using a Bakes on Mesh viewer. If they are not, they will see your avatar as a mesh of red, blue and yellow colours showing through your mesh parts.

Left: Bakes on Mesh when seen via a non Bakes on Mesh viewer: the system avatar will show through the mesh body parts, covered by default system-supplied BoM marker textures. Centre and Right: using a “Bakes on Mesh applier” on a non-BoM body and head and via a Bakes on Mesh capable viewer. The centre image shows the “before” avatar state: the system layer skin and clothing are worn, but do not conform to the mesh body and head (which must be worn without their corresponding alphas for this type of applier to work), and so “poke through” (highlighted in places by the red circles). The right image shows how things look after the”Bakes on Mesh” appliers have been used – the system layer clothing and skin now mostly conform to the mesh head / body, with the exception of fingers and toes (highlighted) which will generally require an additional “glove” or “mask” fix.

“Bakes on Mesh Appliers”

During the testing of Bakes on Mesh, at least two experimental applier systems were produced to allow BoM to be tested on non-BoM flagged bodies and heads. For example, Omega produced an experimental BoM applier system, with instructions here.

Since then, and given that several mesh body and head creators have yet to produce BoM flagged updates to their bodies / heads, several more such “BoM appliers” have been produced, some of which are available for free, some are provided by the mesh head / body creator, and others are available at a nominal cost, and may be for specific purposes (e.g. the Bakes on Mesh skin applier (Omega) by Conor Shostakovich at L$125).

These essentially work by allowing you to dress your system avatar with the required system wearables, then wearing your mesh body / head without their alpha masks, and then using the applier to apply the system layers to the mesh body / head in a similar manner to “traditional” appliers – but again, as a single composite layer when baked.

  • How effective these systems are can be variable.
  • Due to differences in the way skin skin textures / UV maps work and the way mesh bodies tend to be put together, such appliers may not work particularly well around feet and hands.

Note: links to products does not constitute endorsement. Always check the Marketplace for products and reviews.

Such appliers are intended as an interim “fix” for using Bakes on Mesh until such time as the major head and body creators provided full Bakes on Mesh support.

Some Possible Points of Contention

However, there are what might be regarded by some as “negatives” around Bakes on Mesh, a couple of the more prominent ones being:

  • The Bakes Service – and thus Bakes on Mesh – does not support materials (normal and specular maps). How much this impacts people’s acceptance of BoM is open to debate. However, when needed, materials still can be added manually (if the mesh / mesh face in question is editable) or via a suitable applier.
  • Appliers are convenient, as they are an all-in-one solution requiring only one or two items in inventory – the outfit applier HUD and possibly an intermediary relay tool like Omega.
    • With Bakes on mesh, wearables are all individual inventory assets, which could lead to inventory growth, some of which might be quite extensive as a result of creators providing multiple options / layers (although in fairness, some applier systems can be like this – I have seen a Hugo’s Design outfit with no fewer the 40 individual items, both system layer clothing and multiple applier options).
    • Some of the inventory “bloat” BoM might cause can potentially be managed via the use of the viewer’s Outfits capability (although this obviously also adds to bloat with inventory links) or via a new form of applier system that utilises system wearables created at 1024×1024 resolution.

How much these may impinge on consumer’s willingness to adopt BoM remains to be seen.

Closing Remarks

Like all new capabilities, Bakes on Mesh will take time to gain understanding and traction. Also like all new features, it has its outright fans, and those who have – even before really getting to work with it in earnest – decided its is bad / wrong / pointless / a step back, etc.

I’m personally sitting in the middle. If it does what is claimed on the tin, and if it gains traction among mesh body and head creators (and several have been working on BoM for the 12+ months its been in development) and clothing creators, then it could do its own little bit towards a better “optimisation” (quotes used intentionally, as there is still a lot more than can be done in terms of optimisations cross SL), and make things a little better for everyone.

But it will take time for Bakes on Mesh to mature in terms of general use – creators need to update their heads / bodies (although Slink is apparently ahead of the curve, and their new bodies are said to work with existing appliers, and other creators may also be providing products / updates, I’ve just not encountered any as yet). Those making system wearables are going to need time to update to the 1024×1024 where preferred (if they haven’t already, and so on. And, most obviously, it will take a little time for the Bakes on Mesh code to percolate out to all TPVs.

In the meantime, some links to useful resources.