Second Life: Mesh vs Classic Bodies

The question keeps coming up in the SL Forum, what is a mesh body and why won’t my clothes show? I am so confused… Yeah, I can see how that would happen. So, I need something I can link them to. This is the ‘something’. I’ve tried to keep it simple for noobs without 3D modeling experience.


To understand Classic and Mesh avatars one has to understand Second Life™ has a history and understand some of the basics of 3D modeling.

Mesh & Classic Avatar 2017

SL Started in 2003, 2004 depending on what you define as ‘starting’. It started with a basic avatar that evolved over time. That is the Classic avatar. It is still with us.

If you take off everything you can take off your avatar is wearing, you are looking at the Classic avatar. You can click the top menu Developer (press Ctrl-Alt-Q to reveal the menu item if it isn’t showing)->Avatar->Character Tests->Test Male/Female. This will set your avatar to the very basic (Classic) avatar known as Ruth.

If you press Ctrl-Shift-T, you can see that everything in SL is mesh (wire frame image above). What is not obvious are the things we call primitives or prims for short. These are things like the classic avatar, cubes, cones, spheres, etc. The mesh part, or list of vertices/polygons, of these are built into the viewer and are part of what you downloaded when you installed the viewer.

These are parametric primitives. This means that all the cube-prims in SL use the mesh built into the viewer. The size and color of all the cubes are controlled by parameters. Only the parameters are downloaded when your viewer needs to render a cube. This process was created when the Internet was SLOW to allow better performance. It saves downloading lists of vertices.


For avatars, the built-in mesh was personalized by what we call SHAPE. An SL shape is a set of parameters for face, body, feet, etc.

There are some milestone points for changes in the SL system. Understanding those helps one understand the avatar we have today. It also helps when you have to figure out which tutorial is useful and currently meaningful.

A big change was the addition of a new prim we call ‘mesh’ in 2013. This can be confusing as everything in SL is mesh, polygons. A ‘mesh’ prim is a prim that does NOT have its set of vertices/polygons built into the viewer. The list of polygons making up the item is a parameter and is downloaded from the asset servers as needed.

We can build those vertex/polygon lists using 3D modeling programs like Blender.

Once the feature was added to SL people begin making mesh clothes. A significant problem of the era was the Appearance Sliders used to make an avatar shape did not affect the mesh clothes. Finding clothes that fit was a major headache.

The next milestone was the creation of Fitted Mesh, added about 2014. Clothes could be made as Fitted Mesh and the shape sliders would change the size of the fitted mesh clothes. It became much easier to make clothes that fit. But, it was still a headache, just a smaller headache.

Fitted mesh clothes just didn’t fit Classic avatars all that well. Because of technical complications the avatar shape and fitted mesh clothes’ sizes grew and shrank at different rates. If you wanted a fat or skinny avatar, it was almost impossible to find clothes that fit. One had to stay in the middle ranges of size for a good fit.

In 2015 and 2016 creative people made fitted mesh bodies that were the same type of mesh as fitted mesh clothes. So, they both responded to the shape sliders at the same rate. This mean the same clothing item for a skinny avatar, average avatar, or fat avatar pretty much fit. Thus, the popularity of fitted mesh bodies… plus a number of other technical factors and better looks.

A fitted mesh body, hands, feet, and head are all mesh primitives used as attachments to the Classic avatar. They cover the Classic avatar body. They hide the Classic body.

System Clothes vs Mesh Clothes

The viewer’s built in shirt, pants, underwear, and other layers are called System or Classic Clothes. In inventory, they have unique icons denoting shirts, pants, etc. They are for the Classic body. These are all hidden by a mesh body or clothes.

A skin can be made for the Classic avatar as a System skin using GIMP/Photoshop and the built-in viewer tools. These are pretty much decals stuck on the Classic avatar body.

When you wear a fitted mesh body you need an Applier, a HUD, to ‘apply’ the skin to the fitted mesh body attachment. So, using GIMP/Photoshop and an Applier you make a skin for a mesh body. There are no built-in viewer tools needed to make those skins.

In inventory these ‘mesh’ items are all represented by the cube icon used for objects, basically user made things.

Fitted Mesh clothes do not have to have the same form as the body. They are not a decal. They are an attachment with a unique form. These clothes can often be worn with a Classic body or a Mesh body, but usually fit the mesh body better.

Because of the rate mesh changes in regard to the Appearance Shape Sliders, it is common for clothes to be made for a specific brand of mesh bodies. Most clothes are sold with multiple versions for different bodies. Wearing made for Maitreya body on a Slink body usually doesn’t work.


For different activities in SL people prefer different avatars, Classic or Mesh.

For various reasons, people mix Classic and Mesh. For a time, I wore a Classic head and body with mesh hands and feet. Then I moved to a mesh body I liked, with mesh hands and feet. I’ve kept my Classic head. But, I am looking at Mesh heads.

I have outfits for Classic and Mesh bodies. I tend to prefer Mesh bodes and clothes these days.


In 2016 the Classic avatar built into the viewer changed. Linden Lab places a high priority on maintaining legacy compatibility. So, changes are somewhat restricted. However, Bento adds to the Classic avatar while retaining all the parts of the previous avatar.

Bento added bones to allow us to animate more of the avatar body. Prior to Bento fingers could not be animated. Nor could faces. All Classic facial expressions are built into the viewer. The built-in expressions (morphs) are not the same type of animation possible with Bento.

Bento allows us to add wings, tail, head, and ears that we can animate. We are no longer restricted to the built-in expressions.

So, fitted mesh built to use the new Bento bones is labeled ‘Bento’. So, heads and hands are the current big upgrades to appearance (2017).

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