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Avatar Body Parts Intro – IMVU Studio

Introduction:

In IMVU, you can replace the default avatar clothing with clothing of your own design. You can make individual pieces of clothing, complete outfits or anything in between. Shirts. Pants. Fawn legs. Bear suits. Peg legs. The choices are limitless.

However, building clothing is hard as it requires a patience and technical exactness that most other product types do not require. The two main reasons for this are simple:

  1. There are hundreds of thousands of preexisting products that define how an avatar’s skin is supposed to be out. Customer expectation is that avatar skin will always be right so any deviation is viewed upon negatively.
  2. As humans, we’re programmed to notice even the most subtle differences in anatomy and movement of that anatomy. Therefore, the movement of, say, the shoulder really matters to your customers’ end experience.

While its true that building clothing is hard because you need to know how to model and map fairly well while, at the same time, you need to know how to use Physique fairly well, take comfort in the fact that thousands of IMVU content creators have done it. You can too!

Before jumping into building an avatar body part, please read the Introduction to Mesh Building Tutorial.

What is a Body Pattern?

Each avatar is made up of several, interconnected assets: A skeleton, several meshes, several materials and textures, and both triggered and idle animations. This patchwork of assets is called a ‘Body Pattern’.

Body Patterns

IMVU uses two main Body Patterns, the female (product 80) and the male (product 191).

…and a Body Part?

Each mesh included in an avatar body pattern is called a ‘Body Part’. An avatar can be made up of any number of body parts. IMVU’s two main avatars are made up of ten body parts and each of them (or combinations of them) can be replaced by products found in the IMVU catalog.

For example, if you want to change your hair, you just put on a new hair product. Under the hood, though, the original hair body part is being replaced with a new product that calls the same body part.

Override Body Parts on the default avatar

A new piece of clothing is made visible by means of overriding a Body Part on the default avatar Body Pattern. For example, if you see a woman wearing a hoody sweatshirt in IMVU, it is because that hoody sweatshirt is overriding product 80’s Body Part number 2 (the ‘top’). The same is true when you see someone wearing a peg leg. The peg leg has no foot and so overrides both the leg (part 6) and the foot (part 8).

Body Part Override

Every body part product (shirts, gloves, shoes, etc.) can get its override information from IMVU Studio. Studio is IMVU’s next-generation product-making program which allows you to combine exported assets into IMVU products.

To learn more about IMVU Studio, please go to the Intro to IMVU Studio tutorial

Once you have a project open, go to the Info tab and scroll down to Body Parts. Click on the three dots and hit Override Body Parts. A dialog box will appear.

Please remember that an avatar can only wear one instance of a body part ID. For example, if a pair of stockings is set to override body parts 6 and 7 and then your customer decides to put on a pair of eyelashes that also call body parts 6 and 7, the stockings will be removed to make way for the newly applied eyelashes.

Overriding

You can override multiple body parts or no body parts. Knowing this can influence what you decide to build. An example of overwriting multiple body parts would be if you wanted to could build a peg leg. You could do so by overriding both the foot and the leg with one product. At the same time, it can be useful to override no body parts. For example, If you wanted to keep your outfit on but also wanted to add a trench coat – you could do that if the trench coat did not override any body parts.

What Parts Can Change?

The IMVU avatars allow you to change the following body parts:

0. Head

1. Hair

2. Upper Body

3. Right Hand

4. Left Hand

5. Pelvis

6. Right Leg

7. Left Leg

8. Right Foot

9. Left Foot

Simply by checking the box in the Override Body Parts dialog, those body parts will disappear. Then, you will need to add new geometry to be inserted for the overridden body parts.

To learn how to add geometry in IMVU Studio, please go to the Mesh Tab Tutorial.

Starter Files

To build new clothing, hairstyle and head geometry for the IMVU avatars, you need to begin with an avatar that is positioned in the ‘weighting pose’. Starter files for popular 3D authoring apps can be found on the FBX Starter Files page. We are going to reference 3ds Max here.

Files for both the female and male avatar are supplied in the folders named ‘3ds – Avatar 80 Female Full Body’ and ‘3ds – Avatar 191 Male Full Body’.

In each file you will find:

  • Skeleton with a root node named ‘avatar.RIG’
  • 10 mesh objects that are named such that they will be automatically associated with each of the corresponding avatar body parts
    • female_UpperBody
    • female_RightLeg
    • female_RightHand
    • female_RightFoot
    • female_NakePelvis
    • female_LeftLeg
    • female_leftHand
    • female_LeftFoot
    • female_Head
    • Female_Hair

Each of the meshes has a ‘skin’ modifier applied and is skinned to just the bones that affect the mesh.

New Avatars

Considering that completely new avatar products will not work across all Furniture, Rooms, Head and Action menu items, we will not be covering how to build your own entirely new avatar from scratch in these tutorials.

One skeleton – two bodies

The IMVU female and male avatar use the exact same skeleton. However, the shapes of the two bodies are quite different. What’s more, their weighting poses (or, the position of the skeleton bones when the geometry is exported) are different. So, please remember that, should you build a cool jacket for the male that you want to also work on the female, you will essentially have to rebuild the mesh and redo the weighting. Otherwise, the boundary vertices will look broken when applied in IMVU.

Geometric Complexity

A body part can be as simple as one polygon, if you so choose. It can also contain as many or as few morph targets as you like.

The IMVU body parts supplied in the starter files can be pushed and pulled to become a wide variety of shapes while still maintaining the same mapping across problem areas (like shoulders and hips).

NOTE:

By using the supplied body parts, you also get the peace of mind of knowing that other products like skin will work with your product too.

Budgets

Download and runtime file size is an issue that should be kept in mind whenever designing for IMVU. If your Head’s file size is too big, it is unlikely that your potential customer will purchase and download it and, if they do, there is a very high chance that they will review your product poorly and your sales will go down.

Therefore, it is good practice to try to keep the texture size, vertex/face count of your meshes and animation length down to the bare minimum. There really is no reason to have a 256×256 texture for a button on a shirt: it just won’t be seen in the IMVU messenger. In fact, we have found that the smaller the texture, the BETTER it looks in IMVU. Go figure.

Also, please know that IMVU automatically resizes assets that are too large or teched incorrectly.

To learn more, please go to the Mapping Materials Tutorial.

Boundary Vertices?

A vertex is a point on a 3D mesh. The space between vertices is called ‘geometry’ and that geometry is what is drawn on screen when you’re chatting in IMVU. A boundary is defined as the open ends of a mesh where it is meant to meet up with connecting parts. So, the vertices that live along the boundaries of a body part are called ‘boundary verts’.

For example, an avatar top product has boundary verts along the neck (where it connects to the head), waist (where it connects to the lower body) and wrists (where it connects to the hands). Each boundary vert needs to be placed in the exact same location as its neighboring body part. What’s more, each boundary vert needs to be weighted the exact same way as its neighboring part. Otherwise, you get nasty seams in the messenger.

NOTE: This ‘nasty seams’ business is actually very important. When new geometry does not work well with existing clothes, customers complain and the overall sales of that Creator are hurt. So, take the time to get your placement and weighting right on your boundary verts. It really matters.

Oh, Snap!

To get the boundary verts of two connecting pieces to be in the EXACT same location, just click the move icon and then click on the Snaps Toggle tool. Now, you can click on one of the verts in your mesh and drag it towards its destination. This will, as they say, ‘snap’ the vertex to the exact same 3D space as another vertex.

Note: Please make sure you only snap the verts of the mesh you are working on. For example, if you’re building a new glove, make sure that you only move the vertices of your glove to the exact location of the wrist verts on the avatar top. In the case of the glove, if you move the verts of the wrist on the ‘top’ body part, you will end up with a hole in your wrist when the glove finally shows up in IMVU. As they say in northern Siberia, “Yuck.”

Match the Skeleton

Although it is true that you can build your own avatar (complete with unique skeleton), most people utilize the enormous market that the existing body definitions represent. Consequently, most people will want to use the existing skeleton as the basis for their clothing.

While building your mesh, please take care to note the placement of the actual joints of the IMVU skeleton and built your joints in the same general area. This will save you a lot of time later when weighting your mesh.

Material IDs and Mapping

Although IMVU covers the basics of Material IDs and Mapping in the Mapping Materials Tutorial, there are enough avatar-specific mapping tips to warrant their own tutorial.

To learn more, please go to the Avatar Material IDs and Texture Mapping Tutorial. 

Use IMVU’s Skin Mapping

If you are building a body part that is meant to work seamlessly with the rest of products in the IMVU catalog, please remember to use the texture mapping already embedded in the meshes supplied in the starter files.

As mentioned above, IMVU users expect their skin texture products to work perfectly across all clothing meshes. When their skin texture products do not work perfectly, they get upset, leave bad reviews and spread the word that your products are unreliable. So, please err on the side of delighting your customers and use the texture mapping IMVU has already lovingly built for you.

Above is the 256×512 plaid texture we use to make sure that our mapping is near perfect. When this texture is applied to the avatar body in MAX, the horizontal and vertical lines are drawn as near straight as possible. This should allow you to more easily see how the skin on your new meshes is mapped and, more importantly, whether or not it matches what is on the master meshes.

Weight the Mesh

With your body part completely built, it is time to weight it. ‘Weighting‘ means that each vertex in a mesh knows which bone it ought to move with. If a mesh isn’t weighted, it won’t show up in IMVU.

IMPORTANT

Limit skin weighting to 4 bones per vertex!

Products created with skin weighting of more than 4 bones per vertex may appear distorted in Next platforms (Desktop, Web, Mobile and Studio).

We strongly consider using the Skin modifier instead of Physique because of this limitation

To learn more, please go to the Weighting Using Skin Tutorial.

Export FBX

After completing your meshing work you are now ready to export your work from 3ds Max. To do this follow these steps:

  • Select the entire skeleton and each of the body part meshes you wish export
  • Select ‘File>Export>Export Selected’
  • In the file dialog
    • Select a location and name for the file you want to export.
    • From the ‘Save as type:’ dropdown select ‘Autodesk (*.fbx)
  • In the FBX Export dialog use these settings (check boxes should unchecked unless noted) :
    • Geometry
      • Smoothing Groups: CHECKED
      • TurboSmooth: CHECKED
      • Convert Deforming Dummies to Bones: CHECKED
      • Preserve edge orientation: CHECKED
    • Units (Scale Factor: 1.0)
      • Automatic: UNCHECKED
      • Scene units converted to: METERS
    • Axis Conversion
      • Up Axis: Y-up
    • FBX File Format
      • Type: ASCII (or Binary)
      • Version: FBX 2016/2017

Importing into IMVU Studio

From the Menu Button select ‘Edit>Import’ or from the ‘Asset’ panel click the ‘Import’ button

In the import window select ‘Skeleton & Mesh’

  • Set ‘Scale’ to 0.01
  • For each body part mesh the associated body part ‘Mesh ID’ should automatically be assigned.

Complete your import

To learn more about importing FBX files to IMVU Studio, please go to the Importing FBX to IMVU Studio tutorial. 

Updated on March 1, 2021

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