Intro to Avatar Attachments

Introduction

In IMVU, you can create Avatar Attachments. Avatar Attachments, often referred to as Accessories in the IMVU catalog, are products that have their own skeleton and are not weighted to the avatar skeleton. Like their name suggests, they get attached to a bone in an avatar’s skeleton. This means that you have the power to make watches, halos, wings. Anything! The power is in your hands.

Just like Furniture products can be added to Room products, Avatar Attachments can be added to Avatars.

Building an Avatar Attachments from scratch is not easy. However, it can be much easier than building avatar clothing from scratch. This is because you need to know how to model and map in 3D as well as weight meshes. Should that deter you? No! Of course not. Thousands of people have built their own Avatar Attachment products and so can you.

Avatar Attachment Basics

An Avatar Attachment product is just like any other base 3D product in IMVU in that it contains its own skeleton, its own geometry, its own materials and its own textures.

Since Avatar Attachments contain their own skeleton, they can also contain their own animations.

For Position Only

You will NOT actually use or export any piece of the original base avatar mesh or embedded avatar skeleton.

You are building a separate Avatar Attachment product which means you are building a product that contains its own skeletons, meshes and materials. The reason you need the avatar mesh and embedded avatar skeleton is only for the placement/alignment of your Avatar Attachment product.

The Avatar Attachment Skeleton

An Avatar Attachment skeleton can be very simple. The most simple Avatar Attachment skeleton must contain two bones/nodes. These bones/nodes can be called anything you like. One will be your master bone (or, the top of the hierarchy) and one will be the bone you actually weight the mesh to.

IMVU has called the master bone AttachmentRoot and called the second bone AttachmentNode. You will note that AttachmentRoot and AttachmentNode are both in the exact same location. You will also note that the AttachmentNode bone is parented to the AttachmentRoot bone. This is how these two bones should be set up regardless of how many other bones you may add in more complex products.

Skeleton Placement

All you need do is align the AttachmentRoot bone to the avatar bone with which you want your attachment to move.

For example, if you want to build a bracelet, you would not align your AttachmentRoot bone/node to the avatar’s Head bone because then you would have a bracelet that moved when the head moved. Instead, you would align the AttachmentRoot bone to one of the wrist bones.

In the image example, the glasses avatar attachment mesh found in the avatar weighting file has been scaled larger for legibility. The glasses mesh is weighted to the AttachmentNode bone.

The orientation of all of the bones in the avatar skeleton is not the same. This means that a pair of glasses moved to, say, the lfCalf bone will not point forward the way they do on the Head or rtWrist bones. This is why it is important to align your skeleton to the intended bone location *before* building your mesh. That way, you will guarantee that the mesh will actually show up in IMVU the way you see it in your 3D program.

Can I Make My Own Skeleton?

Of course you can. However, remember that you must always use the AttachmentRoot/Node for your Avatar Attachment skeleton, then build the rest of the skeleton off of that.

Building the Mesh

Avatar Attachments for Avatar heads

If you are building an Avatar Attachment for an avatar head (glasses, earrings, unicorn horns, etc.), there are a few things to keep in mind.

The current IMVU head products are all built around the same basic head shape for Male or Female products. The only difference in all of the heads built by IMVU is only found in the shape of the face. Head size is dictated at run time in the IMVU messenger.

The cranium, the bridge of the nose and the position of the ears do not move position from head design to head design (built by IMVU). This allows each human head product IMVU has made to use all of the pre-existing Avatar Attachments without any glaring aesthetic bugs. However, this means that things like facial jewelry, beards, mustaches, fangs, etc. will not look right from head to head (because Avatar Attachment products do not animate when avatar facial animations are playing.)

Z-fighting

The mesh for your Avatar Attachment can end up being very close to the mesh for the avatar as in the case of earrings, glasses and watches. However, if they are too close you may get Z fighting (or shimmering) in IMVU. It is worth testing in IMVU Studio. If you see Z fighting in Studio, you will see it in IMVU.

To correct that shimmering effect, you should pull your Avatar Attachment geometry away from the avatar mesh.

Weight the Mesh

If you are building something that is meant to move with one bone only (Glasses, Earrings, etc.), weight all of your vertices to AttachmentNode.

Your Avatar Attachment mesh should never be weighted to any bones in the avatar skeleton. Your Avatar Attachment has its own skeleton (which you just created). If you weight your Avatar Attachment to anything but the Avatar Attachment skeleton, it will not work.

Avatar Attachment Animations

Since Avatar Attachments contain their own skeletons, they can have animations. Even more, since they also contain meshes, they can also contain morph animations.

Avatar Animation System

An Avatar Attachment can “utilize the system that calls animations triggered by the IMVU avatar”?!! How does that work?

The IMVU avatar can play three classes of Actions:

1. Idle Actions
2. Stance Actions
3. Triggered Actions

A stance animation is dictated by a room or furniture seat node. For example, if a seat node is named seat01.FloatinInWater, then the IMVU code wants to play an animation called stance.FloatingInWater. If an Action with the same name exists in either the avatar product or within the Room or Furniture product, that animation will be applied to the avatar. The three main Idle/Stance Actions names are stance.Idle, stance.Standing and stance.Sitting. So, if your Avatar Attachment contains Actions with those names, the system will play those Actions whenever the avatar joins a Standing or Sitting seat. Even better, if the system can’t find, say, stance.FloatingInWater in your Avatar Attachment, it will try to default to stance.Idle or stance.Standing. In this way, your Avatar Attachment could always be playing an Idle animation. Cool.

A triggered action is an action that plays once (or loops infinitely until removed) and then goes away. When you type LOL in IMVU, you ‘trigger’ the LOL animation to play on your avatar. This means that your Avatar Attachment could have an animation that is triggered by the word ‘LOL’. This means that if you type LOL in a chat in IMVU, both the avatar animation and the Avatar Attachment animation will be triggered.

Budgets

Download and runtime file size is an issue that should be kept in mind whenever designing for IMVU. Avatar Attachment products have 2 MB (2304 KB) maximum product size, but that does not mean you should use it all.

If your Avatar Attachment’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.

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

On to IMVU Studio

With your Avatar Attachment assets built and exported, its time to put them all together in IMVU Studio.

There are some special parts of IMVU Studio, though, that are specific to Avatar Attachment products. Read on, oh Avatar Attachment maker…

Derive

If you want to create a new Avatar Attachment product, you must first derive from an existing Avatar Attachment. To do this, launch IMVU Studio and click the Create button on the upper-right to open the derive dialog.

Navigate to the Accessories Category on the left side of your window and derive from the “Empty Male/Female Accessory” product

IMVU Studio: Skeleton tab

When you click Derive, a new project will open. Click the Skeleton tab on the left. When an Avatar Attachment is being derived, the skeleton variables will be visible under the Inspector Tab to the right.

 

Here you will see the following options:

1. Asset
The Asset drop down is where you select the Skeleton to be used by your Avatar Attachment product. When you derive a new project this will default to the skeleton of the product you have derived from. You can replace which skeleton your product uses by clicking the dropdown button and selecting the skeleton that was imported when importing using FBX or select Add New .XSF option to import a skeleton file directly.

2. Node
The Node is the name of a bone in the avatar Skeleton you wish to have your Avatar Attachment attach to when worn. You can change where your Avatar Attachment is placed on the avatar by selecting a bone from the drop down or by typing the name of the bone.

IMVU Studio: Compatibility

You can change the gender compatibility in the Info Panel on the right side of your window.