The Eye Rig

Rigging and animating eyes is well supported by the Avastar rig. this documents provides information about how to work with the Eye Rig. If you are an animator, then please move to the second part of this document Animate the Eyes further down on the page.

Set up the Eye Rig for your custom mesh

As long as you only do classic weighting, rigging the eyes is easy:

Take care that the eyes are separate mesh parts. You can either separate them as submeshes in your head object, or just make separate objects for each eye, it does not matter
Take care that the eyes are rigged to your Avastar. If the eye meshes are submeshes of the head, then they are already rigged together with the head. if they are separate objects, then take care to bind them to your mesh as usual
Take care that the entire eye mesh of the left eye is only weighted to the mEyeLeft bone
Take care that the right eye is only weighted to the mEyeRight Bone

Now export as usual. Things should work fine for you.

Details for the System character

You can understand the following chapter best when you have knowledge about the principles of skeletal animation. We have created a document that hopefully helps to understand the basics:

Skinning Fundamentals

Now lets take a more detailed look at what is going on with the Eyes in the Secondlife Avatar. So please do this in Blender (Avastar):

Create a new Avastar using Add -> Avastar ..
Select the left Eye
In Avastar -> Settings select the preset named “Skin&Weight”

Now the Armature is in pose mode and the mesh is in weight paint mode.

When you select the left eye bone mEyeLeft, then you see the left eye turns red which indicates that the entire eye mesh is weighted to the mEyeLeft bone.

In the Object data properties of the Eye you see there is only one single vertext group (weight map) available, so the left eye has been fully weighted to the left eye bone.

But having each vertex of an eye weighted to exactly one bone and having all vertices of the mesh weighted to the same bone (mEyeLeft) is exactly the same as if the left eye is clamped to the left eye bone.

And just like the left eye has only one weightgroup named mEyeLeft the right eye also has just one weight group named mEyeRigh. And this is all you need to know.. almost

Details for custom mesh characters

mFaceEyeAltLeft and mFaceEyeAltRight is a second set of eye bones.

Animate the eyes

For the System character we have (see image):

The System Eyes: EyeLeft and EyeRight
The system target: EyeTarget

Avastar by default has enabled the eye bones for the System character. The setting is available in the Rig Display Panel:

Eye Focus : show the Eye target bone for the System eyes
Checkmark: (near Eye Focus) Enable the focus target for animation

Note: By default the Eye Target bones are very far in front of the head (about 2 meters). this is to keep the eyes watch “straight forward” by default.

Additionally we have an alternative set for Custom meshes:

The System Eyes: FaceEyeAltLeft and FaceEyeAltRight
The system target: FaceEyeAltTarget

Animating the eye targets

When you move the Eye target in the scene, then by default the eyes follow the target.
When you move the eye target closer to the eyes, then the eyes start to cross (see image)
When you move the targets behind the head, then the eyes still follow, although this is no longer a natural eye movement of course.