Rigging the Avatar
This page goes into the details of rigging your avatar meshes.
There are a couple of different ways to apply an avatar model to a skeleton, also known as rigging.
Rig is both the name of the skeleton and the action of applying the skeleton to the mesh. Blender uses Armature as the skeleton as well.
There are two common ways to rig an avatar, manually or automatically, both with pros and cons. Either approach is fine, and understanding both will allow you to customise and polish your avatar. The Mixamo approach is faster and easier but requires more tools such as Mixamo (to autorig the avatar) and Hyperfy Tools (to rename the bones from Mixamo automatically).
Export your models as an .fbx from Blender.
Go to the Mixamo website here.
Use the Upload Character button on the right.
If your .fbx does not work, try using a .obj instead.
Select Next.
Position the key points on your avatar as needed. The points will include the following :
Chin
Wrists
Elbows
Knees
Groin
You can turn symmetry on/off as needed at the bottom.
Use the Next button at the bottom for processing (which will take a moment).
Select the Next button.
Test other animations using the Mixamo library, this can help decide if you need to do any cleaning up in your 3D application.
Download the result with the 'Download' button at the top right.
Remove any animations that you tested with before exporting the file as this will export the animation, not the avatar itself.
Selecting T-Pose on Download is recommended as the VRM requires a T-Pose to use animation correctly and this will save a step later on.
Once you have your model rigged using Mixamo, you will need to take it back into Blender to refine and export as a VRM.
Hyperfy Tools
Using Mixamo may save a fair amount of work during the Rigging stage, but will require some renaming of bones due to VRMs requiring very specific bone names to work. This can be done quickly with tools like Hyperfy Tools.
Hyperfy Tools automatically renames the Mixamo rig bones to VRM compatible names. If this is not done, your VRM will not work.
Installing Hyperfy Tools
Download or install the Hyperfy Tools Addon from the website.
Using the Hyperfy Tools Add-on
Select the Armature.
Select the Hyperfy tab at the top right of the Viewport.
Select the 'Mixamo > VRM' button.
Custom Bones
As VRMs only use a specific rig for animation it is rare to utilise custom bones unless you have custom animations on the platform for the specific bone names you create. It is possible however to add custom bones for secondary animation that bounce or spring to the movement such as for hair, capes, long ears, tails etc. These do not need to be manually animated as the tool adds a spring effect to the bones themselves.
The easiest way to add bones in Blender is to go into 'Edit' Mode on the armature/rig and use duplicate and extrude on bones. Make sure that all the bones are part of the one rig. If they are separate rigs then it will not work.
Select the Armature/rig/skeleton
Go into Edit mode, or press tab to enter Edit mode.
Select a bone and use 'Shift + d' to duplicate it.
Use a bone under the parent you would like you new bones to be under. eg. if you want something parented to the spine, select the upper arm.
After duplicating you can easy position the bone using the usual 'G' to position, 'R' to rotate, and 'S' to scale.
To reparent a bone, select the target bone, then shift + click the parent bone. Right click and select 'Parent > Make > Keep Offset/Connected'.
Add extra bones to a limb by extruding a current bone.
Press 'E' to extrude or use the Extrude button on the left of the viewport. You can select the end of the bone, or the bone itself.
If you need to polish or add Spring Bones into your avatar you will need to do some Weight Painting. Weight Painting is applying vertices to bones by weight, and for that we have the next tutorial!
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