The feature you are looking for is likely Blendshape Optimization —specifically the ability to remove unused blendshapes and bake complex shape keys to improve the VRChat performance rating of an avatar.
For creators using the VRChat Creator Companion to build avatars, this parameter is often used within a blend tree in the FX animator layer.
: By providing more realistic and nuanced ways for avatars to express emotions, VRC FaceBlend could also play a role in making virtual interactions more accessible and inclusive. Users with disabilities might find it easier to communicate and connect with others in virtual spaces.
If you’ve ever dipped your toes into VRChat avatar creation—specifically custom visemes or eye tracking—you’ve likely stumbled upon a peculiar term in the Unity Animator parameters list: .
In the world of avatar creation, VRCFaceBlendH is a specialized built-in parameter used to drive horizontal facial expressions through the avatar’s animator. While it was more common in the early days of Avatars 3.0, it remains a fundamental part of the default VRChat expression system for creators who want to implement basic mood shifting without building complex custom logic from scratch. What is VRCFaceBlendH?
Have you run into a weird issue where your vrcfaceblendh isn't responding? Double-check the parameter is in the Expressions Parameters list AND that the animation clip has the correct Skinned Mesh Renderer selected. 90% of the time, it’s one of those two.
In your 3D software (Blender, Maya, etc.), name your BlendShape something clear, e.g., Mouth_Smile , Brow_Angry , Cheek_Squint .