Expression Selection Menu Generator for Avatars

[zuedev]

Currently, users rely heavily on controller gestures to trigger facial expressions. This can be clunky, prone to accidental triggers, and limiting for desktop players or users with alternative controllers.

We need a custom Unity component that allows avatar creators to easily configure a dedicated "Expression Selection" radial sub-menu. This component should automate the setup of toggles, parameters, and icons for various facial expressions, giving users precise, menu-based control over their avatar's face.

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User Story

As an avatar creator, I want a streamlined Unity inspector component where I can define a list of facial expressions, assign icons, and map them to animation clips, so that I don't have to manually build out complex VRChat layers, parameters, and menus for simple expression toggles.

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Key Features & Requirements

• Custom Unity Inspector UI: A clean interface that allows creators to add, remove, and reorder expressions in a list.
• Expression Configuration Fields: Each item in the list should accept:
  • Expression Name (String)
  • Menu Icon (Texture2D/Sprite)
  • Animation Clip (AnimationClip)
  • Toggle Behavior (Boolean: Saved/Not Saved on avatar reset)
• Automated VRChat SDK Integration:
  • Automatically generate or update the VRCExpressionsMenu.
  • Automatically add the required tracking parameters to VRCExpressionParameters.
  • Generate the FX Animator Layer with appropriate states, transitions, and write defaults handling.
• Mutually Exclusive Toggles (Optional/Nice-to-Have): An option to make the expressions mutually exclusive (selecting one turns off the others) or allow stacking.

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Acceptance Criteria

• Component can be added to any VRChat Avatar Descriptor GameObject.
• Successfully generates a functional sub-menu with correct icons and toggles in the VRChat SDK build pipeline.
• Toggling an expression in-game correctly overrides the base gesture animations.
• Validates inputs to ensure creators don't exceed the 8-control limit per VRChat sub-menu without warning them.
• Does not break existing, manually configured FX layers or parameters when updating.

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Technical Notes

VRChat SDK 3 Compatibility: This component must interface directly with VRC.SDK3.Avatars.Components.VRCAvatarDescriptor, updating the expressionsMenu and expressionParameters fields programmatically via an Editor script.

Avoid modifying the animator controller directly if it can be done via a generated blend tree or a dedicated sub-layer to keep the asset non-destructive.