ARFace.swift

func updateFeatures(for node: SCNNode, using anchor: ARFaceAnchor) {
    for (feature, indices) in zip(features, featureIndices) {
        let child = node.childNode(withName: feature, recursively: false) as? EmojiNode
        let vertices = indices.map { anchor.geometry.vertices[$0] }
        child?.updatePosition(for: vertices)

        switch feature {
        case "leftEye":
            let scaleX = child?.scale.x ?? 1.0
            let eyeBlinkValue = anchor.blendShapes[.eyeBlinkLeft]?.floatValue ?? 0.0
            child?.scale = SCNVector3(scaleX, 1.0 - eyeBlinkValue, 1.0)

        case "rightEye":
            let scaleX = child?.scale.x ?? 1.0
            let eyeBlinkValue = anchor.blendShapes[.eyeBlinkRight]?.floatValue ?? 0.0
            child?.scale = SCNVector3(scaleX, 1.0 - eyeBlinkValue, 1.0)

        case "mouth":
            let jawOpenValue = anchor.blendShapes[.jawOpen]?.floatValue ?? 0.2
            child?.scale = SCNVector3(1.0, 0.8 + jawOpenValue, 1.0)

        default:
            break
        }
    }
}