MouthOpenParam.cs

using UnityEngine;
using Live2D.Cubism.Core;


public class MouthOpenParam : MonoBehaviour
{
    [SerializeField] DlibWebCamFaceDetector faceDetector;
    [SerializeField] CubismParameter mouthOpenParameterX;
    [SerializeField] CubismParameter mouthOpenParameterY;
    [SerializeField] float lerpT = 0.2f;
    private float _mouthOpenX;
    private float _mouthOpenY;

    private void LateUpdate()
    {
        var landmarks = faceDetector.Landmarks;

        // 口の開き(X軸)
        float distanceOfMouthWidth = new Vector2(landmarks[48].x - landmarks[54].x, landmarks[48].y - landmarks[54].y)
            .sqrMagnitude;
        float distanceBetweenEyes = new Vector2(landmarks[39].x - landmarks[42].x, landmarks[39].y - landmarks[42].y)
            .sqrMagnitude;
        // ゼロ除算対策
        if (distanceBetweenEyes != 0)
        {
            float ratio = distanceOfMouthWidth / distanceBetweenEyes;
            float currentMouthOpenX = Mathf.InverseLerp(1.8f, 2.0f, ratio);
            _mouthOpenX = Mathf.Lerp(_mouthOpenX, currentMouthOpenX, lerpT);
        }

        // 口の開き(Y軸)
        float distanceOfMouthHeight = new Vector2(landmarks[51].x - landmarks[57].x, landmarks[51].y - landmarks[57].y)
            .sqrMagnitude;
        float distanceOfNoseHeight = new Vector2(landmarks[33].x - (landmarks[39].x + landmarks[42].x) / 2,
            landmarks[33].y - (landmarks[39].y + landmarks[42].y) / 2).sqrMagnitude;
        // ゼロ除算対策
        if (distanceOfNoseHeight != 0)
        {
            float ratio = distanceOfMouthHeight / distanceOfNoseHeight;
            float currentMouthOpenY = Mathf.InverseLerp(0.2f, 0.6f, ratio);
            _mouthOpenY = Mathf.Lerp(_mouthOpenY, currentMouthOpenY, lerpT);
        }

        SetParameter(mouthOpenParameterX, _mouthOpenX);
        SetParameter(mouthOpenParameterY, _mouthOpenY);
    }

    void SetParameter(CubismParameter parameter, float value)
    {
        if (parameter != null)
        {
            parameter.Value = Mathf.Clamp(value, parameter.MinimumValue, parameter.MaximumValue);
        }
    }
}