我正在使用触摸输入来执行捏夹功能。捏夹功能正常，但我想检测两个手指是捏入（彼此靠近）还是捏出（彼此远离）。如何做到这一点？
我已经尝试过存储当前比率与先前比率以便检查下一次迭代，但由于我在每一帧都存储它，因此它会波动。此外，如果用户从未抬起手指，该如何工作？

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.InputSystem;
using UnityEngine.InputSystem.EnhancedTouch;
using Touch = UnityEngine.InputSystem.EnhancedTouch.Touch;
 
public class DetectTouch: MonoBehaviour {
 
//Touch
    int prevtouchCount;
    float firstDistance;
    float originalZoom;
    float currentZoom;
    float distance;
 
    float ratio;
    float previousRatio;
 
    void Update () {
 
        //Touch
        if (Touch.activeFingers.Count == 2) {
 
            Touch touch1 = Touch.activeFingers[0].currentTouch;
            Touch touch2 = Touch.activeFingers[1].currentTouch;
 
            distance = Vector2.Distance (touch1.screenPosition, touch2.screenPosition);
 
            if (prevtouchCount != 2) {
                firstDistance = distance;
                originalZoom = Camera.main.fieldOfView;
            }
 
            ratio = distance / firstDistance;
 
            if (ratio < previousRatio) {
                Debug.Log("NOT PINCHING");
                previousRatio = ratio;
               
            } else {
                Debug.Log("PINCHING");
                previousRatio = ratio;
               
            }
 
        }
 
    }
}