TouchZoom

using UnityEngine;
public class TouchZoom : MonoBehaviour
{
    public Vector2 startPos;
    public Vector2 mouseStartPos;
    float dist0 = 0f;
    float dist1 = 0f;
    float scale = 0f;
    float oldDist = 0f;//前回の2点間の距離
    float minRate = 0.3f;
    float maxRate = 2f;
    Vector2 v = Vector2.zero;
    void Update()
    {
        /*
        if (Input.touchCount == 1)
        {
            Touch t1 = Input.GetTouch(0);
            if (t1.phase == TouchPhase.Began)
            {
                //移動したいUIオブジェクトの最初の位置
                startPos = transform.position;
                //ドラッグを開始したときのマウスの位置
                mouseStartPos = t1.position;
            }
            else if (t1.phase == TouchPhase.Moved)
            {
                //ドラッグ中のUIオブジェクトの位置
                transform.position
                        = startPos + (t1.position - mouseStartPos);
            }
        }
        */
        if (Input.touchCount >= 2)
        {
            Touch t1 = Input.GetTouch(0);
            Touch t2 = Input.GetTouch(1);
            if (t2.phase == TouchPhase.Began)
            {
                dist0 = Vector2.Distance(t1.position, t2.position);
                oldDist = dist0;
            }
            else if (t1.phase == TouchPhase.Moved && t2.phase == TouchPhase.Moved)
            {
                dist1 = Vector2.Distance(t1.position, t2.position);
                if (dist0 < 0.001f || dist1 < 0.001f)
             {
              return;
          } else {
              v = transform.localScale;
          scale = v.x;
         scale += (dist1 - oldDist) / 400f;
           if (scale > maxRate) { scale = maxRate; }
           if (scale < minRate) { scale = minRate; }
          oldDist = dist1;
         }
       transform.localScale = new Vector3(scale, scale, scale);
     }
    }
 }
}