Unity 触屏缩放模型

using UnityEngine;
using System.Collections;
using System.IO;

public class ScaleAndRotate : MonoBehaviour
{
    /// <summary>
    /// 上次触摸点1(手指1)
    /// </summary>
    private Touch oldTouch1;  
    /// <summary>
    /// 上次触摸点2(手指2)
    /// </summary>
    private Touch oldTouch2;  
    
    /// <summary>
    /// 用于显示滑动距离
    /// </summary>
    private float oldDis = 0;
    private float newDis = 0;
    private float scaler = 0;


    void Update()
    {
        //没有触摸
        if (Input.touchCount <= 0)
        {
            return;
        }

        //单点触摸， 水平上下旋转
        if (1 == Input.touchCount)
        {
            Touch touch = Input.GetTouch(0);
            Vector2 deltaPos = touch.deltaPosition;
            transform.Rotate(Vector3.down * deltaPos.x, Space.World);
            transform.Rotate(Vector3.right * deltaPos.y, Space.World);
        }

        //多点触摸, 放大缩小
        Touch newTouch1 = Input.GetTouch(0);
        Touch newTouch2 = Input.GetTouch(1);

        //第2点刚开始接触屏幕, 只记录，不做处理
        if (newTouch2.phase == TouchPhase.Began)
        {
            oldTouch2 = newTouch2;
            oldTouch1 = newTouch1;
            return;
        }

        //计算老的两点距离和新的两点间距离，变大要放大模型，变小要缩放模型
        float oldDistance = Vector2.Distance(oldTouch1.position, oldTouch2.position);
        float newDistance = Vector2.Distance(newTouch1.position, newTouch2.position);
        oldDis = oldDistance;
        newDis = newDistance;

        //两个距离之差，为正表示放大手势， 为负表示缩小手势
        float offset = newDistance - oldDistance;

        //放大因子， 一个像素按 0.01倍来算(100可调整)
        float scaleFactor = offset / 100f;
        Vector3 localScale = transform.localScale;
        Vector3 scale = new Vector3(localScale.x + scaleFactor,
                                    localScale.y + scaleFactor,
                                    localScale.z + scaleFactor);
        scaler = scaleFactor;

        //允许模型最小缩放到 0.3 倍最大放大2倍
        if (scale.x > 0.3f && scale.y > 0.3f && scale.z > 0.3f)
        {
            //实用差值运算，模型平滑缩放
            transform.localScale = Vector3.Lerp(transform.localScale,new Vector3(Mathf.Clamp(localScale.x + scaleFactor, 0.3f, 2f), 
                                               Mathf.Clamp(localScale.y + scaleFactor, 0.3f, 2f),
                                               Mathf.Clamp(localScale.z + scaleFactor, 0.3f, 2f)),1f);
        }
        //记住最新的触摸点，下次使用
        oldTouch1 = newTouch1;
        oldTouch2 = newTouch2;
    }

    void OnGUI()
    {
        GUILayout.Label("oldDis:" + oldDis);
        GUILayout.Label("newDis:" + newDis);
        GUILayout.Label("scaler:" + scaler);
        GUILayout.Label("localScale:" + this.transform.localScale);

        if (Input.GetKeyDown(KeyCode.Escape))
        {
            Application.Quit();
        }
    }

}