触摸旋转和缩放3D模型

using UnityEngine;
using System.Collections;

public class SmoothController : MonoBehaviour
{
    public Transform Target = null;
    public Camera MainCamera = null;

    private float XAngle = 0f;
    private float YAngle = 0f;
    private float XSpeed = 250f;
    private float YSpeed = 120f;

    private float Distance = 50f;
    private float DisSpeed = 10f;
    private float MinDistance = 0f;
    private float MaxDistance = 50f;

    private Vector2 Vec2Pos1 = Vector2.zero;
    private Vector2 Vec2Pos2 = Vector2.zero;

    void Start()
    {
        MainCamera = Camera.main;
    }

    void OnGUI()
    {
        if (GUI.Button(new Rect(0f, 0f, 100f, 50f), "ReSet"))
        {
            Distance = 50f;
            Target.transform.rotation = Quaternion.identity;
        }
    }

    void Update()
    {
        if (Input.touchCount == 1)
        {
            if (Input.GetTouch(0).phase == TouchPhase.Moved)
            {
                XAngle += Input.GetAxis("Mouse X") * XSpeed * 0.02f;
                YAngle -= Input.GetAxis("Mouse Y") * YSpeed * 0.02f;
            }
        }

        if (Input.touchCount > 1)
        {
            if (Input.GetTouch(1).phase == TouchPhase.Began)
            {
                Vec2Pos1 = Input.GetTouch(0).position;
                Vec2Pos2 = Input.GetTouch(1).position;
            }
            else if (Input.GetTouch(0).phase == TouchPhase.Moved || Input.GetTouch(1).phase == TouchPhase.Moved)
            {
                var tempPosition1 = Input.GetTouch(0).position;
                var tempPosition2 = Input.GetTouch(1).position;

                float deltaDis = DeltaDistance(Vec2Pos1, Vec2Pos2, tempPosition1, tempPosition2);
                // 如果在扩大
                if (deltaDis < 0f)
                    Distance += deltaDis * DisSpeed;
                else
                    Distance += deltaDis * DisSpeed;

                // 记录旧的位置
                Vec2Pos1 = tempPosition1;
                Vec2Pos2 = tempPosition2;
            }
        }

    }

    void LateUpdate()
    {
        // 旋转的更新
        ClampXY();
        Target.transform.Rotate(-YAngle, -XAngle, 0f, Space.World);
        XAngle = 0f;
        YAngle = 0f;

        // 摄像机位置的更新
        ClampDistance();
        Vector3 cameraPos = MainCamera.transform.position;
        cameraPos.z = -Distance;
        MainCamera.transform.position = cameraPos;
    }

    bool IsEnlarge(Vector2 oP1, Vector2 oP2, Vector2 nP1, Vector2 nP2)
    {
        float leng1 = Mathf.Sqrt((oP1.x - oP2.x) * (oP1.x - oP2.x) + (oP1.y - oP2.y) * (oP1.y - oP2.y));
        float leng2 = Mathf.Sqrt((nP1.x - nP2.x) * (nP1.x - nP2.x) + (nP1.y - nP2.y) * (nP1.y - nP2.y));
        if (leng1 < leng2)
            return true;
        else
            return false;
    }

    float DeltaDistance(Vector2 oP1, Vector2 oP2, Vector2 nP1, Vector2 nP2)
    {
        float leng1 = Mathf.Sqrt((oP1.x - oP2.x) * (oP1.x - oP2.x) + (oP1.y - oP2.y) * (oP1.y - oP2.y));
        float leng2 = Mathf.Sqrt((nP1.x - nP2.x) * (nP1.x - nP2.x) + (nP1.y - nP2.y) * (nP1.y - nP2.y));
        return leng1 - leng2;
    }

    void ClampXY()
    {
        if (XAngle < -360)
            XAngle += 360;
        if (XAngle > 360)
            XAngle -= 360;
        if (YAngle < -360)
            YAngle += 360;
        if (YAngle > 360)
            YAngle -= 360;
    }

    void ClampDistance()
    {
        Distance = Mathf.Clamp(Distance, MinDistance, MaxDistance);
    }

}