using System.Collections;

using System.Collections.Generic;

using UnityEngine;

public class CameraFollowss : MonoBehaviour {

    //跟随目标

    //先确定相机围绕哪个物体进行旋转，缩放，平移;也就是需要确定相机的父物体

  //先写右键旋转（相机）,确定相机旋转的速度

  public Transform target;

  //旋转的初始角度

  private float x = 0.0f;

    private float y = 0.0f;

  //相机旋转的速率

  private float rSpeed = 10.0f;

  //获取相机Transform对象

  private Transform cam;

  //相机距离目标物体的起始距离(距离设置为负值，是因为相机是在目标物体的正后方)

  private float distance = -5;

  //相机距离的物体的最近和最远距离

  private float minDistance = -1;

    private float maxDistance = -30;

  //初始位置

  private float camPostion_x = 0;

    private float camPostion_y = 0;

    void Awake()

    {

        transform.position = target.position;

        transform.rotation = Quaternion.Euler(y, x, 0);

        cam = GameObject.Find("Main Camera").transform;

        cam.localPosition = new Vector3(0, 0, distance);

    }

    void Update()

    {

        if (Input.GetMouseButton(1))

        {

      //右键按下

      x += Input.GetAxis("Mouse X") * rSpeed;

            y -= Input.GetAxis("Mouse Y") * rSpeed;

            x = ClampAngle(x, -360, 360);

            y = ClampAngle(y, -70, 70);

            var rotation = Quaternion.Euler(y, x, 0);

            transform.rotation = rotation;

        }

        else if (Input.GetAxis("Mouse ScrollWheel") != 0)

        {

      //中键滚动缩放

      distance += Input.GetAxis("Mouse ScrollWheel") * 5;

            distance = Mathf.Clamp(distance, maxDistance, minDistance);

            cam.localPosition = new Vector3(camPostion_x, camPostion_y, distance);

        }

    //中键按下平移

    if (Input.GetMouseButton(2))

        {

            camPostion_x -= Input.GetAxis("Mouse X") * 0.04f;

            camPostion_y -= Input.GetAxis("Mouse Y") * 0.04f;

            cam.localPosition = new Vector3(camPostion_x, camPostion_y, distance);

        }

    }

    static float ClampAngle(float angle, float minAngle, float maxAngle)

    {

        if (angle < -360)

            angle += 360;

        if (angle > 360)

            angle -= 360;

        return Mathf.Clamp(angle, minAngle, maxAngle);

    }

}