using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class MoveCamera : MonoBehaviour
{
    public Transform target;
    public float xSpeed = 200, ySpeed = 200, mSpeed = 10;  //分别定义相机横向、纵向的旋转速度，视野缩放速度
    public float yMinLimit = 5, yMaxLimit = 50; //限制纵向的最小最大旋转角
    public float distance = 50, minDistance = 2, maxDistance = 100; //设置初始状态相机的视野范围，以及相机所能缩放的最小最大范围
    public bool needDamping = true; //是否需要相机阻尼效果
    float damping = 5f; //相机阻尼系数
    public float x = 0f; //初始状态照相机横向旋转角度
    public float y = 0f; //初始状态照相机纵向旋转角度


    private Vector3 m_mouseMovePos;
    private Camera camera;


    private void Start()
    {
        camera = GetComponent<Camera>();
    }
    // Update is called once per frame
    void LateUpdate()
    {


        if (target)
        {
            //鼠标点击右键划动控制相机围绕target旋转；鼠标滚轮改变视野
            if (Input.GetMouseButton(1))
            {
                x += Input.GetAxis("Mouse X") * xSpeed * 0.02f;
                y -= Input.GetAxis("Mouse Y") * ySpeed * 0.02f;


                y = ClampAngle(y, yMinLimit, yMaxLimit);
            }
            distance -= Input.GetAxis("Mouse ScrollWheel") * mSpeed;
            distance = Mathf.Clamp(distance, minDistance, maxDistance);


            Quaternion rotation = Quaternion.Euler(y, x, 0.0f);  //
            Vector3 disVector = new Vector3(0f, 0f, -distance);
            Vector3 position = rotation * disVector + target.position;
            if (needDamping)
            {
                transform.rotation = Quaternion.Lerp(transform.rotation, rotation, Time.deltaTime * damping);
                transform.position = Vector3.Lerp(transform.position, position, Time.deltaTime * damping);
            }
            else
            {
                transform.rotation = rotation;
                transform.position = position;
            }

        }
    }
    static float ClampAngle(float angle, float min, float max)
    {
        if (angle < -360)
            angle += 360;
        if (angle > 360)
            angle -= 360;
        return Mathf.Clamp(angle, min, max);
    }
}