using UnityEngine;

public class MoveCameraByMouse : MonoBehaviour
{
    public static MoveCameraByMouse instance;
    [Header("设置初始视角")]
    public Vector3 initialPosition = new Vector3(376f, 565f, 155f);
    public Vector3 initialRotation = new Vector3(58.3f, -90f, 0f);

    [Header("围绕旋转的目标物体")]
    public Transform target;
    [Header("是否开启旋转")]
    public bool ison = true;

    [Header("设置旋转角度")]
    public float x = 154.6f, y = 31.5f, z = 0f;

    [Header("旋转速度值")]
    public float xSpeed = 100, ySpeed = 100;
    [Header("缩放速度值")]
    public float mSpeed = 2;

    [Header("y轴角度限制，设置成一样则该轴不旋转")]
    public float yMinLimit = -365, yMaxLimit = 365;

    [Header("x轴角度限制")]
    public float leftMax = -365, rightMax = 365;

    [Header("距离限制")]
    public float distance = 7f, minDistance = 0.1f, maxDistance = 10f;

    [Header("阻尼设置")]
    public bool needDamping = true;
    public float damping = 3f;

    [Header("是否正在旋转")]
    public bool isRotate;
    [Header("是否正在缩放")]
    public bool isZoom;

    private void Start()
    {
        instance = this;
        transform.position = initialPosition;
        transform.rotation = Quaternion.Euler(initialRotation);
    }
    public void LateUpdate()
    {
        if (target && ison == true)
        {
            if (Input.GetMouseButton(0))
            {
                isRotate = true;
                // 判断是否需要反向旋转
                if ((y > 90f && y < 270f) || (y < -90 && y > -270f))
                {
                    x -= Input.GetAxis("Mouse X") * xSpeed * 0.02f;
                }
                else
                {
                    x += Input.GetAxis("Mouse X") * xSpeed * 0.02f;
                }
                y -= Input.GetAxis("Mouse Y") * ySpeed * 0.02f;

                x = ClampAngle(x, leftMax, rightMax);
                y = ClampAngle(y, yMinLimit, yMaxLimit);
            }
            else
                isRotate = false;
            if (Input.GetAxis("Mouse ScrollWheel") != 0)
            {
                isZoom = true;
            }
            else
                isZoom = false;
            distance -= Input.GetAxis("Mouse ScrollWheel") * mSpeed;
            distance = Mathf.Clamp(distance, minDistance, maxDistance);

            Quaternion rotation = Quaternion.Euler(y, x, z);
            Vector3 disVector = new Vector3(0.0f, 0.0f, -distance);
            Vector3 position = rotation * disVector + target.position;

            // 阻尼感
            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;
            }

        }
    }

    // 对数值进行限制；
    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);
    }
}