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

public class CameraOrbit : MonoBehaviour
{
    public float distance; // 摄像头与指定点的距离
    public float xSpeed = 120.0f; // 水平旋转速度
    public float ySpeed = 120.0f; // 垂直旋转速度
    public bool canScroll = true;

    private float x = 0.0f;
    private float y = 0.0f;
    private float z = 1.0f;

    void Start()
    {
        Vector3 angles = transform.eulerAngles;
        x = angles.y;
        y = angles.x;
        distance = Vector3.Distance(transform.position, new Vector3(0, z, 0));
    }

    void LateUpdate()
    {
        if (Input.GetMouseButton(1))
        {
            x += Input.GetAxis("Mouse X") * xSpeed * distance * 0.02f;
            y -= Input.GetAxis("Mouse Y") * ySpeed * 0.02f;

            Quaternion rotation = Quaternion.Euler(y, x, 0);
            Vector3 position = rotation * new Vector3(0.0f, 0.0f, -distance) + new Vector3(0, z, 0);

            transform.rotation = rotation;
            transform.position = position;
        }

        else if (Input.GetAxis("Mouse ScrollWheel") != 0 && canScroll)
        {
            if (Input.GetAxis("Mouse ScrollWheel") < 0)
            {
                if (Camera.main.fieldOfView <= 100)
                    Camera.main.fieldOfView += 2;
                if (Camera.main.orthographicSize <= 20)
                    Camera.main.orthographicSize += 0.5F;
            }
            if (Input.GetAxis("Mouse ScrollWheel") > 0)
            {
                if (Camera.main.fieldOfView > 2)
                    Camera.main.fieldOfView -= 2;
                if (Camera.main.orthographicSize >= 1)
                    Camera.main.orthographicSize -= 0.5F;
            }
        }

        else if (Input.GetMouseButton(0))
        {
            var d = Input.GetAxis("Mouse Y") * ySpeed * 0.0005f;
            z -= d;
            Vector3 position = transform.position;
            position.y -= d;
            transform.position = position;

        }
    }
 }