//放在攝像頭上，實現旋轉、縮放觀察物體
using UnityEngine;
public class BaseCam : MonoBehaviour
{
    public Vector3 mousePos1;                           //記錄滑鼠點下去瞬間的位置
    public Vector3 mousePos2;                           //記錄滑鼠任何時刻的位置
    public Quaternion start_qua;                        //角度使用四元數
    public Vector3 start_pos;                           //位置座標

    public int offsetx = 1;
    public int offsety = 1;
                                                        // Use this for initialization
    void Start()
    {
        //記錄相機開始的角度與位置
        start_qua = transform.rotation;
        start_pos = transform.position;
    }
    // Update is called once per frame
    void Update()
    {
        //記錄滑鼠實時移動的點
        mousePos2 = Input.mousePosition;
    }
    void OnGUI()
    {
        // keyboard
        if (Input.GetKey(KeyCode.UpArrow)) {
            offsetx = 5;
            transform.RotateAround(new Vector3(0, 0, 0), transform.right, -Time.deltaTime * offsety * 5f);
            //以物體上方為旋轉軸（Vector3.up == new Vector3(0, 1.0f, 0)），物體左右旋轉角度與滑鼠橫向移動距離相關，變化速率2f
            
        }
        
        if (Input.GetKey(KeyCode.DownArrow)) {
            //offsetx = -5;
            transform.RotateAround(new Vector3(0, 0, 0), transform.right, Time.deltaTime * offsety * 5f);
            //以物體上方為旋轉軸（Vector3.up == new Vector3(0, 1.0f, 0)），物體左右旋轉角度與滑鼠橫向移動距離相關，變化速率2f
            
        }

        if (Input.GetKey(KeyCode.RightArrow)) {
                offsety = 10;
                //以物體上方為旋轉軸（Vector3.up == new Vector3(0, 1.0f, 0)），物體左右旋轉角度與滑鼠橫向移動距離相關，變化速率2f
                
                transform.RotateAround(new Vector3(0, 0, 0), Vector3.up, Time.deltaTime * offsetx * 5f);
        }

         if (Input.GetKey(KeyCode.LeftArrow)) {
                offsety = 10;
                //以物體上方為旋轉軸（Vector3.up == new Vector3(0, 1.0f, 0)），物體左右旋轉角度與滑鼠橫向移動距離相關，變化速率2f
                
                transform.RotateAround(new Vector3(0, 0, 0), Vector3.up, -Time.deltaTime * offsetx * 5f);
        }

        //滑鼠左鍵
        if (Input.GetMouseButton(0))
        {
            mousePos1 = Input.mousePosition;            //記錄滑鼠點選瞬間的點
            Vector3 offset = mousePos1 - mousePos2;     //記錄滑鼠移動的距離
                                                        //上下與左右 旋轉分開，絕對值比較
            if (Mathf.Abs(offset.x) > Mathf.Abs(offset.y))
            {
                //以物體上方為旋轉軸（Vector3.up == new Vector3(0, 1.0f, 0)），物體左右旋轉角度與滑鼠橫向移動距離相關，變化速率2f
                transform.RotateAround(new Vector3(0, 0, 0), Vector3.up, Time.deltaTime * offset.x * 5f);
            }
            else
            {
                //以世界座標右方為旋轉軸（transform.right，是會變化的量），物體上下旋轉角度與滑鼠縱向移動距離相關，變化速率2f
                transform.RotateAround(new Vector3(0, 0, 0), transform.right, -Time.deltaTime * offset.y * 5f);
            }
            //列印資料transform.right變數
            Debug.Log("pos: "+transform.right.ToString());
        }
        //滑鼠中鍵，物體恢復原來的角度與位置
        if (Input.GetMouseButton(2))
        {
            transform.rotation = start_qua;
            transform.position = start_pos;
        }
        //滑鼠中鍵滑動，物體縮放，攝像頭前後移動距離範圍在2f~5f，變化速率3f
        if (Input.GetAxis("Mouse ScrollWheel") > 0f && Vector3.Distance(transform.position, new Vector3(0, 0, 0)) > 2f)
        {
            transform.Translate(Vector3.forward * Time.deltaTime * Input.GetAxis("Mouse ScrollWheel") * 5f);
        }
        if (Input.GetAxis("Mouse ScrollWheel") < 0f && Vector3.Distance(transform.position, new Vector3(0, 0, 0)) < 5f)
        {
            transform.Translate(Vector3.back * Time.deltaTime * (-Input.GetAxis("Mouse ScrollWheel")) * 5f);
        }
    }
}