using UnityEngine;

//摄像机控制器
public class PreviewSceneCamera
{
    #region//属性
    //摄像机实例
    public Transform TransformInst { get; set; }
    //当前跟随目标
    public Transform TargetTrans { get; set; }
    //当前pitch
    public float CurPitch = 32f;
    //当前yaw
    public float CurYaw = 135f;
    //当前跟随距离
    public float CurDis = 25f;
    //当前Y轴偏移量
    public float CurOffsetY = 2f;
    //当前X轴偏移量
    public float CurOffsetX = 0f;
    #endregion

    #region//共有函数
    public void Update()
    {
        if (TransformInst == null || TargetTrans == null)
            return;

        if (CurPitch < -89f)
            CurPitch = -89f;
        if(CurPitch > 89f)
            CurPitch = 89f;

        var targetPos = TargetTrans.position + Vector3.up * CurOffsetY;
        Quaternion rot = Quaternion.Euler(CurPitch, CurYaw, 0f);
        var selfPos = targetPos - rot * Vector3.forward * CurDis;
        if (CurOffsetX != 0)
        {
            var dir = (TargetTrans.position - selfPos);
            dir.y = 0;
            dir = Quaternion.AngleAxis(90, Vector3.up) * dir;
            dir = dir.normalized;

            targetPos = targetPos + dir * CurOffsetX;
            selfPos = targetPos - rot * Vector3.forward * CurDis;
        }

        TransformInst.position = selfPos;
        TransformInst.rotation = rot;
    }
    #endregion
}