/********************************************************
** project   :  xx
** date      ： 05/09/2016
** auth      ： Anne
** desc      :  镜头更随~
** Version   :  1.0
********************************************************/
using UnityEngine;
using System.Collections;
/// <summary>
/// 
/// </summary>
public class CameraSmoothFollow : MonoBehaviour
{
    /// <summary>
    /// 跟随目标
    /// </summary>
    public Transform mFollowTarget;

    /// <summary>
    /// 跟随距离
    /// </summary>
    public float mDistance = 0f;

    /// <summary>
    /// 高度
    /// </summary>
    public float mHeight = 0f;
    /// <summary>
    /// 是否平滑旋转
    /// </summary>
    public bool bolSmoothRotation = true;

    /// <summary>
    /// 
    /// </summary>
    public float damping = 5.0f;
    /// <summary>
    /// 是否在身后跟随
    /// </summary>
    public bool bolFollowBehind = true;

    /// <summary>
    /// 旋转衰减
    /// </summary>
    public float mRotationDamping = 10.0f;

    /// <summary>
    /// 是否和目标同一个方向
    /// </summary>
    public bool bolStaticOffset = false;

    /// <summary>
    /// 当前方向
    /// </summary>
    private Vector3 mWantedPosition = Vector3.zero;

    /// <summary>
    /// 相机跟随在late,防止Update中逻辑丢失
    /// </summary>
    void LateUpdate()
    {
        if (bolStaticOffset)
        {
            mWantedPosition = mFollowTarget.position + new Vector3(0, mHeight, mDistance);
        }
        else
        {
            if (bolFollowBehind)
            {
                mWantedPosition = mFollowTarget.TransformPoint(0, mHeight, -1 * mDistance);
            }
            else
            {
                mWantedPosition = mFollowTarget.TransformPoint(0, mHeight, mDistance);
            }
        
        }
        transform.position = Vector3.Lerp(transform.position, mWantedPosition, Time.deltaTime * damping);
        if (bolSmoothRotation)
        {
            Quaternion mWantedRotation = Quaternion.LookRotation(mFollowTarget.position - transform.position, mFollowTarget.up);
            transform.rotation = Quaternion.Slerp(transform.rotation, mWantedRotation, Time.deltaTime * mRotationDamping);
        }
        else {
            transform.LookAt(mFollowTarget, mFollowTarget.up);
        }

    }
}