Unity使用Animator实现人物头部朝向鼠标

using UnityEngine;
using System.Collections;

public class LookAtTest : MonoBehaviour {

private Animator _animator;
private Vector3 _pos ;

// Use this for initialization
void Start () {
_animator = GetComponent<Animator>();
}

void OnAnimatorIK(int layer){
if (layer == 1) {
Vector3 pos =  Camera.main.ScreenToWorldPoint (new Vector3(Input.mousePosition.x,Input.mousePosition.y,Camera.main.transform.position.z));
_pos = Vector3.Lerp (_pos, pos, 0.075f);

_animator.SetLookAtPosition (_pos);
_animator.SetLookAtWeight (0.25f,0.5f,1f,1f,0.6f);
}
}
}