CharacterController移动角色(SimpleMove)

using UnityEngine;
using System.Collections;

public class Test1 : MonoBehaviour 
{
    //声明一个CharacterController类型的私有变量
    private CharacterController controller;
    //角色的初始移动速度
    private float playerSpeed=0.0f;

    void Start () 
    {
        //获取CharacterController组件
        controller=GetComponent<CharacterController>();
    }    

    void Update () 
    {
        //角色的朝向
        Vector3 playerForward=this.transform.TransformDirection(Vector3.forward);
        //向前移动
        if (Input.GetKey (KeyCode.W))
        {
            playerSpeed=5.0f;
        }
        else if (Input.GetKey(KeyCode.S))
        {
            playerSpeed=-5.0f;
        }
        else if (Input.GetKey(KeyCode.A))
        {
            this.transform.Rotate (Vector3.up*-10);
        }
        else if (Input.GetKey(KeyCode.D))
        {
            this.transform.Rotate (Vector3.up*10);
        }
        else
        {
            playerSpeed=0.0f;
        }
        controller.SimpleMove(playerForward*playerSpeed);
    }
}