unity游戏教程 space shooter （玩家控制器）

为了更好地理解unity，模仿了教程，以下均为教程中的代码：

PlayerController.cs:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[System.Serializable]
public class Boundary{
public float xMin,xMax,zMin,zMax;
}
public class PlayerController : MonoBehaviour {
public float speed;
public float tilt;
public Boundary boundary;

private float nextFire;
public float fireRate;
public GameObject shot;
public Transform shotSpawn;

// Use this for initialization
void Start () {
    
}

// Update is called once per frame
void Update () {
    if (Input.GetButton("Fire1")&&Time.time > nextFire){
        nextFire = Time.time + fireRate;
        Instantiate (shot,shotSpawn.position,shotSpawn.rotation);
        GetComponent ().Play ();
    }


}

void FixedUpdate(){

    float moveHorizontal = Input.GetAxis ("Horizontal");
    float moveVertical = Input.GetAxis ("Vertical");
    Vector3 movement = new Vector3 (moveHorizontal, 0.0f, moveVertical);

    GetComponent ().velocity = speed * movement;
    GetComponent ().position = new Vector3 (Mathf.Clamp(GetComponent().position.x,boundary.xMin,boundary.xMax),
        0.0f,
        Mathf.Clamp(GetComponent().position.z,boundary.zMin,boundary.zMax));
    GetComponent ().rotation = Quaternion.Euler (0.0f, 0.0f, GetComponent ().velocity.x * -tilt);
}

}