這一篇我們要讓貪吃蛇吃掉一顆蘋果後，身體變長一節
新增身體部分
在hieracky中新增一個circle，並改變它的顏色，接著把他拉到底下project的部分

在snack的腳本中新增這一行：public Transform bodyPrefab;
完整程式碼：

using UnityEngine;

public class Snack : MonoBehaviour
{
    Vector3 direction;
    public float speed;
    public Transform bodyPrefab;
    // Start is called once before the first execution of Update after the MonoBehaviour is created
    void Start()
    {
        Debug.Log(transform.position);

        Time.timeScale = speed;
    }

    // Update is called once per frame
    void Update()
    {
        if (Input.GetKeyDown(KeyCode.W))
        {
            Debug.Log("W");
            direction = Vector3.up;
        }
        if (Input.GetKeyDown(KeyCode.A))
        {
            Debug.Log("A");
            direction = Vector3.left;
        }
        if (Input.GetKeyDown(KeyCode.S))
        {
            Debug.Log("S");
            direction = Vector3.down;
        }

        if (Input.GetKeyDown(KeyCode.D))
        {
            Debug.Log("D");
            direction = Vector3.right;
        }


    }
    void FixedUpdate()
    {
        transform.Translate(direction);

    }
}

儲存好後，unity的頁面會多一個body prefab變數，再將body拖曳進去

打開apple，inspector介面有一個tag選項，打開後按add tag，接著按＋，輸入Food，出去後再按tag，選擇剛剛新增的Food


最後，在Snack的腳本裡輸入這串完整程式碼：

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

public class Snack : MonoBehaviour
{
    Vector3 direction;
    public float speed;
    public Transform bodyPrefab;

    public List<Transform> bodies = new List<Transform>();
    void Start()
    {

        Time.timeScale = speed;
        bodies.Add(transform);
    }

    // Update is called once per frame
    void Update()
    {
        if (Input.GetKeyDown(KeyCode.W))
        {
            Debug.Log("W");
            direction = Vector3.up;
        }
        if (Input.GetKeyDown(KeyCode.A))
        {
            Debug.Log("A");
            direction = Vector3.left;
        }
        if (Input.GetKeyDown(KeyCode.S))
        {
            Debug.Log("S");
            direction = Vector3.down;
        }

        if (Input.GetKeyDown(KeyCode.D))
        {
            Debug.Log("D");
            direction = Vector3.right;
        }


    }
    private void FixedUpdate()
    {
        for(int i = bodies.Count - 1; i > 0; i--)
        {
            bodies[i].position = bodies[i - 1].position;
        }
        transform.Translate(direction);

    }
    private void OnTriggerEnter2D(Collider2D collision)
    {

        if (collision.CompareTag("Food"))
        {

            bodies.Add(Instantiate(bodyPrefab
            , transform.position
            , Quaternion.identity));

        }
    }
}