抛光简单的贪吃蛇游戏

Question

按照我找到的这个教程，我一直在Unity(C#)中创建了一个简单的贪吃蛇游戏:

https://www.youtube.com/watch?v=U8gUnpeaMbQ

我发现这是一个非常好的教程，到最后我有一个完美的蛇游戏，但是，我想走得更远一点，使运动更加愉快，添加尾巴，Gameover等。

现在我的问题是，如果一个玩家快速连续按下两个可接受的方向试图抓住一些食物，蛇的头会跳过食物，完全错过它。

发生这种情况是由于以下代码位：

private void Update() //Gets Key Inputs and execute Commands
{   
    if (Input.GetKeyDown(KeyCode.UpArrow) )
    {
        while(tempPosition == _segments[0].position)
        {
            for (int i = _segments.Count - 1; i > 0; i--)
            {
                _segments[i].position = _segments[i - 1].position;
            }
            this.transform.position = new Vector3(
                Mathf.Round(this.transform.position.x + _direction.x),
                Mathf.Round(this.transform.position.y + _direction.y),
                0.0f
                );
        }
        if(_direction != Vector2.down)
        {
            _direction = Vector2.up;
            tempPosition = _segments[0].position;
        }
        
    }
    else if (Input.GetKeyDown(KeyCode.LeftArrow) )
    {
        while (tempPosition == _segments[0].position)
        {
            for (int i = _segments.Count - 1; i > 0; i--)
            {
                _segments[i].position = _segments[i - 1].position;
            }
            this.transform.position = new Vector3(
                Mathf.Round(this.transform.position.x + _direction.x),
                Mathf.Round(this.transform.position.y + _direction.y),
                0.0f
                );
        }
        if (_direction != Vector2.right)
        {
            _direction = Vector2.left;
            tempPosition = _segments[0].position;
        }
    }
    else if (Input.GetKeyDown(KeyCode.RightArrow) )
    {
        while (tempPosition == _segments[0].position)
        {
            for (int i = _segments.Count - 1; i > 0; i--)
            {
                _segments[i].position = _segments[i - 1].position;
            }
            this.transform.position = new Vector3(
                Mathf.Round(this.transform.position.x + _direction.x),
                Mathf.Round(this.transform.position.y + _direction.y),
                0.0f
                );
        }
        if (_direction != Vector2.left)
        {
            _direction = Vector2.right;
            tempPosition = _segments[0].position;
        }
    }
    else if (Input.GetKeyDown(KeyCode.DownArrow) )
    {            
        while (tempPosition == _segments[0].position)
        {
            for(int i = _segments.Count -1; i>0; i--)
            {
                _segments[i].position = _segments[i - 1].position;
            }
            this.transform.position = new Vector3(
                Mathf.Round(this.transform.position.x + _direction.x),
                Mathf.Round(this.transform.position.y + _direction.y),
                0.0f
                );
        }
        if (_direction != Vector2.up)
        {
            _direction = Vector2.down;
            tempPosition = _segments[0].position;
        }
    }

如您所见，按下一个键会立即移动蛇头，从而导致问题。

然而，如果没有像这样编码，快速连续地按2个键会导致蛇与自身碰撞（假设蛇正在向右移动，如果向上和向左快速连续地按压，蛇将开始向左移动，然后才能向上移动，与它的身体碰撞）。

以下是完整代码：

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

public class Snake : MonoBehaviour
{
private Vector2 _direction = Vector2.right;
public List<Transform> _segments = new List<Transform>();
public Transform segmentPrefab;
public Transform tail;
public int initialSize = 4;
public int score = 0;
private Vector3 tempPosition;
public GameObject food;
public Text gameOver;
private void Start()
{
    ResetState();
}
private void Update() //Gets Key Inputs and execute Commands
{   
    if (Input.GetKeyDown(KeyCode.UpArrow) )
    {
        while(tempPosition == _segments[0].position)
        {
            for (int i = _segments.Count - 1; i > 0; i--)
            {
                _segments[i].position = _segments[i - 1].position;
            }
            this.transform.position = new Vector3(
                Mathf.Round(this.transform.position.x + _direction.x),
                Mathf.Round(this.transform.position.y + _direction.y),
                0.0f
                );
        }
        if(_direction != Vector2.down)
        {
            _direction = Vector2.up;
            tempPosition = _segments[0].position;
        }
        
    }
    else if (Input.GetKeyDown(KeyCode.LeftArrow) )
    {
        while (tempPosition == _segments[0].position)
        {
            for (int i = _segments.Count - 1; i > 0; i--)
            {
                _segments[i].position = _segments[i - 1].position;
            }
            this.transform.position = new Vector3(
                Mathf.Round(this.transform.position.x + _direction.x),
                Mathf.Round(this.transform.position.y + _direction.y),
                0.0f
                );
        }
        if (_direction != Vector2.right)
        {
            _direction = Vector2.left;
            tempPosition = _segments[0].position;
        }
    }
    else if (Input.GetKeyDown(KeyCode.RightArrow) )
    {
        while (tempPosition == _segments[0].position)
        {
            for (int i = _segments.Count - 1; i > 0; i--)
            {
                _segments[i].position = _segments[i - 1].position;
            }
            this.transform.position = new Vector3(
                Mathf.Round(this.transform.position.x + _direction.x),
                Mathf.Round(this.transform.position.y + _direction.y),
                0.0f
                );
        }
        if (_direction != Vector2.left)
        {
            _direction = Vector2.right;
            tempPosition = _segments[0].position;
        }
    }
    else if (Input.GetKeyDown(KeyCode.DownArrow) )
    {            
        while (tempPosition == _segments[0].position)
        {
            for(int i = _segments.Count -1; i>0; i--)
            {
                _segments[i].position = _segments[i - 1].position;
            }
            this.transform.position = new Vector3(
                Mathf.Round(this.transform.position.x + _direction.x),
                Mathf.Round(this.transform.position.y + _direction.y),
                0.0f
                );
        }
        if (_direction != Vector2.up)
        {
            _direction = Vector2.down;
            tempPosition = _segments[0].position;
        }
    }
    if(Input.GetKeyDown(KeyCode.R))
    {
        ResetState();
    }
}
private void FixedUpdate() //Handles moviment
{
    if (gameOver.gameObject.activeSelf == false)
    {            
        for (int i = _segments.Count - 1; i > 0; i--)
        {
            _segments[i].position = _segments[i - 1].position;
        }
        this.transform.position = new Vector3(
            Mathf.Round(this.transform.position.x + _direction.x),
            Mathf.Round(this.transform.position.y + _direction.y),
            0.0f
            );
    }
}
/*Instantiates a new segment, sets it's position to tail position,
  destroys tail from list and adds new segment in it's place, adds new tail at end*/
private void Grow() 
{
    Transform segment = Instantiate(this.segmentPrefab);
    segment.position = _segments[_segments.Count - 1].position;
    Destroy(_segments[_segments.Count - 1].gameObject);
    _segments.Remove(_segments[_segments.Count - 1]);
    _segments.Add(segment);
    Transform segmenttail = Instantiate(this.tail);

    segmenttail.position = _segments[_segments.Count - 1].position;

    _segments.Add(segmenttail);
}
private void ResetState()
{
    gameOver.gameObject.SetActive(false);
    tempPosition.x = 1000;
    score = 0;
    for (int i = 1; i < _segments.Count; i++)
    {
        Destroy(_segments[i].gameObject);
    }
    _segments.Clear();
    _segments.Add(this.transform);
    for (int i = 1; i < initialSize; i++)
    {
        _segments.Add(Instantiate(this.segmentPrefab));
    }
    _segments.Add(Instantiate(this.tail));
    this.transform.position = Vector3.zero;
    this.GetComponent<SpriteRenderer>().enabled = (true);
    food.GetComponent<Food>().RandomizePosition();
}
private void OnTriggerEnter2D(Collider2D other)
{
    if (other.tag == "Food")
    {
        Grow();
        score++;
    }
    else if(other.tag == "Obstacle")
    {
        for (int i = 1; i < _segments.Count; i++)
        {
            Destroy(_segments[i].gameObject);
        }
        this.GetComponent<SpriteRenderer>().enabled=(false);
        _segments.Clear();
        food.gameObject.SetActive(false);
        gameOver.gameObject.SetActive(true);
    }

}

}

tl；dr：在一个简单的蛇游戏中，当两个方向快速连续按下时，我如何确保蛇在转向第二个方向之前会朝第一个方向移动，而不会出现虫子。

谢谢！

Answer 1

做一个红色的立方体，控制蛇移动的方向，还有遇到食物和吃食物的功能，在Update（）中，WSAD和方向键控制蛇头的移动方向，而蛇头向上移动时不能向下移动，蛇向左移动时不能向右移动。

         void Update () {
         if (Input.GetKey(KeyCode.W)||Input.GetKey("up")&&direction!= 
Vector2.down)
    {
        direction = Vector2.up;
    }
    if (Input.GetKey(KeyCode.S) || Input.GetKey("down") && direction != Vector2.up)
    {
        direction = Vector2.down;
    }
    if (Input.GetKey(KeyCode.A) || Input.GetKey("left") && direction != Vector2.right)
    {
        direction = Vector2.left;
    }
    if (Input.GetKey(KeyCode.D) || Input.GetKey("right") && direction != Vector2.left)
    {
        direction = Vector2.right;
    }

}

蛇与食物相撞后，身体会长出一段，在遇到食物时，会先破坏食物，然后增加自己身体的长度，此时设定的相撞位旗会变成真，身体长度会增加，但当它撞到自己时，撞到墙上时，它会死亡，此时，它会在开始时被导入场景。

  void OnTriggerEnter(Collider other)
  {
    if (other.gameObject.CompareTag("Food"))
    {
        //Debug.Log("hit it!");
        Destroy(other.gameObject);
        flag = true;

    }
    else
    {
        //SceneManager.LoadScene(0)
        Application.LoadLevel(1);
    }
}

身体每次生长的算法是吃蛇的难度。互联网上的许多算法都是使用链表实现的。链表的节点表明增加或减少snake非常方便。移动时，只需添加头部节点并将其移除。尾部节点就足够了，要吃东西，只需要添加一个头部节点。这个算法绝对是巧妙的，但由于互联网上的蛇太多，下面是另一个通过链表实现的吃蛇算法。蛇头一动不动，身体的最后一部分向前移动，然后慢慢向后移动。下面的蓝色方块（身体部位的设置）一步一步地移动，您可以看到这种效果。蛇身体部位的代码发布在下面。如果食物被吃了，国旗是真的。这是将一个预制的立方体插入蛇的身体，蛇的身体会变长。当没有食物时，它会在此时查看身体的数量。当数字大于0时，最后一个将放在前面，循环将持续到结束。

  void Move()
  {
    Vector3 VPosition = transform.position;
    transform.Translate(direction);
    if (flag)
    {
        GameObject bodyPrefab = (GameObject)Instantiate(gameObjecgtBody, VPosition, Quaternion.identity);
        Body.Insert(0, bodyPrefab.transform);
        flag = false;
    }
    else if (Body.Count > 0)
    {
        Body.Last().position = VPosition;
        Body.Insert(0, Body.Last());
        Body.RemoveAt(Body.Count - 1);
    }
}

食物的出现是一个随机的过程。这时，食物出现在一个随机的位置。InvokeRepeating("ShowFood "，1，4)；意味着四秒后将调用ShowFood()函数，此时它会随机出现在ShowFood中。食物。下面是ShowFood()函数的代码

void ShowFood()
 {
    int x = Random.Range(-30, 30);
    int y = Random.Range(-22, 22);
    Instantiate(SSFood, new Vector2(x,y), Quaternion.identity);
    
  }

特别要注意的是，在制作蛇头和蛇体时，如果将碰撞体的体积设置为1单元，蛇体的侧面也会撞击食物，触发对撞机。所以把对撞机的体积设置为0.8，也略小于1.我也从网上找到了信息，希望能帮到你，这个链接就是源代码 https://github.com/xiaogeformax/Snake/tree/master/Snake5.2