我最近才开始学习 C++。我决定编写一个在控制台中运行的小贪吃蛇游戏。它相对简单，看起来并不令人惊奇，但它确实做到了它应该做的事情。
我遇到的唯一问题是我的 Snake 不会连续转两次。换句话说，你不能用它做急转弯。但是，按下按钮后它会立即转动。 (除非你刚转过)。
我的代码有 120 行，所以这里是:

首先是我的包含和命名空间:

#include <iostream>
#include <vector>
#include <conio.h>
#include <windows.h>
#include <random>

using namespace std;

此函数在控制台中绘制整个字段:

void drawGrid(vector<vector<char>> &g, int height, int width, int score, int time)
{
    SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), { 0,0 });
    for (int r = 0; r < height; r++)
    {
        for (int c = 0; c < width; c++) std::cout << g[c][r] << " ";
        std::cout << '|' << endl;
    }
    std::cout << "Current score: " << score << "     ";
    std::cout << "\nCurrent speed: " << time << "      ";
}

这个函数检查食物是否在蛇下面:

bool foodSnake(vector<int> &f, vector<vector<int>> &t, int l)
{
    for (int i = 0; i < l; i++) 
        if (f[0] == t[i][0] && f[1] == t[i][1]) return true;
    return false;
}

这是大布袋鼠:

int main(void)
{
    int sleeptime = 1000;    // how long the break is between each frame
    bool foodExists = 0;
    int width = 20;    //width and height of the field
    int height = 15;
    mt19937_64 engine;    //random distributions for food generation
    uniform_int_distribution<int> heightDist(0, height - 1);
    uniform_int_distribution<int> widthDist(0, width - 1);
    int tailLengthstart = 4;
    int tailLength = tailLengthstart;
    char movementDirection = 'u';    //starts moving upwards
    char input;
    bool alive = 1;   //keeps the program running on death = 0
    vector<int> pos = { (width - 1) / 2,(height - 1) / 2 };    //starts in the middle of field
    vector<int> foodPos = pos;  // so that the food generates at the beginning
    vector<vector<int>> tail(tailLength, pos);
    vector<vector<char>> emptyGrid(width, vector<char>(height, ' '));
    vector<vector<char>> grid = emptyGrid;
    while (alive)  //runs main program until alive == 0
    {
        grid = emptyGrid; // clear grid
        grid[pos[0]][pos[1]] = 'Q';  //place head in grid
        if (!foodExists) //generates food if it was eaten
        {
            while (foodSnake(foodPos, tail, tailLength) || foodPos == pos)
            { // keeps regenerating until it isn't under the snake
                foodPos[0] = widthDist(engine);
                foodPos[1] = heightDist(engine);
            }
            foodExists = 1;
        }
        grid[foodPos[0]][foodPos[1]] = 'X'; //place food in grid
        for (int i = 0; i < tailLength; i++) grid[tail[i][0]][tail[i][1]] = 'O'; // place tail in grid
        drawGrid(grid, height, width, tailLength - tailLengthstart, sleeptime); //call above function to draw the grid
        input = '_';
        Sleep(sleeptime);
        if (_kbhit()) { //this was the best way I found to wait for input
            input = _getch();
            switch (input)
            { //disallows moving in opposite direction otherwise changes direction
                case 'w':
                    if (movementDirection == 'd') break;
                    movementDirection = 'u';
                    break;
                case 'a':
                    if (movementDirection == 'r') break;
                    movementDirection = 'l';
                    break;
                case 's':
                    if (movementDirection == 'u') break;
                    movementDirection = 'd';
                    break;
                case 'd':
                    if (movementDirection == 'l') break;
                    movementDirection = 'r';
                    break;
                case '_':
                    break;
            }
        }
        for (int i = tailLength - 1; i > 0; i--)
            tail[i] = tail[i - 1]; 
        tail[0] = pos; //move the tail along
        if (movementDirection == 'u') pos[1]--;
        if (movementDirection == 'l') pos[0]--;
        if (movementDirection == 'r') pos[0]++;
        if (movementDirection == 'd') pos[1]++; // move the head
        if (pos[0] < 0 || pos[0] > width - 1 || pos[1] < 0 || pos[1] > height - 1) 
            alive = 0; // if head is out of bounds -> dead
        for (int i = 0; i < tailLength; i++) 
            if (pos == tail[i]) 
                alive = 0; // if head is on tail -> dead
        if (foodPos == pos)
        { // if head is on food -> eat
            foodExists = 0; // food needs to be generated
            tail.push_back(tail[tailLength - 1]); //tail adds a link
            tailLength++; // tail is now longer
            if (tailLength % 5 == 0) sleeptime *= 0.75; // at certain lengths game speeds up
        }
    }

下一部分发生在你是死是活 == 0

    std::system("cls");
    std::cout << endl << endl << endl << endl << "\tYou have died" << endl << endl << endl << endl;

    std::cout << endl;
    std::system("pause");
    return 0;
}

因此，如果有人知道为什么转得不快，请提供帮助。或者任何其他改进想法也欢迎。

最佳答案

运动问题是由于您向前推进尾部而改变方向导致头部立即前进。这意味着在蛇真正转向之前总有一步。

我看到的状态集:

1. 设置场景。
2. 检查 key 。
3. 如果按下键并且与当前方向不相反，则改变移动方向。
4. 制作旧头部尾部并从旧头部沿设定方向添加头部元素。
5. 检查是否死亡
6. 检查食物。
7. 如果找到食物，通过改变 TailLength 来长出尾部。
8. 如果蛇的长度大于 TailLength，则移除尾部元素直到它们相等。
9. 渲染场景
10. sleep 去2。

最好用列表而不是 vector 来表示蛇。它不会在大小更改时重新分配内存，或者如果您要删除第一个元素。

如果您的平台是 Windows(显然，您使用的是 Sleep() 函数而不是 usleep)，则此问题的答案为按键检测提供了更好的解决方案。 Get key press in windows console

POSIX 平台存在类似的解决方案。

关于c++ - C++ 中的蛇不会连续转两次，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/52946565/