标签 Game 下的文章

使用C++ SDL2编写一个snake贪吃蛇游戏

作者: 麦克不能飞
时间: 2023-09-21
分类: C++

OIG.puUcNNdAsG.jpeg

之前使用python里面的pygame可以很容易构建snake游戏，其实pygame后端也是封装了sdl库，所以pygame编写的snake，使用C++
SDL2编写应该很容易移植过来

不过我不想自己亲自编写，我想偷懒让人工智能帮我完成看看，结果表明要一次达成目标似乎也不是那么顺利
经过几次对话，好歹勉强实现了贪吃蛇的基础功能

第一次尝试
第一次对话
代码

#include <SDL.h>
#include <iostream>
#include <vector>
#include <cstdlib>
#include <ctime>

using namespace std;

// 定义游戏窗口的宽度和高度
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;

// 定义Snake的单元格大小
const int CELL_SIZE = 20;

// 定义Snake的初始长度
const int INITIAL_LENGTH = 5;

// 定义Snake的方向
enum class Direction { UP, DOWN, LEFT, RIGHT };

// 定义Snake的单元格结构体
struct Cell {
    int x, y;
};

// Snake类
class Snake {
public:
    Snake();
    void HandleInput(SDL_Event &e);
    void Move();
    bool CheckCollision();
    void Grow();
    void Render(SDL_Renderer* renderer);
private:
    vector<Cell> body;
    Direction direction;
};

Snake::Snake() {
    // 初始化Snake的位置和方向
    for (int i = 0; i < INITIAL_LENGTH; ++i) {
        body.push_back({SCREEN_WIDTH / 2 - i * CELL_SIZE, SCREEN_HEIGHT / 2});
    }
    direction = Direction::RIGHT;
}

void Snake::HandleInput(SDL_Event &e) {
    // 处理用户输入，改变Snake的方向
    if (e.type == SDL_KEYDOWN) {
        switch (e.key.keysym.sym) {
            case SDLK_UP:
                if (direction != Direction::DOWN)
                    direction = Direction::UP;
                break;
            case SDLK_DOWN:
                if (direction != Direction::UP)
                    direction = Direction::DOWN;
                break;
            case SDLK_LEFT:
                if (direction != Direction::RIGHT)
                    direction = Direction::LEFT;
                break;
            case SDLK_RIGHT:
                if (direction != Direction::LEFT)
                    direction = Direction::RIGHT;
                break;
        }
    }
}

void Snake::Move() {
    // 移动Snake的头部
    int newHeadX = body.front().x;
    int newHeadY = body.front().y;

    switch (direction) {
        case Direction::UP:
            newHeadY -= CELL_SIZE;
            break;
        case Direction::DOWN:
            newHeadY += CELL_SIZE;
            break;
        case Direction::LEFT:
            newHeadX -= CELL_SIZE;
            break;
        case Direction::RIGHT:
            newHeadX += CELL_SIZE;
            break;
    }

    // 添加新的头部
    body.insert(body.begin(), {newHeadX, newHeadY});
}

bool Snake::CheckCollision() {
    // 检查是否与自身相撞
    for (size_t i = 1; i < body.size(); ++i) {
        if (body[i].x == body.front().x && body[i].y == body.front().y) {
            return true;
        }
    }

    // 检查是否超出屏幕边界
    if (body.front().x < 0 || body.front().x >= SCREEN_WIDTH || body.front().y < 0 || body.front().y >= SCREEN_HEIGHT) {
        return true;
    }

    return false;
}

void Snake::Grow() {
    // Snake吃到食物时增加长度
    int tailX = body.back().x;
    int tailY = body.back().y;

    switch (direction) {
        case Direction::UP:
            tailY += CELL_SIZE;
            break;
        case Direction::DOWN:
            tailY -= CELL_SIZE;
            break;
        case Direction::LEFT:
            tailX += CELL_SIZE;
            break;
        case Direction::RIGHT:
            tailX -= CELL_SIZE;
            break;
    }

    body.push_back({tailX, tailY});
}

void Snake::Render(SDL_Renderer* renderer) {
    // 渲染Snake
    for (const Cell& cell : body) {
        SDL_Rect rect = {cell.x, cell.y, CELL_SIZE, CELL_SIZE};
        SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255); // Snake颜色
        SDL_RenderFillRect(renderer, &rect);
    }
}

// 主程序
int main(int argc, char* args[]) {
    SDL_Init(SDL_INIT_VIDEO);
    SDL_Window* window = SDL_CreateWindow("Snake Game", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    srand(time(nullptr));

    Snake snake;

    // 游戏主循环
    bool quit = false;
    SDL_Event e;
    while (!quit) {
        while (SDL_PollEvent(&e) != 0) {
            if (e.type == SDL_QUIT) {
                quit = true;
            }
            snake.HandleInput(e);
        }

        // 移动Snake
        snake.Move();

        // 检查碰撞
        if (snake.CheckCollision()) {
            quit = true;
        }

        // 渲染
        SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); // 清空屏幕
        SDL_RenderClear(renderer);
        snake.Render(renderer);
        SDL_RenderPresent(renderer);

        // 控制游戏速度
        SDL_Delay(100);
    }

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

运行结果，看起来不符合预期
第一次运行结果

第二次尝试

代码

#include <SDL.h>
#include <iostream>
#include <vector>
#include <cstdlib>
#include <ctime>

using namespace std;

const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int CELL_SIZE = 20;

enum class Direction { UP, DOWN, LEFT, RIGHT };

struct Cell {
    int x, y;
};

class Snake {
public:
    Snake();
    void HandleInput(SDL_Event &e);
    void Move();
    bool CheckCollision();
    void Grow();
    void Render(SDL_Renderer* renderer);
private:
    vector<Cell> body;
    Direction direction;
};

Snake::Snake() {
    body.push_back({SCREEN_WIDTH / 2, SCREEN_HEIGHT / 2});
    direction = Direction::RIGHT;
}

void Snake::HandleInput(SDL_Event &e) {
    if (e.type == SDL_KEYDOWN) {
        switch (e.key.keysym.sym) {
            case SDLK_UP:
                if (direction != Direction::DOWN)
                    direction = Direction::UP;
                break;
            case SDLK_DOWN:
                if (direction != Direction::UP)
                    direction = Direction::DOWN;
                break;
            case SDLK_LEFT:
                if (direction != Direction::RIGHT)
                    direction = Direction::LEFT;
                break;
            case SDLK_RIGHT:
                if (direction != Direction::LEFT)
                    direction = Direction::RIGHT;
                break;
        }
    }
}

void Snake::Move() {
    int newHeadX = body.front().x;
    int newHeadY = body.front().y;

    switch (direction) {
        case Direction::UP:
            newHeadY -= CELL_SIZE;
            break;
        case Direction::DOWN:
            newHeadY += CELL_SIZE;
            break;
        case Direction::LEFT:
            newHeadX -= CELL_SIZE;
            break;
        case Direction::RIGHT:
            newHeadX += CELL_SIZE;
            break;
    }

    body.insert(body.begin(), {newHeadX, newHeadY});
}

bool Snake::CheckCollision() {
    for (size_t i = 1; i < body.size(); ++i) {
        if (body[i].x == body.front().x && body[i].y == body.front().y) {
            return true;
        }
    }

    if (body.front().x < 0 || body.front().x >= SCREEN_WIDTH || body.front().y < 0 || body.front().y >= SCREEN_HEIGHT) {
        return true;
    }

    return false;
}

void Snake::Grow() {
    int tailX = body.back().x;
    int tailY = body.back().y;

    switch (direction) {
        case Direction::UP:
            tailY += CELL_SIZE;
            break;
        case Direction::DOWN:
            tailY -= CELL_SIZE;
            break;
        case Direction::LEFT:
            tailX += CELL_SIZE;
            break;
        case Direction::RIGHT:
            tailX -= CELL_SIZE;
            break;
    }

    body.push_back({tailX, tailY});
}

void Snake::Render(SDL_Renderer* renderer) {
    for (size_t i = 0; i < body.size(); ++i) {
        SDL_Rect rect = {body[i].x, body[i].y, CELL_SIZE, CELL_SIZE};
        if (i == 0) {
            SDL_SetRenderDrawColor(renderer, 255, 255, 0, 255); // Snake头部为黄色
        } else {
            SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255); // Snake身体为绿色
        }
        SDL_RenderFillRect(renderer, &rect);
    }
}

int main(int argc, char* args[]) {
    SDL_Init(SDL_INIT_VIDEO);
    SDL_Window* window = SDL_CreateWindow("Snake Game", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    srand(time(nullptr));

    Snake snake;

    bool quit = false;
    SDL_Event e;
    while (!quit) {
        while (SDL_PollEvent(&e) != 0) {
            if (e.type == SDL_QUIT) {
                quit = true;
            }
            snake.HandleInput(e);
        }

        snake.Move();

        if (snake.CheckCollision()) {
            quit = true;
        }

        SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
        SDL_RenderClear(renderer);
        snake.Render(renderer);
        SDL_RenderPresent(renderer);

        SDL_Delay(100);
    }

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

结果貌似还是不符合预期
截图 2023-09-23 12-38-08.png

第三次尝试
截图 2023-09-23 12-40-39.png

代码

#include <SDL.h>
#include <iostream>
#include <vector>
#include <cstdlib>
#include <ctime>

using namespace std;

const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int CELL_SIZE = 20;

enum class Direction { UP, DOWN, LEFT, RIGHT };

struct Cell {
    int x, y;
};

class Snake {
public:
    Snake();
    void HandleInput(SDL_Event &e);
    void Move();
    bool CheckCollision();
    void Grow();
    void Render(SDL_Renderer* renderer);
    Cell GetHeadPosition();
private:
    vector<Cell> body;
    Direction direction;
};

Snake::Snake() {
    body.push_back({SCREEN_WIDTH / 2, SCREEN_HEIGHT / 2});
    direction = Direction::RIGHT;
}

void Snake::HandleInput(SDL_Event &e) {
    if (e.type == SDL_KEYDOWN) {
        switch (e.key.keysym.sym) {
            case SDLK_UP:
                if (direction != Direction::DOWN)
                    direction = Direction::UP;
                break;
            case SDLK_DOWN:
                if (direction != Direction::UP)
                    direction = Direction::DOWN;
                break;
            case SDLK_LEFT:
                if (direction != Direction::RIGHT)
                    direction = Direction::LEFT;
                break;
            case SDLK_RIGHT:
                if (direction != Direction::LEFT)
                    direction = Direction::RIGHT;
                break;
        }
    }
}

void Snake::Move() {
    int newHeadX = body.front().x;
    int newHeadY = body.front().y;

    switch (direction) {
        case Direction::UP:
            newHeadY -= CELL_SIZE;
            break;
        case Direction::DOWN:
            newHeadY += CELL_SIZE;
            break;
        case Direction::LEFT:
            newHeadX -= CELL_SIZE;
            break;
        case Direction::RIGHT:
            newHeadX += CELL_SIZE;
            break;
    }

    body.insert(body.begin(), {newHeadX, newHeadY});
}

bool Snake::CheckCollision() {
    for (size_t i = 1; i < body.size(); ++i) {
        if (body[i].x == body.front().x && body[i].y == body.front().y) {
            return true;
        }
    }

    if (body.front().x < 0 || body.front().x >= SCREEN_WIDTH || body.front().y < 0 || body.front().y >= SCREEN_HEIGHT) {
        return true;
    }

    return false;
}

void Snake::Grow() {
    // 在Snake的尾部增加一个单元格
    int tailX = body.back().x;
    int tailY = body.back().y;

    switch (direction) {
        case Direction::UP:
            tailY += CELL_SIZE;
            break;
        case Direction::DOWN:
            tailY -= CELL_SIZE;
            break;
        case Direction::LEFT:
            tailX += CELL_SIZE;
            break;
        case Direction::RIGHT:
            tailX -= CELL_SIZE;
            break;
    }

    body.push_back({tailX, tailY});
}

void Snake::Render(SDL_Renderer* renderer) {
    for (size_t i = 0; i < body.size(); ++i) {
        SDL_Rect rect = {body[i].x, body[i].y, CELL_SIZE, CELL_SIZE};
        if (i == 0) {
            SDL_SetRenderDrawColor(renderer, 255, 255, 0, 255); // Snake头部为黄色
        } else {
            SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255); // Snake身体为绿色
        }
        SDL_RenderFillRect(renderer, &rect);
    }
}

Cell Snake::GetHeadPosition() {
    return body.front();
}

int main(int argc, char* args[]) {
    SDL_Init(SDL_INIT_VIDEO);
    SDL_Window* window = SDL_CreateWindow("Snake Game", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    srand(time(nullptr));

    Snake snake;

    // 初始化食物位置
    Cell food = {rand() % (SCREEN_WIDTH / CELL_SIZE) * CELL_SIZE, rand() % (SCREEN_HEIGHT / CELL_SIZE) * CELL_SIZE};

    bool quit = false;
    SDL_Event e;
    while (!quit) {
        while (SDL_PollEvent(&e) != 0) {
            if (e.type == SDL_QUIT) {
                quit = true;
            }
            snake.HandleInput(e);
        }

        snake.Move();

        if (snake.GetHeadPosition().x == food.x && snake.GetHeadPosition().y == food.y) {
            // Snake吃到食物时，增加长度并生成新的食物位置
            snake.Grow();
            food = {rand() % (SCREEN_WIDTH / CELL_SIZE) * CELL_SIZE, rand() % (SCREEN_HEIGHT / CELL_SIZE) * CELL_SIZE};
        }

        if (snake.CheckCollision()) {
            quit = true;
        }

        SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
        SDL_RenderClear(renderer);
        snake.Render(renderer);

        // 渲染食物
        SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255); // 食物为绿色
        SDL_Rect foodRect = {food.x, food.y, CELL_SIZE, CELL_SIZE};
        SDL_RenderFillRect(renderer, &foodRect);

        SDL_RenderPresent(renderer);

        SDL_Delay(100);
    }

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

运行结果，依然不符合预期，真是糟糕
截图 2023-09-23 12-42-20.png

第四次尝试，看看
截图 2023-09-23 12-42-55.png

代码

#include <SDL.h>
#include <iostream>
#include <vector>
#include <cstdlib>
#include <ctime>

using namespace std;

const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int CELL_SIZE = 20;

enum class Direction { UP, DOWN, LEFT, RIGHT };

struct Cell {
    int x, y;
};

class Snake {
public:
    Snake();
    void HandleInput(SDL_Event &e);
    void Move();
    bool CheckCollision();
    void Grow();
    void Render(SDL_Renderer* renderer);
    Cell GetHeadPosition();
private:
    vector<Cell> body;
    Direction direction;
    bool growing;  // 用于标记是否吃到食物后需要增长
};

Snake::Snake() {
    body.push_back({SCREEN_WIDTH / 2, SCREEN_HEIGHT / 2});
    direction = Direction::RIGHT;
    growing = false;  // 初始化时不需要增长
}

void Snake::HandleInput(SDL_Event &e) {
    if (e.type == SDL_KEYDOWN) {
        switch (e.key.keysym.sym) {
            case SDLK_UP:
                if (direction != Direction::DOWN)
                    direction = Direction::UP;
                break;
            case SDLK_DOWN:
                if (direction != Direction::UP)
                    direction = Direction::DOWN;
                break;
            case SDLK_LEFT:
                if (direction != Direction::RIGHT)
                    direction = Direction::LEFT;
                break;
            case SDLK_RIGHT:
                if (direction != Direction::LEFT)
                    direction = Direction::RIGHT;
                break;
        }
    }
}

void Snake::Move() {
    int newHeadX = body.front().x;
    int newHeadY = body.front().y;

    switch (direction) {
        case Direction::UP:
            newHeadY -= CELL_SIZE;
            break;
        case Direction::DOWN:
            newHeadY += CELL_SIZE;
            break;
        case Direction::LEFT:
            newHeadX -= CELL_SIZE;
            break;
        case Direction::RIGHT:
            newHeadX += CELL_SIZE;
            break;
    }

    body.insert(body.begin(), {newHeadX, newHeadY});

    // 如果吃到食物，则不删除尾部，实现增长
    if (!growing) {
        body.pop_back();
    } else {
        growing = false;
    }
}

bool Snake::CheckCollision() {
    for (size_t i = 1; i < body.size(); ++i) {
        if (body[i].x == body.front().x && body[i].y == body.front().y) {
            return true;
        }
    }

    if (body.front().x < 0 || body.front().x >= SCREEN_WIDTH || body.front().y < 0 || body.front().y >= SCREEN_HEIGHT) {
        return true;
    }

    return false;
}

void Snake::Grow() {
    // 在Snake的尾部增加一个单元格
    int tailX = body.back().x;
    int tailY = body.back().y;

    switch (direction) {
        case Direction::UP:
            tailY += CELL_SIZE;
            break;
        case Direction::DOWN:
            tailY -= CELL_SIZE;
            break;
        case Direction::LEFT:
            tailX += CELL_SIZE;
            break;
        case Direction::RIGHT:
            tailX -= CELL_SIZE;
            break;
    }

    body.push_back({tailX, tailY});
    growing = true;  // 标记为需要增长
}

void Snake::Render(SDL_Renderer* renderer) {
    for (size_t i = 0; i < body.size(); ++i) {
        SDL_Rect rect = {body[i].x, body[i].y, CELL_SIZE, CELL_SIZE};
        if (i == 0) {
            SDL_SetRenderDrawColor(renderer, 255, 255, 0, 255); // Snake头部为黄色
        } else {
            SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255); // Snake身体为绿色
        }
        SDL_RenderFillRect(renderer, &rect);
    }
}

Cell Snake::GetHeadPosition() {
    return body.front();
}

int main(int argc, char* args[]) {
    SDL_Init(SDL_INIT_VIDEO);
    SDL_Window* window = SDL_CreateWindow("Snake Game", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    srand(time(nullptr));

    Snake snake;

    // 初始化食物位置
    Cell food = {rand() % (SCREEN_WIDTH / CELL_SIZE) * CELL_SIZE, rand() % (SCREEN_HEIGHT / CELL_SIZE) * CELL_SIZE};

    bool quit = false;
    SDL_Event e;
    while (!quit) {
        while (SDL_PollEvent(&e) != 0) {
            if (e.type == SDL_QUIT) {
                quit = true;
            }
            snake.HandleInput(e);
        }

        snake.Move();

        if (snake.GetHeadPosition().x == food.x && snake.GetHeadPosition().y == food.y) {
            // Snake吃到食物时，增加长度并生成新的食物位置
            snake.Grow();
            food = {rand() % (SCREEN_WIDTH / CELL_SIZE) * CELL_SIZE, rand() % (SCREEN_HEIGHT / CELL_SIZE) * CELL_SIZE};
        }

        if (snake.CheckCollision()) {
            quit = true;
        }

        SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
        SDL_RenderClear(renderer);
        snake.Render(renderer);

        // 渲染食物
        SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255); // 食物为绿色
        SDL_Rect foodRect = {food.x, food.y, CELL_SIZE, CELL_SIZE};
        SDL_RenderFillRect(renderer, &foodRect);

        SDL_RenderPresent(renderer);

        SDL_Delay(100);
    }

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

运行结果，看起来达到预期
截图 2023-09-23 12-44-48.png

透过这几次对话，我们可以看到要想快速达到预期的结果，提问非常关键，如果一开始就给出比较细致的说明，应该能够一次成功，需要试试！

透过比较几次代码的差异，也可以从中学习到程序bug产生的原因

C++ SDL2 入门

作者: 麦克不能飞
时间: 2023-09-20
分类: C++

新的编程工具使用，总是需要环境搭建

IDE + 库

SDL2_mixer-devel-2.6.3-mingw.zip

SDL2 Hello World版本

#include <SDL.h>
#include <iostream>
#include <SDL_ttf.h>

int main(int argc, char* argv[])
{
    // 初始化SDL
    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
        std::cerr << "无法初始化SDL: " << SDL_GetError() << std::endl;
        return 1;
    }

    // 创建窗口
    SDL_Window* window = SDL_CreateWindow("Hello SDL", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 800, 600, SDL_WINDOW_SHOWN);
    if (!window) {
        std::cerr << "无法创建窗口: " << SDL_GetError() << std::endl;
        SDL_Quit();
        return 1;
    }

    // 创建渲染器
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    if (!renderer) {
        std::cerr << "无法创建渲染器: " << SDL_GetError() << std::endl;
        SDL_DestroyWindow(window);
        SDL_Quit();
        return 1;
    }

    if (TTF_Init() == -1) {
        std::cerr << "无法初始化TTF库: " << TTF_GetError() << std::endl;
        SDL_Quit();
        return 1;
    }

    TTF_Font* font = TTF_OpenFont("Pacifico.ttf", 36);
    if (!font) {
        std::cerr << "无法加载字体: " << TTF_GetError() << std::endl;
        TTF_Quit();
        SDL_Quit();
        return 1;
    }




    // 渲染一些文本
    SDL_Surface* surface = SDL_GetWindowSurface(window);
    SDL_FillRect(surface, NULL, SDL_MapRGB(surface->format, 255, 255, 255));
    SDL_Color textColor = {255, 255, 255};
    SDL_Surface* textSurface = TTF_RenderText_Solid(font, "Hello, SDL!", textColor);
    SDL_Rect textRect = {200, 200, textSurface->w, textSurface->h};

    SDL_Texture* textTexture = SDL_CreateTextureFromSurface(renderer, textSurface);
    SDL_RenderCopy(renderer, textTexture, NULL, &textRect);

    SDL_RenderPresent(renderer);

    // 处理事件循环
    bool quit = false;
    SDL_Event event;
    while (!quit) {
        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_QUIT) {
                quit = true;
            }
        }
    }

    // 清理资源
    TTF_CloseFont(font);
    TTF_Quit();

    SDL_DestroyTexture(textTexture);
    SDL_FreeSurface(textSurface);
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

hello world详细解释

#include <SDL.h>
#include <iostream>

这两行是包含头文件的指令。第一行包含了SDL2的头文件，它是用于与SDL2库交互的必要头文件。第二行包含了C++标准库的头文件iostream，它用于在控制台输出错误信息。

int main(int argc, char* argv[]) {

这是C++程序的入口点。main 函数是程序运行的起始点。int argc 和 char* argv[] 用于传递命令行参数。

    // 初始化SDL
    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
        std::cerr << "无法初始化SDL: " << SDL_GetError() << std::endl;
        return 1;
    }

这一部分初始化了SDL2库。SDL_Init(SDL_INIT_VIDEO) 函数初始化SDL2的视频子系统。如果初始化失败，会输出错误信息并返回1表示程序出错。

    // 创建窗口
    SDL_Window* window = SDL_CreateWindow("Hello SDL", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 800, 600, SDL_WINDOW_SHOWN);
    if (!window) {
        std::cerr << "无法创建窗口: " << SDL_GetError() << std::endl;
        SDL_Quit();
        return 1;
    }

这一部分创建了一个窗口。SDL_CreateWindow 函数用于创建一个窗口，并指定窗口的标题、位置和大小。如果创建失败，会输出错误信息，然后清理SDL2并返回1。

    // 创建渲染器
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    if (!renderer) {
        std::cerr << "无法创建渲染器: " << SDL_GetError() << std::endl;
        SDL_DestroyWindow(window);
        SDL_Quit();
        return 1;
    }

这一部分创建了一个渲染器，用于在窗口上绘制图形。SDL_CreateRenderer 函数将渲染器与窗口关联起来。如果创建失败，会输出错误信息，然后清理窗口和SDL2，并返回1。

    // 渲染一些文本
    SDL_Surface* surface = SDL_GetWindowSurface(window);
    SDL_FillRect(surface, NULL, SDL_MapRGB(surface->format, 255, 255, 255));

这部分代码获取窗口表面并用白色填充整个窗口，以准备绘制文本。

    SDL_Color textColor = {0, 0, 0};
    SDL_Surface* textSurface = TTF_RenderText_Solid(font, "Hello, SDL!", textColor);
    SDL_Rect textRect = {200, 200, textSurface->w, textSurface->h};

这一部分定义了文本的颜色，并创建了一个包含文本的表面（textSurface）。你需要先定义一个字体（font），这里并没有包含在示例中。

    SDL_Texture* textTexture = SDL_CreateTextureFromSurface(renderer, textSurface);
    SDL_RenderCopy(renderer, textTexture, NULL, &textRect);
    SDL_RenderPresent(renderer);

这一部分将文本表面转换为纹理，并使用渲染器将文本绘制到窗口上，最后调用SDL_RenderPresent函数来更新窗口显示。

    // 处理事件循环
    bool quit = false;
    SDL_Event event;
    while (!quit) {
        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_QUIT) {
                quit = true;
            }
        }
    }

这一部分处理SDL2的事件循环。它会一直运行，直到收到退出事件（如关闭窗口按钮）。

    // 清理资源
    SDL_DestroyTexture(textTexture);
    SDL_FreeSurface(textSurface);
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

最后，这部分清理了所有分配的资源，包括纹理、表面、渲染器、窗口，并调用SDL_Quit来关闭SDL2库。最后，返回0表示程序成功结束。

上面的代码bug

仔细看我们并没有定义font？

解决方法：

首先，你需要在代码中包含SDL2_ttf头文件：
```
#include <SDL_ttf.h>
```

然后，在主函数的开头，初始化TTF库：

if (TTF_Init() == -1) {
  std::cerr << "无法初始化TTF库: " << TTF_GetError() << std::endl;
  SDL_Quit();
  return 1;
}

接下来，你需要加载一个TrueType字体文件，例如：

TTF_Font* font = TTF_OpenFont("path/to/your/font.ttf", 36);
if (!font) {
  std::cerr << "无法加载字体: " << TTF_GetError() << std::endl;
  TTF_Quit();
  SDL_Quit();
  return 1;
}

请确保将 "path/to/your/font.ttf" 替换为你自己字体文件的路径。

最后，在绘制文本部分，使用这个字体来渲染文本：

SDL_Surface* textSurface = TTF_RenderText_Solid(font, "Hello, SDL!", textColor);

这样，你就可以使用指定的字体来渲染文本了。请不要忘记在程序结束时清理字体资源：

TTF_CloseFont(font);
TTF_Quit();

例子工程代码：

hello world SDL2-helloworld.zip
加在图片 SDL2_imageSDL2-pictures.zip
播放mp3 SDL2_mixer SDL2-mixer.zip
snake game