window 启动时调用 sfml event::close

Question

当由于某种原因创建 sfml window 时，调用 sf::Event::Closed 然后关闭 window 是否有办法解决这个问题？

另请注意，有时在第一次更改 sfml 函数并重新编译和运行ning 时，此问题不会仅在第二次运行之后出现，依此类推

注意我还在学习sfml和c++

这里是 snakepart header

struct  snakepart{

    int x, y;
    snakepart(int col, int row);
    snakepart();
};

这里是主要功能

#include "Snake.cpp"

int main() {
        SnakeClass s;
        s.start();
        return 0;
    }

这是包含大多数文件声明的主要 header 文件

#include "SnakePart.hpp"
#include <vector>
enum class Keys {
    key_up,
    key_down,
    key_left,
    key_right,
    quit,
    nothing,
    };
class IsdlClass {

public:
    virtual bool    OnInit() = 0;
    virtual Keys    OnEvent() = 0;
    virtual void    OnCleanup() = 0;
    virtual bool    pollEvent() = 0;
};

#endif

这是 SFML 函数的 header 文件

#include "../libsfmld/include/SFML/Window.hpp"
#include "../libsfmld/include/SFML/Graphics.hpp"
#include "../../includes/IFunctions.hpp"

class SFML :public IsdlClass {

public:
    SFML();
    virtual ~SFML();
    virtual bool    OnInit();
    virtual Keys    OnEvent();
    virtual void    OnCleanup();
    virtual bool    pollEvent();
    sf::RenderWindow window;

private: 

    sf::ContextSettings settings;
    sf::Event event;

};

extern "C"   {
    SFML    *start(void);
    void        deletesdl(SFML *sfml);
}

#endif

这里是蛇函数header

#include <iostream>
#include <vector>
#include <unistd.h>

#include "IFunctions.hpp"

class SnakeClass{

public:
    SnakeClass();
    ~SnakeClass();
    int    start();
    int     points, delay, maxW, maxH;
    char    direction, body, border, foodItem;
    bool    get;
    snakepart food;
    std::vector<snakepart> snake;
    void    dlerror_wrapper();

private:
    void    putfood();
    bool    collision();
    void    movesnake(Keys key);
    IsdlClass   *SFML;
    void    *dl_handle;
    bool    Running;
};

#endif

下面是用于调用 SFML 函数的代码。

  snakepart::snakepart(int col, int row) {

        x = col;
        y = row;
    }

    snakepart::snakepart() {

        x = 0;
        y = 0;
    }  


bool    SnakeClass::collision() {

        if (snake[0].x == 0 || snake[0].x == maxW / 10 - 1 || snake[0].y == 0 || snake[0].y == maxH / 10 - 3)
            return true;
        for (size_t i = 2; i < snake.size(); i++)
            if (snake[0].x == snake[i].x && snake[i].y == snake[0].y)
                return true;
        if (snake[0].x == food.x && snake[0].y == food.y) {

            get = true;
            // points += 10;
            // char c[5];
            // sprintf(c, "%d", points);
            if ((points%50) == 0 && delay > 0)
                delay -= 10;
        }else 
            get = false;
        return false;
    }

    void    SnakeClass::movesnake(Keys key) {

            while(this->SFML->pollEvent()) {
                std::cout << "after poll event\n";
                    switch(key)
                    {
                        case Keys::key_left:
                                if(direction!='r')
                                        direction='l';
                                break;
                        case Keys::key_up:
                                if(direction !='d')
                                        direction='u';
                                break;
                        case Keys::key_down:
                                if(direction!='u')
                                        direction='d';
                                break;
                        case Keys::key_right:
                                if(direction!='l')
                                        direction='r';
                                break;
                        case Keys::quit: //this is called when window is opened
                                direction = 'q';
                                break;
                        default:
                               break;
                    }
                if (key == Keys::nothing)
                    continue;
            }
        }

        void    SnakeClass::dlerror_wrapper(void) {
            std::cerr << "Error: " << dlerror() << std::endl;
            exit(EXIT_FAILURE);
        }

        int    SnakeClass::start() {
            dl_handle = dlopen("sfml/libsfml.dylib", RTLD_LAZY);
            IsdlClass * (*func)(void);
            func = (IsdlClass * (*)(void)) dlsym(dl_handle, "start");
            if (!func)
                dlerror_wrapper();
            this->SFML = NULL;
            this->SFML = func();
            if (this->SFML == NULL)
                std::cout << "error\n";
            maxH = 480;
            maxW = 640;
            if (this->SFML->OnInit() == false)
               Running = false;
            for (int i = 0; i < 5; i++)
                snake.push_back(snakepart(40 + i, 10));
            points = 0;
            delay = 110;
            get = false;
            direction = 'l'; //snake moves to the left
            srand(time(NULL));
                while(Running)
                {

                    if(collision())
                    {
                        std::cout << "game over" << std::endl;
                        break;
                    }
                    // while(this->SFML->pollEvent()) {
                        // std::cout << " events\n";
                        movesnake(this->SFML->OnEvent());
                    // }
                    // 
                    if(direction=='q')
                            break;
                }
            void    (*del)(IsdlClass *);
            del = (void (*)(IsdlClass *)) dlsym(dl_handle, "deletesdl");
            dlclose(dl_handle);
           return (0);
        }

下面是SFML图形函数 *注意我正在返回上述函数的枚举

    bool    SFML::pollEvent() {
        return (window.pollEvent(event));
}

bool    SFML::OnInit() {
    settings.antialiasingLevel = 8;
    window.create(sf::VideoMode(640, 480), "My window", sf::Style::Default, settings);
    window.setVerticalSyncEnabled(true);
    return true;
}

Keys    SFML::OnEvent() {

    window.setKeyRepeatEnabled(false);
    switch(event.type) {
            case sf::Event::Closed:
            std::cout << "Event close\n"; //this is called and returns the enum quit
                return (Keys::quit);
                break;
            case sf::Event::KeyPressed:
                if (sf::Keyboard::isKeyPressed(sf::Keyboard::A))
                {
                    std::cout <<"a\n";
                    return (Keys::key_left);
                }
                else if (sf::Keyboard::isKeyPressed(sf::Keyboard::D))
                {
                    std::cout <<"d\n";
                    return (Keys::key_right);
                }
                else if (sf::Keyboard::isKeyPressed(sf::Keyboard::S))
                {
                    std::cout <<"s\n";
                    return (Keys::key_down);
                }
                else if (sf::Keyboard::isKeyPressed(sf::Keyboard::W))
                {
                    std::cout <<"w\n";
                    return (Keys::key_up);
                }
                else if (sf::Keyboard::isKeyPressed(sf::Keyboard::Escape))
                {
                    return (Keys::quit);
                }
                break;
            default:
                break;
        }
}



SFML    *start() {
    std::cout << "create\n";
    return new SFML();
}

void    deletesdl(SFML *sfml) {
    delete sfml;
}

P.S 我不得不使用它的动态库来调用它并保持游戏逻辑和图形库彼此分离

Answer 1

您对某些函数的调用顺序有疑问。当你这样做时：

movesnake(this->SFML->OnEvent());

OnEvent 将首先被调用，然后是 movesnake。但是，由于您之前从未进行过轮询并且 OnEvent 正在使用您的 event 变量，因此任何事情都有可能发生。事实上，event 永远不会被 window.pollEvent 正确填充，因此你有未定义的行为。

最后，OnEvent returns Keys::quit因为UB，所以movesnake这样处理。将轮询移到 movesnake 之外（可能在 OnEvent 中，就在处理事件之前）可以解决问题。

window 启动时调用 sfml event::close

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