当健康为 0 时，如何在 Qt 中退出 "game"

Question

我对 Qt 很陌生，但我开始尝试制作 2D 游戏。我开始了一个非常粗糙和简单的游戏，但我有一个问题。每当生命值变为 0 时，游戏就不会结束。我只想知道如何结束游戏以及在制作 "Game Over" 屏幕之前将此退出命令放在哪里。我的代码在下面，据我所知，我假设 QApplication::quit() 进入 Game.cpp 文件。通过从 Health.cpp 和 Health.h 中获取健康整数并将其放入 Game.cpp 来执行此操作。任何帮助表示赞赏。这是我认为答案就在其中的代码，如果需要更多信息，请询问。

Game.h

#ifndef GAME_H
#define GAME_H

#include <QGraphicsView>
#include <QWidget>
#include <QGraphicsScene>
#include "Player.h"
#include "Score.h"
#include "Health.h"
#include "Level.h"
#include "Main.h"

class Game: public QGraphicsView{
public:
    Game(QWidget * parent=0);

    QGraphicsScene * scene;
    Player * player;
    Score * score;
    Health * health;
    Level * level;
    Main * close;
    int end();
};

#endif // GAME_H

Game.cpp

#include "Game.h" 
#include <QTimer>
#include <QGraphicsTextItem>
#include <QFont>
#include "Enemy.h"
#include <QMediaPlayer>
#include <QBrush>
#include <QImage>
#include <QApplication>

Game::Game(QWidget *parent){
    // create the scene
    scene = new QGraphicsScene();
    scene->setSceneRect(0,0,800,600); // make the scene 800x600        instead of infinity by infinity (default)
    setBackgroundBrush(QBrush(QImage(":/images/bg.png")));

    // make the newly created scene the scene to visualize (since Game is a QGraphicsView Widget,
    // it can be used to visualize scenes)
    setScene(scene);
    setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setFixedSize(800,600);

    // create the player
    player = new Player();
    player->setPos(400,500); // TODO generalize to always be in the     middle bottom of screen
    // make the player focusable and set it to be the current focus
    player->setFlag(QGraphicsItem::ItemIsFocusable);
    player->setFocus();
    // add the player to the scene
    scene->addItem(player);

    // create the score/health
    score = new Score();
    scene->addItem(score);
    health = new Health();
    health->setPos(health->x(),health->y()+25);
    scene->addItem(health);
    level = new Level();
    scene->addItem(level);Bull
    level->setPos(level->x(),level->y()+50);

    // spawn enemies
    QTimer * timer = new QTimer();
    QObject::connect(timer,SIGNAL(timeout()),player,SLOT(spawn()));
    timer->start(2000);

    // play background music
    QMediaPlayer * music = new QMediaPlayer();
    music->setMedia(QUrl("qrc:/sounds/bgsound.mp3"));
    music->play();

    show();
}

int Game::end(){
    if (health == 0){
        QApplication::quit();
    }
    return 0;
}

Health.h

#ifndef HEALTH_H
#define HEALTH_H

#include <QGraphicsTextItem>

class Health: public QGraphicsTextItem{
public:
    Health(QGraphicsItem * parent=0);
    void decrease();
    int getHealth();
private:
    int health;
};

#endif // HEALTH_H

Health.cpp

#include "Health.h"
#include <QFont>
#include <QApplication>

Health::Health(QGraphicsItem *parent): QGraphicsTextItem(parent){
    // initialize the score to 0
    health = 3;

    // draw the text
    setPlainText(QString("Health: ") + QString::number(health)); //   Health: 3
    setDefaultTextColor(Qt::red);
    setFont(QFont("times",16));
}

void Health::decrease(){
    health--;
    setPlainText(QString("Health: ") + QString::number(health)); //     Health: 2
}

int Health::getHealth(){
    return health;
}

main.cpp

#include <QApplication>
#include "Game.h"
#include "Main.h"

Game * game;

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

    game = new Game();
    game->show();

    return a.exec();
}

Answer 1

您的 end() 函数从未被调用。

实现您想要的目标的最佳方法是使用 Qt's signal/slot mechanism。将事件（信号）连接到动作（插槽）很容易：

将Q_OBJECT宏添加到Health和Game类并确保你的编译环境moc's两个头文件
在 Health 中声明一个名为 dead()

signal

从Health::decrease()
使 Game::end() 成为 slot 并成为 void
将 Health::dead() 连接到 Game::end()

然后，一旦 Health 达到零，就会调用 Game::end()。

class Health: public QGraphicsTextItem 
{
    Q_OBJECT
public:
    Health(QGraphicsItem * parent=0);
    void decrease();
    int getHealth();
signals:
    void dead();
private:
    int health;
};

...

class Game: public QGraphicsView{
    Q_OBJECT
public:
    ...

public slots:
    void end();
};

...

void Health::decrease(){
    health--;
    setPlainText(QString("Health: ") + QString::number(health));
    if ( health == 0 )
        emit dead();
}

...

Game::Game(QWidget *parent){

    ...

    connect( health, SIGNAL(dead()), this, SLOT(end()) );

}

...

void Game::end(){
    // no need to test health anymore, as signal is emited when health is zero
    // do some extra stuff before exiting
    QApplication::quit();
}

如果end()只调用了QApplication::quit()，你可以去掉它，直接把信号连接到QApplication::quit()，像这样：

connect( health, SIGNAL(dead()), qApp, SLOT(quit()) );

另请注意，您在 Game::end() 中测试 health == 0，但 health 是一个指针，并且查看您的代码，它永远不会是 0（你可能打算写 if ( health->getHealth() == 0 ).

Answer 2

在 Health::decrease 中发出信号或将其逻辑放在 "player is shot" 区域中。 ~~但要做到这一点，您需要 Health 或 class 的逻辑是 QObject 以便它获得 header 中的信号和槽.~~ 编辑 QGraphicsTextItem 已经是 QObject。查看评论。

在 Health class 或 Player class 实例化后立即将信号连接到视图的 close()。

http://doc.qt.io/qt-5/signalsandslots.html

希望对您有所帮助。

当健康为 0 时，如何在 Qt 中退出 "game"

How to exit a "game" in Qt when health is 0

qt

2d

exit

qapplication