如何呈现开始菜单？用户需要按一个键才能开始游戏

如何解决如何呈现开始菜单？用户需要按一个键才能开始游戏

我正在做一项需要使用 C++ 进行 OOP 游戏概念的作业。但是，我无法呈现另一个菜单，该菜单需要用户按下游戏键才能开始。这是当前的代码实现。我还提供了一些屏幕截图以提供更清晰的上下文（见图）

到目前为止，每当我运行该程序时，游戏都会自动启动，并且石头会开始掉落。但是，我希望实现一个弹出菜单，要求玩家按 ENTER 按钮开始游戏。

#include "Engine.h"
#include "Graphics\TextureManager.h"
#include "Inputs\Input.h"
#include "Characters\Warrior.h"
#include "DeltaTime\DeltaTime.h"
#include "Map\MapParser.h"
#include <iostream>
#include "SDL_image.h"
#include "Camera/Camera.h"
#include "Characters/Rocks.h"
#include "SDL.h"
#include <string>
#include "Characters/Rocks.h"
#include "UILabel/UILabel.h"
#include "SDL_ttf.h"


//initialise the instance because this is a static object
Engine* Engine::s_Instance = nullptr;
Warrior* player;
Rocks* rock;
std::vector<Rocks*> fallingRocks;
int points;

bool Engine::Init()
{

    //We need to initialise SDL and ensure that SDL is properly initialise
    //So we always check to see if SDL was initialise properly
    if (SDL_Init(SDL_INIT_VIDEO) != 0 && IMG_Init(IMG_INIT_JPG || IMG_INIT_PNG) != 0)
    {
        //when sdl init is unsuccessful it returns !0
        SDL_Log("Failed to initialize SDL: %s",SDL_GetError());
        return false;
    }
    SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);

    //create window
    m_Window = SDL_CreateWindow("Bullet Barrage",SDL_WINDOWPOS_CENTERED,SCREEN_WIDTH,SCREEN_HEIGHT,window_flags);
    if (m_Window == nullptr)
    {
        //window not initialised
        SDL_Log("Failed to create window SDL: %s",SDL_GetError());
        return false;
    }

    //create renderer
    m_Renderer = SDL_CreateRenderer(m_Window,-1,SDL_RENDERER_ACCELERATED || SDL_RENDERER_PRESENTVSYNC);
    if (m_Renderer == nullptr)
    {
        //renderer not initialised
        SDL_Log("Failed to create renderer SDL: %s",SDL_GetError());
        return false;
    }

    //check if map generator is working
    if (!MapParser::GetInstance()->Load()) {
        std::cout << "Failed to load map" << std::endl;
        return false;
    }
    
    //use the id from map generator to generate the map
    m_LevelMap = MapParser::GetInstance()->GetMap("level1");
    
    //check if font is loaded properly
    if (TTF_Init() == -1) {
        std::cout << "Error: SDL_TTF" << std::endl;
    }

    //load map texture
    TextureManager::GetInstance()->Load("background","assets/maps/BG.png");
    TextureManager::GetInstance()->Load("player","assets/adventurer.png");
    TextureManager::GetInstance()->Load("rock","assets/Lava.png");
    TextureManager::GetInstance()->Load("end","assets/gameover.png");
    //load font
    TextureManager::GetInstance()->AddFont("arial","assets/arial.ttf",30);

    

    //start state of player is idle,animation is idle
    //load image of player
    player = new Warrior(new Properties("player",100,560,50,37));           //initialise player

    for (int i = 0; i < TOTALROCKS; ++i) {
        int temp = rand() % 1024;
        int temp2 = rand() % 100+49;
        rock = new Rocks(new Properties("rock",temp,-200,temp2,temp2),rand() %6+2); //x,y,w,h
        fallingRocks.push_back(rock);
    }
    //Camera::GetInstance()->SetTarget(player->Getorigin());

}

void Engine::Render()
{
    if (player_dead == false) {
        SDL_RenderClear(m_Renderer);
        //render background
        TextureManager::GetInstance()->Draw("background",1024,640);

        // Show score top right (Fm) 
        SDL_Color color = { 0,0 };
        std::string result = "Current score = " + std::to_string(points);
        UILabel test(750,20,result,"arial",color);
        test.draw();

        // Show Life top right (Fm) 
        std::string result2 = "Current HP = " + std::to_string(player->health);
        UILabel test2(750,result2,color);
        test2.draw();

        //throw loaded map onto the screen

        for (int i = 0; i < TOTALROCKS; ++i) {

            fallingRocks[i]->Draw();
        }

        m_LevelMap->Render();
        player->Draw();                         //draw player
    }
    else {
        SDL_Color color= { 0,0 };
        std::string result = "Total score = " + std::to_string(points);
        UILabel test(380,380,color);
        test.draw();

        TextureManager::GetInstance()->Draw("end",270,500,250);
        //TTF_Font* font = TTF_OpenFont("assets/arial.ttf",24); //this opens a font style and sets a size

        //SDL_Color White = { 255,0};  // this is the color in rgb format,maxing out all would give you the color white,and it will be your text's color

        //SDL_Surface* surfaceMessage = TTF_RenderText_Solid(font,"put your text here",White); // as TTF_RenderText_Solid Could only be used on SDL_Surface then you have to create the surface first

        //SDL_Texture* Message = SDL_CreateTextureFromSurface(Engine::GetInstance()->GetRenderer(),surfaceMessage); //Now you can convert it into a texture

        //SDL_Rect Message_rect; //create a rect
        //Message_rect.x = 0;  //controls the rect's x coordinate 
        //Message_rect.y = 0; // controls the rect's y coordinte
        //Message_rect.w = 100; // controls the width of the rect
        //Message_rect.h = 100; // controls the height of the rect

        ////Mind you that (0,0) is on the top left of the window/screen,think a rect as the text's Box,that way it would be very simple to understand

        ////Now since it's a texture,you have to put Rendercopy in your game loop area,the area where the whole code executes

        //SDL_Rendercopy(Engine::GetInstance()->GetRenderer(),Message,NULL,&Message_rect);
    }

    //player died,so draw out menu
    //just rendering some random color
    SDL_SetRenderDrawColor(m_Renderer,124,218,254,255);
    SDL_RenderPresent(m_Renderer);
    //points == total rocks dodge. do a congrats u died u dodge xx rocks

    

}

void Engine::Update()
{
    if (player_dead == false) {
        float dt = DeltaTime::GetInstance()->GetDeltaTime();        //store delta time into dt

    //use delta time as parameter ensure that it runs smoothly from com to com

        m_LevelMap->Update();
        player->CheckCollision(rock->getBox());
        player->Update(dt);
        if (player->health == 0) {
            player_dead = true;
        }

        for (int i = 0; i < TOTALROCKS; ++i) {
            if (player->CheckCollision(fallingRocks[i]->getBox())) {
                //remove object and reinsert
                fallingRocks[i] = nullptr;
                int temp = rand() % 1024;
                int temp2 = rand() % 100 + 49;
                rock = new Rocks(new Properties("rock",rand() % 6 + 2); //x,h
                fallingRocks[i] = rock;
            }
            if (fallingRocks[i]->offScreen()) {
                fallingRocks[i] = nullptr;
                int temp = rand() % 1024;
                int temp2 = rand() % 100 + 49;
                rock = new Rocks(new Properties("rock",h
                fallingRocks[i] = rock;
                points++;
            }
            fallingRocks[i]->Update(dt);
        }
    }

    //Camera::GetInstance()->Update(dt);
}

void Engine::Events()
{
    Input::GetInstance()->Listen(); //listen for player inputs.
}

bool Engine::Clean()
{
    //when clean function is called from main
    //will destriy and clean up all textures to free memory
    TextureManager::GetInstance()->Clean();
    MapParser::GetInstance()->Clean();
    SDL_DestroyRenderer(m_Renderer);
    SDL_DestroyWindow(m_Window);
    IMG_Quit();
    SDL_Quit();

    return true;
}

void Engine::Quit()
{
    m_IsRunning = false;    //set isrunning to false to stop the event
}

解决方法

我这样做的方法是创建一些像这样的位标志：

enum GameFlags {
      Menu = 0x01,Gameplay = 0x02
};

现在只需在主要游戏的代码周围添加一个 if 语句，如下所示：

if (flag & GameFlags::Gameplay) { }

然后菜单代码也一样。因此，您可以将标志变量初始化为菜单，然后在用户使用 sdl 事件单击时将其更改为游戏玩法。