无法用SDL / C ++打开一个窗口

时间:2016-09-08 13:57:22

标签: c++ window sdl

我在我的代码中遇到了一个大错误,在运行之后我无法打开游戏的第一个窗口!它只是打开空白几个secondes然后它自动关闭。我不知道我的代码有什么问题,因为我正在学习一系列教程,而我的代码看起来就像教程中的代码一样。这是我的代码:

#include "stdafx.h"
#include "FirstClass.h"


FirstClass::FirstClass(void){

bool quit = false;
window = NULL;
window = SDL_CreateWindow("Snaykie v1.0",350, 150, 800, 500, SDL_WINDOW_SHOWN);
if (window == NULL){
    std::cout << "Can not open the game!" << std::endl;
}
renderer = NULL;
renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
evt = new SDL_Event();
//background image
txt = NULL;
txt = IMG_LoadTexture(renderer, "mainview.bmp");

rct.x = 0 ;
rct.y = 0;
rct.h = 500;
rct.w = 800;
//button start 
sbutt = NULL;
sbutt = IMG_LoadTexture(renderer, "startbutton.bmp");

startrct.x = 0 ;
startrct.y = 0;
startrct.h = 100;
startrct.w = 100;
}


FirstClass::~FirstClass(void)
{
SDL_DestroyTexture(txt);
SDL_DestroyTexture(sbutt);
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
delete evt;
} 
//the code below is the loops that let the window stucks forever to keep      opened
void FirstClass ::  GameStart(void){
while (!quit && evt->type != SDL_QUIT){

    SDL_PollEvent(evt);
   SDL_RenderClear(renderer);
   SDL_RenderCopy(renderer, txt, NULL, &rct);
   SDL_RenderCopy(renderer, sbutt, NULL, &startrct);
   SDL_RenderPresent(renderer);

}
}

请帮帮我,谢谢我真的遇到了大问题。

1 个答案:

答案 0 :(得分:1)

您正在以错误的方式处理evt变量。它已分配但未初始化,您将未初始化的值与SDL_QUIT进行比较。您应该重新排序FirstClass::GameStart内的代码,最好使用局部变量(因为实际上不需要使用动态分配的变量),并从构造函数和析构函数中删除现有evt的分配和删除。这是FirstClass::GameStart的更好版本:

void FirstClass::GameStart(void){
    SDL_Event evt;
    while (SDL_PollEvent(&evt)){
        if (evt.type == SDL_QUIT) {
            // a user requested termination has been received, exit the loop
            break;
        }
        else {
            // filter the event?
            SDL_RenderClear(renderer);
            SDL_RenderCopy(renderer, txt, NULL, &rct);
            SDL_RenderCopy(renderer, sbutt, NULL, &startrct);
            SDL_RenderPresent(renderer);
        }
    }
}

同时确保您实际从FirstClass::GameStart调用main函数,也许您根本就没有运行事件循环。