c-SDL-窗口不显示任何内容

我正在SDL(C)中迈出第一步,并从www获得了一些教程.

但是有一个问题.我已经在Linux Mint System上安装了SDL2,并编译了教程代码：

#ifdef __cplusplus
    #include <cstdlib>
#else
    #include <stdlib.h>
#endif

#include <stdio.h>
#include <SDL2/SDL.h>

#include <iostream>

int main ( int argc, char** argv )
{
    if (SDL_Init(SDL_INIT_EVERYTHING) != 0){
        std::cout << "SDL_Init Error: " << SDL_GetError() << std::endl;
        return 1;
    }

    SDL_Window *win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480,
    SDL_WINDOW_SHOWN);
    if (win == NULL){
        std::cout << "SDL_CreateWindow Error: " << SDL_GetError() << std::endl;
        return 1;
    }

    SDL_Renderer *ren = SDL_CreateRenderer(win, -1,
    SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
    if (ren == NULL){
        std::cout << "SDL_CreateRenderer Error: " << SDL_GetError() << std::endl;
        return 1;
    }

    SDL_Surface *bmp = SDL_LoadBMP("cb.bmp");
    if (bmp == NULL){
        std::cout << "SDL_LoadBMP Error: " << SDL_GetError() << std::endl;
        return 1;
    }

    SDL_Texture *tex = SDL_CreateTextureFromSurface(ren, bmp);
    SDL_FreeSurface(bmp);
    if (tex == NULL){
        std::cout << "SDL_CreateTextureFromSurface Error: "
            << SDL_GetError() << std::endl;
        return 1;
    }

    SDL_Delay(4000);

    SDL_DestroyTexture(tex);
    SDL_DestroyRenderer(ren);
    SDL_DestroyWindow(win);
    SDL_Quit();

    return 0;
}

使用以下编译命令：

g++ main.cpp -lSDL2 -o prog

我得到了：

没有任何内部的窗框.我必须在哪里寻找这个错误？

最终密码

第一：感谢starrify！

#ifdef __cplusplus
    #include <cstdlib>
#else
    #include <stdlib.h>
#endif

#include <stdio.h>
#include <SDL2/SDL.h>

#include <iostream>

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

    if (SDL_Init(SDL_INIT_EVERYTHING) != 0){
        std::cout << "SDL_Init Error: " << SDL_GetError() << std::endl;
        return 1;
    }

    SDL_Window *window = SDL_CreateWindow("Hello World!", 100, 100, 640, 480,
    SDL_WINDOW_SHOWN);
    if (window == NULL){
        std::cout << "SDL_CreateWindow Error: " << SDL_GetError() << std::endl;
        return 1;
    }
/*
    SDL_Renderer *ren = SDL_CreateRenderer(window, -1,
    SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
    if (ren == NULL){
        std::cout << "SDL_CreateRenderer Error: " << SDL_GetError() << std::endl;
        return 1;
    }
*/
    SDL_Surface *surface_bmp = SDL_LoadBMP("cb.bmp");
    if (surface_bmp == NULL){
        std::cout << "SDL_LoadBMP Error: " << SDL_GetError() << std::endl;
        return 1;
    }
/*
    SDL_Texture *tex = SDL_CreateTextureFromSurface(ren, surface_bmp);
    SDL_FreeSurface(surface_bmp);
    if (tex == NULL){
        std::cout << "SDL_CreateTextureFromSurface Error: "
            << SDL_GetError() << std::endl;
        return 1;
    }
*/

    SDL_Surface *surface_window = SDL_GetWindowSurface(window);

    /*
     * Copies the bmp surface to the window surface
     */
    SDL_BlitSurface(surface_bmp,
                    NULL,
                    surface_window,
                    NULL);

    /*
     * Now updating the window
     */
    SDL_UpdateWindowSurface(window);

    /*
     * This function used to update a window with OpenGL rendering.
     * This is used with double-buffered OpenGL contexts, which are the default.
     */
/*    SDL_GL_SwapWindow(window); */

    SDL_Delay(5000);

/*    SDL_DestroyTexture(tex);*/
/*    SDL_DestroyRenderer(ren);*/
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

告诉我这个结果:)

我看到这确实很容易.这样,我不需要openGL进行绘制.这将是下一步.
如果您能帮助我改进此示例,以使其与openGL一起使用,…

解决方法:

SDL – window doesn’t show anything

原因是您没有绘制任何东西.您创建了一个窗口,一个渲染器,一个表面和一个纹理.但是,您什么都没画.视觉效果完全反映了您所做的事情.

要仅显示BMP图像,请将图像加载到曲面中,然后使用SDL_BlitSurface将其复制到屏幕上.或使用纹理,应像使用OpenGL一样绘制诸如三角形或四边形的图元.

还有另一个问题：为什么您的窗口看起来充满了空白屏幕以外的其他内容？
这是因为这些年默认的视频模式设置为double buffering,这意味着要显示一个前缓冲区和一个要渲染的后缓冲区.完成渲染单个帧时,应调用诸如SDL_Flip(似乎在SDL2中已作废)或SDL_UpdateWindowSurface之类的内容.

编辑：我已经编辑了您的代码,这是可行的：(删除了渲染器/纹理,添加了SDL_BlitSurface和SDL_UpdateWindowSurface)

#ifdef __cplusplus
    #include <cstdlib>
#else
    #include <stdlib.h>
#endif

#include <stdio.h>
#include <SDL2/SDL.h>

#include <iostream>

int main ( int argc, char** argv )
{
    if (SDL_Init(SDL_INIT_EVERYTHING) != 0){
        std::cout << "SDL_Init Error: " << SDL_GetError() << std::endl;
        return 1;
    }

    SDL_Window *win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480,
    SDL_WINDOW_SHOWN);
    if (win == NULL){
        std::cout << "SDL_CreateWindow Error: " << SDL_GetError() << std::endl;
        return 1;
    }

    SDL_Surface *bmp = SDL_LoadBMP("cb.bmp");
    if (bmp == NULL){
        std::cout << "SDL_LoadBMP Error: " << SDL_GetError() << std::endl;
        return 1;
    }

    SDL_BlitSurface(bmp, 0, SDL_GetWindowSurface(win), 0);
    SDL_UpdateWindowSurface(win);

    SDL_Delay(4000);

    SDL_DestroyWindow(win);
    SDL_Quit();

    return 0;
}

标签：sdl-2,c,linux
来源： https://codeday.me/bug/20191011/1895816.html