C++ SDL一起繪製文本和數字

Question

我正在做一個大項目，我想向用戶顯示看起來不錯的信息。

我需要的就是能夠在裏面畫正方形和文字。

我畫了文字和正方形，但我不能把它們放在一起。我甚至發現了一個問題所在。它的功能是SDL_SetVideoMode（mwidth，mheight，bpp，flags）。

這個地方被突出顯示。提前致謝！

using namespace std; 
#define SPACING 0 
TTF_Font *font=0; 
int font_size=16; 
SDL_Surface *screen;) 



void draw_text_at(SDL_Surface *scr,char *msg, int x0, int y0) 
{ 
    int h; 
    SDL_Rect r; 

    SDL_Color fg={0,0,0,255}; 
    h=TTF_FontLineSkip(font); 

    r.x=x0; 
    r.y=y0-h; 
    r.x=x0-TTF_GetFontOutline(font); 
    r.y+=h+SPACING-TTF_GetFontOutline(font); 

    SDL_Surface *surf=TTF_RenderText_Blended(font,msg,fg); 

     if(surf) 
     { SDL_BlitSurface(surf,0,scr,&r); 
      SDL_FreeSurface(surf); 
     } 
} 

void window::handle_key_down(SDL_keysym * keysym) 
{ 
    switch(keysym->sym) 
    { 
    case SDLK_ESCAPE: 
    exit(0); 
    break; 

    default: 
    break; 
    } 
} 


void window::setup_opengl() 
{ 
    float ratio=(float)mwidth/(float)mheight; 
    glShadeModel(GL_SMOOTH); 
    glCullFace(GL_BACK); 
    glFrontFace(GL_CCW); 

    glEnable(GL_CULL_FACE); 
    glClearColor(1.0f,1.0f,1.0f,1.0f); 
    glViewport(0,0,mwidth,mheight); 

    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 

    gluPerspective(60.0,ratio,1.0,1024.0); 
    glEnable(GL_DEPTH_TEST); 
    glDepthFunc(GL_LEQUAL); 
    glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST); 
} 


void window::draw_screen() 
{ 
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
    glLoadIdentity(); // set system of coordinates to the center of the screen 
    glTranslatef(0.0,0.0,-10.0); 
    glColor4f(0.0,1.0,1.0,1.0); 

    glBegin(GL_QUADS); 
    glVertex3f(-8, 0-2 ,0); 
    glVertex3f(-2+-8,0-2 ,0); 
    glVertex3f(-2+-8,-2-2,0); 
    glVertex3f(0+-8, -2-2,0); 
    glEnd(); 

    glBegin(GL_QUADS); 
    glVertex3f(-8+3, 0-2 ,0); 
    glVertex3f(-2+-8+3,0-2 ,0); 
    glVertex3f(-2+-8+3,-2-2,0); 
    glVertex3f(0+-8+3, -2-2,0); 
    glEnd(); 

    SDL_GL_SwapBuffers(); 
} 


void window(int quantity_of_disks, hard_disk &disk) 
{ 
    if((SDL_Init(SDL_INIT_VIDEO)<0)) 
    {printf("Could not initialize SDL: %s.\n", SDL_GetError()); 
    exit(-1); //return -1; 
    } 

    if(TTF_Init()==-1) 
    { printf("TTF_Init: %s\n", TTF_GetError()); 
     exit(-2); 
    } 

    const SDL_VideoInfo *info=NULL; 
    int flags=0,bpp=0; 
    info=SDL_GetVideoInfo(); 

    if(!info) 
    { fprintf(stderr,"Video query failed"); 
     SDL_Quit(); 
     exit(0); 
    } 

    bpp=info->vfmt->BitsPerPixel; 

    SDL_GL_SetAttribute(SDL_GL_RED_SIZE,5); 
    SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE,5); 
    SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE,5); 
    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE,16); 
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1); 

這裏 如果我設置標誌爲零，我見文
如果標誌設置爲SDL_OPENGL或SDL_OPENGLBLIT，我看到廣場

FLAS被轉移到功能SDL_SetVideoMode 但我希望看到這兩個。我試圖改變它，但..

flags= 0; 
// SDL_ANYFORMAT | SDL_OPENGLBLIT | SDL_ASYNCBLIT 

這一刻是在這裏：

 screen = SDL_SetVideoMode(mwidth,mheight,bpp,flags); 

    if (screen == NULL) 
    { fprintf(stderr, "Couldn't set video mode: %s\n", SDL_GetError()); 
     exit(-2); //return -2; 
     } 
    SDL_WM_SetCaption ("MBR informant",NULL); 
    setup_opengl(); 

    glMatrixMode(GL_MODELVIEW); 

    char *path_to_font="freefont-ttf/sfd/FreeMono.ttf"; 
    load_font(path_to_font, font_size); 

    SDL_FillRect(screen,0,~0); 

    while (1) 
    { draw_screen(); 
     char *msg="we typed it"; 
     draw_text_at(screen,msg,50,50); 
     SDL_Flip(screen); 

     SDL_Delay(1000); 
     process_events(); 
     } 

    SDL_Quit(); 
    } 

它看起來像：

時可變標誌= 0

時可變標誌= SDL_OPENGL

由於代碼的大小，我只留下了與繪畫相關的功能。 全部文件：http://rghost.net/37518422

SOLUTION

感謝羅我已經解決了這個問題，所以： 我定義的矩形。 SDL_Rect rect; rect.x = 0; rect.y = 0; rect.w = 150; rect.h = 140;

和我修改一個部分：

 while (1) 
     { draw_screen(); 
      char *msg="we typed it"; 
      draw_text_at(screen,msg,50,50); 
      **SDL_FillRect (screen,&rect,100);** 
      SDL_Flip(screen); 
     SDL_Delay(1000); 
     process_events(); 
     } 

，我得到了我想要的東西：

Answer 1

你跟SDL_BlitSurface()塊傳輸文本。究竟爲什麼會出現問題，我不知道，但SDL維基克利裏說，（SDL_BlitSurface）：

Like most surface manipulation functions in SDL, it should not be used together with OpenGL.

如果你想堅持使用OpenGL的，這個問題涵蓋了文本渲染一些可能性：

How to do OpenGL live text-rendering for a GUI?