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对于我正在开发的游戏，我希望将 OpenGL 用于大量图形和SDL_TTF文本。我可以让两者都工作，但不能同时工作。这是我的代码（基于 Lazy Foo）：

#include "SDL/SDL.h"
#include "SDL/SDL_ttf.h"
#include "GL/gl.h"

const bool useOpenGl = true;

//The surfaces
SDL_Surface *message = NULL;
SDL_Surface *screen = NULL;

//The event structure
SDL_Event event;

//The font that's going to be used
TTF_Font *font = NULL;

//The color of the font
SDL_Color textColor = {255, 255, 255};

void apply_surface(int x, int y, SDL_Surface* source, SDL_Surface* destination, SDL_Rect* clip = NULL)
{
    //Holds offsets
    SDL_Rect offset;

    //Get offsets
    offset.x = x;
    offset.y = y;

    //Blit
    SDL_BlitSurface(source, clip, destination, &offset);
}

bool init()
{
    SDL_Init (SDL_INIT_EVERYTHING);
    if (useOpenGl)
    {
        screen = SDL_SetVideoMode (1280, 720, 32, SDL_SWSURFACE | SDL_OPENGL); //With SDL_OPENGL flag only opengl is sceen, without only text is
    } else {
        screen = SDL_SetVideoMode (1280, 720, 32, SDL_SWSURFACE);
    }

    TTF_Init();

    SDL_WM_SetCaption ("TTF Not Working With OpenGL", NULL);

    if (useOpenGl)
    {
        glClearColor(1.0, 0.0, 0.0, 0.0);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(0.0, screen->w, screen->h, 1.0, -1.0, 1.0);
        glEnable(GL_BLEND);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    }

    return true;
}

bool load_files()
{
    font = TTF_OpenFont ("arial.ttf", 28);

    return true;
}

void clean_up()
{
    SDL_FreeSurface (message);

    TTF_CloseFont (font);
    TTF_Quit();

    SDL_Quit();
}

int main(int argc, char* args[])
{
    //Quit flag
    bool quit = false;

    init();
    load_files();

    if (useOpenGl)
    {
        glClear(GL_COLOR_BUFFER_BIT); //clearing the screen
        glPushMatrix();


        glBegin(GL_QUADS);
        glColor3f(1.0, 0.0, 0.0);
        glVertex2f(0, 0);
        glColor3f(0.0, 1.0, 0.0);
        glVertex2f(1280, 0);
        glColor3f(0.0, 0.0, 1.0);
        glVertex2f(1280, 720);
        glColor4f(0.5, 0.5, 1.0, 0.1);
        glVertex2f(0, 720);
        glEnd();

        glPopMatrix();
        glFlush();
    }

    //Render the text
    message = TTF_RenderText_Solid (font, "The quick brown fox jumps over the lazy dog", textColor);

    //Apply the images to the screen
    apply_surface (0, 150, message, screen);

    //I'm guessing this is where the problem is coming from
    SDL_GL_SwapBuffers();
    SDL_Flip (screen);


    while (quit == false)
    {
        while (SDL_PollEvent (&event))
        {
            if (event.type == SDL_QUIT)
            {
                quit = true;
            }
        }
    }

    clean_up();

    return 0;
}

如果变量useOpenGl设置为 false 程序将只使用SDL_TTF，如果设置为 true 它将同时使用SDL_TTFOpenGL 和 OpenGL。从玩弄它，问题似乎在于我在创建窗口时是否使用“SDL_OPENGL”标志。

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1 回答 1

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SDL_TTF 使用软件渲染，不兼容 OpenGL 模式。

您可能需要寻找另一个库，例如FTGL或freetype-gl。

于 2013-02-05T18:37:11.010 回答