SDL OpenGL纹理显示问题

Question

我正在关注this tutorial以便从SDL_Surface 加载OpenGL纹理，我复制/粘贴代码并对其进行调整但它只显示错误的旧部分缓冲区这有点烦人...因为我无法弄清楚什么是错的。我也在Mac Os X上使用Qt5。这是我的代码

GLuint texture;         // This is a handle to our texture object
SDL_Surface *surface;   // This surface will tell us the details of the image
GLenum texture_format;
GLint  nOfColors;
surface = IMG_Load("/brique.png");

if ( surface ) {

    // get the number of channels in the SDL surface
    nOfColors = surface->format->BytesPerPixel;
    if (nOfColors == 4)     // contains an alpha channel
    {
        if (surface->format->Rmask == 0x000000ff)
            texture_format = GL_RGBA;
        else
            texture_format = GL_BGRA;
    } else if (nOfColors == 3)     // no alpha channel
    {
        if (surface->format->Rmask == 0x000000ff)
            texture_format = GL_RGB;
        else
            texture_format = GL_BGR;
    } else {
        printf("warning: the image is not truecolor..  this will probably break\n");
        // this error should not go unhandled
    }

    glEnable( GL_TEXTURE_2D );
    // Have OpenGL generate a texture object handle for us
    glGenTextures( 1, &texture );

    // Bind the texture object
    glBindTexture( GL_TEXTURE_2D, texture );

    // Set the texture's stretching properties
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );

    // Edit the texture object's image data using the information SDL_Surface gives us
    glTexImage2D( GL_TEXTURE_2D, 0, nOfColors, surface->w, surface->h, 0, texture_format, GL_UNSIGNED_BYTE, surface->pixels );
}
else {
    printf("SDL could not load image.bmp: %s\n", SDL_GetError());
    SDL_Quit();
    exit (1);
}

// Free the SDL_Surface only if it was successfully created
if ( surface ) {
    SDL_FreeSurface( surface );
}

这是结果：

这是函数glTexImage2D

的调试

Answer 1

你可能或者没有声明（这会翻转屏幕缓冲区）

SDL_GL_SwapBuffers();

这样做把它放在循环的最后一部分：

qglClearColor(qtPurple.dark());

/****************************************
... some ogl initialization code here ...
****************************************/

while (!done)
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

   /***********************************
   ... some ogl rendering code here ...
   ***********************************/

   SDL_GL_SwapBuffers();
}

在QT5 OGL上查看本教程：

• http://qt-project.org/doc/qt-5.0/qtopengl/hellogl.html