c++ - 纹理在 opengl 中显示为白色

Question

我无法加载 BMP 纹理并将其显示在立方体的面上。
我正在使用 Windows 7。我的编译器是 Visual Studio 2010 Express。我使用 FreeImage 加载 bmp。我的图像位深度是 24。我的图像大小是 256 * 256。我正在使用 SDL 创建窗口并处理事件。
当我编译并运行程序时，我的立方体仍然是白色的，它的表面没有任何显示。我正在将纹理加载到 GLuint 变量中。当我打印该变量时，它只打印“1”。我的一个 friend 告诉我，我的显卡与这个版本的 OpenGL 不兼容。所以我在虚拟机上的 Ubuntu 中编译并运行了程序，它运行良好.立方体纹理成功。你能帮我在我的Windows上正常运行吗？
如果你需要我的显卡是NVIDIA GT240 DDR5。

编辑

这是我的 initgl 函数:

//OpenGL initialization.
int initGL(void)
{
    glEnable(GL_TEXTURE_2D); //Enable texture mapping.
    if(!loadGLTextures("bmp_24.bmp"))
        return false;

    glShadeModel(GL_SMOOTH);
    glClearColor(0.0f , 0.0f , 0.0f , 0.5f);
    glClearDepth(1.0f);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    //Nice perspective.
    glHint(GL_PERSPECTIVE_CORRECTION_HINT , GL_NICEST);
    return true;
}

这是加载图像的函数。GLuint 纹理[1] 之前已定义:

//This function will load a bitmap image.
bool loadGLTextures(const char* file)
{
    FREE_IMAGE_FORMAT fif = FIF_UNKNOWN;

    fif = FreeImage_GetFileType(file , 0);
    if(fif == FIF_UNKNOWN)
        fif = FreeImage_GetFIFFromFilename(file);
    if(fif == FIF_UNKNOWN)
        return false;

    FIBITMAP* dib = FreeImage_Load(fif , file);

    if(!dib)
        return false;
    
    //Create the texture.
    glGenTextures(1 , &texture[0]);

    //Typical texture generation using data from the bitmap.
    glBindTexture(GL_TEXTURE_2D , texture[0]);

    //Generate the texture.
    glTexImage2D(GL_TEXTURE_2D , 0 , GL_RGB , FreeImage_GetWidth(dib) , 
        FreeImage_GetHeight(dib) , 0 , GL_BGR_EXT , GL_UNSIGNED_BYTE , 
        FreeImage_GetBits(dib));



    //Linear filtering.
    glTexParameteri(GL_TEXTURE_2D , GL_TEXTURE_MIN_FILTER , GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D , GL_TEXTURE_MAG_FILTER , GL_LINEAR);

    printf("%d" , texture[0]);

    FreeImage_Unload(dib);

    return true;

}

这是我的渲染函数:

//All of the drawing goes through this.
int drawGLScene(void)
{
    static float xrot = 0 , yrot = 0 , zrot = 0;
    //Clear screen and depth buffer.
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();

    glTranslatef(0.0f , 0.0f , -5.0f);
    glRotatef(xrot , 1.0f , 0.0f , 0.0f);
    glRotatef(yrot , 0.0f , 1.0f , 0.0f);
    glRotatef(zrot , 0.0f , 0.0f  ,1.0f);

    //Select the texture.
    glBindTexture(GL_TEXTURE_2D , texture[0]);

    glBegin(GL_QUADS);
    //Front:
    //Bottom left of the texture and quad.
    glTexCoord2f(0.0f , 0.0f); glVertex3f(-1.0f , -1.0f , 1.0f);
    //Bottom right fo the texture and quad.
    glTexCoord2f(1.0f , 0.0f); glVertex3f(1.0f , -1.0f , 1.0f);
    //Top right of the texture and quad.
    glTexCoord2f(1.0f , 1.0f); glVertex3f(1.0f , 1.0f , 1.0f);
    //Top left of the texture and quad.
    glTexCoord2f(0.0f , 1.0f); glVertex3f(-1.0f , 1.0f , 1.0f);

    //Back:
    //Bottom left of the texture and quad.
    glTexCoord2f(0.0f , 0.0f); glVertex3f(1.0f , -1.0f , -1.0f);
    //Bottom right of the texture and quad.
    glTexCoord2f(1.0f , 0.0f); glVertex3f(-1.0f , -1.0f , -1.0f);
    //Top right of the texture and the quad.
    glTexCoord2f(1.0f , 1.0f); glVertex3f(-1.0f , 1.0f , -1.0f);
    //Top left of the texture and the quad.
    glTexCoord2f(0.0f , 1.0f); glVertex3f(1.0f , 1.0f , -1.0f);

    //Top:
    //Top right of the texture and quad.
    glTexCoord2f(1.0f , 1.0f); glVertex3f(1.0f , 1.0f , -1.0f);
    //Top left of the texture and quad.
    glTexCoord2f(0.0f , 1.0f); glVertex3f(-1.0f , 1.0f , -1.0f);
    //Bottom left of the texture and quad.
    glTexCoord2f(0.0f , 0.0f); glVertex3f(-1.0f , 1.0f , 1.0f);
    //Bottom right of the texture and quad.
    glTexCoord2f(0.0f , 1.0f); glVertex3f(1.0f , 1.0f , 1.0f);

    //Bottom:
    //Top left of the texture and quad.
    glTexCoord2f(0.0f , 1.0f); glVertex3f(-1.0f , -1.0f , 1.0f);
    //Bottom left of the texture and quad.
    glTexCoord2f(0.0f , 0.0f); glVertex3f(-1.0f , -1.0f , -1.0f);
    //Bottom right of the texture and quad.
    glTexCoord2f(1.0f , 0.0f); glVertex3f(1.0f , -1.0f , -1.0f);
    //Top right of the texture and quad.
    glTexCoord2f(1.0f , 1.0f); glVertex3f(1.0f , -1.0f , 1.0f);

    //Right:
    //Bottom right of the texture and quad.
    glTexCoord2f(1.0f , 0.0f); glVertex3f(1.0f , -1.0f , -1.0f);
    //Top right of the texture and quad.
    glTexCoord2f(1.0f , 1.0f); glVertex3f(1.0f , 1.0f , -1.0f);
    //Top left of the texture and quad.
    glTexCoord2f(0.0f , 1.0f); glVertex3f(1.0f , 1.0f , 1.0f);
    //Bottom left of the texture and quad.
    glTexCoord2f(0.0f , 0.0f); glVertex3f(1.0f , -1.0f , 1.0f);

    //Left:
    //Bottom left of the texture and quad.
    glTexCoord2f(0.0f , 0.0f); glVertex3f(-1.0f , -1.0f , -1.0f);
    //Bottom right of the texture and quad.
    glTexCoord2f(1.0f , 0.0f); glVertex3f(-1.0f , -1.0f , 1.0f);
    //Top right of the texture and quad.
    glTexCoord2f(1.0f , 1.0f); glVertex3f(-1.0f , 1.0f , 1.0f);
    //Top left of the texture and quad.
    glTexCoord2f(0.0f , 1.0f); glVertex3f(-1.0f , 1.0f , -1.0f);
    glEnd();

    SDL_GL_SwapBuffers();

    xrot += 0.1;
    yrot += 0.1;
    zrot += 0.1;

    return true;

}

Answer 1

您的代码中有很多地方可能会出错。

我的怀疑是，您过早地调用了 initGL()，即没有可用的上下文。您没有显示有问题的代码，所以我只能对此进行猜测。

启用纹理单元仅对绘图很重要。您可以在禁用纹理单元的情况下上传纹理数据。我强烈建议您将 glEnable(GL_TEXTURE_2D); 放在您的四边形绘图代码之前，而不是其他地方(实际上，出于多种原因，您应该只调用 glEnable 和 glDisable 到绘图代码中)。

加载纹理时您未能执行多项健全性检查。此外，您忘记正确设置像素存储参数，但这会使您的纹理看起来失真。此外，从加载函数返回纹理 ID 而不是 bool 值并将 ID 放入全局变量也是有意义的。纹理 ID 0 已保留，因此您可以使用它来指示错误。

尽管您设置了过滤模式，所以这不是未定义 mipmap 级别的问题。