Question

当我使用SetPixelFormat为hDC设置像素格式时，它返回false。我使用GetLastError（），我得到一个错误代码2000（意味着无效的像素格式）。

代码如下：

// Set pixel format attributes
int pixelAttributes[] = {
    WGL_DRAW_TO_WINDOW_ARB, GL_TRUE,
    WGL_SUPPORT_OPENGL_ARB, GL_TRUE,
    WGL_DOUBLE_BUFFER_ARB, GL_TRUE,
    WGL_PIXEL_TYPE_ARB, WGL_TYPE_RGBA_ARB,
    WGL_COLOR_BITS_ARB, bits,
    WGL_DEPTH_BITS_ARB, 24,
    WGL_STENCIL_BITS_ARB, 8,
    WGL_SAMPLE_BUFFERS_ARB, 1,      
    WGL_SAMPLES_ARB, 4,             
    0
};

int pixelFormat;
UINT numFormat;

// using wgl ext get valid pixel format number.
if (!wglChoosePixelFormatARB(hDC, pixelAttributes, NULL, 1, &pixelFormat, &numFormat)) {
    KillGLWindow();     
    MessageBox(NULL, L"Get pixel format failed", L"Error", MB_OK | MB_ICONEXCLAMATION);
    return FALSE;
}

if (!SetPixelFormat(hDC, pixelFormat, &pfd))        // try to set pixel format
{
    auto x = GetLastError();
    KillGLWindow();                             // close

    MessageBox(NULL, L"Unable to set pixel format.", L"Error", MB_OK | MB_ICONEXCLAMATION);
    return FALSE;
}

这些代码在创建并激活FALSE openGL上下文Create WGL之后。

Answer 1

SetPixelFormat在PIXELFORMATDESCRIPTOR结构中看起来很挑剔。为了满足这一要求，最好的方法是使用pfd初始化DescribePixelFormat：

INT iPF;
UINT num_formats_choosen;
if( !ChoosePixelFormatARB(
        hDC, 
        pPFAttribs, 
        NULL,
        1,
        &iPF,
        &num_formats_choosen)
 || !num_formats_choosen ) {
    goto fail_choose_pf;
}

PIXELFORMATDESCRIPTOR pfd;
memset(&pfd, 0, sizeof(pfd));
/* now this is a kludge; we need to pass something in the
 * PIXELFORMATDESCRIPTOR to SetPixelFormat; it will be ignored,
 * mostly. OTOH we want to send something sane, we're nice
 * people after all - it doesn't hurt if this fails. */
DescribePixelFormat(hDC, iPF, sizeof(pfd), &pfd);

if( !SetPixelFormat(hDC, iPF, &pfd) ) {
    goto fail_set_pf;
}

使用从wglChoosePixelFormatARB获取的像素格式时，SetPixelFormat返回false

1 个答案: