我有一个问题。我想渲染透明纹理在一个黑色窗口在opengl c++。我能够创建窗口，加载纹理和渲染它。但它是不透明的渲染时。这是我的代码，我不明白是什么做错了这里：
我创建了如下窗口：

HWND              hWnd;
    MSG               msg;
    HDC               hDC;
    HGLRC             hRC;

    WNDCLASSEX wc;
    ZeroMemory(&wc, sizeof(WNDCLASSEX));
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_DBLCLKS | CS_VREDRAW;
    wc.lpfnWndProc = WindowProc;
    wc.hInstance = NULL;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)COLOR_WINDOW;
    wc.lpszClassName = L"MainWindow";
    RegisterClassEx(&wc);

    RECT* lpRect = new RECT();
    lpRect->left = 200;
    lpRect->top = 200;
    lpRect->right = 800;
    lpRect->bottom = 800;
    hWnd = CreateWindowEx(NULL,
        L"MainWindow",
        L"Texture Rendering Practice",
        WS_POPUP | WS_VISIBLE,
        lpRect->left,
        lpRect->top,
        lpRect->right - lpRect->left,
        lpRect->bottom - lpRect->top,
        NULL,
        NULL,
        NULL,
        NULL);
    if (hWnd)
    {
        RECT rc;
        GetWindowRect(hWnd, &rc);
        app = new App(*&hWnd, rc.right - rc.left, rc.bottom - rc.top);
        InitGL(*&hWnd);

        hDC = GetDC(hWnd);
        hRC = wglCreateContext(hDC);
        wglMakeCurrent(hDC, hRC);

        ShowWindow(hWnd, SW_SHOW);
        UpdateWindow(hWnd);
    }
    else
    {
        return 0;
    }

InitGL（）函数看起来像这样（它在另一个类中：

int                   pf;
    HDC                   hDC;
    PIXELFORMATDESCRIPTOR pfd;

    hDC = GetDC(hWnd);

    memset(&pfd, 0, sizeof(pfd));
    pfd.nSize = sizeof(pfd);
    pfd.nVersion = 1;
    pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL;
    pfd.iPixelType = PFD_TYPE_RGBA;
    pfd.cColorBits = 32;

    pf = ChoosePixelFormat(hDC, &pfd);

    SetPixelFormat(hDC, pf, &pfd);

    DescribePixelFormat(hDC, pf, sizeof(PIXELFORMATDESCRIPTOR), &pfd);

    ReleaseDC(hWnd, hDC);

    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClearDepth(1.0f);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    glShadeModel(GL_SMOOTH);
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
    glEnable(GL_BLEND);

然后我加载纹理如下：

int w;
    int h;
    int comp;
    unsigned char* image = stbi_load("tex.png", &w, &h, &comp, STBI_rgb_alpha);

    if (image == nullptr)
        throw(std::string("Failed to load texture"));

    glGenTextures(1, &this->texName);

    glBindTexture(GL_TEXTURE_2D, this->texName);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    if (comp == 3)
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, w, h, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
    else if (comp == 4)
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);

    glBindTexture(GL_TEXTURE_2D, 0);

    stbi_image_free(image);

（this-〉texName是Gluint对象保存的纹理地址）
然后我就像这样渲染纹理：

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glEnable(GL_TEXTURE_2D);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
    glBindTexture(GL_TEXTURE_2D, texName);

    glBegin(GL_QUADS);

    glTexCoord2f(0.0, 0.0); glVertex3f(-0.5, 0.5, 0.1);
    glTexCoord2f(1.0, 0.0); glVertex3f(0.5, 0.5, 0.1);
    glTexCoord2f(1.0, 1.0); glVertex3f(0.5, -0.5, 0.1);
    glTexCoord2f(0.0, 1.0); glVertex3f(-0.5, -0.5, 0.1);

    glEnd();

    glDisable(GL_TEXTURE_2D);

    glFlush();

输出如下所示：

它应该只是一个黑色背景的树，因为背景是透明的，但它在这里显示为白色。顺便说一句，我检查了图像文件中确实有透明的背景。