用过opengl的请进！解决了可以再加分！

我用VC＋＋进行OpenGL编程，OnDraw函数代码如下：  
 void CLoadFileView::OnDraw(CDC* pDC)
{
    CLoadFileDoc* pDoc = GetDocument();
    ASSERT_VALID(pDoc);
    GLfloat light_position[]={4.0,4.0,18.0,1.0};
    wglMakeCurrent(pDC->m_hDC, m_hglrc);      
    glDepthFunc(GL_LEQUAL);   
    glEnable(GL_DEPTH_TEST);
    glLightfv(GL_LIGHT0, GL_POSITION, light_position);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0); 
    glShadeModel(GL_FLAT);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
    glColor3f(1.0,0.0,0.0);
    glBegin(GL_POLYGON);
    glVertex2f(-2,-2);
    glVertex2f(-2,2);
    glVertex2f(2,2);
    glVertex2f(2,-2);
    ......
}
但是画出来的竟是白色的平面，不知为什么？我明明设了glColor3f(1.0,0.0,0.0);
应该是红色才对，请大家帮帮忙！