QGLWidget is empty on Mac, cannot draw

I have a problem with using QGLWidget on mac. My code works correctly on Windows and Linux. On mac I can only change the background fill color of OpenGL, but nothing is being drawn. I am using Qt 4.8.4.

Here is the most crucial part of the code:

Code:

void OpenGLWidget::initializeGL()
{
    qglClearColor(Qt::white);
    glShadeModel( GL_FLAT );
    glClearDepth(1.0f);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
 
    if (m_lines) {
        glPolygonMode(GL_BACK, GL_LINE);
        glPolygonMode(GL_FRONT, GL_LINE);
    } else {
        glPolygonMode(GL_BACK, GL_FILL);
        glPolygonMode(GL_FRONT, GL_FILL);
    }
}
 
void OpenGLWidget::resizeGL(int width, int height)
{
    glViewport(0, 0, width, height);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective( 10.0f, (GLfloat)width / (GLfloat)height, 0.25, 100*m_zoom );
    glMatrixMode(GL_MODELVIEW);
}
 
void OpenGLWidget::paintGL()
{
    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
    glFlush();
    draw();
}
 
void OpenGLWidget::draw()
{
    if (!m_data)
        return;
 
    glLoadIdentity();
    glTranslatef( m_panX, m_panY, m_zoom );
    glRotatef( m_rotationX, 1.0, 0.0, 0.0 );
    glRotatef( m_rotationY, 0.0, 1.0, 0.0 );
    glRotatef( m_rotationZ, 0.0, 0.0, 1.0 );
 
    glBegin(GL_QUADS);
 
    const int maxX = m_width-1;
    const int maxY = m_height-1;
 
    int value;
 
    for (int x=0; x < maxX; ++x) {
        for (int y=0; y < maxY; ++y) {
            value = (int)((((m_map[x][y][2]+1)/2)*0xff));
            qglColor( m_faceColors[ value ] );
 
            glVertex3f( m_map[x][y][0],       m_map[x][y][1],       m_map[x][y][2] );
            glVertex3f( m_map[x][y+1][0],     m_map[x][y+1][1],     m_map[x][y+1][2] );
            glVertex3f( m_map[x+1][y+1][0],   m_map[x+1][y+1][1],   m_map[x+1][y+1][2] );
            glVertex3f( m_map[x+1][y][0],     m_map[x+1][y][1],     m_map[x+1][y][2] );
        }
    }
 
    glEnd();
}
 
void OpenGLWidget::setBackgroundColor(const QColor &color)
{
    qglClearColor(color);
    updateGL();
}

Does anybody know what is wrong?