virtual void draw() {
    glClearColor(0, 1, 1, 1);
    glClear(GL_COLOR_BUFFER_BIT);

    if (sm->AcquireFrame(true) == PXC_STATUS_NO_ERROR) {
      PXCCapture::Sample *sample = sm->QuerySample();
      sample->color()->
      sm->ReleaseFrame();
    }
  }