add prints

selfdrive/ui/qt/onroad.cc

@@ -375,6 +375,7 @@ void NvgWindow::paintGL() {
   UIState *s = uiState();
   const cereal::ModelDataV2::Reader &model = (*s->sm)["modelV2"].getModelV2();
   CameraViewWidget::setFrameId(model.getFrameId());
+  qDebug() << "NvgWindow::paintGL: frame to draw:" << model.getFrameId();
   CameraViewWidget::paintGL();
 
   QPainter painter(this);

selfdrive/ui/qt/widgets/cameraview.cc

@@ -225,8 +225,12 @@ void CameraViewWidget::paintGL() {
   glClear(GL_STENCIL_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
 
   int frame_idx = (draw_frame_id + frame_offset) % 4;
+  qDebug() << "Frame offset:" << frame_offset;
   if (frames[frame_idx] == nullptr) return;
+
+//  qDebug() << "CameraViewWidget::paintGL: frame to draw:" << draw_frame_id;
   VisionBuf *frame = frames[frame_idx]->frame;
+  qDebug() << "Drawing frame:" << frames[(draw_frame_id + frame_offset) % 4]->frame_id;
 
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
   glViewport(0, 0, width(), height());