Porting OpenGL GLUT example use QOpenGLWidget Issues

[Levi]

I have an example which leverages a rendering engine to produce an image which then it is displayed. This works great when using glut directly but when switching to using QOpenGLWidget I am constantly running into issues and not sure why. I am assuming that it may be related to difference in how Qt initializes OpenGL versus Glut/Glew. Is there a way to initialize Qt so it is initially setup the same way Glut/Glew would be? Below I have outlined some differences and an issue that is not resolved.

Glut/Glew Display Callback

  if (g_display)
  {
    glXMakeCurrent(g_display, g_drawable, g_context);
  }

  auto camera = g_cameras[g_cameraIndex];
  camera->SetImageHeight(imgh);
  camera->SetImageWidth(imgw);
  camera->SetAspectRatio(static_cast<double>(imgw) / static_cast<double>(imgh));
  ir::Image image = camera->CreateImage();
  g_image = std::make_shared<ir::Image>(image);
  camera->Capture(*g_image);

  auto *data = g_image->Data<unsigned char>();

  handleMouse();

  glXMakeCurrent(g_glutDisplay, g_glutDrawable, g_glutContext);

  glClearColor(0.5, 0.5, 0.5, 1);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
  glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
  glPixelStorei(GL_UNPACK_SKIP_ROWS, 0);
  glPixelZoom(1, -1);
  glRasterPos2f(-1, 1);
  glDrawPixels(imgw, imgh, GL_RGB, GL_UNSIGNED_BYTE, data);
  glutSwapBuffers();

The first issue was the matrix for each of the MatrixModes were not identity which they were in Glut on initialization so I had to add the following. Is there a way to configure thing in the initializeGL() method so this is not needed?

  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();

The current issue I am running into is if I add an object to the render engine that has an alpha not equal to 1.0 when drawing the image it behaves oddly. If I pan over the object the whole screen goes to a solid color of the color with an alpha not equal to 1.0. If I pan the object out of screen everything goes back to normal. Any ideas why this would be happening? I tried to upload the image but getting a server error. I will try again.

Note: All of this works using the glut displayCB but when porting to QOpenGLWidget things breakdown and not sure why.

[Levi]

Here is the image. You see it has the coordinate system marker in the middle which is causing the issue. If this is added with an alpha of 1 it loads the image fine, but anything else I get one of the three colors(red, green or blue) taking up the entire screen. If I pan it off the screen everything goes back to normal and I see a portion of the grid.

I have also tired saving the image the loading it with QImage and drawing the image using the same glDrawPixels command but get the same behavior.