Example: opengl_video_viewport_demo

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2024, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

#include <mrpt/gui/CDisplayWindow3D.h>
#include <mrpt/hwdrivers/CCameraSensor.h>
#include <mrpt/opengl.h>

#include <chrono>
#include <iostream>
#include <thread>

using namespace std;
using namespace mrpt;
using namespace mrpt::gui;
using namespace mrpt::opengl;
using namespace mrpt::math;
using namespace mrpt::obs;

// ------------------------------------------------------
//              TestOpenGLVideo
// ------------------------------------------------------
void TestOpenGLVideo()
{
  // Show to the user a list of possible camera drivers and creates and open
  // the selected camera.
  cout << "Please, select the input video file or camera...\n";

  mrpt::hwdrivers::CCameraSensor::Ptr cam = mrpt::hwdrivers::prepareVideoSourceFromUserSelection();
  if (!cam) return;

  cout << "Video stream open OK\n";

  // Create 3D window:
  CDisplayWindow3D win("#1: Demo of image mode viewport", 320, 240);
  CDisplayWindow3D win2("#2: Demo of image mode viewport", 500, 400);

  // Win #1:
  //  Get the smart pointer to the main viewport object in this window:
  Viewport::Ptr gl_view_main;
  {
    Scene::Ptr& theScene = win.get3DSceneAndLock();
    gl_view_main = theScene->getViewport("main");
    ASSERT_(gl_view_main);
    // IMPORTANT!!! IF NOT UNLOCKED, THE WINDOW WILL NOT BE UPDATED!
    win.unlockAccess3DScene();
  }

  // Win #2:
  //  Get the smart pointer to the main viewport object in this window:
  Viewport::Ptr gl_view_aux;
  {
    Scene::Ptr& theScene = win2.get3DSceneAndLock();
    theScene->insert(mrpt::opengl::CGridPlaneXY::Create());

    // Create small auxiliary viewport
    gl_view_aux = theScene->createViewport("aux");

    gl_view_aux->setViewportPosition(10, 10, 300, 200);
    gl_view_aux->setTransparent(true);

    // IMPORTANT!!! IF NOT UNLOCKED, THE WINDOW WILL NOT BE UPDATED!
    win2.unlockAccess3DScene();
  }

  win.setPos(10, 10);
  win2.setPos(400, 100);

  cout << "Close any window to end.\n";
  while (win.isOpen() && win2.isOpen())
  {
    win.addTextMessage(5, 5, format("%.02fFPS", win.getRenderingFPS()));
    win2.addTextMessage(5, 5, format("%.02fFPS", win2.getRenderingFPS()));
    std::this_thread::sleep_for(1ms);

    // Grab new video frame:
    CObservation::Ptr obs = cam->getNextFrame();
    if (obs)
    {
      if (IS_CLASS(*obs, CObservationImage))
      {
        CObservationImage::Ptr o = std::dynamic_pointer_cast<CObservationImage>(obs);
        win.get3DSceneAndLock();
        gl_view_main->setImageView(o->image);
        win.unlockAccess3DScene();
        win.repaint();

        win2.get3DSceneAndLock();
        gl_view_aux->setImageView(std::move(o->image));
        win2.unlockAccess3DScene();
        win2.repaint();
      }
    }
  }
}

// ------------------------------------------------------
//                      MAIN
// ------------------------------------------------------
int main()
{
  try
  {
    TestOpenGLVideo();

    return 0;
  }
  catch (const std::exception& e)
  {
    std::cerr << "MRPT error: " << mrpt::exception_to_str(e) << std::endl;
    return -1;
  }
}