Example: opengl_video_demo

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2022, 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.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(
        "Demo of video textures with MRPT's OpenGL objects", 640, 480);

    // XY Grid
    opengl::CGridPlaneXY::Ptr gl_ground =
        opengl::CGridPlaneXY::Create(-7, 7, -7, 7, 0, 1);
    gl_ground->setColor(0.7, 0.7, 0.7);

    // An opengl plane with the video texture
    opengl::CTexturedPlane::Ptr gl_plane1 =
        opengl::CTexturedPlane::Create(0, 1, 0, 0.75);  // 4/3 aspect ratio
    opengl::CTexturedPlane::Ptr gl_plane2 =
        opengl::CTexturedPlane::Create(0, 1, 0, 0.75);
    opengl::CTexturedPlane::Ptr gl_plane3 =
        opengl::CTexturedPlane::Create(0, 1, 0, 0.75);

    gl_plane1->setPose(
        mrpt::poses::CPose3D(0, 0, 1, 0.0_deg, 0.0_deg, -90.0_deg));
    gl_plane2->setPose(
        mrpt::poses::CPose3D(1, 0, 1, 120.0_deg, 0.0_deg, -90.0_deg));
    gl_plane3->setPose(
        mrpt::poses::CPose3D(0, 0, 1, 60.0_deg, 0.0_deg, -90.0_deg));

    win.setCameraZoom(5);

    // Insert objects in scene:
    {
        COpenGLScene::Ptr& theScene = win.get3DSceneAndLock();
        theScene->insert(gl_ground);
        theScene->insert(gl_plane1);
        theScene->insert(gl_plane2);
        theScene->insert(gl_plane3);
        // IMPORTANT!!! IF NOT UNLOCKED, THE WINDOW WILL NOT BE UPDATED!
        win.unlockAccess3DScene();
    }
    win.repaint();

    cout << "Close the window to end.\n";
    while (win.isOpen())
    {
        win.addTextMessage(5, 5, format("%.02fFPS", win.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_plane1->assignImage(o->image);
                gl_plane2->assignImage(o->image);
                gl_plane3->assignImage(o->image);
                win.unlockAccess3DScene();
                win.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;
    }
}