Example: opengl_offscreen_render_example

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2021, 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/img/CImage.h>
#include <mrpt/io/CFileGZInputStream.h>
#include <mrpt/opengl/CFBORender.h>
#include <mrpt/serialization/CArchive.h>

#include <iostream>

using namespace std;
using namespace mrpt;
using namespace mrpt::opengl;
using namespace mrpt::io;
using namespace mrpt::serialization;
using namespace mrpt::img;
// ------------------------------------------------------
//              TestOffscreenRender
// ------------------------------------------------------
int TestOffscreenRender(int argc, char* argv[])
{
    if (argc != 5)
    {
        cerr
            << "Usage: " << argv[0]
            << " <FILE.3Dscene> <WIDTH> <HEIGHT> <OUTPUT_IMAGE>\n"
               " Output image can be in many formats: .png, .jpg, .tif, etc.\n";
        return 1;
    }

    const string sFil = argv[1];
    const int width = atoi(argv[2]);
    const int height = atoi(argv[3]);
    const string sOut = argv[4];

    ASSERT_ABOVE_(width, 0);
    ASSERT_ABOVE_(height, 0);

    COpenGLScene scene;
    CFileGZInputStream f(sFil);
    archiveFrom(f) >> scene;

    CFBORender render(width, height);
    CImage frame(width, height, CH_RGB);

    // here you can put your preferred camera rendering position
    {
        CCamera& camera = render.getCamera(scene);
        camera.setOrthogonal(true);
        camera.setZoomDistance(70);
        camera.setAzimuthDegrees(-90);
        camera.setElevationDegrees(90);
    }

    // render the scene
    render.getFrame2(scene, frame);
    frame.saveToFile(sOut);

    return 0;
}

// ------------------------------------------------------
//                      MAIN
// ------------------------------------------------------
int main(int argc, char* argv[])
{
    try
    {
        return TestOffscreenRender(argc, argv);
    }
    catch (const std::exception& e)
    {
        std::cerr << "MRPT error: " << mrpt::exception_to_str(e) << std::endl;
        return -1;
    }
    catch (...)
    {
        printf("Untyped exception!!");
        return -1;
    }
}