Example: opengl_offscreen_render_example

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/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_GT_(width, 0);
  ASSERT_GT_(height, 0);

  Scene 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.render_RGB(scene, frame);
  bool savedOk = frame.saveToFile(sOut);
  ASSERT_(savedOk);

  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;
  }
}