using read_polygon_mesh for input to support more file formats

#include <string>

#include <sstream>

#include <CGAL/Polygon_mesh_processing/IO/polygon_mesh_io.h>

#include <CGAL/Polygon_mesh_processing/triangulate_faces.h>

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>

#include <CGAL/Mesh_triangulation_3.h>

};

template< typename Polyhedron >

void readPolyhedron(Polyhedron & polyhedron, const std::string & filePath)

void readPolyhedron(Polyhedron & polyhedron, const std::string & filePath, bool verbose = true)

{

	std::ifstream input(filePath);

	input >> polyhedron;

	if (input.fail()) {

	// the function from the Polygon_mesh_processing does some repairs and orientations

	// to obtain a valid polygon mesh

	// https://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__IO__grp.html

	if (!CGAL::Polygon_mesh_processing::IO::read_polygon_mesh(filePath, polyhedron, CGAL::parameters::verbose(verbose))) {

		std::cerr << "Error: Could not read file '" <<  filePath << "'" << std::endl;

		std::exit(EXIT_FAILURE);

	}

	input.close();

	if (!CGAL::is_triangle_mesh(polyhedron)) {

		std::cout << "Input surface mesh is not triangular, calling triangulate_faces..." << std::endl;

	args.set_cli_options(cli);

	// positional arguments (should be generally defined after optional arguments)

	cli |= lyra::arg(input_file, "input_file")("Input file (must be in the OFF format).").required();

	cli |= lyra::arg(input_file, "input_file")("Input file (supported formats: OFF, STL, VTP, OBJ, GOCAD).").required();

	cli |= lyra::arg(output_dir, "output_dir")("Output directory." + fmt_default(output_dir));

	auto result = cli.parse({ argc, argv });