OBJWriter.cpp

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// Modified version of read_obj from libigl to include reading polyline elements
// as edges.
//
// Copyright (C) 2013 Alec Jacobson <alecjacobson@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla Public License
// v. 2.0. If a copy of the MPL was not distributed with this file, You can
// obtain one at http://mozilla.org/MPL/2.0/.
 
#include "OBJWriter.hpp"
 
#include <polyfem/utils/Logger.hpp>
 
#include <fstream>
 
namespace polyfem::io
{
    bool OBJWriter::write(const std::string &path, const Eigen::MatrixXd &v, const Eigen::MatrixXi &e, const Eigen::MatrixXi &f)
    {
        const Eigen::IOFormat OBJ_VERTEX_FORMAT(
            /*precision=*/Eigen::FullPrecision,
            /*flags=*/Eigen::DontAlignCols,
            /*coeffSeparator=*/" ",
            /*rowSeparator=*/"",
            /*rowPrefix=*/"v ",
            /*rowSuffix=*/v.cols() == 2 ? " 0\n" : "\n",
            /*matPrefix=*/"",
            /*fill=*/"");
 
        std::ofstream obj(path, std::ios::out);
        if (!obj.is_open())
            return false;
 
        obj << fmt::format(
            "# Vertices: {:d}\n# Edges: {:d}\n# Faces: {:d}\n",
            v.rows(), e.rows(), f.rows());
 
        for (int i = 0; i < v.rows(); ++i)
            obj << v.row(i).format(OBJ_VERTEX_FORMAT);
 
        for (int i = 0; i < e.rows(); ++i)
            obj << fmt::format("l {} {}\n", e(i, 0) + 1, e(i, 1) + 1);
 
        for (int i = 0; i < f.rows(); ++i)
            obj << fmt::format("f {} {} {}\n", f(i, 0) + 1, f(i, 1) + 1, f(i, 2) + 1);
 
        return true;
    }
} // namespace polyfem::io