ply_reader_writer.h

/********************************************************************
 * Copyright (C) 2015 Liangliang Nan <liangliang.nan@gmail.com>
 * https://3d.bk.tudelft.nl/liangliang/
 *
 * This file is part of Easy3D. If it is useful in your research/work,
 * I would be grateful if you show your appreciation by citing it:
 * ------------------------------------------------------------------
 *      Liangliang Nan.
 *      Easy3D: a lightweight, easy-to-use, and efficient C++ library
 *      for processing and rendering 3D data.
 *      Journal of Open Source Software, 6(64), 3255, 2021.
 * ------------------------------------------------------------------
 *
 * Easy3D is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License Version 3
 * as published by the Free Software Foundation.
 *
 * Easy3D is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 ********************************************************************/
 
#ifndef EASY3D_FILEIO_PLY_READER_WRITER_H
#define EASY3D_FILEIO_PLY_READER_WRITER_H
 
 
#include <string>
#include <vector>
 
#include <easy3d/core/types.h>
 
// Todo: check happly, a header-only implementation of the .ply file format.
//       https://github.com/nmwsharp/happly
 
namespace easy3d {
 
    namespace io {
 
        template <typename VT>
        class GenericProperty : public std::vector<VT> {
        public:
            explicit GenericProperty(const std::string &prop_name = "", const std::vector<VT> &values = std::vector<VT>())
                    : std::vector<VT>(values), name(prop_name) {}
            std::string name;
        };
 
        typedef GenericProperty<vec3>                   Vec3Property;
        typedef GenericProperty<vec2>                   Vec2Property;
        typedef GenericProperty<float>                  FloatProperty;
        typedef GenericProperty<int>                    IntProperty;
        typedef GenericProperty< std::vector<float> >   FloatListProperty;
        typedef GenericProperty< std::vector<int> >     IntListProperty;
 
        struct Element {
            explicit Element(const std::string &elem_name, std::size_t n_instances = 0) : name(elem_name),
                                                                                 num_instances(n_instances) {}
 
            std::string name;           // e.g., "vertex", "face", "edge"
            std::size_t num_instances;  // number of instances
 
            std::vector<Vec3Property>       vec3_properties;    // for "point", "normal", "color", and vector fields
            std::vector<Vec2Property>       vec2_properties;    // for "texcoord"
            std::vector<FloatProperty>      float_properties;   // for scalar fields of float values
            std::vector<IntProperty>        int_properties;     // for scalar fields of integer values
            std::vector<FloatListProperty>  float_list_properties;  // for properties of a list of float values
            std::vector<IntListProperty>    int_list_properties;    // for properties of a list of integer values
 
            std::string property_statistics() const;
        };
 
 
        class PlyReader
        {
        public:
            PlyReader() = default;
            ~PlyReader();
 
            bool read(const std::string& file_name, std::vector<Element>& elements);
 
            static std::size_t num_instances(const std::string& file_name, const std::string& element_name);
 
        private:
            // Collect all elements stored as general properties (in list_properties_ and value_properties_).
            // Meanwhile, convert the "list" intermediate representation into the user requested format.
            void collect_elements(std::vector<Element>& elements) const;
 
        private:
            // For simpler code, it is possible to save all data as properties of type PLY_LIST with value type double.
            // This can allow us to use a single callback function to handle all the properties. However, the
            // performance is not optimal. Thus, I process list properties and value properties separately.
            struct PlyProperty { 
                int orig_value_type;    // e.g., PLY_INT, PLY_FLOAT
            };
 
            struct ListProperty : PlyProperty, GenericProperty< std::vector<double> > {
                ListProperty(const std::string &elem_name, const std::string &prop_name)
                        : GenericProperty<std::vector<double> >(prop_name), element_name(elem_name) {}
                std::string element_name;
            };
 
            struct ValueProperty : PlyProperty, GenericProperty< double > {
                ValueProperty(const std::string &elem_name, const std::string &prop_name)
                        : GenericProperty<double>(prop_name), element_name(elem_name) {}
                std::string element_name;
            };
 
            std::vector< ListProperty* >    list_properties_;
            std::vector< ValueProperty* >   value_properties_;
        };
 
 
        class PlyWriter {
        public:
            static bool write(
                    const std::string &file_name,
                    const std::vector<Element> &elements,
                    const std::string &comment = "",
                    bool binary = false
            );
 
        };
 
        bool is_big_endian();
 
    } // namespace io
 
} // namespace easy3d
 
#endif  // EASY3D_FILEIO_PLY_READER_WRITER_H