几种mesh 数据文件格式

几种mesh 数据文件格式

1、Ply格式

PLY - Polygon File Format (paulbourke.net)

2、Obj格式

http://paulbourke.net/dataformats/obj/   

https://people.cs.clemson.edu/~dhouse/courses/405/docs/brief-obj-file-format.html

 Read obj

/**
 * @file read_obj.cpp
 * @author your name (you@domain.com)
 * @brief
 * @version 0.1
 * @date 2022-08-22
 *
 * @copyright Copyright (c) 2022
 *
 */

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <vector>
#include <unordered_map>

int stringSplit(std::string &str, std::string &str1, std::string &str2)
{
    std::string::size_type pos;
    pos = str.find("/");
    if (pos != str.npos)
    {
        str1 = str.substr(0, pos);
        str2 = str.substr(pos + 1);
    }
    else
    {
        str1 = str;
        str2 = "";
    }

    return 0;
}

template <class PointType, class PointType2D>
int readObj(
    const std::string &in_path,
    const std::string &obj_file,
    std::vector<PointType> &out_vertces,
    std::vector<PointType2D> &out_uvs,
    std::vector<uint32_t> &out_tria,
    std::vector<uint32_t> &out_tria_uv,
    std::vector<int> &out_triangle_texture_ids,
    std::vector<std::string> &out_texture_names)
{
    // 0. read obj
    std::ifstream infile(in_path + "/" + obj_file);
    if (!infile.is_open())
    {
        std::cout << "open obj file failed ...\n";
        return -1;
    }

    std::vector<std::string> tex_names;
    std::string mtl_file;
    std::string Fline;
    while (getline(infile, Fline)) // Fline中不包括每行的换行符
    {
        std::string buf;
        std::stringstream ss(Fline);     // 字符流ss
        std::vector<std::string> tokens; // vector
        while (ss >> buf)                // stringstream  按空格分开字符输入
        {
            tokens.push_back(buf);
        }

        // mtl
        if (tokens.size() == 2 && tokens[0] == "mtllib")
        {
            mtl_file = tokens[1];
        }

        // vertex
        if (tokens.size() == 4 && tokens[0] == "v")
        {
            PointType pt;
            pt[0] = atof(tokens[1].c_str());
            pt[1] = atof(tokens[2].c_str());
            pt[2] = atof(tokens[3].c_str());
            out_vertces.emplace_back(pt);
        }

        // vt
        if (tokens.size() == 3 && tokens[0] == "vt")
        {
            PointType2D uv;
            uv[0] = atof(tokens[1].c_str());
            uv[1] = atof(tokens[2].c_str());
            out_uvs.emplace_back(uv);
        }

        // usemtl
        if (tokens.size() == 2 && tokens[0] == "usemtl")
        {
            tex_names.emplace_back(tokens[1]);
        }

        // face
        if (tokens.size() == 4 && tokens[0] == "f")
        {
            std::string str1, str2;

            stringSplit(tokens[1], str1, str2);
            out_tria.emplace_back(atoi(str1.c_str()));
            out_tria_uv.emplace_back(atoi(str2.c_str()));

            stringSplit(tokens[2], str1, str2);
            out_tria.emplace_back(atoi(str1.c_str()));
            out_tria_uv.emplace_back(atoi(str2.c_str()));

            stringSplit(tokens[3], str1, str2);
            out_tria.emplace_back(atoi(str1.c_str()));
            out_tria_uv.emplace_back(atoi(str2.c_str()));

            out_triangle_texture_ids.emplace_back(tex_names.size() - 1);
        }
    }
    infile.close();

    // 1. read stl
    std::ifstream stl_file(in_path + "/" + mtl_file);
    if (!stl_file.is_open())
    {
        std::cout << "open stl file failed ...\n";
        return -1;
    }

    std::unordered_map<std::string, std::string> stl_map;
    std::string tt;
    while (getline(stl_file, Fline)) // Fline中不包括每行的换行符
    {
        std::string buf;
        std::stringstream ss(Fline);     // 字符流ss
        std::vector<std::string> tokens; // vector
        while (ss >> buf)                // stringstream  按空格分开字符输入
        {
            tokens.push_back(buf);
        }

        if (tokens.size() == 2 && tokens[0] == "newmtl")
        {
            tt = tokens[1];
        }

        if (tokens.size() == 2 && tokens[0] == "map_Kd")
        {
            stl_map[tt] = tokens[1];
        }
    }
    stl_file.close();

    out_texture_names.resize(tex_names.size());
    for (int i = 0; i < tex_names.size(); i++)
    {
        /* code */
        if (stl_map.find(tex_names[i]) != stl_map.end())
        {
            out_texture_names[i] = stl_map[tex_names[i]];
        }
    }

    return 0;
}

/////////////////////////////////////////////////////////////////////////
class Point3D
{
public:
    /* data */
    double x, y, z;

    Point3D()
    {
    }

    double &operator[](uint32_t id)
    {
        if (id == 0)
        {
            return this->x;
        }
        else if (id == 1)
        {
            return this->y;
        }
        else if (id == 2)
        {
            return this->z;
        }
    }
};

class Point2D
{
public:
    /* data */
    double x, y;
    Point2D()
    {
    }

    double &operator[](uint32_t id)
    {
        if (id == 0)
        {
            return this->x;
        }
        else if (id == 1)
        {
            return this->y;
        }
    }
};

int main()
{
    std::string path = "C:/Users/86186/Desktop/test/LOD-0";
    std::string obj_file = "Mesh-XL-YL-XL-YL.obj";
    std::vector<Point3D> out_vertces;
    std::vector<Point2D> out_uvs;
    std::vector<uint32_t> out_tria;
    std::vector<uint32_t> out_tria_uv;
    std::vector<int> out_triangle_texture_ids;
    std::vector<std::string> out_texture_names;

    int ret = readObj<Point3D, Point2D>(
        path,
        obj_file,
        out_vertces,
        out_uvs,
        out_tria,
        out_tria_uv,
        out_triangle_texture_ids,
        out_texture_names);

    system("pause");
    return 0;
}