mesh.cpp

#include "mesh.h"

#include <iostream>
#include <fstream>

#include <QFileInfo>
#include <QString>

#define TINYOBJLOADER_IMPLEMENTATION
#include "util/tiny_obj_loader.h"

using namespace Eigen;
using namespace std;

void Mesh::initFromVectors(const vector<Vector3f> &vertices,
                           const vector<Vector3i> &faces)
{
    // Copy vertices and faces into internal vector
    _vertices = vertices;
    _faces    = faces;
}

void Mesh::loadFromFile(const string &filePath)
{
    tinyobj::attrib_t attrib;
    vector<tinyobj::shape_t> shapes;
    vector<tinyobj::material_t> materials;

    QFileInfo info(QString(filePath.c_str()));
    string err;
    bool ret = tinyobj::LoadObj(&attrib, &shapes, &materials, &err,
                                info.absoluteFilePath().toStdString().c_str(), (info.absolutePath().toStdString() + "/").c_str(), true);
    if (!err.empty()) {
        cerr << err << endl;
    }

    if (!ret) {
        cerr << "Failed to load/parse .obj file" << endl;
        return;
    }

    for (size_t s = 0; s < shapes.size(); s++) {
        size_t index_offset = 0;
        for (size_t f = 0; f < shapes[s].mesh.num_face_vertices.size(); f++) {
            unsigned int fv = shapes[s].mesh.num_face_vertices[f];

            Vector3i face;
            for (size_t v = 0; v < fv; v++) {
                tinyobj::index_t idx = shapes[s].mesh.indices[index_offset + v];

                face[v] = idx.vertex_index;
            }
            _faces.push_back(face);

            index_offset += fv;
        }
    }
    for (size_t i = 0; i < attrib.vertices.size(); i += 3) {
        _vertices.emplace_back(attrib.vertices[i], attrib.vertices[i + 1], attrib.vertices[i + 2]);
    }
    cout << "Loaded " << _faces.size() << " faces and " << _vertices.size() << " vertices" << endl;
}

void Mesh::saveToFile(const string &filePath)
{
    ofstream outfile;
    outfile.open(filePath);

    // Write vertices
    for (size_t i = 0; i < _vertices.size(); i++)
    {
        const Vector3f &v = _vertices[i];
        outfile << "v " << v[0] << " " << v[1] << " " << v[2] << endl;
    }

    // Write faces
    for (size_t i = 0; i < _faces.size(); i++)
    {
        const Vector3i &f = _faces[i];
        outfile << "f " << (f[0]+1) << " " << (f[1]+1) << " " << (f[2]+1) << endl;
    }

    outfile.close();
}