bound_voxel.cpp

//!Makefile, replace $USER with your name
//INC=-I/home/$USER/libs/libigl/include -I/home/$USER/libs/eigen3
//all:
//	g++ -std=c++11 $(INC) voxel.cpp -o voxel.out

#include <igl/bounding_box.h>
#include <igl/readOBJ.h>
#include <igl/writeOFF.h>
#include <string>
#include <vector>

using namespace Eigen;
using namespace std;

void push_vertex(double x, double y, double z, double len, vector<Vector3d> &list) {
    for(size_t i=0;i<2;++i)
        for(size_t j=0;j<2;++j)
            for(size_t k=0;k<2;++k){
                list.emplace_back(x + i*len, y + j*len, z + k*len);
            }
}

void push_face(size_t cnt, vector<Vector3i> &list) {
    size_t begin = list.size();
    list.emplace_back(0, 1, 2);
    list.emplace_back(1, 3, 2);
    list.emplace_back(0, 4, 1);
    list.emplace_back(1, 4, 5);
    list.emplace_back(4, 7, 5);
    list.emplace_back(7, 4, 6);
    list.emplace_back(1, 5, 7);
    list.emplace_back(1, 7, 3);
    list.emplace_back(6, 3, 7);
    list.emplace_back(6, 2, 3);
    list.emplace_back(6, 4, 0);
    list.emplace_back(6, 0, 2);
    for(size_t i=begin;i<begin+12;++i){
        list[i][0] += 8 *cnt;
        list[i][1] += 8 *cnt;
        list[i][2] += 8 *cnt;
    }
}

template<class S, class T>
void stdvec_to_eigen(const S& src, T& dst){
    for(size_t i=0;i < src.size(); ++i){
        dst(i, 0) = src[i][0];
        dst(i, 1) = src[i][1];
        dst(i, 2) = src[i][2];
    }
}

int main(int argc, char *argv[]){
    MatrixXd V, F;
    igl::readOBJ(argv[1], V, F);
    MatrixXd BV, BF;
    igl::bounding_box(V, BV, BF);
    
    double len = stod(argv[2]);
    
    vector<Vector3d> vlist;
    vector<Vector3i> flist;
    size_t cnt = 0;
    for(double x = BV(7, 0); x + len <= BV(0, 0); x += len)
        for(double y = BV(7, 1); y + len <= BV(0, 1); y += len)
            for(double z = BV(7, 2); z + len <= BV(0, 2); z += len, ++cnt) {
                push_vertex(x, y, z, len, vlist);
                push_face(cnt, flist);
            }
    MatrixXd OV(vlist.size(), 3);
    MatrixXi OF(flist.size(), 3);

    stdvec_to_eigen(vlist, OV);
    stdvec_to_eigen(flist, OF);

    igl::writeOFF(argv[3], OV, OF);

    return 0;
}