#include <igl/opengl/glfw/Viewer.h>
#include <igl/isolines.h>
int main(int argc, char *argv[])
{
  // Inline mesh of a cube
  const Eigen::MatrixXd V= (Eigen::MatrixXd(8,3)<<
    0.0,0.0,0.0,
    0.0,0.0,1.0,
    0.0,1.0,0.0,
    0.0,1.0,1.0,
    1.0,0.0,0.0,
    1.0,0.0,1.0,
    1.0,1.0,0.0,
    1.0,1.0,1.0).finished();
  const Eigen::MatrixXi F = (Eigen::MatrixXi(12,3)<<
    1,7,5,
    1,3,7,
    1,4,3,
    1,2,4,
    3,8,7,
    3,4,8,
    5,7,8,
    5,8,6,
    1,5,6,
    1,6,2,
    2,6,8,
    2,8,4).finished().array()-1;
    
    Eigen::VectorXd f(8);
    Eigen::Vector3d dir(1.0,1.0,1.0);
    for(int i=0; i<8; i++)
    {
        f[i] = V.row(i).dot(dir);
    }
    Eigen::MatrixXd isoV;
    Eigen::MatrixXi isoE;
    igl::isolines(V, F, f, 1, isoV, isoE);   
    Eigen::MatrixXd C(isoE.rows(), 3);
    C.col(0).setConstant(1.0);
    C.col(1).setZero();
    C.col(2).setZero(); 
    
    std::cout << "Isoline vertices: " << isoV << std::endl;
    std::cout << "Isoline edges: " << isoE << std::endl;

  // Plot the mesh
  igl::opengl::glfw::Viewer viewer;
  viewer.data().set_mesh(V, F);
  viewer.data().set_face_based(true);
  viewer.data().set_edges(isoV, isoE, C);
  viewer.launch();
}