libigl_Martin/tutorial/201_Normals/main.cpp

#include <igl/readOFF.h>
#include <igl/viewer/Viewer.h>
#include <igl/per_vertex_normals.h>
#include <igl/per_face_normals.h>
#include <igl/per_corner_normals.h>

Eigen::MatrixXd V;
Eigen::MatrixXi F;

Eigen::MatrixXd N_vertices;
Eigen::MatrixXd N_faces;
Eigen::MatrixXd N_corners;


// This function is called every time a keyboard button is pressed
bool key_down(igl::Viewer& viewer, unsigned char key, int modifier)
{
  if (key == '1')
    viewer.set_normals(N_vertices);

  if (key == '2')
    viewer.set_normals(N_faces);

  if (key == '3')
    viewer.set_normals(N_corners);

  return false;
}

int main(int argc, char *argv[])
{
  // Load a mesh in OFF format
  igl::readOFF("../shared/fandisk.off", V, F);

  // Compute per-vertex normals
  igl::per_vertex_normals(V,F,N_vertices);

  // Compute per-face normals
  igl::per_face_normals(V,F,N_faces);

  // Compute per-corner normals
  igl::per_corner_normals(V,F,20,N_corners);

  // Plot the mesh
  igl::Viewer viewer;
  viewer.callback_key_down = &key_down;
  viewer.set_mesh(V, F);
  viewer.set_normals(N_vertices);
  viewer.launch();
}