20_gen_dataset_ellipsoid_plane.cpp

This is an example of how to use the netdem library.

#include "contact_solver_factory.hpp"
#include "distribution_uniform.hpp"
#include "igl_wrapper.hpp"
#include "model_linear_spring.hpp"
#include "particle.hpp"
#include "shape_ellipsoid.hpp"
#include "shape_plane.hpp"
#include "solver_gjk_pw.hpp"
#include "spherical_voronoi.hpp"
#include "utils_math.hpp"
#include <fstream>
#include <iostream>
#include <random>
#include <sstream>
#include <string>
using namespace netdem;
using namespace std;
 
void SaveDatasetEllipsoidPlaneDetection(int num_samples, double (*ds_inputs)[4],
                                        bool *ds_cnt_flags, string filename) {
  stringbuf buf;
  ostream os(&buf);
  int os_width = 24;
  os.setf(ios::scientific);
  os.precision(15);
  for (int i = 0; i < num_samples; i++) {
    // write the data as one sample one row
    for (int i_inputs = 0; i_inputs < 4; i_inputs++) {
      os.width(os_width);
      os << ds_inputs[i][i_inputs] << ", ";
    }
    os.width(3);
    os << (ds_cnt_flags[i] ? 1 : 0) << endl;
  }
 
  ofstream outfile;
  outfile.open(filename);
  if (!outfile) {
    cout << "cannot open file: " << filename << endl;
  }
  outfile << buf.str();
  outfile.close();
  cout << "data saved to: " << filename << endl;
}
 
void SaveDatasetEllipsoidPlaneResolution(int num_samples,
                                         double (*ds_inputs)[4],
                                         double (*ds_cnt_feats)[4],
                                         string filename) {
  stringbuf buf;
  ostream os(&buf);
  int os_width = 24;
  os.setf(ios::scientific);
  os.precision(15);
  for (int i = 0; i < num_samples; i++) {
    // skip the non-contact data
    if (ds_cnt_feats[i][0] < 0)
      continue;
 
    // write the data as one sample one row
    for (int i_inputs = 0; i_inputs < 4; i_inputs++) {
      os.width(os_width);
      os << ds_inputs[i][i_inputs] << ", ";
    }
    for (int i_outputs = 0; i_outputs < 3; i_outputs++) {
      os.width(os_width);
      os << ds_cnt_feats[i][i_outputs] << ", ";
    }
    os.width(os_width);
    os << ds_cnt_feats[i][3] << endl;
  }
 
  ofstream outfile;
  outfile.open(filename);
  if (!outfile) {
    cout << "cannot open file: " << filename << endl;
  }
  outfile << buf.str();
  outfile.close();
  cout << "data saved to: " << filename << endl;
}
 
void GenDatasetEllipsoidPlane(int num_samples = 100) {
  // load particle
  Ellipsoid ellipsoid = Ellipsoid(1, 1, 2);
  ellipsoid.SetSize(1.0);
  Particle obj_p = Particle(&ellipsoid);
  cout << "particle created ... " << endl;
 
  // load wall
  Plane plane(0, 0, 0, 0, 0, 1);
  Wall obj_w = Wall(&plane);
  cout << "wall created ... " << endl;
 
  // allocate memory
  double(*ds_inputs)[4] = new double[num_samples][4];
  bool *ds_cnt_flags = new bool[num_samples];
  double(*ds_cnt_feats)[4] = new double[num_samples][4];
 
  // random generator
  UniformDistribution uniform_dist(0.0, 1.0);
 
  // use spherical centroidal voronoi to sample uniform unit VecXT
  VecXT<Vec3d> vertices = SphericalVoronoi::Solve(1000, 10000, 1.0e-4);
  VecXT<Vec3i> facets;
  IGLWrapper::ConvexHull(vertices, &vertices, &facets);
 
  // random cases
  for (int trial = 0, i = 0; trial < num_samples * 100; trial++) {
    // random normal
    int id_facet = floor(uniform_dist.Get() * facets.size());
    auto vert_0 = vertices[facets[id_facet][0]];
    auto vert_1 = vertices[facets[id_facet][1]];
    auto vert_2 = vertices[facets[id_facet][2]];
 
    double u_vert = uniform_dist.Get();
    double v_vert = uniform_dist.Get() * (1 - u_vert);
    double w_vert = 1 - u_vert - v_vert;
 
    Vec3d dir_n = u_vert * vert_0 + v_vert * vert_1 + w_vert * vert_2;
    Math::Normalize(&dir_n);
 
    // random distance
    Vec3d sup_pos, sup_dir{-dir_n[0], -dir_n[1], -dir_n[2]};
    sup_pos = ellipsoid.SupportPoint(sup_dir);
    double dist_sup = -Math::Dot(dir_n, sup_pos);
 
    // use this to control the ratio of contact and non-contact cases
    double cnt_prob = uniform_dist.Get();
    double dist_min = cnt_prob > 0.6 ? dist_sup - 0.05 : dist_sup;
    double dist_max = cnt_prob > 0.6 ? dist_sup : ellipsoid.GetBoundSphereRadius();
    double dist_pc_to_plane =
        dist_min + uniform_dist.Get() * (dist_max - dist_min);
    double len_n = dist_sup - dist_pc_to_plane;
 
    // transform the inputs to the wall position and rotation
    // this is only for verification. No need to do this in contact solver
    Vec3d dir_n_ref{0, 0, 1}, rot_axis;
    rot_axis = Math::Cross(dir_n_ref, dir_n);
 
    Vec4d quat;
    quat[0] = 1 + Math::Dot(dir_n, dir_n_ref);
    quat[1] = rot_axis[0];
    quat[2] = rot_axis[1];
    quat[3] = rot_axis[2];
    Math::Quaternion::Normalize(&quat);
 
    obj_w.SetPosition(-dist_pc_to_plane * dir_n[0],
                      -dist_pc_to_plane * dir_n[1],
                      -dist_pc_to_plane * dir_n[2]);
    obj_w.SetQuaternion(quat[0], quat[1], quat[2], quat[3]);
 
    if (len_n <= 0) {
      // use distance from particle centroid to plane and plane normal as inputs
      ds_inputs[i][0] = dist_pc_to_plane;
      ds_inputs[i][1] = dir_n[0];
      ds_inputs[i][2] = dir_n[1];
      ds_inputs[i][3] = dir_n[2];
 
      // contact status
      ds_cnt_flags[i] = 0;
 
      // volume and directional cross-section area of intersection as outputs
      ds_cnt_feats[i][0] = -1;
      ds_cnt_feats[i][1] = -1;
      ds_cnt_feats[i][2] = -1;
      ds_cnt_feats[i][3] = -1;
 
      i++;
    } else {
      // use distance from particle centroid to plane and plane normal as inputs
      ds_inputs[i][0] = dist_pc_to_plane;
      ds_inputs[i][1] = dir_n[0];
      ds_inputs[i][2] = dir_n[1];
      ds_inputs[i][3] = dir_n[2];
 
      // contact status
      ds_cnt_flags[i] = 1;
 
      // volume and directional cross-section area of intersection as outputs
      ds_cnt_feats[i][0] = len_n;
      ds_cnt_feats[i][1] = sup_pos[0] + 0.5 * len_n * dir_n[0];
      ds_cnt_feats[i][2] = sup_pos[1] + 0.5 * len_n * dir_n[1];
      ds_cnt_feats[i][3] = sup_pos[2] + 0.5 * len_n * dir_n[2];
 
      // SolverGJKPW cnt_solver;
      // LinearSpring cnt_model;
      // cnt_solver.Init(&obj_p, &obj_w);
      // auto cnt = ContactPW(&obj_p, &obj_w);
      // cnt.SetCollisionModel(&cnt_model);
      // cnt_solver.Detect();
      // cnt_solver.ResolveInit(&cnt, 1.0e-4);
      // auto &cnt_geoms = cnt.collision_entries[0].cnt_geoms;
 
      // cout << cnt_geoms.len_n << ", " << cnt_geoms.pos[0] << ", "
      //      << cnt_geoms.pos[1] << ", " << cnt_geoms.pos[2] << endl;
 
      // cout << ds_cnt_feats[i][0] << ", " << ds_cnt_feats[i][1] << ", "
      //      << ds_cnt_feats[i][2] << ", " << ds_cnt_feats[i][3] << endl;
 
      i++;
    }
 
    if (((i + 1) % 100) == 0) {
      cout << "number of samples: " << i + 1 << " ..." << endl;
    }
    if (i >= num_samples) {
      break;
    }
  }
 
  string root_dir = "local/examples/netdem/ann_models/ellipsoid_plane/";
  SaveDatasetEllipsoidPlaneDetection(num_samples, ds_inputs, ds_cnt_flags,
                                     root_dir + "dataset_detection.txt");
  SaveDatasetEllipsoidPlaneResolution(num_samples, ds_inputs, ds_cnt_feats,
                                      root_dir + "dataset_resolution.txt");
 
  delete[] ds_inputs;
  delete[] ds_cnt_flags;
  delete[] ds_cnt_feats;
}