00_gen_dataset_trimesh_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_volume_based.hpp"
#include "particle.hpp"
#include "shape_trimesh.hpp"
#include "solver_boolean_pp.hpp"
#include "solver_boolean_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 SaveDatasetTrimeshPlaneDetection(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 SaveDatasetTrimeshPlaneResolution(int num_samples, double (*ds_inputs)[4],
                                       double (*ds_cnt_feats)[5],
                                       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 < 4; i_outputs++) {
      os.width(os_width);
      os << ds_cnt_feats[i][i_outputs] << ", ";
    }
    os.width(os_width);
    os << ds_cnt_feats[i][4] << 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 GenDatasetTrimeshPlane(int num_samples = 100) {
  // load particle
  TriMesh tri_mesh_1;
  tri_mesh_1.InitFromSTL("data/particle_template.stl");
  tri_mesh_1.Decimate(200);
  tri_mesh_1.AlignAxes();
  tri_mesh_1.SetSize(1.0);
  Particle obj_p = Particle(&tri_mesh_1);
  obj_p.need_update_stl_model = true;
  cout << "particle created ... " << endl;
 
  // load wall (use trimesh as a substitute of plane to generate the dataset)
  // because the contact detection and resolution between trimesh and plane is
  // not implemented
  TriMesh tri_mesh_2;
  tri_mesh_2.InitFromSTL("data/plate_z0.stl");
  Wall obj_w = Wall(&tri_mesh_2);
  obj_w.need_update_stl_model = true;
  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)[5] = new double[num_samples][5];
 
  // use bound sphere to narrow down the random space
  double dist_max = obj_p.shape->GetBoundSphereRadius() * 1.1;
  double dist_min{dist_max};
  for (auto &vert : tri_mesh_1.vertices) {
    dist_min = min(Math::NormL2(vert), dist_min);
  }
  dist_min *= 0.9;
  double dist_range = dist_max - dist_min;
 
  // 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);
 
  // the solver and dummy contact model
  SolverBooleanPW cnt_solver;
  VolumeBased cnt_model;
 
  // random cases
  for (int trial = 0, i = 0; trial < num_samples * 100; trial++) {
    // random direction
    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;
    dir_n[0] = u_vert * vert_0[0] + v_vert * vert_1[0] + w_vert * vert_2[0];
    dir_n[1] = u_vert * vert_0[1] + v_vert * vert_1[1] + w_vert * vert_2[1];
    dir_n[2] = u_vert * vert_0[2] + v_vert * vert_1[2] + w_vert * vert_2[2];
    Math::Normalize(&dir_n);
 
    // random position
    double dist_pc_to_plane = dist_min + uniform_dist.Get() * dist_range;
 
    // obtain the rotation quaternion for the wall (currently, the wall is
    // represented by trimesh, thus need to convert dir_n and dist to the
    // rotation quaternion of the wall. The benchmark solution is based on
    // boolean operation.)
    Vec3d dir_n_ref{0, 0, 1};
    Vec3d 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);
 
    // update the wall with random position and rotation
    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]);
 
    // contact detection and resolution
    cnt_solver.Init(&obj_p, &obj_w);
    bool cnt_flag = cnt_solver.Detect();
 
    if (!cnt_flag) {
      // 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] = cnt_flag;
 
      // 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;
      ds_cnt_feats[i][4] = -1;
 
      i++;
    } else {
      auto cnt = ContactPW(&obj_p, &obj_w);
      cnt.SetCollisionModel(&cnt_model);
      cnt_solver.ResolveInit(&cnt, 1.0e-4);
      auto &cnt_geoms = cnt.collision_entries[0].cnt_geoms;
 
      // skip the contact if overlap is too large
      if (cnt_geoms.vol * cnt_geoms.sn > 6.0e-4)
        continue;
 
      // 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] = cnt_flag;
 
      // volume and directional cross-section area of intersection as outputs
      ds_cnt_feats[i][0] = cnt_geoms.vol;
      ds_cnt_feats[i][1] = cnt_geoms.sn;
      ds_cnt_feats[i][2] = cnt_geoms.pos[0];
      ds_cnt_feats[i][3] = cnt_geoms.pos[1];
      ds_cnt_feats[i][4] = cnt_geoms.pos[2];
 
      // cout << ds_inputs[i][0] << ", " << ds_inputs[i][1] << ", "
      //      << ds_inputs[i][2] << ", " << ds_inputs[i][3] << endl;
 
      // cout << ds_cnt_feats[i][0] << ", " << ds_cnt_feats[i][1] << ", "
      //      << ds_cnt_feats[i][2] << ", " << ds_cnt_feats[i][3] << ", "
      //      << ds_cnt_feats[i][4] << 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/trimesh_plane/";
  SaveDatasetTrimeshPlaneDetection(num_samples, ds_inputs, ds_cnt_flags,
                                   root_dir + "dataset_detection.txt");
 
  SaveDatasetTrimeshPlaneResolution(num_samples, ds_inputs, ds_cnt_feats,
                                    root_dir + "dataset_resolution.txt");
 
  delete[] ds_inputs;
  delete[] ds_cnt_flags;
  delete[] ds_cnt_feats;
}