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FacesHelper.hpp
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1 // This file is part of the Acts project.
2 //
3 // Copyright (C) 2020 CERN for the benefit of the Acts project
4 //
5 // This Source Code Form is subject to the terms of the Mozilla Public
6 // License, v. 2.0. If a copy of the MPL was not distributed with this
7 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 
9 #pragma once
10 
13 
14 #include <numeric>
15 #include <utility>
16 #include <vector>
17 
18 namespace Acts {
19 
20 namespace detail {
21 
23 struct FacesHelper {
24  using FaceVector = std::vector<Polyhedron::FaceType>;
25 
34  static std::pair<FaceVector, FaceVector> convexFaceMesh(
35  const std::vector<Vector3D>& vertices, bool centerLast = false) {
36  FaceVector faces;
37  FaceVector triangularMesh;
38  // Write the face
39  unsigned int offset = centerLast ? 1 : 0;
40  std::vector<size_t> face(vertices.size() - offset);
41  std::iota(face.begin(), face.end(), 0);
42  faces.push_back(face);
44  unsigned int anker = centerLast ? vertices.size() - 1 : 0;
45  for (unsigned int it = 2 - offset; it < vertices.size() - offset; ++it) {
46  triangularMesh.push_back({anker, it - 1, it});
47  }
48  // Close for centered reference point
49  if (centerLast) {
50  triangularMesh.push_back({anker, vertices.size() - 2, 0});
51  }
52  return {faces, triangularMesh};
53  }
54 
66  static std::pair<FaceVector, FaceVector> cylindricalFaceMesh(
67  const std::vector<Vector3D>& vertices, bool fullTwoPi = true) {
68  FaceVector faces;
69  FaceVector triangularMesh;
70  size_t nqfaces = 0.5 * vertices.size();
71  size_t reduce = (not fullTwoPi) ? 1 : 0;
72  for (size_t iface = 0; iface < nqfaces - reduce; ++iface) {
73  size_t p2 = (iface + 1 == nqfaces) ? 0 : iface + 1;
74  std::vector<size_t> face = {iface, p2, p2 + nqfaces, nqfaces + iface};
75  faces.push_back(face);
76  std::vector<size_t> triA = {iface, p2, p2 + nqfaces};
77  triangularMesh.push_back(triA);
78  std::vector<size_t> triB = {p2 + nqfaces, nqfaces + iface, iface};
79  triangularMesh.push_back(triB);
80  }
81  return {faces, triangularMesh};
82  }
83 };
84 
85 } // namespace detail
86 
87 } // namespace Acts