ConvexPolygonBounds.ipp

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// This file is part of the Acts project.
//
// Copyright (C) 2019 CERN for the benefit of the Acts project
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include "Acts/Utilities/ThrowAssert.hpp"

template <typename coll_t>
void Acts::ConvexPolygonBoundsBase::convex_impl(
    const coll_t& vertices) noexcept(false) {
  static_assert(std::is_same<typename coll_t::value_type, Vector2>::value,
                "Must be collection of Vector2");

  const size_t N = vertices.size();
  for (size_t i = 0; i < N; i++) {
    size_t j = (i + 1) % N;
    const Vector2& a = vertices[i];
    const Vector2& b = vertices[j];

    const Vector2 ab = b - a;
    const Vector2 normal = Vector2(ab.y(), -ab.x()).normalized();

    bool first = true;
    bool ref = false;
    // loop over all other vertices
    for (size_t k = 0; k < N; k++) {
      if (k == i || k == j) {
        continue;
      }

      const Vector2& c = vertices[k];
      double dot = normal.dot(c - a);

      if (first) {
        ref = std::signbit(dot);
        first = false;
        continue;
      }

      if (std::signbit(dot) != ref) {
        throw std::logic_error(
            "ConvexPolygon: Given vertices do not form convex hull");
      }
    }
  }
}

template <typename coll_t>
Acts::RectangleBounds Acts::ConvexPolygonBoundsBase::makeBoundingBox(
    const coll_t& vertices) {
  Vector2 vmax, vmin;
  vmax = vertices[0];
  vmin = vertices[0];

  for (size_t i = 1; i < vertices.size(); i++) {
    vmax = vmax.cwiseMax(vertices[i]);
    vmin = vmin.cwiseMin(vertices[i]);
  }

  return {vmin, vmax};
}

template <int N>
Acts::ConvexPolygonBounds<N>::ConvexPolygonBounds(
    const std::vector<Acts::Vector2>& vertices) noexcept(false)
    : m_vertices(), m_boundingBox(makeBoundingBox(vertices)) {
  throw_assert(vertices.size() == N,
               "Size and number of given vertices do not match.");
  for (size_t i = 0; i < N; i++) {
    m_vertices[i] = vertices[i];
  }
  checkConsistency();
}

template <int N>
Acts::ConvexPolygonBounds<N>::ConvexPolygonBounds(
    const vertex_array& vertices) noexcept(false)
    : m_vertices(vertices), m_boundingBox(makeBoundingBox(vertices)) {
  checkConsistency();
}

template <int N>
Acts::ConvexPolygonBounds<N>::ConvexPolygonBounds(
    const value_array& values) noexcept(false)
    : m_vertices(), m_boundingBox(0., 0.) {
  for (size_t i = 0; i < N; i++) {
    m_vertices[i] = Vector2(values[2 * i], values[2 * i + 1]);
  }
  makeBoundingBox(m_vertices);
  checkConsistency();
}

template <int N>
Acts::SurfaceBounds::BoundsType Acts::ConvexPolygonBounds<N>::type() const {
  return SurfaceBounds::eConvexPolygon;
}

template <int N>
bool Acts::ConvexPolygonBounds<N>::inside(
    const Acts::Vector2& lposition, const Acts::BoundaryCheck& bcheck) const {
  return bcheck.isInside(lposition, m_vertices);
}

template <int N>
std::vector<Acts::Vector2> Acts::ConvexPolygonBounds<N>::vertices(
    unsigned int /*lseg*/) const {
  return {m_vertices.begin(), m_vertices.end()};
}

template <int N>
const Acts::RectangleBounds& Acts::ConvexPolygonBounds<N>::boundingBox() const {
  return m_boundingBox;
}

template <int N>
void Acts::ConvexPolygonBounds<N>::checkConsistency() const noexcept(false) {
  convex_impl(m_vertices);
}