StrawSurface.cpp

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// This file is part of the Acts project.
//
// Copyright (C) 2016-2020 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/Surfaces/StrawSurface.hpp"

#include "Acts/Geometry/GeometryObject.hpp"
#include "Acts/Geometry/Polyhedron.hpp"
#include "Acts/Surfaces/LineBounds.hpp"
#include "Acts/Surfaces/detail/FacesHelper.hpp"
#include "Acts/Surfaces/detail/VerticesHelper.hpp"

#include <algorithm>
#include <utility>
#include <vector>

Acts::StrawSurface::StrawSurface(const Transform3& transform, double radius,
                                 double halez)
    : GeometryObject(), LineSurface(transform, radius, halez) {}

Acts::StrawSurface::StrawSurface(const Transform3& transform,
                                 std::shared_ptr<const LineBounds> lbounds)
    : GeometryObject(), LineSurface(transform, std::move(lbounds)) {}

Acts::StrawSurface::StrawSurface(
    const std::shared_ptr<const LineBounds>& lbounds,
    const DetectorElementBase& detelement)
    : GeometryObject(), LineSurface(lbounds, detelement) {}

Acts::StrawSurface::StrawSurface(const Acts::StrawSurface& other)
    : GeometryObject(), LineSurface(other) {}

Acts::StrawSurface::StrawSurface(const GeometryContext& gctx,
                                 const StrawSurface& other,
                                 const Transform3& shift)
    : GeometryObject(), LineSurface(gctx, other, shift) {}

Acts::StrawSurface& Acts::StrawSurface::operator=(const StrawSurface& other) {
  if (this != &other) {
    LineSurface::operator=(other);
    m_bounds = other.m_bounds;
  }
  return *this;
}

Acts::Polyhedron Acts::StrawSurface::polyhedronRepresentation(
    const GeometryContext& gctx, size_t lseg) const {
  // Prepare vertices and faces
  std::vector<Vector3> vertices;
  std::vector<Polyhedron::FaceType> faces;
  std::vector<Polyhedron::FaceType> triangularMesh;

  const Transform3& ctransform = transform(gctx);
  // Draw the bounds if more than one segment are chosen
  if (lseg > 1) {
    double r = m_bounds->get(LineBounds::eR);
    auto phiSegs = detail::VerticesHelper::phiSegments();
    // Write the two bows/circles on either side
    std::vector<int> sides = {-1, 1};
    for (auto& side : sides) {
      for (size_t iseg = 0; iseg < phiSegs.size() - 1; ++iseg) {
        int addon = (iseg == phiSegs.size() - 2) ? 1 : 0;
        detail::VerticesHelper::createSegment(
            vertices, {r, r}, phiSegs[iseg], phiSegs[iseg + 1], lseg, addon,
            Vector3(0., 0., side * m_bounds->get(LineBounds::eHalfLengthZ)),
            ctransform);
      }
    }
    auto facesMesh = detail::FacesHelper::cylindricalFaceMesh(vertices);
    faces = facesMesh.first;
    triangularMesh = facesMesh.second;
  }

  size_t bvertices = vertices.size();
  Vector3 left(0, 0, -m_bounds->get(LineBounds::eHalfLengthZ));
  Vector3 right(0, 0, m_bounds->get(LineBounds::eHalfLengthZ));
  // The central wire/straw
  vertices.push_back(ctransform * left);
  vertices.push_back(ctransform * right);
  faces.push_back({bvertices, bvertices + 1});
  vertices.push_back(ctransform * Vector3(0., 0., 0.));
  triangularMesh.push_back({bvertices, bvertices + 2, bvertices + 1});

  return Polyhedron(vertices, faces, triangularMesh, false);
}