PlaneSurface.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/PlaneSurface.hpp"

#include "Acts/Surfaces/EllipseBounds.hpp"
#include "Acts/Surfaces/InfiniteBounds.hpp"
#include "Acts/Surfaces/RectangleBounds.hpp"
#include "Acts/Surfaces/SurfaceError.hpp"
#include "Acts/Surfaces/detail/FacesHelper.hpp"
#include "Acts/Utilities/ThrowAssert.hpp"

#include <cmath>
#include <iomanip>
#include <iostream>
#include <numeric>

Acts::PlaneSurface::PlaneSurface(const PlaneSurface& other)
    : GeometryObject(), Surface(other), m_bounds(other.m_bounds) {}

Acts::PlaneSurface::PlaneSurface(const GeometryContext& gctx,
                                 const PlaneSurface& other,
                                 const Transform3D& shift)
    : GeometryObject(), Surface(gctx, other, shift), m_bounds(other.m_bounds) {}

Acts::PlaneSurface::PlaneSurface(const Vector3D& center, const Vector3D& normal)
    : Surface(), m_bounds(nullptr) {
  Vector3D T = normal.normalized();
  Vector3D U = std::abs(T.dot(Vector3D::UnitZ())) < s_curvilinearProjTolerance
                   ? Vector3D::UnitZ().cross(T).normalized()
                   : Vector3D::UnitX().cross(T).normalized();
  Vector3D V = T.cross(U);
  RotationMatrix3D curvilinearRotation;
  curvilinearRotation.col(0) = U;
  curvilinearRotation.col(1) = V;
  curvilinearRotation.col(2) = T;

  // curvilinear surfaces are boundless
  m_transform = Transform3D{curvilinearRotation};
  m_transform.pretranslate(center);
}

Acts::PlaneSurface::PlaneSurface(
    const std::shared_ptr<const PlanarBounds>& pbounds,
    const Acts::DetectorElementBase& detelement)
    : Surface(detelement), m_bounds(pbounds) {
  throw_assert(pbounds, "PlaneBounds must not be nullptr");
}

Acts::PlaneSurface::PlaneSurface(const Transform3D& transform,
                                 std::shared_ptr<const PlanarBounds> pbounds)
    : Surface(transform), m_bounds(std::move(pbounds)) {}

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

Acts::Surface::SurfaceType Acts::PlaneSurface::type() const {
  return Surface::Plane;
}

Acts::Vector3D Acts::PlaneSurface::localToGlobal(
    const GeometryContext& gctx, const Vector2D& lposition,
    const Vector3D& /*unused*/) const {
  return transform(gctx) *
         Vector3D(lposition[Acts::eBoundLoc0], lposition[Acts::eBoundLoc1], 0.);
}

Acts::Result<Acts::Vector2D> Acts::PlaneSurface::globalToLocal(
    const GeometryContext& gctx, const Vector3D& position,
    const Vector3D& /*unused*/) const {
  Vector3D loc3Dframe = transform(gctx).inverse() * position;
  if (loc3Dframe.z() * loc3Dframe.z() >
      s_onSurfaceTolerance * s_onSurfaceTolerance) {
    return Result<Vector2D>::failure(SurfaceError::GlobalPositionNotOnSurface);
  }
  return Result<Vector2D>::success({loc3Dframe.x(), loc3Dframe.y()});
}

std::string Acts::PlaneSurface::name() const {
  return "Acts::PlaneSurface";
}

const Acts::SurfaceBounds& Acts::PlaneSurface::bounds() const {
  if (m_bounds) {
    return (*m_bounds.get());
  }
  return s_noBounds;
}

Acts::Polyhedron Acts::PlaneSurface::polyhedronRepresentation(
    const GeometryContext& gctx, size_t lseg) const {
  // Prepare vertices and faces
  std::vector<Vector3D> vertices;
  std::vector<Polyhedron::FaceType> faces;
  std::vector<Polyhedron::FaceType> triangularMesh;
  bool exactPolyhedron = true;

  // If you have bounds you can create a polyhedron representation
  if (m_bounds) {
    auto vertices2D = m_bounds->vertices(lseg);
    vertices.reserve(vertices2D.size() + 1);
    for (const auto& v2D : vertices2D) {
      vertices.push_back(transform(gctx) * Vector3D(v2D.x(), v2D.y(), 0.));
    }
    bool isEllipse = bounds().type() == SurfaceBounds::eEllipse;
    bool innerExists = false, coversFull = false;
    if (isEllipse) {
      exactPolyhedron = false;
      auto vStore = bounds().values();
      innerExists = vStore[EllipseBounds::eInnerRx] > s_epsilon and
                    vStore[EllipseBounds::eInnerRy] > s_epsilon;
      coversFull =
          std::abs(vStore[EllipseBounds::eHalfPhiSector] - M_PI) < s_epsilon;
    }
    // All of those can be described as convex
    // @todo same as for Discs: coversFull is not the right criterium
    // for triangulation
    if (not isEllipse or not innerExists or not coversFull) {
      auto facesMesh = detail::FacesHelper::convexFaceMesh(vertices);
      faces = facesMesh.first;
      triangularMesh = facesMesh.second;
    } else {
      // Two concentric rings, we use the pure concentric method momentarily,
      // but that creates too  many unneccesarry faces, when only two
      // are needed to descibe the mesh, @todo investigate merging flag
      auto facesMesh = detail::FacesHelper::cylindricalFaceMesh(vertices, true);
      faces = facesMesh.first;
      triangularMesh = facesMesh.second;
    }
  } else {
    throw std::domain_error(
        "Polyhedron repr of boundless surface not possible.");
  }
  return Polyhedron(vertices, faces, triangularMesh, exactPolyhedron);
}