File Navigator.hpp

namespace Acts

Note

This file is foreseen for the Geometry module to replace Extent

template<typename object_t>
struct NavigationOptions
#include <Acts/Geometry/Layer.hpp>
class Navigator
#include <Acts/Propagator/Navigator.hpp>

Navigator class.

This is an Actor to be added to the ActorList in order to navigate through the static tracking geometry setup.

The current navigation stage is cached in the state struct and updated when necessary. If any surface in the extrapolation flow is hit, it is set to the propagation satate, such that other actors can deal wit it. This navigation actor thus always needs to run first! It does two things: it figures out the order of volumes, layers and surfaces. For each propagation step, the operator() runs, which checks if the current surface (or layer/volume boundary) is reached.

The current target surface is the surface pointed to by of the iterators for the surfaces, layers or volume boundaries. If a surface is found, the state.navigation.currentSurface pointer is set. This enables subsequent actors to react. Secondly, this actor uses the ordered iterators to figure out which surface, layer or volume boundary is supposed to be hit next. It then sets the maximum step size to the path length found out by straight line intersection. If the state is not on surface, it also re-computes the step size, to make sure we end up at the desired surface.

Public Types

using ExternalSurfaces = std::multimap<uint64_t, GeometryIdentifier>
using NavigationBoundaries = boost::container::small_vector<BoundaryIntersection, 4>
using NavigationBoundaryIter = NavigationBoundaries::iterator
using NavigationLayerIter = NavigationLayers::iterator
using NavigationLayers = boost::container::small_vector<LayerIntersection, 10>
using NavigationSurfaceIter = NavigationSurfaces::iterator
using NavigationSurfaces = boost::container::small_vector<SurfaceIntersection, 10>
enum Stage

The navigation stage.

Values:

enumerator undefined
enumerator surfaceTarget
enumerator layerTarget
enumerator boundaryTarget
using SurfaceIter = std::vector<const Surface*>::iterator
using Surfaces = std::vector<const Surface*>

Public Functions

inline explicit Navigator(Config cfg)

Constructor with configuration object.

Parameters

cfg – The navigator configuration

template<typename propagator_state_t, typename stepper_t>
inline void status(propagator_state_t &state, const stepper_t &stepper) const

Navigator status call, will be called in two modes.

(a) It initializes the Navigation stream if start volume is not yet defined:

  • initialize the volume

  • establish the start layer and start volume

  • set the current surface to the start surface

(b) It establishes the currentSurface status during the propagation flow, currentSurface can be

  • surfaces still to be handled within a layer

  • layers still to be handled within a volume

  • boundaries still to be handled to exit a volume

Template Parameters
  • propagator_state_t – is the type of Propagatgor state

  • stepper_t – is the used type of the Stepper by the Propagator

Parameters
  • state[inout] is the mutable propagator state object

  • stepper[in] Stepper in use

template<typename propagator_state_t, typename stepper_t>
inline void target(propagator_state_t &state, const stepper_t &stepper) const

Navigator target call.

Call options (a) there are still surfaces to be resolved: handle those (b) there no surfaces but still layers to be resolved, handle those (c) there are no surfaces nor layers to be resolved, handle boundary

Template Parameters
  • propagator_state_t – is the type of Propagatgor state

  • stepper_t – is the used type of the Stepper by the Propagator

Parameters
  • state[inout] is the mutable propagator state object

  • stepper[in] Stepper in use

Private Functions

template<typename propagator_state_t, typename stepper_t>
inline bool inactive(propagator_state_t &state, const stepper_t &stepper) const

Inactive

This checks if a navigation break had been triggered or navigator is misconfigured

boolean return triggers exit to stepper

Template Parameters
  • propagator_state_t – The state type of the propagagor

  • stepper_t – The type of stepper used for the propagation

Parameters
  • state[inout] is the propagation state object

  • stepper[in] Stepper in use

template<typename propagator_state_t, typename stepper_t>
inline void initialize(propagator_state_t &state, const stepper_t &stepper) const

Initialize call - start of propagation

Template Parameters
  • propagator_state_t – The state type of the propagagor

  • stepper_t – The type of stepper used for the propagation

Parameters
  • state[inout] is the propagation state object

  • stepper[in] Stepper in use

Returns

boolean return triggers exit to stepper

template<typename propagator_state_t, typename stepper_t>
inline void initializeTarget(propagator_state_t &state, const stepper_t &stepper) const

Navigation (re-)initialisation for the target

This is only called a few times every propagation/extrapolation

As a straight line estimate can lead you to the wrong destination Volume, this will be called at:

  • initialization

  • attempted volume switch Target finding by association will not be done again

boolean return triggers exit to stepper

Template Parameters
  • propagator_state_t – The state type of the propagagor

  • stepper_t – The type of stepper used for the propagation

Parameters
  • state[inout] is the propagation state object

  • stepper[in] Stepper in use

template<typename propagator_state_t, typename stepper_t>
inline bool resolveLayers(propagator_state_t &state, const stepper_t &stepper) const

Navigation through layers

Resolve layers.

This initializes the layer candidates when starting or when entering a new volume

Template Parameters
  • propagator_state_t – The state type of the propagagor

  • stepper_t – The type of stepper used for the propagation

Parameters
  • state[inout] is the propagation state object

  • stepper[in] Stepper in use

Returns

boolean return triggers exit to stepper

template<typename propagator_state_t, typename stepper_t>
inline bool resolveSurfaces(propagator_state_t &state, const stepper_t &stepper, const Layer *cLayer = nullptr) const

Resolve the surfaces of this layer.

boolean return triggers exit to stepper

Template Parameters
  • propagator_state_t – The state type of the propagagor

  • stepper_t – The type of stepper used for the propagation

Parameters
  • state[inout] is the propagation state object

  • stepper[in] Stepper in use

  • cLayer[in] is the already assigned current layer, e.g. start layer

template<typename propagator_state_t, typename stepper_t, typename navigation_surfaces_t, typename navigation_iter_t>
inline bool status(propagator_state_t &state, const stepper_t &stepper, navigation_surfaces_t &navSurfaces, const navigation_iter_t &navIter) const

Status call for test surfaces (surfaces, layers, boundaries)

If there are surfaces to be handled, check if the current state is on the surface

Template Parameters
  • propagator_state_t – The state type of the propagagor

  • stepper_t – The type of stepper used for the propagation

  • navigation_surfaces_t – Type of the propagagor

  • navigation_iter_t – Type of the navigation iterator

Parameters
  • state[inout] is the propagation state object

  • stepper[in] Stepper in use

  • navSurfaces[in] is the navigation status objects

  • navIter[in] test surface fore the status test

Returns

boolean return triggers exit to stepper

template<typename propagator_state_t, typename stepper_t>
inline bool targetBoundaries(propagator_state_t &state, const stepper_t &stepper) const

Navigation through volumes

This is the boundary check routine. If the code above set up the boundary surface iterator, we advance through them here. If we are on the boundary surface, we set the current surface to the boundary surface, and get the volume pointed at by the boundary surface. Next we unpack the layers from that volume. If the volume contains layers we set the step size to the straight line path length to the first layer. If we don’t find a next volume, the navigationBreak indicator is set. This ends the navigation. Finally, the boundary iterator is cleared, so that the subsequent call goes back to the layer iteration logic.

If we are not on the current boundary surface, we try the next one. The iterator is advanced and the step size is set. If no straight line intersect is found, the boundary surface is skipped. If we are out of boundary surfaces, the navigation is terminated.

boolean return triggers exit to stepper

Template Parameters
  • propagator_state_t – The state type of the propagagor

  • stepper_t – The type of stepper used for the propagation

Parameters
  • state[inout] is the propagation state object

  • stepper[in] Stepper in use

template<typename propagator_state_t, typename stepper_t>
inline bool targetLayers(propagator_state_t &state, const stepper_t &stepper) const

Target layer candidates.

We are now trying to advance to the next layer (with surfaces) Check if we are on the representing surface of the layer pointed at by navLayerIter. If so, we unpack the compatible surfaces (determined by straight line intersect), and set up the iterator so that the next status() call will enter the surface check mode above. If no surfaces are found, we skip the layer. If we unpack a surface, the step size is set to the path length to the first surface, as determined by straight line intersect.

Template Parameters
  • propagator_state_t – The state type of the propagagor

  • stepper_t – The type of stepper used for the propagation

Parameters
  • state[inout] is the propagation state object

  • stepper[in] Stepper in use

Returns

boolean return triggers exit to stepper

template<typename propagator_state_t, typename stepper_t>
inline bool targetSurfaces(propagator_state_t &state, const stepper_t &stepper) const

Loop over surface candidates here:

  • if an intersect is valid but not yet reached then return with updated step size

  • if an intersect is not valid, switch to next

boolean return triggers exit to stepper

Template Parameters
  • propagator_state_t – The state type of the propagagor

  • stepper_t – The type of stepper used for the propagation

Parameters
  • state[inout] is the propagation state object

  • stepper[in] Stepper in use

template<typename propagator_state_t>
inline std::string volInfo(const propagator_state_t &state) const

Private Members

Config m_cfg
struct Config
#include <Acts/Propagator/Navigator.hpp>

Public Members

bool resolveMaterial = true

stop at every material surface (whether it is passive or not)

bool resolvePassive = false

stop at every surface regardless what it is

bool resolveSensitive = true

Configuration for this Navigator stop at every sensitive surface (whether it has material or not)

double tolerance = s_onSurfaceTolerance

The tolerance used to defined “reached”.

std::shared_ptr<const TrackingGeometry> trackingGeometry = {nullptr}

Tracking Geometry for this Navigator.

struct State
#include <Acts/Propagator/Navigator.hpp>

Nested State struct.

It acts as an internal state which is created for every propagation/extrapolation step and keep thread-local navigation information

Public Functions

inline void reset(const GeometryContext &geoContext, const Vector3 &pos, const Vector3 &dir, NavigationDirection navDir, const Surface *ssurface, const Surface *tsurface)

Reset state.

Parameters
  • geoContext – is the geometry context

  • pos – is the global position

  • dir – is the momentum direction

  • navDir – is the navigation direction

  • ssurface – is the new starting surface

  • tsurface – is the target surface

Public Members

const Surface *currentSurface = nullptr

Navigation state - external state: the current surface.

const TrackingVolume *currentVolume = nullptr

Navigation state: the current volume.

ExternalSurfaces externalSurfaces = {}

Externally provided surfaces - these are tried to be hit.

bool lastHierarchySurfaceReached = false

Indicator that the last VolumeHierarchy surface was reached skip the next layer targeting to the next boundary/volume.

NavigationBoundaries navBoundaries = {}

the vector of boundary surfaces to work through

NavigationBoundaryIter navBoundaryIter = navBoundaries.end()

the current boundary iterator of the navigation state

bool navigationBreak = false

Navigation state : a break has been detected.

Stage navigationStage = Stage::undefined
NavigationLayerIter navLayerIter = navLayers.end()

the current layer iterator of the navigation state

NavigationLayers navLayers = {}

the vector of navigation layers to work through

NavigationSurfaceIter navSurfaceIter = navSurfaces.end()

the current surface iterator of the navigation state

NavigationSurfaces navSurfaces = {}

the vector of navigation surfaces to work through

const Layer *startLayer = nullptr

Navigation state: the start layer.

bool startLayerResolved = false

Indicator for start layer treatment.

const Surface *startSurface = nullptr

Navigation state: the start surface.

const TrackingVolume *startVolume = nullptr

Navigation state: the start volume.

const Layer *targetLayer = nullptr

Navigation state: the target layer.

bool targetReached = false

Indicator if the target is reached.

const Surface *targetSurface = nullptr

Navigation state: the target surface.

const TrackingVolume *targetVolume = nullptr

Navigation state: the target volume.

const TrackingVolume *worldVolume = nullptr

Navigation sate: the world volume.