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.

The current target surface is the surface pointed to by of the index 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 indices 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 NavigationLayers = boost::container::small_vector<LayerIntersection, 10>

using NavigationSurfaces = boost::container::small_vector<SurfaceIntersection, 10>

enum Stage

The navigation stage.

Values:

enumerator undefined

enumerator surfaceTarget

enumerator layerTarget

enumerator boundaryTarget

using Surfaces = std::vector<const Surface*>

Public Functions

inline explicit Navigator(Config cfg, std::shared_ptr<const Logger> _logger = getDefaultLogger("Navigator", Logging::Level::INFO))

Constructor with configuration object.

Parameters

cfg – The navigator configuration
_logger – a logger instance

inline const Surface *currentSurface(const State &state) const

inline void currentSurface(State &state, const Surface *surface) const

inline const TrackingVolume *currentVolume(const State &state) const

inline const IVolumeMaterial *currentVolumeMaterial(const State &state) const

inline void insertExternalSurface(State &state, GeometryIdentifier geoid) const

inline State makeState(const Surface *startSurface, const Surface *targetSurface) const

inline bool navigationBreak(const State &state) const

inline void navigationBreak(State &state, bool navigationBreak) const

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

Reset state.

Parameters

state – is the state
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

inline const Surface *startSurface(const State &state) const

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

inline bool targetReached(const State &state) const

inline void targetReached(State &state, bool targetReached) const

inline const Surface *targetSurface(const State &state) const

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

inline const Logger &logger() const¶

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> inline bool status(propagator_state_t &state, const stepper_t &stepper, const navigation_surfaces_t &navSurfaces, std::size_t navIndex) 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

Parameters

state – [inout] is the propagation state object
stepper – [in] Stepper in use
navSurfaces – [in] is the navigation status objects
navIndex – [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 index, 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 index 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 index 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 navLayerIndex. If so, we unpack the compatible surfaces (determined by straight line intersect), and set up the index 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¶

std::shared_ptr<const Logger> m_logger¶

struct Config

#include <Acts/Propagator/Navigator.hpp>

Public Members

BoundaryCheck boundaryCheckLayerResolving = true: Wether to perform boundary checks for layer resolving (improves navigation for bended tracks)

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 auto navBoundary() const

inline auto navLayer() const

inline auto navSurface() const

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 forceIntersectBoundaries = false: Force intersection with boundaries.

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

std::size_t navBoundaryIndex = navBoundaries.size(): the current boundary index of the navigation state

bool navigationBreak = false: Navigation state : a break has been detected.

Stage navigationStage = Stage::undefined

std::size_t navLayerIndex = navLayers.size(): the current layer index of the navigation state

NavigationLayers navLayers = {}: the vector of navigation layers to work through

std::size_t navSurfaceIndex = navSurfaces.size(): the current surface index 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.