EIC code displayed by LXR master/​acts/​Core/​include/​Acts/​Propagator/​Navigator.hpp	Source navigation Diff markup Identifier search General search
	Version: master test Revert   Change

File indexing completed on 2025-01-18 09:10:58

 // This file is part of the ACTS project.
 //
 // Copyright (C) 2016 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 https://mozilla.org/MPL/2.0/.
 
 #pragma once
 
 #include "Acts/Geometry/GeometryIdentifier.hpp"
 #include "Acts/Geometry/Layer.hpp"
 #include "Acts/Geometry/TrackingGeometry.hpp"
 #include "Acts/Geometry/TrackingVolume.hpp"
 #include "Acts/Propagator/NavigationTarget.hpp"
 #include "Acts/Propagator/NavigatorOptions.hpp"
 #include "Acts/Propagator/NavigatorStatistics.hpp"
 #include "Acts/Surfaces/BoundaryTolerance.hpp"
 #include "Acts/Surfaces/Surface.hpp"
 #include "Acts/Utilities/Intersection.hpp"
 #include "Acts/Utilities/Logger.hpp"
 #include "Acts/Utilities/StringHelpers.hpp"
 
 #include <algorithm>
 #include <optional>
 #include <sstream>
 #include <string>
 
 #include <boost/container/small_vector.hpp>
 
 namespace Acts {
 
 /// @brief The navigation options for the tracking geometry
 ///
 /// @tparam object_t Type of the object for navigation to check against
 template <typename object_t>
 struct NavigationOptions {
   /// The boundary check directive
   BoundaryTolerance boundaryTolerance = BoundaryTolerance::None();
 
   // How to resolve the geometry
   /// Always look for sensitive
   bool resolveSensitive = true;
   /// Always look for material
   bool resolveMaterial = true;
   /// always look for passive
   bool resolvePassive = false;
 
   /// Hint for start object
   const object_t* startObject = nullptr;
   /// Hint for end object
   const object_t* endObject = nullptr;
 
   /// External surface identifier for which the boundary check is ignored
   std::vector<GeometryIdentifier> externalSurfaces = {};
 
   /// The minimum distance for a surface to be considered
   double nearLimit = 0;
   /// The maximum distance for a surface to be considered
   double farLimit = std::numeric_limits<double>::max();
 };
 
 /// @brief Steers the propagation through the geometry by providing the next
 /// surface to be targeted.
 ///
 /// The Navigator is part of the propagation and responsible for steering
 /// the surface sequence to encounter all the relevant surfaces which are
 /// intersected by the trajectory.
 ///
 /// 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 navigation state, such that other actors can deal with it.
 ///
 /// The current target surface is referenced by an index which points into
 /// the navigation candidates. The navigation candidates are ordered by the
 /// path length to the surface. If a surface is hit, the
 /// `state.currentSurface` pointer is set. This actors to observe
 /// that we are on a surface.
 ///
 class Navigator {
  public:
   using NavigationSurfaces =
       boost::container::small_vector<SurfaceIntersection, 10>;
 
   using NavigationLayers =
       boost::container::small_vector<LayerIntersection, 10>;
 
   using NavigationBoundaries =
       boost::container::small_vector<BoundaryIntersection, 4>;
 
   using ExternalSurfaces = std::multimap<std::uint64_t, GeometryIdentifier>;
 
   /// The navigation stage
   enum struct Stage : int {
     initial = 0,
     surfaceTarget = 1,
     layerTarget = 2,
     boundaryTarget = 3,
   };
 
   /// The navigator configuration
   struct Config {
     /// Tracking Geometry for this Navigator
     std::shared_ptr<const TrackingGeometry> trackingGeometry{nullptr};
 
     /// stop at every sensitive surface (whether it has material or not)
     bool resolveSensitive = true;
     /// stop at every material surface (whether it is passive or not)
     bool resolveMaterial = true;
     /// stop at every surface regardless what it is
     bool resolvePassive = false;
   };
 
   /// The navigator options
   struct Options : public NavigatorPlainOptions {
     explicit Options(const GeometryContext& gctx)
         : NavigatorPlainOptions(gctx) {}
 
     /// The surface tolerance
     double surfaceTolerance = s_onSurfaceTolerance;
 
     /// The near limit to resolve surfaces
     double nearLimit = s_onSurfaceTolerance;
 
     /// The far limit to resolve surfaces
     double farLimit = std::numeric_limits<double>::max();
 
     /// Externally provided surfaces - these are tried to be hit
     ExternalSurfaces externalSurfaces = {};
 
     void insertExternalSurface(GeometryIdentifier geoid) {
       externalSurfaces.insert(
           std::pair<std::uint64_t, GeometryIdentifier>(geoid.layer(), geoid));
     }
 
     void setPlainOptions(const NavigatorPlainOptions& options) {
       static_cast<NavigatorPlainOptions&>(*this) = options;
     }
   };
 
   /// @brief Nested State struct
   ///
   /// It acts as an internal state which is created for every propagation and
   /// meant to keep thread-local navigation information.
   struct State {
     explicit State(const Options& options_) : options(options_) {}
 
     Options options;
 
     // Navigation on surface level
     /// the vector of navigation surfaces to work through
     NavigationSurfaces navSurfaces = {};
     /// the current surface index of the navigation state
     std::optional<std::size_t> navSurfaceIndex;
 
     // Navigation on layer level
     /// the vector of navigation layers to work through
     NavigationLayers navLayers = {};
     /// the current layer index of the navigation state
     std::optional<std::size_t> navLayerIndex;
 
     // Navigation on volume level
     /// the vector of boundary surfaces to work through
     NavigationBoundaries navBoundaries = {};
     /// the current boundary index of the navigation state
     std::optional<std::size_t> navBoundaryIndex;
 
     SurfaceIntersection& navSurface() {
       return navSurfaces.at(navSurfaceIndex.value());
     }
     LayerIntersection& navLayer() {
       return navLayers.at(navLayerIndex.value());
     }
     BoundaryIntersection& navBoundary() {
       return navBoundaries.at(navBoundaryIndex.value());
     }
 
     const TrackingVolume* startVolume = nullptr;
     const Layer* startLayer = nullptr;
     const Surface* startSurface = nullptr;
     const TrackingVolume* currentVolume = nullptr;
     const Layer* currentLayer = nullptr;
     const Surface* currentSurface = nullptr;
     const Surface* targetSurface = nullptr;
 
     bool navigationBreak = false;
     Stage navigationStage = Stage::initial;
 
     NavigatorStatistics statistics;
 
     void resetAfterLayerSwitch() {
       navSurfaces.clear();
       navSurfaceIndex.reset();
     }
 
     void resetAfterVolumeSwitch() {
       resetAfterLayerSwitch();
 
       navLayers.clear();
       navLayerIndex.reset();
       navBoundaries.clear();
       navBoundaryIndex.reset();
 
       currentLayer = nullptr;
     }
 
     void reset() {
       resetAfterVolumeSwitch();
 
       currentVolume = nullptr;
       currentSurface = nullptr;
 
       navigationBreak = false;
       navigationStage = Stage::initial;
     }
   };
 
   /// Constructor with configuration object
   ///
   /// @param cfg The navigator configuration
   /// @param _logger a logger instance
   explicit Navigator(Config cfg,
                      std::shared_ptr<const Logger> _logger =
                          getDefaultLogger("Navigator", Logging::Level::INFO))
       : m_cfg{std::move(cfg)}, m_logger{std::move(_logger)} {}
 
   State makeState(const Options& options) const {
     State state(options);
     state.startSurface = options.startSurface;
     state.targetSurface = options.targetSurface;
     return state;
   }
 
   const Surface* currentSurface(const State& state) const {
     return state.currentSurface;
   }
 
   const TrackingVolume* currentVolume(const State& state) const {
     return state.currentVolume;
   }
 
   const IVolumeMaterial* currentVolumeMaterial(const State& state) const {
     if (state.currentVolume == nullptr) {
       return nullptr;
     }
     return state.currentVolume->volumeMaterial();
   }
 
   const Surface* startSurface(const State& state) const {
     return state.startSurface;
   }
 
   const Surface* targetSurface(const State& state) const {
     return state.targetSurface;
   }
 
   bool endOfWorldReached(const State& state) const {
     return state.currentVolume == nullptr;
   }
 
   bool navigationBreak(const State& state) const {
     return state.navigationBreak;
   }
 
   /// @brief Initialize the navigator
   ///
   /// This function initializes the navigator for a new propagation.
   ///
   /// @param state The navigation state
   /// @param position The start position
   /// @param direction The start direction
   /// @param propagationDirection The propagation direction
   void initialize(State& state, const Vector3& position,
                   const Vector3& direction,
                   Direction propagationDirection) const {
     (void)propagationDirection;
 
     ACTS_VERBOSE(volInfo(state) << "Initialization.");
 
     state.reset();
 
     // Fast Navigation initialization for start condition:
     // - short-cut through object association, saves navigation in the
     // - geometry and volume tree search for the lowest volume
     if (state.startSurface != nullptr &&
         state.startSurface->associatedLayer() != nullptr) {
       ACTS_VERBOSE(
           volInfo(state)
           << "Fast start initialization through association from Surface.");
 
       state.startLayer = state.startSurface->associatedLayer();
       state.startVolume = state.startLayer->trackingVolume();
     } else if (state.startVolume != nullptr) {
       ACTS_VERBOSE(
           volInfo(state)
           << "Fast start initialization through association from Volume.");
 
       state.startLayer = state.startVolume->associatedLayer(
           state.options.geoContext, position);
     } else {
       ACTS_VERBOSE(volInfo(state)
                    << "Slow start initialization through search.");
       ACTS_VERBOSE(volInfo(state)
                    << "Starting from position " << toString(position)
                    << " and direction " << toString(direction));
 
       // current volume and layer search through global search
       state.startVolume = m_cfg.trackingGeometry->lowestTrackingVolume(
           state.options.geoContext, position);
 
       if (state.startVolume != nullptr) {
         state.startLayer = state.startVolume->associatedLayer(
             state.options.geoContext, position);
       } else {
         ACTS_ERROR(volInfo(state)
                    << "No start volume resolved. Nothing left to do.");
         state.navigationBreak = true;
       }
     }
 
     state.currentVolume = state.startVolume;
     state.currentLayer = state.startLayer;
     state.currentSurface = state.startSurface;
 
     if (state.currentVolume != nullptr) {
       ACTS_VERBOSE(volInfo(state) << "Start volume resolved "
                                   << state.currentVolume->geometryId());
       assert(state.currentVolume->inside(position,
                                          state.options.surfaceTolerance) &&
              "We did not end up inside the volume.");
     }
     if (state.currentLayer != nullptr) {
       ACTS_VERBOSE(volInfo(state) << "Start layer resolved "
                                   << state.currentLayer->geometryId());
     }
     if (state.currentSurface != nullptr) {
       ACTS_VERBOSE(volInfo(state) << "Start surface resolved "
                                   << state.currentSurface->geometryId());
       assert(state.currentSurface->isOnSurface(
                  state.options.geoContext, position, direction,
                  BoundaryTolerance::Infinite(),
                  state.options.surfaceTolerance) &&
              "Stepper not on surface");
     }
   }
 
   /// @brief Get the next target surface
   ///
   /// This function gets the next target surface for the propagation.
   ///
   /// @param state The navigation state
   /// @param position The current position
   /// @param direction The current direction
   ///
   /// @return The next target surface
   NavigationTarget nextTarget(State& state, const Vector3& position,
                               const Vector3& direction) const {
     if (inactive(state)) {
       return NavigationTarget::None();
     }
 
     ACTS_VERBOSE(volInfo(state) << "Entering Navigator::nextTarget.");
 
     // Reset the current surface
     state.currentSurface = nullptr;
 
     auto tryGetNextTarget = [&]() -> NavigationTarget {
       // Try targeting the surfaces - then layers - then boundaries
 
       if (state.navigationStage == Stage::initial) {
         ACTS_VERBOSE(volInfo(state) << "Target surfaces.");
         state.navigationStage = Stage::surfaceTarget;
       }
 
       if (state.navigationStage == Stage::surfaceTarget) {
         if (!state.navSurfaceIndex.has_value()) {
           // First time, resolve the surfaces
           resolveSurfaces(state, position, direction);
           state.navSurfaceIndex = 0;
         } else {
           ++state.navSurfaceIndex.value();
         }
         if (state.navSurfaceIndex.value() < state.navSurfaces.size()) {
           ACTS_VERBOSE(volInfo(state) << "Target set to next surface.");
           return NavigationTarget(*state.navSurface().object(),
                                   state.navSurface().index(),
                                   BoundaryTolerance::None());
         } else {
           // This was the last surface, switch to layers
           ACTS_VERBOSE(volInfo(state) << "Target layers.");
           state.navigationStage = Stage::layerTarget;
         }
       }
 
       if (state.navigationStage == Stage::layerTarget) {
         if (!state.navLayerIndex.has_value()) {
           // First time, resolve the layers
           resolveLayers(state, position, direction);
           state.navLayerIndex = 0;
         } else {
           ++state.navLayerIndex.value();
         }
         if (state.navLayerIndex.value() < state.navLayers.size()) {
           ACTS_VERBOSE(volInfo(state) << "Target set to next layer.");
           return NavigationTarget(*state.navLayer().first.object(),
                                   state.navLayer().first.index(),
                                   BoundaryTolerance::None());
         } else {
           // This was the last layer, switch to boundaries
           ACTS_VERBOSE(volInfo(state) << "Target boundaries.");
           state.navigationStage = Stage::boundaryTarget;
         }
       }
 
       if (state.navigationStage == Stage::boundaryTarget) {
         if (!state.navBoundaryIndex.has_value()) {
           // First time, resolve the boundaries
           resolveBoundaries(state, position, direction);
           state.navBoundaryIndex = 0;
         } else {
           ++state.navBoundaryIndex.value();
         }
         if (state.navBoundaryIndex.value() < state.navBoundaries.size()) {
           ACTS_VERBOSE(volInfo(state) << "Target set to next boundary.");
           return NavigationTarget(*state.navBoundary().first.object(),
                                   state.navBoundary().first.index(),
                                   BoundaryTolerance::None());
         } else {
           // This was the last boundary, we have to leave the volume somehow,
           // renavigate
           ACTS_VERBOSE(volInfo(state)
                        << "Boundary targets exhausted. Renavigate.");
         }
       }
 
       ACTS_VERBOSE(volInfo(state)
                    << "Unknown state. No target found. Renavigate.");
       return NavigationTarget::None();
     };
 
     NavigationTarget nextTarget = tryGetNextTarget();
     if (!nextTarget.isNone()) {
       return nextTarget;
     }
 
     state.reset();
     ++state.statistics.nRenavigations;
 
     // We might have punched through a boundary and entered another volume
     // so we have to reinitialize
     state.currentVolume = m_cfg.trackingGeometry->lowestTrackingVolume(
         state.options.geoContext, position);
 
     if (state.currentVolume == nullptr) {
       ACTS_VERBOSE(volInfo(state) << "No volume found, stop navigation.");
       state.navigationBreak = true;
       return NavigationTarget::None();
     }
 
     state.currentLayer = state.currentVolume->associatedLayer(
         state.options.geoContext, position);
 
     ACTS_VERBOSE(volInfo(state) << "Resolved volume and layer.");
 
     // Rerun the targeting
     nextTarget = tryGetNextTarget();
     if (!nextTarget.isNone()) {
       return nextTarget;
     }
 
     ACTS_VERBOSE(
         volInfo(state)
         << "No targets found again, we got really lost! Stop navigation.");
     state.navigationBreak = true;
     return NavigationTarget::None();
   }
 
   /// @brief Check if the current target is still valid
   ///
   /// This function checks if the target is valid.
   ///
   /// @param state The navigation state
   /// @param position The current position
   /// @param direction The current direction
   ///
   /// @return True if the target is valid
   bool checkTargetValid(const State& state, const Vector3& position,
                         const Vector3& direction) const {
     (void)position;
     (void)direction;
 
     return state.navigationStage != Stage::initial;
   }
 
   /// @brief Handle the surface reached
   ///
   /// This function handles the surface reached.
   ///
   /// @param state The navigation state
   /// @param position The current position
   /// @param direction The current direction
   /// @param surface The surface reached
   void handleSurfaceReached(State& state, const Vector3& position,
                             const Vector3& direction,
                             const Surface& surface) const {
     if (inactive(state)) {
       return;
     }
 
     ACTS_VERBOSE(volInfo(state) << "Entering Navigator::handleSurfaceReached.");
 
     state.currentSurface = &surface;
 
     if (state.navigationStage == Stage::surfaceTarget &&
         state.navSurface().object() == &surface) {
       ACTS_VERBOSE(volInfo(state) << "Handling surface status.");
 
       return;
     }
 
     if (state.navigationStage == Stage::layerTarget &&
         state.navLayer().first.object() == &surface) {
       ACTS_VERBOSE(volInfo(state) << "Handling layer status.");
 
       // Switch to the next layer
       state.currentLayer = state.navLayer().second;
       state.navigationStage = Stage::surfaceTarget;
 
       // partial reset
       state.resetAfterLayerSwitch();
 
       return;
     }
 
     if (state.navigationStage == Stage::boundaryTarget &&
         state.navBoundary().first.object() == &surface) {
       ACTS_VERBOSE(volInfo(state) << "Handling boundary status.");
 
       // Switch to the next volume using the boundary
       const BoundarySurface* boundary = state.navBoundary().second;
       state.currentVolume = boundary->attachedVolume(state.options.geoContext,
                                                      position, direction);
 
       // partial reset
       state.resetAfterVolumeSwitch();
 
       if (state.currentVolume != nullptr) {
         ACTS_VERBOSE(volInfo(state) << "Volume updated.");
         state.navigationStage = Stage::layerTarget;
       } else {
         ACTS_VERBOSE(volInfo(state)
                      << "No more volume to progress to, stopping navigation.");
         state.navigationBreak = true;
       }
 
       return;
     }
 
     ACTS_ERROR(volInfo(state) << "Surface reached but unknown state.");
   }
 
  private:
   /// @brief Resolve compatible surfaces
   ///
   /// This function resolves the compatible surfaces for the navigation.
   ///
   /// @param state The navigation state
   /// @param position The current position
   /// @param direction The current direction
   void resolveSurfaces(State& state, const Vector3& position,
                        const Vector3& direction) const {
     ACTS_VERBOSE(volInfo(state) << "Searching for compatible surfaces.");
 
     const Layer* currentLayer = state.currentLayer;
 
     if (currentLayer == nullptr) {
       ACTS_VERBOSE(volInfo(state) << "No layer to resolve surfaces.");
       return;
     }
 
     const Surface* layerSurface = &currentLayer->surfaceRepresentation();
 
     NavigationOptions<Surface> navOpts;
     navOpts.resolveSensitive = m_cfg.resolveSensitive;
     navOpts.resolveMaterial = m_cfg.resolveMaterial;
     navOpts.resolvePassive = m_cfg.resolvePassive;
     navOpts.startObject = state.currentSurface;
     navOpts.endObject = state.targetSurface;
     navOpts.nearLimit = state.options.nearLimit;
     navOpts.farLimit = state.options.farLimit;
 
     if (!state.options.externalSurfaces.empty()) {
       auto layerId = layerSurface->geometryId().layer();
       auto externalSurfaceRange =
           state.options.externalSurfaces.equal_range(layerId);
       navOpts.externalSurfaces.reserve(
           state.options.externalSurfaces.count(layerId));
       for (auto itSurface = externalSurfaceRange.first;
            itSurface != externalSurfaceRange.second; itSurface++) {
         navOpts.externalSurfaces.push_back(itSurface->second);
       }
     }
 
     // Request the compatible surfaces
     state.navSurfaces = currentLayer->compatibleSurfaces(
         state.options.geoContext, position, direction, navOpts);
     std::ranges::sort(state.navSurfaces, SurfaceIntersection::pathLengthOrder);
 
     // Print surface information
     if (logger().doPrint(Logging::VERBOSE)) {
       std::ostringstream os;
       os << state.navSurfaces.size();
       os << " surface candidates found at path(s): ";
       for (auto& sfc : state.navSurfaces) {
         os << sfc.pathLength() << "  ";
       }
       logger().log(Logging::VERBOSE, os.str());
     }
 
     if (state.navSurfaces.empty()) {
       ACTS_VERBOSE(volInfo(state) << "No surface candidates found.");
     }
   }
 
   /// @brief Resolve compatible layers
   ///
   /// This function resolves the compatible layers for the navigation.
   ///
   /// @param state The navigation state
   /// @param position The current position
   /// @param direction The current direction
   void resolveLayers(State& state, const Vector3& position,
                      const Vector3& direction) const {
     ACTS_VERBOSE(volInfo(state) << "Searching for compatible layers.");
 
     NavigationOptions<Layer> navOpts;
     navOpts.resolveSensitive = m_cfg.resolveSensitive;
     navOpts.resolveMaterial = m_cfg.resolveMaterial;
     navOpts.resolvePassive = m_cfg.resolvePassive;
     navOpts.startObject = state.currentLayer;
     navOpts.nearLimit = state.options.nearLimit;
     navOpts.farLimit = state.options.farLimit;
 
     // Request the compatible layers
     state.navLayers = state.currentVolume->compatibleLayers(
         state.options.geoContext, position, direction, navOpts);
     std::ranges::sort(state.navLayers, [](const auto& a, const auto& b) {
       return SurfaceIntersection::pathLengthOrder(a.first, b.first);
     });
 
     // Print layer information
     if (logger().doPrint(Logging::VERBOSE)) {
       std::ostringstream os;
       os << state.navLayers.size();
       os << " layer candidates found at path(s): ";
       for (auto& lc : state.navLayers) {
         os << lc.first.pathLength() << "  ";
       }
       logger().log(Logging::VERBOSE, os.str());
     }
 
     if (state.navLayers.empty()) {
       ACTS_VERBOSE(volInfo(state) << "No layer candidates found.");
     }
   }
 
   /// @brief Resolve compatible boundaries
   ///
   /// This function resolves the compatible boundaries for the navigation.
   ///
   /// @param state The navigation state
   /// @param position The current position
   /// @param direction The current direction
   void resolveBoundaries(State& state, const Vector3& position,
                          const Vector3& direction) const {
     ACTS_VERBOSE(volInfo(state) << "Searching for compatible boundaries.");
 
     NavigationOptions<Surface> navOpts;
     navOpts.startObject = state.currentSurface;
     navOpts.nearLimit = state.options.nearLimit;
     navOpts.farLimit = state.options.farLimit;
 
     ACTS_VERBOSE(volInfo(state)
                  << "Try to find boundaries, we are at: " << toString(position)
                  << ", dir: " << toString(direction));
 
     // Request the compatible boundaries
     state.navBoundaries = state.currentVolume->compatibleBoundaries(
         state.options.geoContext, position, direction, navOpts, logger());
     std::ranges::sort(state.navBoundaries, [](const auto& a, const auto& b) {
       return SurfaceIntersection::pathLengthOrder(a.first, b.first);
     });
 
     // Print boundary information
     if (logger().doPrint(Logging::VERBOSE)) {
       std::ostringstream os;
       os << state.navBoundaries.size();
       os << " boundary candidates found at path(s): ";
       for (auto& bc : state.navBoundaries) {
         os << bc.first.pathLength() << "  ";
       }
       logger().log(Logging::VERBOSE, os.str());
     }
 
     if (state.navBoundaries.empty()) {
       ACTS_VERBOSE(volInfo(state) << "No boundary candidates found.");
     }
   }
 
   /// @brief Check if the navigator is inactive
   ///
   /// This function checks if the navigator is inactive.
   ///
   /// @param state The navigation state
   ///
   /// @return True if the navigator is inactive
   bool inactive(const State& state) const {
     // Void behavior in case no tracking geometry is present
     if (m_cfg.trackingGeometry == nullptr) {
       return true;
     }
 
     // Turn the navigator into void when you are instructed to do nothing
     if (!m_cfg.resolveSensitive && !m_cfg.resolveMaterial &&
         !m_cfg.resolvePassive) {
       return true;
     }
 
     if (state.navigationBreak) {
       return true;
     }
 
     return false;
   }
 
  private:
   template <typename propagator_state_t>
   std::string volInfo(const propagator_state_t& state) const {
     return (state.currentVolume != nullptr ? state.currentVolume->volumeName()
                                            : "No Volume") +
            " | ";
   }
 
   const Logger& logger() const { return *m_logger; }
 
   Config m_cfg;
 
   std::shared_ptr<const Logger> m_logger;
 };
 
 }  // namespace Acts

This page was automatically generated by the 2.3.7 LXR engine. The LXR team