refactor!: Consistent naming for direction (#2343)

The last PR in the series of having consistent naming for `direction`

After
- #2251
- #2250

Core/include/Acts/EventData/GenericBoundTrackParameters.hpp

@@ -183,7 +183,7 @@ class GenericBoundTrackParameters {
   Vector4 fourPosition(const GeometryContext& geoCtx) const {
     Vector4 pos4;
     pos4.segment<3>(ePos0) =
-        m_surface->localToGlobal(geoCtx, localPosition(), unitDirection());
+        m_surface->localToGlobal(geoCtx, localPosition(), direction());
     pos4[eTime] = m_params[eBoundTime];
     return pos4;
   }
@@ -197,16 +197,16 @@ class GenericBoundTrackParameters {
   /// select the appropriate transformation and might be a computationally
   /// expensive operation.
   Vector3 position(const GeometryContext& geoCtx) const {
-    return m_surface->localToGlobal(geoCtx, localPosition(), unitDirection());
+    return m_surface->localToGlobal(geoCtx, localPosition(), direction());
   }
   /// Time coordinate.
   Scalar time() const { return m_params[eBoundTime]; }
 
   /// Unit direction three-vector, i.e. the normalized momentum
   /// three-vector.
-  Vector3 unitDirection() const {
-    return makeDirectionUnitFromPhiTheta(m_params[eBoundPhi],
-                                         m_params[eBoundTheta]);
+  Vector3 direction() const {
+    return makeDirectionFromPhiTheta(m_params[eBoundPhi],
+                                     m_params[eBoundTheta]);
   }
   /// Absolute momentum.
   Scalar absoluteMomentum() const {
@@ -217,7 +217,7 @@ class GenericBoundTrackParameters {
     return std::sin(m_params[eBoundTheta]) * absoluteMomentum();
   }
   /// Momentum three-vector.
-  Vector3 momentum() const { return absoluteMomentum() * unitDirection(); }
+  Vector3 momentum() const { return absoluteMomentum() * direction(); }
 
   /// Particle electric charge.
   Scalar charge() const {

Core/include/Acts/EventData/GenericCurvilinearTrackParameters.hpp

@@ -81,8 +81,7 @@ class GenericCurvilinearTrackParameters
       const Vector4& pos4, Scalar phi, Scalar theta, Scalar p, Scalar q,
       std::optional<CovarianceMatrix> cov = std::nullopt)
       : Base(Surface::makeShared<PlaneSurface>(
-                 pos4.segment<3>(ePos0),
-                 makeDirectionUnitFromPhiTheta(phi, theta)),
+                 pos4.segment<3>(ePos0), makeDirectionFromPhiTheta(phi, theta)),
              detail::transformFreeToCurvilinearParameters(
                  pos4[eTime], phi, theta, (q != Scalar(0)) ? (q / p) : (1 / p)),
              q, std::move(cov)) {
@@ -105,8 +104,7 @@ class GenericCurvilinearTrackParameters
       const Vector4& pos4, Scalar phi, Scalar theta, Scalar qOverP,
       std::optional<CovarianceMatrix> cov = std::nullopt)
       : Base(Surface::makeShared<PlaneSurface>(
-                 pos4.segment<3>(ePos0),
-                 makeDirectionUnitFromPhiTheta(phi, theta)),
+                 pos4.segment<3>(ePos0), makeDirectionFromPhiTheta(phi, theta)),
              detail::transformFreeToCurvilinearParameters(pos4[eTime], phi,
                                                           theta, qOverP),
              std::move(cov)) {}

Core/include/Acts/EventData/GenericFreeTrackParameters.hpp

@@ -83,7 +83,7 @@ class GenericFreeTrackParameters {
         m_chargeInterpreter(std::abs(q)) {
     assert((0 <= p) and "Absolute momentum must be positive");
 
-    auto dir = makeDirectionUnitFromPhiTheta(phi, theta);
+    auto dir = makeDirectionFromPhiTheta(phi, theta);
     m_params[eFreePos0] = pos4[ePos0];
     m_params[eFreePos1] = pos4[ePos1];
     m_params[eFreePos2] = pos4[ePos2];
@@ -110,7 +110,7 @@ class GenericFreeTrackParameters {
                              Scalar qOverP,
                              std::optional<CovarianceMatrix> cov = std::nullopt)
       : m_params(FreeVector::Zero()), m_cov(std::move(cov)) {
-    auto dir = makeDirectionUnitFromPhiTheta(phi, theta);
+    auto dir = makeDirectionFromPhiTheta(phi, theta);
     m_params[eFreePos0] = pos4[ePos0];
     m_params[eFreePos1] = pos4[ePos1];
     m_params[eFreePos2] = pos4[ePos2];
@@ -158,7 +158,7 @@ class GenericFreeTrackParameters {
   Scalar time() const { return m_params[eFreeTime]; }
 
   /// Unit direction three-vector, i.e. the normalized momentum three-vector.
-  Vector3 unitDirection() const {
+  Vector3 direction() const {
     return m_params.segment<3>(eFreeDir0).normalized();
   }
   /// Absolute momentum.
@@ -179,7 +179,7 @@ class GenericFreeTrackParameters {
     return (transverseMagnitude / magnitude) * absoluteMomentum();
   }
   /// Momentum three-vector.
-  Vector3 momentum() const { return absoluteMomentum() * unitDirection(); }
+  Vector3 momentum() const { return absoluteMomentum() * direction(); }
 
   /// Particle electric charge.
   Scalar charge() const {

Core/include/Acts/EventData/MultiComponentBoundTrackParameters.hpp

@@ -209,8 +209,8 @@ class MultiComponentBoundTrackParameters {
 
   /// Unit direction three-vector, i.e. the normalized momentum
   /// three-vector.
-  Vector3 unitDirection() const {
-    return reduce([](const SingleParameters& p) { return p.unitDirection(); })
+  Vector3 direction() const {
+    return reduce([](const SingleParameters& p) { return p.direction(); })
         .normalized();
   }
 

Core/include/Acts/EventData/TrackParametersConcept.hpp

@@ -47,7 +47,7 @@ using ReturnTypePosition = decltype(std::declval<T>().position());
 template <typename T>
 using ReturnTypeTime = decltype(std::declval<T>().time());
 template <typename T>
-using ReturnTypeUnitDirection = decltype(std::declval<T>().unitDirection());
+using ReturnTypeDirection = decltype(std::declval<T>().direction());
 template <typename T>
 using ReturnTypeAbsoluteMomentum =
     decltype(std::declval<T>().absoluteMomentum());
@@ -78,8 +78,8 @@ struct BoundTrackParametersConceptImpl {
       identical_to<Vector3, ReturnTypePositionFromContext, const T>;
   constexpr static bool hasMethodTime =
       identical_to<TypeScalar<T>, ReturnTypeTime, const T>;
-  constexpr static bool hasMethodUnitDirection =
-      identical_to<Vector3, ReturnTypeUnitDirection, const T>;
+  constexpr static bool hasMethodDirection =
+      identical_to<Vector3, ReturnTypeDirection, const T>;
   constexpr static bool hasMethodAbsoluteMomentum =
       identical_to<TypeScalar<T>, ReturnTypeAbsoluteMomentum, const T>;
   constexpr static bool hasMethodCharge =
@@ -98,8 +98,7 @@ struct BoundTrackParametersConceptImpl {
   static_assert(hasMethodPositionFromContext,
                 "Missing or invalid 'position' method");
   static_assert(hasMethodTime, "Missing or invalid 'time' method");
-  static_assert(hasMethodUnitDirection,
-                "Missing or invalid 'unitDirection' method");
+  static_assert(hasMethodDirection, "Missing or invalid 'direction' method");
   static_assert(hasMethodAbsoluteMomentum,
                 "Missing or invalid 'absoluteMomentum' method");
   static_assert(hasMethodCharge, "Missing or invalid 'charge' method");
@@ -110,7 +109,7 @@ struct BoundTrackParametersConceptImpl {
       require<hasTypeScalar, hasTypeParametersVector, hasTypeCovarianceMatrix,
               hasMethodParameters, hasMethodCovariance,
               hasMethodFourPositionFromContext, hasMethodPositionFromContext,
-              hasMethodTime, hasMethodUnitDirection, hasMethodAbsoluteMomentum,
+              hasMethodTime, hasMethodDirection, hasMethodAbsoluteMomentum,
               hasMethodCharge, hasMethodReferenceSurface>;
 };
 
@@ -135,8 +134,8 @@ struct FreeTrackParametersConceptImpl {
       identical_to<Vector3, ReturnTypePosition, const T>;
   constexpr static bool hasMethodTime =
       identical_to<TypeScalar<T>, ReturnTypeTime, const T>;
-  constexpr static bool hasMethodUnitDirection =
-      identical_to<Vector3, ReturnTypeUnitDirection, const T>;
+  constexpr static bool hasMethodDirection =
+      identical_to<Vector3, ReturnTypeDirection, const T>;
   constexpr static bool hasMethodAbsoluteMomentum =
       identical_to<TypeScalar<T>, ReturnTypeAbsoluteMomentum, const T>;
   constexpr static bool hasMethodCharge =
@@ -152,16 +151,15 @@ struct FreeTrackParametersConceptImpl {
                 "Missing or invalid 'fourPosition' method");
   static_assert(hasMethodPosition, "Missing or invalid 'position' method");
   static_assert(hasMethodTime, "Missing or invalid 'time' method");
-  static_assert(hasMethodUnitDirection,
-                "Missing or invalid 'unitDirection' method");
+  static_assert(hasMethodDirection, "Missing or invalid 'direction' method");
   static_assert(hasMethodAbsoluteMomentum,
                 "Missing or invalid 'absoluteMomentum' method");
   static_assert(hasMethodCharge, "Missing or invalid 'charge' method");
 
   constexpr static bool value =
       require<hasTypeScalar, hasTypeParametersVector, hasTypeCovarianceMatrix,
               hasMethodParameters, hasMethodCovariance, hasMethodFourPosition,
-              hasMethodPosition, hasMethodTime, hasMethodUnitDirection,
+              hasMethodPosition, hasMethodTime, hasMethodDirection,
               hasMethodAbsoluteMomentum, hasMethodCharge>;
 };
 

Core/include/Acts/EventData/TrackProxy.hpp

@@ -376,14 +376,14 @@ class TrackProxy {
 
   /// Get a unit vector along the track direction at the reference surface
   /// @return The direction unit vector
-  Vector3 unitDirection() const {
-    return makeDirectionUnitFromPhiTheta(phi(), theta());
+  Vector3 direction() const {
+    return makeDirectionFromPhiTheta(phi(), theta());
   }
 
   /// Get the global momentum vector
   /// @return the global momentum vector
   Vector3 momentum() const {
-    return absoluteMomentum() * unitDirection();
+    return absoluteMomentum() * direction();
   }
 
   /// Get a range over the track states of this track. Return value is

Core/include/Acts/Propagator/AtlasStepper.hpp

@@ -98,7 +98,7 @@ class AtlasStepper {
         covTransport = true;
         useJacobian = true;
         const auto transform = pars.referenceSurface().referenceFrame(
-            geoContext, pos, pars.unitDirection());
+            geoContext, pos, pars.direction());
 
         pVector[8] = transform(0, eBoundLoc0);
         pVector[16] = transform(0, eBoundLoc1);

Core/include/Acts/Propagator/EigenStepper.hpp

@@ -82,7 +82,7 @@ class EigenStepper {
           fieldCache(std::move(fieldCacheIn)),
           geoContext(gctx) {
       pars.template segment<3>(eFreePos0) = par.position(gctx);
-      pars.template segment<3>(eFreeDir0) = par.unitDirection();
+      pars.template segment<3>(eFreeDir0) = par.direction();
       pars[eFreeTime] = par.time();
       pars[eFreeQOverP] = par.parameters()[eBoundQOverP];
 

Core/include/Acts/Propagator/MultiEigenStepperLoop.ipp

@@ -99,7 +99,7 @@ auto MultiEigenStepperLoop<E, R, A>::curvilinearState(State& state,
           state.components[i].state, transportCov);
 
       pos4 += state.components[i].weight * cp.fourPosition(state.geoContext);
-      dir += state.components[i].weight * cp.unitDirection();
+      dir += state.components[i].weight * cp.direction();
       qop += state.components[i].weight * (cp.charge() / cp.absoluteMomentum());
       if (cp.covariance()) {
         cov += state.components[i].weight * *cp.covariance();

Core/include/Acts/Propagator/RiddersPropagator.ipp

@@ -41,7 +41,7 @@ auto Acts::RiddersPropagator<propagator_t>::propagate(
     // replace the covariance of the nominal result w/ the ridders covariance
     nominalResult.endParameters = CurvilinearTrackParameters(
         nominalFinalParameters.fourPosition(options.geoContext),
-        nominalFinalParameters.unitDirection(),
+        nominalFinalParameters.direction(),
         nominalFinalParameters.absoluteMomentum(),
         nominalFinalParameters.charge(), std::move(cov));
   }

Core/include/Acts/Propagator/StraightLineStepper.hpp

@@ -81,7 +81,7 @@ class StraightLineStepper {
           geoContext(gctx) {
       (void)mctx;
       pars.template segment<3>(eFreePos0) = par.position(gctx);
-      pars.template segment<3>(eFreeDir0) = par.unitDirection();
+      pars.template segment<3>(eFreeDir0) = par.direction();
       pars[eFreeTime] = par.time();
       pars[eFreeQOverP] = par.parameters()[eBoundQOverP];
       if (par.covariance()) {

Core/include/Acts/TrackFitting/GaussianSumFitter.hpp

@@ -221,7 +221,7 @@ struct GaussianSumFitter {
         sParameters.referenceSurface()
             .intersect(GeometryContext{},
                        sParameters.position(GeometryContext{}),
-                       sParameters.unitDirection(), true)
+                       sParameters.direction(), true)
             .intersection.status;
 
     if (intersectionStatusStartSurface != Intersection3D::Status::onSurface) {

Core/include/Acts/TrackFitting/detail/GsfActor.hpp

@@ -369,10 +369,9 @@ struct GsfActor {
         old_bound.position(state.stepping.geoContext), state.options.direction,
         MaterialUpdateStage::FullUpdate);
 
-    auto pathCorrection =
-        surface.pathCorrection(state.stepping.geoContext,
-                               old_bound.position(state.stepping.geoContext),
-                               old_bound.unitDirection());
+    auto pathCorrection = surface.pathCorrection(
+        state.stepping.geoContext,
+        old_bound.position(state.stepping.geoContext), old_bound.direction());
     slab.scaleThickness(pathCorrection);
 
     // Emit a warning if the approximation is not valid for this x/x0

Core/include/Acts/Utilities/UnitVectors.hpp

@@ -45,7 +45,7 @@ inline Eigen::Matrix<T, 3, 1> makeDirectionUnitFromPhiEta(T phi, T eta) {
 ///       unexpected implicit type conversions and forces the user to
 ///       explicitly cast mismatched input types.
 template <typename T>
-inline Eigen::Matrix<T, 3, 1> makeDirectionUnitFromPhiTheta(T phi, T theta) {
+inline Eigen::Matrix<T, 3, 1> makeDirectionFromPhiTheta(T phi, T theta) {
   const auto cosTheta = std::cos(theta);
   const auto sinTheta = std::sin(theta);
   return {

Core/include/Acts/Vertexing/HelicalTrackLinearizer.ipp

@@ -25,7 +25,7 @@ Acts::Result<Acts::LinearizedTrack> Acts::
   // This allows us to determine whether we need to propagate the track
   // forward or backward to arrive at the PCA.
   auto intersection = perigeeSurface->intersect(gctx, params.position(gctx),
-                                                params.unitDirection(), false);
+                                                params.direction(), false);
 
   // Create propagator options
   propagator_options_t pOptions(gctx, mctx);

Core/include/Acts/Vertexing/NumericalTrackLinearizer.ipp

@@ -35,7 +35,7 @@ Acts::NumericalTrackLinearizer<propagator_t, propagator_options_t>::
   // This allows us to determine whether we need to propagate the track
   // forward or backward to arrive at the PCA.
   auto intersection = perigeeSurface->intersect(gctx, params.position(gctx),
-                                                params.unitDirection(), false);
+                                                params.direction(), false);
 
   // Setting the propagation direction using the intersection length from
   // above.
@@ -108,8 +108,8 @@ Acts::NumericalTrackLinearizer<propagator_t, propagator_options_t>::
     // Create curvilinear track object from our parameters. This is needed for
     // the propagation. Note that we work without covariance since we don't need
     // it to compute the derivative.
-    Vector3 wiggledDir = makeDirectionUnitFromPhiTheta(paramVecCopy(eLinPhi),
-                                                       paramVecCopy(eLinTheta));
+    Vector3 wiggledDir = makeDirectionFromPhiTheta(paramVecCopy(eLinPhi),
+                                                   paramVecCopy(eLinTheta));
     // Since we work in 4D we have eLinPosSize = 4
     CurvilinearTrackParameters wiggledCurvilinearParams(
         paramVecCopy.head(eLinPosSize), wiggledDir, paramVecCopy(eLinQOverP));

Core/include/Acts/Visualization/EventDataView3D.hpp

@@ -148,7 +148,7 @@ struct EventDataView3D {
 
     // Draw the parameter shaft and cone
     auto position = parameters.position(gctx);
-    auto direction = parameters.unitDirection();
+    auto direction = parameters.direction();
     double p = parameters.absoluteMomentum();
 
     ViewConfig lparConfig = parConfig;

Core/src/EventData/TransformationBoundToFree.cpp

@@ -19,8 +19,8 @@ Acts::FreeVector Acts::detail::transformBoundToFreeParameters(
     const Acts::Surface& surface, const GeometryContext& geoCtx,
     const Acts::BoundVector& boundParams) {
   // convert angles to global unit direction vector
-  Vector3 direction = makeDirectionUnitFromPhiTheta(boundParams[eBoundPhi],
-                                                    boundParams[eBoundTheta]);
+  Vector3 direction = makeDirectionFromPhiTheta(boundParams[eBoundPhi],
+                                                boundParams[eBoundTheta]);
 
   // convert local position to global position vector
   Vector2 local(boundParams[eBoundLoc0], boundParams[eBoundLoc1]);

Examples/Algorithms/Digitization/src/DigitizationAlgorithm.cpp

@@ -286,7 +286,7 @@ ActsExamples::DigitizationAlgorithm::channelizing(
 
   auto driftedSegment =
       m_surfaceDrift.toReadout(gctx, surface, geoCfg.thickness, hit.position(),
-                               hit.unitDirection(), driftDir);
+                               hit.direction(), driftDir);
   auto maskedSegmentRes = m_surfaceMask.apply(surface, driftedSegment);
   if (maskedSegmentRes.ok()) {
     auto maskedSegment = maskedSegmentRes.value();

Examples/Algorithms/Digitization/src/PlanarSteppingAlgorithm.cpp

@@ -151,8 +151,7 @@ ActsExamples::ProcessCode ActsExamples::PlanarSteppingAlgorithm::execute(
 
       Acts::Vector2 localIntersect =
           (invTransfrom * simHit.position()).head<2>();
-      Acts::Vector3 localDirection =
-          invTransfrom.linear() * simHit.unitDirection();
+      Acts::Vector3 localDirection = invTransfrom.linear() * simHit.direction();
 
       // compute digitization steps
       const auto thickness = dg.detectorElement->thickness();

Examples/Algorithms/TrackFitting/src/RefittingAlgorithm.cpp

@@ -96,7 +96,7 @@ ActsExamples::ProcessCode ActsExamples::RefittingAlgorithm::execute(
 
     ACTS_VERBOSE("Initial parameters: "
                  << initialParams.fourPosition(ctx.geoContext).transpose()
-                 << " -> " << initialParams.unitDirection().transpose());
+                 << " -> " << initialParams.direction().transpose());
 
     ACTS_DEBUG("Invoke direct fitter for track " << itrack);
     auto result = (*m_cfg.fit)(trackSourceLinks, initialParams, options,

Examples/Algorithms/TrackFitting/src/TrackFittingAlgorithm.cpp

@@ -123,7 +123,7 @@ ActsExamples::ProcessCode ActsExamples::TrackFittingAlgorithm::execute(
 
     ACTS_VERBOSE("Initial parameters: "
                  << initialParams.fourPosition(ctx.geoContext).transpose()
-                 << " -> " << initialParams.unitDirection().transpose());
+                 << " -> " << initialParams.direction().transpose());
 
     // Clear & reserve the right size
     trackSourceLinks.clear();

Examples/Framework/include/ActsExamples/EventData/AverageSimHits.hpp

@@ -55,7 +55,7 @@ inline std::tuple<Acts::Vector2, Acts::Vector4, Acts::Vector3> averageSimHits(
     // averaged position is still on the surface. the averaged global position
     // might not be on the surface anymore.
     auto result = surface.globalToLocal(gCtx, simHit.position(),
-                                        simHit.unitDirection(), 0.5_um);
+                                        simHit.direction(), 0.5_um);
     if (result.ok()) {
       avgLocal += result.value();
     } else {
@@ -66,7 +66,7 @@ inline std::tuple<Acts::Vector2, Acts::Vector4, Acts::Vector3> averageSimHits(
     // global position should already be at the intersection. no need to perform
     // an additional intersection call.
     avgPos4 += simHit.fourPosition();
-    avgDir += simHit.unitDirection();
+    avgDir += simHit.direction();
   }
 
   // only need to average if there are at least two inputs