feat: make stepping logger volume agnostic (#2454)

This PR removes the explicit setting of `TrackingVolume` in favour of
the `GeometryIdentifier` (which is the only thing that is accessed from
the `TrackingVolume` in the `Step` struct of the `SteppingLogger` and
thus makes the step logging infrastructure accessible to the new
`Acts::Detector` geometry as well.

Core/include/Acts/Propagator/detail/SteppingLogger.hpp

@@ -13,6 +13,7 @@
 #include "Acts/Definitions/Direction.hpp"
 #include "Acts/Geometry/GeometryIdentifier.hpp"
 #include "Acts/Propagator/ConstrainedStep.hpp"
+#include "Acts/Surfaces/Surface.hpp"
 #include "Acts/Utilities/Logger.hpp"
 
 #include <memory>
@@ -21,19 +22,21 @@
 namespace Acts {
 
 class Surface;
-class Layer;
-class TrackingVolume;
 
 namespace detail {
 
-/// @brief the step information for
+/// @brief The step information for recording
+///
+/// The surface object could be a temporarily created object
+/// and as the Step vector is collected and written out at a
+/// later stage, the surface is referenced counted here.
 struct Step {
   ConstrainedStep stepSize;
   Direction navDir;
   Vector3 position = Vector3(0., 0., 0.);
   Vector3 momentum = Vector3(0., 0., 0.);
   std::shared_ptr<const Surface> surface = nullptr;
-  const TrackingVolume* volume = nullptr;
+  GeometryIdentifier geoID = 0;
 };
 
 /// @brief a step length logger for debugging the stepping
@@ -65,23 +68,25 @@ struct SteppingLogger {
   void operator()(propagator_state_t& state, const stepper_t& stepper,
                   const navigator_t& navigator, result_type& result,
                   const Logger& /*logger*/) const {
-    // don't log if you have reached the target
+    // Don't log if you have reached the target or are sterile
     if (sterile or navigator.targetReached(state.navigation)) {
       return;
     }
-    // record the propagation state
+    // Record the propagation state
     Step step;
     step.stepSize = state.stepping.stepSize;
     step.navDir = state.options.direction;
     step.position = stepper.position(state.stepping);
     step.momentum = stepper.momentum(state.stepping);
 
+    // Record the information about the surface
     if (navigator.currentSurface(state.navigation) != nullptr) {
-      // hang on to surface
       step.surface = navigator.currentSurface(state.navigation)->getSharedPtr();
+      step.geoID = step.surface->geometryId();
+    } else if (navigator.currentVolume(state.navigation) != nullptr) {
+      // If there's no surface but a volume, this sets the geoID
+      step.geoID = navigator.currentVolume(state.navigation)->geometryId();
     }
-
-    step.volume = navigator.currentVolume(state.navigation);
     result.steps.push_back(std::move(step));
   }
 };

Examples/Io/Root/src/RootPropagationStepsWriter.cpp

@@ -102,12 +102,12 @@ ActsExamples::ProcessCode ActsExamples::RootPropagationStepsWriter::writeT(
   // Exclusive access to the tree while writing
   std::lock_guard<std::mutex> lock(m_writeMutex);
 
-  // we get the event number
+  // Get the event number
   m_eventNr = context.eventNumber;
 
-  // loop over the step vector of each test propagation in this
+  // Loop over the step vector of each test propagation in this
   for (auto& steps : stepCollection) {
-    // clear the vectors for each collection
+    // Clear the vectors for each collection
     m_volumeID.clear();
     m_boundaryID.clear();
     m_layerID.clear();
@@ -127,37 +127,21 @@ ActsExamples::ProcessCode ActsExamples::RootPropagationStepsWriter::writeT(
     m_step_usr.clear();
     m_nStepTrials.clear();
 
-    // loop over single steps
+    // Loop over single steps
     for (auto& step : steps) {
-      // the identification of the step
-      Acts::GeometryIdentifier::Value volumeID = 0;
-      Acts::GeometryIdentifier::Value boundaryID = 0;
-      Acts::GeometryIdentifier::Value layerID = 0;
-      Acts::GeometryIdentifier::Value approachID = 0;
-      Acts::GeometryIdentifier::Value sensitiveID = 0;
+      const auto& geoID = step.geoID;
+      m_sensitiveID.push_back(geoID.sensitive());
+      m_approachID.push_back(geoID.approach());
+      m_layerID.push_back(geoID.layer());
+      m_boundaryID.push_back(geoID.boundary());
+      m_volumeID.push_back(geoID.volume());
+
       int material = 0;
-      // get the identification from the surface first
       if (step.surface) {
-        auto geoID = step.surface->geometryId();
-        volumeID = geoID.volume();
-        boundaryID = geoID.boundary();
-        layerID = geoID.layer();
-        approachID = geoID.approach();
-        sensitiveID = geoID.sensitive();
         if (step.surface->surfaceMaterial() != nullptr) {
           material = 1;
         }
       }
-      // a current volume overwrites the surface tagged one
-      if (step.volume != nullptr) {
-        volumeID = step.volume->geometryId().volume();
-      }
-      // now fill
-      m_sensitiveID.push_back(sensitiveID);
-      m_approachID.push_back(approachID);
-      m_layerID.push_back(layerID);
-      m_boundaryID.push_back(boundaryID);
-      m_volumeID.push_back(volumeID);
       m_material.push_back(material);
 
       // kinematic information
@@ -189,13 +173,13 @@ ActsExamples::ProcessCode ActsExamples::RootPropagationStepsWriter::writeT(
         m_step_type.push_back(3);
       }
 
-      // step size information
+      // Step size information
       m_step_acc.push_back(Acts::clampValue<float>(accuracy));
       m_step_act.push_back(Acts::clampValue<float>(actor));
       m_step_abt.push_back(Acts::clampValue<float>(aborter));
       m_step_usr.push_back(Acts::clampValue<float>(user));
 
-      // stepper efficiency
+      // Stepper efficiency
       m_nStepTrials.push_back(step.stepSize.nStepTrials);
     }
     m_outputTree->Fill();

Examples/Python/tests/root_file_hashes.txt

@@ -72,9 +72,9 @@ test_vertex_fitting_reading[AMVF-False-100]__performance_vertexing.root: 009e4b1
 test_vertex_fitting_reading[AMVF-True-100]__performance_vertexing.root: 2d0dc1e02bfd1f7eaae26ef8ac657ce0291f70c7e4efddd35d171d31988a631e
 test_bfield_writing__solenoid.root: 7ab4d298cd1657c93c90ad7759ea536ad93f52b11cc90f8e3abe611b9cf13234
 test_bfield_writing__solenoid2.root: 948435fab0d2d23b61884acb44e150adc6ab7b432dc41e4e03ae289d8ac30224
-test_root_prop_step_writer[configPosConstructor]__prop_steps.root: 2bc273f9ec51d800de0b16fd3332ba6453c66d9be8eb3c28ce5856927b295ac3
-test_root_prop_step_writer[configKwConstructor]__prop_steps.root: 2bc273f9ec51d800de0b16fd3332ba6453c66d9be8eb3c28ce5856927b295ac3
-test_root_prop_step_writer[kwargsConstructor]__prop_steps.root: 2bc273f9ec51d800de0b16fd3332ba6453c66d9be8eb3c28ce5856927b295ac3
+test_root_prop_step_writer[configPosConstructor]__prop_steps.root: 53adaabc7856c888ad4005bacb2fb4c0af6ac74f5b7f0255c296cd8e1f2601a3
+test_root_prop_step_writer[configKwConstructor]__prop_steps.root: 53adaabc7856c888ad4005bacb2fb4c0af6ac74f5b7f0255c296cd8e1f2601a3
+test_root_prop_step_writer[kwargsConstructor]__prop_steps.root: 53adaabc7856c888ad4005bacb2fb4c0af6ac74f5b7f0255c296cd8e1f2601a3
 test_root_particle_writer[configPosConstructor]__particles.root: 8ca3987523360e4cd52f9bc138e82230996baa105c77ddb2cde775733d8acc4c
 test_root_particle_writer[configKwConstructor]__particles.root: 8ca3987523360e4cd52f9bc138e82230996baa105c77ddb2cde775733d8acc4c
 test_root_particle_writer[kwargsConstructor]__particles.root: 8ca3987523360e4cd52f9bc138e82230996baa105c77ddb2cde775733d8acc4c