Acts/ActsMaterial/src/MaterialMapping.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
#include "MaterialMapping.h"
#include "GaudiKernel/IInterface.h"
#include "ActsInterop/Logger.h"
#include "Acts/Geometry/TrackingGeometry.hpp"
#include "Acts/Material/IntersectionMaterialAssigner.hpp"
#include "Acts/Material/BinnedSurfaceMaterialAccumulator.hpp"
#include "Acts/Material/TrackingGeometryMaterial.hpp"
 
ActsTrk::MaterialMapping::MaterialMapping(const std::string& name, ISvcLocator* pSvcLocator) :
    AthReentrantAlgorithm(name, pSvcLocator)
{}
 
ActsTrk::MaterialMapping::~MaterialMapping()
{}
 
StatusCode ActsTrk::MaterialMapping::initialize()
{
    ATH_CHECK(m_materialTrackCollectionKey.initialize());
    ATH_CHECK(m_mappedMaterialTrackCollectionKey.initialize());
    ATH_CHECK(m_unmappedMaterialTrackCollectionKey.initialize());
 
    ATH_CHECK(m_trackingGeometrySvc.retrieve());
 
    ATH_CHECK(m_materialDumper.retrieve());
 
    // Retrieve the material surfaces
    std::vector<const Acts::Surface*> materialSurfaces = {};
 
    auto surfaceSelector = [&](const Acts::Surface* surface) {
        if (surface->surfaceMaterial() != nullptr &&
            std::ranges::find(materialSurfaces, surface) == materialSurfaces.end()) {
                materialSurfaces.push_back(surface);
        }
    };
 
    // Visit all surfaces (second argument = if true only sensitive surfaces are visited)
    m_trackingGeometrySvc->trackingGeometry()->visitSurfaces(surfaceSelector, false);
 
    // The material intersection assigner
    Acts::IntersectionMaterialAssigner::Config assingerConfig;
    assingerConfig.surfaces = materialSurfaces;
    auto materialAssigner = std::make_shared<Acts::IntersectionMaterialAssigner>(assingerConfig,
                                                                                 makeActsAthenaLogger(this, "MaterialAssigner"));
 
    // The binned surface material accumulator
    Acts::BinnedSurfaceMaterialAccumulator::Config accumulatorConfig;
    accumulatorConfig.materialSurfaces = std::move(materialSurfaces);
    auto materialAccumulator = std::make_shared<Acts::BinnedSurfaceMaterialAccumulator>(accumulatorConfig,
                                                                                        makeActsAthenaLogger(this, "MaterialAccumulator"));

    Acts::MaterialMapper::Config mapperConfig;
    mapperConfig.assignmentFinder = materialAssigner;
    mapperConfig.surfaceMaterialAccumulator = materialAccumulator;
    m_materialMapper = std::make_shared<Acts::MaterialMapper> (mapperConfig,
                                                               makeActsAthenaLogger(this, "MaterialMapper"));
 
    // Create the state object
    const ActsTrk::GeometryContext& geoContext{m_trackingGeometrySvc->getNominalContext()};
    m_mappingState = m_materialMapper->createState(geoContext.context());
 
    return StatusCode::SUCCESS;
}
 
StatusCode ActsTrk::MaterialMapping::finalize()
{
    const ActsTrk::GeometryContext& geoContext{m_trackingGeometrySvc->getNominalContext()};
    Acts::TrackingGeometryMaterial detectorMaterial = m_materialMapper->finalizeMaps(*m_mappingState, geoContext.context());
 
    // Dump the maps through the material writers
    m_materialDumper->dumpMaterial(geoContext, detectorMaterial);
 
    return StatusCode::SUCCESS;
}
 
StatusCode
ActsTrk::MaterialMapping::execute (const EventContext& ctx) const
{
    // Read the collection to the EventStore
    SG::ReadHandle<ActsTrk::RecordedMaterialTrackCollection> materialTracks(m_materialTrackCollectionKey, ctx);
    // Check if all is fine
    if (!materialTracks.isValid()) {
        ATH_MSG_ERROR("Failed to read " << m_materialTrackCollectionKey.key());
        return StatusCode::FAILURE;
    }
 
    // Write to the collection to the EventStore
    SG::WriteHandle<ActsTrk::RecordedMaterialTrackCollection> unmappedMaterialTracks(m_unmappedMaterialTrackCollectionKey, ctx);
    SG::WriteHandle<ActsTrk::RecordedMaterialTrackCollection> mappedMaterialTracks(m_mappedMaterialTrackCollectionKey, ctx);
 
    // Record the collection once per event if not already there
    // You do it once for the unmapped material tracks ...
    if (!unmappedMaterialTracks.isPresent()) {
        auto coll = std::make_unique<ActsTrk::RecordedMaterialTrackCollection>();
        ATH_CHECK(unmappedMaterialTracks.record(std::move(coll)));
    }
    auto* unmappedColl = unmappedMaterialTracks.ptr();
    if (!unmappedColl) {
        ATH_MSG_ERROR("RecordedMaterialTrackCollection ptr() is null for key "
                      << m_unmappedMaterialTrackCollectionKey.key());
        return StatusCode::FAILURE;
    }
    // ... and then for the mapped material tracks
    if (!mappedMaterialTracks.isPresent()) {
        auto coll = std::make_unique<ActsTrk::RecordedMaterialTrackCollection>();
        ATH_CHECK(mappedMaterialTracks.record(std::move(coll)));
    }
    auto* mappedColl = mappedMaterialTracks.ptr();
    if (!mappedColl) {
        ATH_MSG_ERROR("RecordedMaterialTrackCollection ptr() is null for key "
                      << m_mappedMaterialTrackCollectionKey.key());
        return StatusCode::FAILURE;
    }
 
    auto mappingState = const_cast<Acts::MaterialMapper::State*>(m_mappingState.get());
 
    const ActsTrk::GeometryContext& geoContext{m_trackingGeometrySvc->getNominalContext()};
    Acts::MagneticFieldContext magFieldContext;
 
    // Loop over the material tracks and map them on the surfaces
    for (const auto& materialTrack : *materialTracks) {
        auto [mapped, unmapped] = m_materialMapper->mapMaterial(
            *mappingState, geoContext.context(), magFieldContext, materialTrack);
        // collect mapped and unmapped states
        mappedColl->push_back(mapped);
        unmappedColl->push_back(unmapped);
  }
 
  return StatusCode::SUCCESS;
 
}