Enable externally-filled surface hits for Simphony optical photon transport - #97
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Ningclover wants to merge 3 commits into
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Enable externally-filled surface hits for Simphony optical photon transport#97Ningclover wants to merge 3 commits into
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- Use CreateAttValues() instead of deprecated GetAttValues() in PersistencyManager - Null-check theStackingAction before calling SetKillOpticalPhotons in SurfaceSD - Move external actions call before early-return in UserEventAction so GPU optical plugins always run per event Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- HitSurface: add a value constructor for photon transport that is offloaded from Geant4 (e.g. GPU tracking), where no G4Step exists to copy the hit information from. Pure initializer list; no change for existing callers or the persistent TG4PhotonHit/ROOT I/O layer. - PersistencyManager: null-guard the hit collections in SummarizePhotonDetectors and SummarizeSegmentDetectors. The G4HCtable lists every registered collection, but GetHC() returns null for a slot not filled in a given event - possible for sensitive detectors that are not attached to a volume (their Initialize() is never called). The old code dereferenced unconditionally and segfaulted. Together these let an external plugin convert offloaded photon hits into a HitSurface collection that lands in TG4Event.PhotonDetectors under its own sensitive-detector name, with any persistency backend. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
ClarkMcGrew
reviewed
Aug 4, 2026
| void EDepSim::UserEventAction::EndOfEventAction(const G4Event* theEvent) { | ||
| EDepSimInfo("Event " << theEvent->GetEventID() << " completed."); | ||
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| // Run external actions unconditionally first, before the early-return |
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Moving this code earlier means that the EDepSim::Trajectory will not be completely filled when the G4UserEventAction is called. I wonder if this means that there should be two call backs (e.g. the current EndOfEventAction() that doesn't modify the trajectories, and a new "PreEndOfEventAction()" that can add stuff).
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Actually, a better solution might be to leave the original call at the end, and move this into the "if (!HCofEvent)".
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Summary
edep-sim already provides the framework for surface sensitive detectors,
EDepSim::HitSurface, photon-detector summarisation, and thefExternalActionshook on the user event action. This PR makes thatframework usable from an external plugin that transports optical photons
outside Geant4 (e.g. on a GPU) and fills the resulting hits back into the
event.
The changes are deliberately minimal and additive — no existing behaviour
changes for a normal CPU-only run.
Changes
EDepSimHitSurface.{hh,cc}— new value-based constructor.Adds
HitSurface(primaryId, energyDeposit, position, start, pdgEncoding, creatorType, creatorSubtype). Photons transported outside Geant4 have noG4Step, so the existingG4Step-based constructor can't be used torecord their hits. The original constructor is untouched.
EDepSimUserEventAction.cc— run external actions before the earlyreturn. The
fExternalActionsloop is moved to the top ofEndOfEventAction, ahead of the ionization-hit handling that can returnearly. An external optical plugin must run on every event, including
events with no ionization hits in any sensitive detector.
EDepSimSurfaceSD.cc— null-guard the stacking action. When photontransport is offloaded the user stacking action may not be installed;
SetKillOpticalPhotonsis now only called when it is present, avoiding anull dereference.
EDepSimPersistencyManager.cc— null-guard hit collections. InSummarizePhotonDetectorsandSummarizeSegmentDetectors, guard against anull
G4VHitsCollection(which can occur when collections are filledexternally) before calling
GetSize().EDepSimPersistencyManager.cc— useCreateAttValues()in thetrajectory-point debug print.
GetAttValues()can return null in thispath;
CreateAttValues()is the safe accessor. This only affects anerror-logging branch. (Minor correctness fix noticed while working here —
happy to split it out if preferred.)
Testing
Built against Clark's
masterand exercised with an external GPU opticalplugin (eic-opticks / simphony). CPU-only runs are unaffected. Branch merges
cleanly into
master.