From 38c6bfaa6f014c3af2b1e5219c383cf36483c9c3 Mon Sep 17 00:00:00 2001
From: David Nathan Brown <dave_brown@lbl.gov>
Date: Tue, 21 Nov 2023 16:05:47 -0600
Subject: [PATCH] Add index leaf to allow navigation to sub-ranked genealogy
 sim info.  Allow matching multiple sim particles by default

---
 fcl/prolog.fcl            | 4 +++-
 inc/SimInfo.hh            | 1 +
 src/InfoMCStructHelper.cc | 4 +++-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fcl/prolog.fcl b/fcl/prolog.fcl
index 9d072e8..cd1ca37 100644
--- a/fcl/prolog.fcl
+++ b/fcl/prolog.fcl
@@ -97,13 +97,15 @@ dioLLWeight : {
 }
 genCountLogger: { module_type: GenEventCountReader }
 
-AllOpt : { fillMC : true
+AllOpt : {
+  fillMC : true
   trkqual : "TrkQual"
   fillTrkQual : true
   trkpid : "TrkPID"
   fillTrkPID : true
   fillHits : true
   genealogyDepth : -1
+  matchDepth : -1
 }
 
 DeM : { input : "KK"
diff --git a/inc/SimInfo.hh b/inc/SimInfo.hh
index 3124be7..0615e42 100644
--- a/inc/SimInfo.hh
+++ b/inc/SimInfo.hh
@@ -20,6 +20,7 @@ namespace mu2e
     Int_t proc = -1; // process code
     Int_t gen = -1; // generator code
     Float_t time = -1.0;  // Origin time of the SimParticle
+    Int_t index; // index into the SimInfo vector
     XYZVectorF mom = XYZVectorF();  // origin momentumof the SimParticle
     XYZVectorF pos = XYZVectorF();  // origin position of the SimParticle
     MCRelationship prirel = MCRelationship::none; // relationship to the event primary particles
diff --git a/src/InfoMCStructHelper.cc b/src/InfoMCStructHelper.cc
index e76d3a4..8159644 100644
--- a/src/InfoMCStructHelper.cc
+++ b/src/InfoMCStructHelper.cc
@@ -160,7 +160,8 @@ namespace mu2e {
           sim_info.nhits = kseedmc.simParticle(imatch)._nhits;
           sim_info.nactive = kseedmc.simParticle(imatch)._nactive;
         }
-
+        // record the index this object will have
+        sim_info.index = siminfos.size();
         siminfos.push_back(sim_info);
         if (current_sim_particle.parent().isNonnull()) {
           current_sim_particle_ptr = current_sim_particle.parent();
@@ -189,6 +190,7 @@ namespace mu2e {
         auto trkprimaryptr = kseedmc.simParticle().simParticle(_spcH);
         sim_info.trkrel = MCRelationship(spp, trkprimaryptr);
         sim_info.prirel = MCRelationship(spp, spp);
+        sim_info.index = siminfos.size();
         siminfos.push_back(sim_info);
       }
     }