From e0a1514ca0bcf4dcbc62fd4f440b611fb75da0a4 Mon Sep 17 00:00:00 2001
From: Pierre-Alain Loizeau <p.-a.loizeau@gsi.de>
Date: Thu, 6 Apr 2023 16:25:42 +0200
Subject: [PATCH] GeoAssembly bounding box after alignment: use ROOT expert
 patch

- cf discussion in https://github.com/root-project/root/issues/12242
- Improvement of PR #1244
- see also Issue #1243
- Solves new sub-case of Cbmroot issue https://redmine.cbm.gsi.de/issues/2620

More generic solution also catching edge case where only Nodes inside assembly are aligned but not assembly itself

(cherry picked from commit b4b5f0edcffe3130d7c49ffb8a049c70d90a5664)
---
 alignment/FairAlignmentHandler.cxx | 42 ++++++++++++++++--------------
 alignment/FairAlignmentHandler.h   |  4 +--
 2 files changed, 24 insertions(+), 22 deletions(-)

diff --git a/alignment/FairAlignmentHandler.cxx b/alignment/FairAlignmentHandler.cxx
index cb63e623a4..b7cac4f761 100644
--- a/alignment/FairAlignmentHandler.cxx
+++ b/alignment/FairAlignmentHandler.cxx
@@ -5,10 +5,8 @@
 #include <TGeoManager.h>
 #include <TGeoPhysicalNode.h>
 #include <TGeoShapeAssembly.h>
-
-FairAlignmentHandler::FairAlignmentHandler() {}
-
-FairAlignmentHandler::~FairAlignmentHandler() {}
+#include <TGeoVoxelFinder.h>
+#include <fairlogger/Logger.h>
 
 void FairAlignmentHandler::AlignGeometry() const
 {
@@ -22,8 +20,9 @@ void FairAlignmentHandler::AlignGeometry() const
             AlignGeometryByFullPath();
         }
 
-        // --- Force BoundingBox recomputation for AssemblyVolumes as they may have been corrupted by alignment
-        // FIXME: will hopefully be fixed in Root in near future, temp fix in meantime
+        // --- Force BoundingBox recomputation for volumes/nodes needing it after alignment
+        // FIXME: May be added to RefreshPhysicalNode step in Root in near future, temp fix needed here in meantime
+        ///       cf https://github.com/root-project/root/issues/12242
         RecomputePhysicalAssmbBbox();
 
         LOG(info) << "Refreshing geometry...";
@@ -104,20 +103,23 @@ void FairAlignmentHandler::AddAlignmentMatrices(const std::map<std::string, TGeo
 
 void FairAlignmentHandler::RecomputePhysicalAssmbBbox() const
 {
-    TObjArray* pPhysNodesArr = gGeoManager->GetListOfPhysicalNodes();
-
-    TGeoPhysicalNode* pPhysNode = nullptr;
-    TGeoShapeAssembly* pShapeAsb = nullptr;
-
-    Int_t iNbNodes = pPhysNodesArr->GetEntriesFast();
-    for (Int_t iInd = 0; iInd < iNbNodes; ++iInd) {
-        pPhysNode = dynamic_cast<TGeoPhysicalNode*>(pPhysNodesArr->At(iInd));
-        if (pPhysNode) {
-            pShapeAsb = dynamic_cast<TGeoShapeAssembly*>(pPhysNode->GetShape());
-            if (pShapeAsb) {
-                // Should reach here only if the original node was a TGeoShapeAssembly
-                pShapeAsb->ComputeBBox();
-            }
+    /// After alignment, forces the recomputation of the bounding box of all volumesAssemblies and the rebuilding of
+    /// Nodes requiring it.
+    /// => Not done after each change to geometry in ROOT for perf reason
+    /// => to be called once all changes done
+    /// => original snippet proposed in https://github.com/root-project/root/issues/12242 by A. Gheata
+    TObjArray* volumes = gGeoManager->GetListOfVolumes();
+    for (auto vol : TRangeDynCast<TGeoVolume>(volumes)) {
+        if (!vol) {
+            continue;
+        }
+        if (vol->IsAssembly()) {
+            vol->GetShape()->ComputeBBox();
+        }
+        auto finder = vol->GetVoxels();
+        if (finder && finder->NeedRebuild()) {
+            finder->Voxelize();
+            vol->FindOverlaps();
         }
     }
 }
diff --git a/alignment/FairAlignmentHandler.h b/alignment/FairAlignmentHandler.h
index 3535ea5697..a9ca37181b 100644
--- a/alignment/FairAlignmentHandler.h
+++ b/alignment/FairAlignmentHandler.h
@@ -18,8 +18,8 @@ class FairAlignmentHandler
     void RecomputePhysicalAssmbBbox() const;
 
   public:
-    FairAlignmentHandler();
-    virtual ~FairAlignmentHandler();
+    FairAlignmentHandler() = default;
+    virtual ~FairAlignmentHandler() = default;
 };
 
 #endif