void PNodeTest()
{
// Test physical nodes visualization
//
// Creating physical nodes:
// 1. TGeoPhysicalNode *node = gGeoManager->MakePhysicalNode(const char *path)
//   - creates a physical node represented by path
// 2. TGeoPhysicalNode *node = gGeoManager->MakePhysicalNode()
//   - creates a physical node representing the current modeller state

// Setting visualisation options for TGeoPhysicalNode *node:
// 1.   node->SetVisibility(Bool_t flag); // set node visible(*) or invisible
// 2.   node->SetIsVolAtt(Bool_t flag);   // set line attributes to match the ones of the volumes in the branch
//    - default - TRUE 
//    - when called with FALSE - the attributes defined for the physical node will be taken
//       node->SetLineColor(color);
//       node->SetLineWidth(width);
//       node->SetLineStyle(style);
// 3.   node->SetVisibleFull(Bool_t flag); // not only last node in the branch is visible (default) 
//
// Activating/desactivating physical nodes drawing
// gGeoManager->SetDrawExtraPaths(Bool_t flag)

   gROOT->LoadMacro("$ROOTSYS/tutorials/rootgeom.C");
   gInterpreter->ProcessLine("rootgeom()");
   TGeoPhysicalNode *node;
   // Draw an "R" with different line settings
   node = gGeoManager->MakePhysicalNode("TOP_1/REPLICA_2/ROOT_3/R_1/bar1_1");
   node->SetLineColor(kBlue);
   node->SetLineWidth(2);
   node->SetIsVolAtt(kFALSE);
   node = gGeoManager->MakePhysicalNode("TOP_1/REPLICA_2/ROOT_3/R_1/bar2_1");
   node->SetLineColor(kBlue);
   node->SetLineWidth(2);
   node->SetIsVolAtt(kFALSE);
   node = gGeoManager->MakePhysicalNode("TOP_1/REPLICA_2/ROOT_3/R_1/bar2_2");
   node->SetLineColor(kBlue);
   node->SetLineWidth(2);
   node->SetIsVolAtt(kFALSE);
   node = gGeoManager->MakePhysicalNode("TOP_1/REPLICA_2/ROOT_3/R_1/tub1_1");
   node->SetLineColor(kBlue);
   node->SetLineWidth(2);
   node->SetIsVolAtt(kFALSE);
   node = gGeoManager->MakePhysicalNode("TOP_1/REPLICA_2/ROOT_3/R_1/bar3_1");
   node->SetLineColor(kBlue);
   node->SetLineWidth(2);
   node->SetIsVolAtt(kFALSE);
   // Draw all volumes on the path of an "O" and keep original colors
   node = gGeoManager->MakePhysicalNode("TOP_1/REPLICA_3/ROOT_4/O_1/bar4_1");
   node->SetVisibleFull(kTRUE);
   node = gGeoManager->MakePhysicalNode("TOP_1/REPLICA_3/ROOT_4/O_1/bar4_2");
   node->SetVisibleFull(kTRUE);
   node = gGeoManager->MakePhysicalNode("TOP_1/REPLICA_3/ROOT_4/O_1/tub1_1");
   node->SetVisibleFull(kTRUE);
   node = gGeoManager->MakePhysicalNode("TOP_1/REPLICA_3/ROOT_4/O_1/tub1_2");
   node->SetVisibleFull(kTRUE);
   
   // Just activate visibility of extra paths
   gGeoManager->SetDrawExtraPaths(kTRUE);
   gGeoManager->SetVisLevel(1); // nothing really seen with this drawing option, except physical nodes
   gGeoManager->GetTopVolume()->Draw();
}