Problem 1956

After issuing the following GEANT4 commands to VRML-visualize a certain detector geometry, GEANT4 issues several error messages and then freezes.
/vis/open VRML2FILE
/vis/drawVolume
/vis/viewer/update
/vis/viewer/flush

GEANT4 output:

===========================================
Output VRML 2.0 file: g4_00.wrl
Maximum number of files in the destination directory: 100
  (Customizable with the environment variable: G4VRMLFILE_MAX_FILE_NUM)
===========================================
G4VSceneHandler::RequestPrimitives
  Polyhedron not available for outerBox.
  This means it cannot be visualized on most systems.
  Contact the Visualization Coordinator.
(this is repeated 8 times)
ERROR: G4VSceneHandler::RequestPrimitives
  Polyhedron not available for endmountBox.
  This means it cannot be visualized on most systems.
  Contact the Visualization Coordinator.
(after this, GEANT4 freezes)

It appears that this is triggered by the attempted creation of a HepPolyhedron for a boolean solid - G4VSolid::GetPolyhedron() - in which the second solid is itself a boolean solid.

The following [recursive] code properly creates the HepPolyhedron from any G4VSolid (named "solid"), but doesn't - can't - store it in the G4VSolid's internal state:

HepPolyhedron* polyhedron = NULL;
if ((solid->GetEntityType() == "G4IntersectionSolid") ||
    (solid->GetEntityType() == "G4UnionSolid") ||
    (solid->GetEntityType() == "G4SubtractionSolid") ||
    (solid->GetEntityType() == "G4BooleanSolid")) {
  polyhedron = getBooleanSolidPolyhedron(solid);
} else {
  polyhedron = solid->GetPolyhedron();
}

HepPolyhedron* getBooleanSolidPolyhedron(G4VSolid* solid)
{
  G4VSolid* solidA = solid->GetConstituentSolid(0);
  G4VSolid* solidB = solid->GetConstituentSolid(1);
  HepPolyhedron* polyhedronA = NULL;
  if ((solidA->GetEntityType() == "G4IntersectionSolid") ||
      (solidA->GetEntityType() == "G4UnionSolid") ||
      (solidA->GetEntityType() == "G4SubtractionSolid") ||
      (solidA->GetEntityType() == "G4BooleanSolid")) {
    polyhedronA = getBooleanSolidPolyhedron(solidA);
  } else {
    polyhedronA = new HepPolyhedron(*(solidA->GetPolyhedron()));
  }
  HepPolyhedron* polyhedronB = NULL;
  G4VSolid* solidB2 = solidB;
  if (solidB->GetEntityType() == "G4DisplacedSolid") {
    solidB2 = ((G4DisplacedSolid*)solidB)->GetConstituentMovedSolid();
  }
  if ((solidB2->GetEntityType() == "G4IntersectionSolid") ||
      (solidB2->GetEntityType() == "G4UnionSolid") ||
      (solidB2->GetEntityType() == "G4SubtractionSolid") ||
      (solidB2->GetEntityType() == "G4BooleanSolid")) {
    polyhedronB = getBooleanSolidPolyhedron(solidB2);
    if (solidB != solidB2) { // was solidB a G4DisplacedSolid?
      polyhedronB->Transform(G4Transform3D(
                              ((G4DisplacedSolid*)solidB)->GetObjectRotation(),
                              ((G4DisplacedSolid*)solidB)->GetObjectTranslation()));
    }
  } else {
    polyhedronB = new HepPolyhedron(*(solidB->GetPolyhedron()));
  }
  HepPolyhedron* result = new HepPolyhedron();
  if (solid->GetEntityType() == "G4UnionSolid") {
    *result = polyhedronA->add(*polyhedronB);
  } else if (solid->GetEntityType() == "G4SubtractionSolid") {
    *result = polyhedronA->subtract(*polyhedronB);
  } else if (solid->GetEntityType() == "G4IntersectionSolid") {
    *result = polyhedronA->intersect(*polyhedronB);
  } else {
    // warning: "getBooleanSolidPolyhedron(): Unrecognized boolean solid " << solid->GetName() <<
              " of type " << solid->GetEntityType()
  }
  delete polyhedronA;
  delete polyhedronB;
  return result;
}