G4OCCT_STEPSolid.cc

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// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 2026 G4OCCT Contributors
 
#include <DD4hep/DetFactoryHelper.h>
#include <DD4hep/Printout.h>
#include "G4OCCT/TGeoOCCTSolid.hh"
 
#include <stdexcept>
#include <string>
 
using namespace dd4hep;
 
static Ref_t create_step_solid(Detector& description, xml_h e, SensitiveDetector /*sens*/) {
  xml_det_t x_det   = e;
  xml_comp_t x_step = x_det.child(_Unicode(step_file));
  xml_comp_t x_pos  = x_det.child(_Unicode(position));
  xml_comp_t x_rot  = x_det.child(_Unicode(rotation));
  xml_comp_t x_mat  = x_det.child(_Unicode(material));
 
  std::string name = x_det.nameStr();
  std::string path = x_step.attr<std::string>(_Unicode(path));
 
  TGeoOCCTSolid* stepSolid = nullptr;
  try {
    stepSolid = TGeoOCCTSolid::FromSTEP(name.c_str(), path);
  } catch (const std::exception& ex) {
    throw std::runtime_error("G4OCCT_STEPSolid: failed to import '" + path + "' (" + ex.what() +
                             ")");
  }
  if (!stepSolid) {
    throw std::runtime_error("G4OCCT_STEPSolid: import of '" + path +
                             "' returned a null TGeoOCCTSolid");
  }
  printout(INFO, "G4OCCT_STEPSolid", "Imported '%s' from '%s' as exact TGeoOCCTSolid", name.c_str(),
           path.c_str());
 
  // ── DD4hep volume and placement ──────────────────────────────────────────
  Material mat = description.material(x_mat.attr<std::string>(_Unicode(name)));
  Volume vol(name + "_vol", Solid(stepSolid), mat);
  vol.setVisAttributes(description, x_det.visStr());
 
  DetElement det(name, x_det.id());
  Position pos(x_pos.x(), x_pos.y(), x_pos.z());
  RotationZYX rot(x_rot.z(), x_rot.y(), x_rot.x());
  PlacedVolume pv = description.pickMotherVolume(det).placeVolume(vol, Transform3D(rot, pos));
  pv.addPhysVolID("system", x_det.id());
  det.setPlacement(pv);
  return det;
}
 
DECLARE_DETELEMENT(G4OCCT_STEPSolid, create_step_solid)