uLib/src/Vtk/HEP/Geant/vtkGeantSolid.cpp

/*//////////////////////////////////////////////////////////////////////////////
// CMT Cosmic Muon Tomography project //////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////

  Copyright (c) 2014, Universita' degli Studi di Padova, INFN sez. di Padova
  All rights reserved

  Authors: Andrea Rigoni Garola < andrea.rigoni@pd.infn.it >

  ------------------------------------------------------------------
  This library is free software;  you  can  redistribute  it  and/or
  modify it  under the  terms  of  the  GNU  Lesser  General  Public
  License as published  by  the  Free  Software  Foundation;  either
  version 3.0 of the License, or (at your option) any later version.

  This library is  distributed in  the hope that it will  be useful,
  but  WITHOUT ANY WARRANTY;  without  even  the implied warranty of
  MERCHANTABILITY  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of  the GNU Lesser General  Public
  License along with this library.

//////////////////////////////////////////////////////////////////////////////*/

#include "vtkGeantSolid.h"

#include <vtkActor.h>
#include <vtkPolyData.h>
#include <vtkPoints.h>
#include <vtkCellArray.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkSmartPointer.h>
#include <vtkTransform.h>
#include <vtkMatrix4x4.h>

#include <Geant4/G4VSolid.hh>
#include <Geant4/G4Polyhedron.hh>
#include <Geant4/G4VPhysicalVolume.hh>

namespace uLib {
namespace Vtk {

GeantSolid::GeantSolid(Content *content)
    : m_SolidActor(vtkActor::New()), m_Content(content) {
  this->InstallPipe();
}

GeantSolid::~GeantSolid() {
  m_SolidActor->Delete();
}

vtkPolyData *GeantSolid::GetPolyData() const {
  if (!m_SolidActor || !m_SolidActor->GetMapper())
    return NULL;
  return vtkPolyData::SafeDownCast(m_SolidActor->GetMapper()->GetInput());
}

void GeantSolid::Update() {
  this->UpdateGeometry();
  this->UpdateTransform();
}

void GeantSolid::UpdateGeometry() {
  if (!m_Content)
    return;

  G4VSolid *g4solid = m_Content->GetG4Solid();
  if (!g4solid)
    return;

  // Get the polyhedron tessellation from Geant4
  G4Polyhedron *polyhedron = g4solid->GetPolyhedron();
  if (!polyhedron)
    return;

  vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
  vtkSmartPointer<vtkCellArray> polys = vtkSmartPointer<vtkCellArray>::New();

  // Extract vertices
  int nVertices = polyhedron->GetNoVertices();
  for (int i = 1; i <= nVertices; ++i) {
    G4Point3D vtx = polyhedron->GetVertex(i);
    
    points->InsertNextPoint(vtx.x(), vtx.y(), vtx.z());
  }

  // Extract facets (polygons)
  int nFacets = polyhedron->GetNoFacets();
  for (int f = 1; f <= nFacets; ++f) {
    G4int nEdges;
    G4int iVertex[4]; // G4Polyhedron facets have at most 4 vertices
    // GetNextFacet returns edges; for quads nEdges=4, for triangles nEdges=3
    polyhedron->GetFacet(f, nEdges, iVertex);

    vtkIdType ids[4];
    for (int e = 0; e < nEdges; ++e) {
      // G4Polyhedron vertices are 1-indexed; VTK expects 0-indexed
      ids[e] = static_cast<vtkIdType>(std::abs(iVertex[e]) - 1);
    }
    polys->InsertNextCell(nEdges, ids);
  }

  vtkPolyData *polyData = GetPolyData();
  if (polyData) {
    polyData->SetPoints(points);
    polyData->SetPolys(polys);
    polyData->Modified();
  }
}

void GeantSolid::UpdateTransform() {
  if (!m_Content || !m_SolidActor)
    return;

  // Apply the Geant4 transform (position/rotation) if placed
  if (m_Content->GetPhysical()) {
    auto *phys = m_Content->GetPhysical();
    G4ThreeVector pos = phys->GetTranslation();
    const G4RotationMatrix *rot = phys->GetRotation();

    vtkSmartPointer<vtkTransform> transform = vtkSmartPointer<vtkTransform>::New();
    transform->Identity();
    transform->Translate(pos.x(), pos.y(), pos.z());

    if (rot) {
      // G4RotationMatrix stores the inverse of the rotation for placement
      G4RotationMatrix invRot = rot->inverse();
      double elements[16] = {
        invRot.xx(), invRot.xy(), invRot.xz(), 0,
        invRot.yx(), invRot.yy(), invRot.yz(), 0,
        invRot.zx(), invRot.zy(), invRot.zz(), 0,
        0, 0, 0, 1
      };
      vtkSmartPointer<vtkMatrix4x4> mat = vtkSmartPointer<vtkMatrix4x4>::New();
      mat->DeepCopy(elements);
      transform->Concatenate(mat);
    }

    m_SolidActor->SetUserTransform(transform);
  }
}

void GeantSolid::InstallPipe() {
  vtkSmartPointer<vtkPolyData> polyData = vtkSmartPointer<vtkPolyData>::New();
  vtkSmartPointer<vtkPolyDataMapper> mapper =
      vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputData(polyData);

  m_SolidActor->SetMapper(mapper);

  // Default look: semi-transparent blue surface
  m_SolidActor->GetProperty()->SetColor(0.4, 0.6, 0.9);
  m_SolidActor->GetProperty()->SetOpacity(0.3);
  m_SolidActor->GetProperty()->SetAmbient(0.5);
  m_SolidActor->GetProperty()->SetDiffuse(0.6);
  m_SolidActor->GetProperty()->SetSpecular(0.2);
  m_SolidActor->GetProperty()->SetEdgeVisibility(1);
  m_SolidActor->GetProperty()->SetEdgeColor(0.2, 0.3, 0.5);

  this->SetProp(m_SolidActor);
}

} // namespace Vtk
} // namespace uLib