WikiExamples/Meshes/AddPointsAndEdges.cxx

#include "itkMesh.h"
#include "itkLineCell.h"

constexpr unsigned int Dimension = 3;
using MeshType = itk::Mesh< float, Dimension >;
  
MeshType::Pointer CreatePointOnlyMesh();
void CreateMeshWithEdges();

int main(int, char *[])
{
  //CreatePointOnlyMesh();
  CreateMeshWithEdges();
 
  return 0;
}


MeshType::Pointer CreatePointOnlyMesh()
{
  MeshType::Pointer  mesh = MeshType::New();

  // Create points
  MeshType::PointType p0,p1,p2,p3;
  
  p0[0]= -1.0; p0[1]= -1.0; p0[2]= 0.0; // first  point ( -1, -1, 0 )
  p1[0]=  1.0; p1[1]= -1.0; p1[2]= 0.0; // second point (  1, -1, 0 )
  p2[0]=  1.0; p2[1]=  1.0; p2[2]= 0.0; // third  point (  1,  1, 0 )
  p3[0]=  1.0; p3[1]=  1.0; p3[2]= 1.0; // third  point (  1,  1, 1 )

  mesh->SetPoint( 0, p0 );
  mesh->SetPoint( 1, p1 );
  mesh->SetPoint( 2, p2 );
  mesh->SetPoint( 3, p3 );

  std::cout << "Points = " << mesh->GetNumberOfPoints() << std::endl;

  // Access points
  using PointsIterator = MeshType::PointsContainer::Iterator;

  PointsIterator  pointIterator = mesh->GetPoints()->Begin();  

  PointsIterator end = mesh->GetPoints()->End();
  while( pointIterator != end ) 
    {
    MeshType::PointType p = pointIterator.Value();  // access the point
    std::cout << p << std::endl;                    // print the point
    ++pointIterator;                                // advance to next point
    }

  return mesh;
}

void CreateMeshWithEdges()
{
  MeshType::Pointer mesh = CreatePointOnlyMesh();
  
  using CellAutoPointer = MeshType::CellType::CellAutoPointer;
  using LineType = itk::LineCell< MeshType::CellType >;
  
  // Create a link to the previous point in the column (below the current point)
  CellAutoPointer colline;
  colline.TakeOwnership(  new LineType  );
        
  //unsigned int pointId0 = 0;
  //unsigned int pointId1 = 1;
  
  unsigned int pointId0 = 2;
  unsigned int pointId1 = 3;
  
  colline->SetPointId(0, pointId0); // line between points 0 and 1
  colline->SetPointId(1, pointId1);
  //std::cout << "Linked point: " << MeshIndex << " and " << MeshIndex - 1 << std::endl;
  mesh->SetCell( 0, colline );

  using CellIterator = MeshType::CellsContainer::Iterator;
  CellIterator  cellIterator = mesh->GetCells()->Begin();
  CellIterator  CellsEnd          = mesh->GetCells()->End();
  
  while( cellIterator != CellsEnd ) 
    {
    MeshType::CellType * cellptr = cellIterator.Value();
    auto * line = dynamic_cast<LineType *>( cellptr );

    itk::IdentifierType* linePoint0 = line->PointIdsBegin();
    //itk::IdentifierType* linePoint1 = line->PointIdsEnd();
  itk::IdentifierType* linePoint1 = linePoint0+1;
    std::cout << "line first point id: " << *linePoint0 << std::endl;
    std::cout << "line second point id: " << *linePoint1 << std::endl;
    
    ++cellIterator;
    }
  
}