DataRepresentation/Mesh/Mesh1.cxx

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//  Software Guide : BeginLatex
//
//  The \doxygen{Mesh} class is intended to represent shapes in space.  It
//  derives from the \doxygen{PointSet} class and hence inherits all the
//  functionality related to points and access to the pixel-data associated
//  with the points.  The mesh class is also n-dimensional which
//  allows a great flexibility in its use.
//
//  In practice a Mesh class can be seen as a PointSet to
//  which cells (also known as elements) of many different dimensions and
//  shapes have been added. Cells in the mesh are defined in terms of the
//  existing points using their point-identifiers.
//
//  In the same way as for the PointSet, two basic styles of
//  Meshes are available in ITK. They are referred to as \emph{static}
//  and \emph{dynamic}. The first one is used when the number of
//  points in the set can be known in advance and it is not expected
//  to change as a consequence of the manipulations performed on the
//  set. The dynamic style, on the other hand, is intended to support
//  insertion and removal of points in an efficient manner. The reason
//  for making the distinction between the two styles is to facilitate
//  fine tuning its behavior with the aim of optimizing
//  performance and memory management. In the case of the Mesh, the
//  dynamic/static aspect is extended to the management of cells.
//
//  \index{itk::Mesh}
//  \index{itk::Mesh!Static}
//  \index{itk::Mesh!Dynamic}
//  \index{itk::Mesh!Header file}
//
//  In order to use the Mesh class, its header file should be included.
//
//  Software Guide : EndLatex

// Software Guide : BeginCodeSnippet
#include "itkMesh.h"
// Software Guide : EndCodeSnippet

int main(int, char *[])
{

  //  Software Guide : BeginLatex
  //
  //  Then, the type associated with the points must be selected and used for
  //  instantiating the Mesh type.
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  typedef   float   PixelType;
  // Software Guide : EndCodeSnippet


  //  Software Guide : BeginLatex
  //
  //  The Mesh type extensively uses the capabilities provided by
  //  \href{http://www.boost.org/more/generic_programming.html}{Generic
  //  Programming}. In particular the Mesh class is parameterized over the
  //  PixelType and the dimension of the space. PixelType is the type of the
  //  value associated with every point just as is done with the
  //  PointSet. The following line illustrates a typical
  //  instantiation of the Mesh.
  //
  //  \index{itk::Mesh!Instantiation}
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  const unsigned int Dimension = 3;
  typedef itk::Mesh< PixelType, Dimension >   MeshType;
  // Software Guide : EndCodeSnippet


  //  Software Guide : BeginLatex
  //
  //  Meshes are expected to take large amounts of memory. For this reason they
  //  are reference counted objects and are managed using SmartPointers. The
  //  following line illustrates how a mesh is created by invoking the
  //  \code{New()} method of the MeshType and the resulting object is assigned
  //  to a \doxygen{SmartPointer}.
  //
  //  \index{itk::Mesh!New()}
  //  \index{itk::Mesh!Pointer()}
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  MeshType::Pointer  mesh = MeshType::New();
  // Software Guide : EndCodeSnippet


  //  Software Guide : BeginLatex
  //
  //  The management of points in the Mesh is exactly the same as in
  //  the PointSet. The type point associated with the mesh can be
  //  obtained through the \code{PointType} trait. The following code shows the
  //  creation of points compatible with the mesh type defined above and the
  //  assignment of values to its coordinates.
  //
  //  \index{itk::Mesh!PointType}
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  MeshType::PointType p0;
  MeshType::PointType p1;
  MeshType::PointType p2;
  MeshType::PointType 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]= 0.0; // fourth point ( -1,  1, 0 )
  // Software Guide : EndCodeSnippet


  //  Software Guide : BeginLatex
  //
  //  The points can now be inserted in the Mesh using the \code{SetPoint()}
  //  method. Note that points are copied into the mesh structure. This means
  //  that the local instances of the points can now be modified without
  //  affecting the Mesh content.
  //
  //  \index{itk::Mesh!SetPoint()}
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  mesh->SetPoint( 0, p0 );
  mesh->SetPoint( 1, p1 );
  mesh->SetPoint( 2, p2 );
  mesh->SetPoint( 3, p3 );
  // Software Guide : EndCodeSnippet


  //  Software Guide : BeginLatex
  //
  //  The current number of points in the Mesh can be queried with the
  //  \code{GetNumberOfPoints()} method.
  //
  //  \index{itk::Mesh!GetNumberOfPoints()}
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  std::cout << "Points = " << mesh->GetNumberOfPoints() << std::endl;
  // Software Guide : EndCodeSnippet


  //  Software Guide : BeginLatex
  //
  //  The points can now be efficiently accessed using the Iterator to the
  //  PointsContainer as it was done in the previous section for the
  //  PointSet.  First, the point iterator type is extracted through
  //  the mesh traits.
  //
  //  \index{PointsContainer!Iterator}
  //  \index{itk::Mesh!GetPoints()}
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  typedef MeshType::PointsContainer::Iterator     PointsIterator;
  // Software Guide : EndCodeSnippet


  //  Software Guide : BeginLatex
  //
  //  A point iterator is initialized to the first point with the
  //  \code{Begin()} method of the PointsContainer.
  //
  //  \index{PointsContainer!Begin()}
  //  \index{itk::Mesh!GetPoints()}
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  PointsIterator  pointIterator = mesh->GetPoints()->Begin();
  // Software Guide : EndCodeSnippet


  //  Software Guide : BeginLatex
  //
  //  The \code{++} operator on the iterator is now used to advance from one
  //  point to the next. The actual value of the Point to which the iterator is
  //  pointing can be obtained with the \code{Value()} method. The loop for
  //  walking through all the points is controlled by comparing the current
  //  iterator with the iterator returned by the \code{End()} method of the
  //  PointsContainer. The following lines illustrate the typical loop for
  //  walking through the points.
  //
  //  \index{PointsContainer!End()}
  //  \index{PointsContainer!Iterator}
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  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
    }
  // Software Guide : EndCodeSnippet

  return 0;
}