vtk-m/vtkm/CellShape.h

//============================================================================
//  Copyright (c) Kitware, Inc.
//  All rights reserved.
//  See LICENSE.txt for details.
//  This software is distributed WITHOUT ANY WARRANTY; without even
//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
//  PURPOSE.  See the above copyright notice for more information.
//
//  Copyright 2014 Sandia Corporation.
//  Copyright 2014 UT-Battelle, LLC.
//  Copyright 2014 Los Alamos National Security.
//
//  Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
//  the U.S. Government retains certain rights in this software.
//
//  Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
//  Laboratory (LANL), the U.S. Government retains certain rights in
//  this software.
//============================================================================
#ifndef vtk_m_CellShape_h
#define vtk_m_CellShape_h

#include <vtkm/StaticAssert.h>
#include <vtkm/Types.h>

VTKM_THIRDPARTY_PRE_INCLUDE
#include <boost/type_traits/integral_constant.hpp>
VTKM_THIRDPARTY_POST_INCLUDE

namespace vtkm {

/// CellShapeId identifies the type of each cell. Currently these are designed
/// to match up with VTK cell types.
///
enum CellShapeIdEnum
{
  // Linear cells
  CELL_SHAPE_EMPTY              = 0,
  CELL_SHAPE_VERTEX             = 1,
  //CELL_SHAPE_POLY_VERTEX      = 2,
  CELL_SHAPE_LINE               = 3,
  //CELL_SHAPE_POLY_LINE        = 4,
  CELL_SHAPE_TRIANGLE           = 5,
  //CELL_SHAPE_TRIANGLE_STRIP   = 6,
  CELL_SHAPE_POLYGON            = 7,
  //CELL_SHAPE_PIXEL              = 8,
  CELL_SHAPE_QUAD               = 9,
  CELL_SHAPE_TETRA              = 10,
  //CELL_SHAPE_VOXEL              = 11,
  CELL_SHAPE_HEXAHEDRON         = 12,
  CELL_SHAPE_WEDGE              = 13,
  CELL_SHAPE_PYRAMID            = 14,

  NUMBER_OF_CELL_SHAPES
};

// If you wish to add cell shapes to this list, in addition to adding an index
// to the enum above, you at a minimum need to define an associated tag with
// VTKM_DEFINE_CELL_TAG and add a condition to the vtkmGenericCellShapeMacro.
// There are also many other cell-specific features that code might expect such
// as \c CellTraits and interpolations.

namespace internal {

/// A class that can be used to determine if a class is a CellShapeTag or not.
/// The class will be either boost::true_type or boost::false_type.
///
template<typename T>
struct CellShapeTagCheck : boost::false_type {  };

} // namespace internal

/// Checks that the argument is a proper cell shape tag. This is a handy
/// concept check to make sure that a template argument is a proper cell shape
/// tag.
///
#define VTKM_IS_CELL_SHAPE_TAG(tag) \
  VTKM_STATIC_ASSERT_MSG( \
    ::vtkm::internal::CellShapeTagCheck<tag>::value, \
    "Provided type is not a valid VTK-m cell shape tag.")

/// A traits-like class to get an CellShapeId known at compile time to a tag.
///
template<vtkm::IdComponent Id>
struct CellShapeIdToTag {
  // If you get a compile error for this class about Id not being defined, that
  // probably means you are using an ID that does not have a defined cell
  // shape.

  typedef boost::false_type valid;
};


// Define a tag for each cell shape as well as the support structs to go
// between tags and ids. The following macro is only valid here.

#define VTKM_DEFINE_CELL_TAG(name, idname) \
  struct CellShapeTag ## name { \
    static const vtkm::IdComponent Id = vtkm::idname; \
  }; \
  namespace internal { \
  template<> \
  struct CellShapeTagCheck<vtkm::CellShapeTag ## name> : boost::true_type {  }; \
  } \
  VTKM_EXEC_CONT_EXPORT \
  const char *GetCellShapeName(vtkm::CellShapeTag ## name) { \
    return #name; \
  } \
  template<> \
  struct CellShapeIdToTag<vtkm::idname> { \
    typedef boost::true_type valid; \
    typedef vtkm::CellShapeTag ## name Tag; \
  }


VTKM_DEFINE_CELL_TAG(Empty, CELL_SHAPE_EMPTY);
VTKM_DEFINE_CELL_TAG(Vertex, CELL_SHAPE_VERTEX);
//VTKM_DEFINE_CELL_TAG(PolyVertex, CELL_SHAPE_POLY_VERTEX);
VTKM_DEFINE_CELL_TAG(Line, CELL_SHAPE_LINE);
//VTKM_DEFINE_CELL_TAG(PolyLine, CELL_SHAPE_POLY_LINE);
VTKM_DEFINE_CELL_TAG(Triangle, CELL_SHAPE_TRIANGLE);
//VTKM_DEFINE_CELL_TAG(TriangleStrip, CELL_SHAPE_TRIANGLE_STRIP);
VTKM_DEFINE_CELL_TAG(Polygon, CELL_SHAPE_POLYGON);
//VTKM_DEFINE_CELL_TAG(Pixel, CELL_SHAPE_PIXEL);
VTKM_DEFINE_CELL_TAG(Quad, CELL_SHAPE_QUAD);
VTKM_DEFINE_CELL_TAG(Tetra, CELL_SHAPE_TETRA);
//VTKM_DEFINE_CELL_TAG(Voxel, CELL_SHAPE_VOXEL);
VTKM_DEFINE_CELL_TAG(Hexahedron, CELL_SHAPE_HEXAHEDRON);
VTKM_DEFINE_CELL_TAG(Wedge, CELL_SHAPE_WEDGE);
VTKM_DEFINE_CELL_TAG(Pyramid, CELL_SHAPE_PYRAMID);

#undef VTKM_DEFINE_CELL_TAG


/// A special cell shape tag that holds a cell shape that is not known at
/// compile time. Unlike other cell set tags, the Id field is set at runtime
/// so its value cannot be used in template parameters. You need to use
/// \c vtkmGenericCellShapeMacro to specialize on the cell type.
///
struct CellShapeTagGeneric {
  VTKM_EXEC_CONT_EXPORT
  CellShapeTagGeneric(vtkm::IdComponent shape) : Id(shape) {  }

  vtkm::IdComponent Id;
};


#define vtkmGenericCellShapeMacroCase(cellShapeId, call) \
  case vtkm::cellShapeId: \
    { \
      typedef \
        typename vtkm::CellShapeIdToTag<vtkm::cellShapeId>::Tag CellShapeTag; \
      call; \
    } \
    break

/// \brief A macro used in a \c switch statement to determine cell shape.
///
/// The \c vtkmGenericCellShapeMacro is a series of case statements for all
/// of the cell shapes supported by VTK-m. This macro is intended to be used
/// inside of a switch statement on a cell type. For each cell shape condition,
/// a \c CellShapeTag typedef is created and the given \c call is executed.
///
/// A typical use case of this class is to create the specialization of a
/// function overloaded on a cell shape tag for the generic cell shape like as
/// following.
///
/// \code{.cpp}
/// template<typename WorkletType>
/// VTKM_EXEC_EXPORT
/// void MyCellOperation(vtkm::CellShapeTagGeneric cellShape,
///                      const vtkm::exec::FunctorBase &worklet)
/// {
///   switch(cellShape.CellShapeId)
///   {
///     vtkmGenericCellShapeMacro(
///       MyCellOperation(CellShapeTag())
///       );
///     default: worklet.RaiseError("Encountered unknown cell shape."); break
///   }
/// }
/// \endcode
///
/// Note that \c vtkmGenericCellShapeMacro does not have a default case. You
/// should consider adding one that gives a
///
#define vtkmGenericCellShapeMacro(call) \
  vtkmGenericCellShapeMacroCase(CELL_SHAPE_EMPTY, call); \
  vtkmGenericCellShapeMacroCase(CELL_SHAPE_VERTEX, call); \
  vtkmGenericCellShapeMacroCase(CELL_SHAPE_LINE, call); \
  vtkmGenericCellShapeMacroCase(CELL_SHAPE_TRIANGLE, call); \
  vtkmGenericCellShapeMacroCase(CELL_SHAPE_POLYGON, call); \
  vtkmGenericCellShapeMacroCase(CELL_SHAPE_QUAD, call); \
  vtkmGenericCellShapeMacroCase(CELL_SHAPE_TETRA, call); \
  vtkmGenericCellShapeMacroCase(CELL_SHAPE_HEXAHEDRON, call); \
  vtkmGenericCellShapeMacroCase(CELL_SHAPE_WEDGE, call); \
  vtkmGenericCellShapeMacroCase(CELL_SHAPE_PYRAMID, call)

} // namespace vtkm

#endif //vtk_m_CellShape_h