pyramid_rules_impl.h

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/*
 * Copyright (c) 2015:  G-CSC, Goethe University Frankfurt
 * Author: Sebastian Reiter
 * 
 * This file is part of UG4.
 * 
 * UG4 is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License version 3 (as published by the
 * Free Software Foundation) with the following additional attribution
 * requirements (according to LGPL/GPL v3 §7):
 * 
 * (1) The following notice must be displayed in the Appropriate Legal Notices
 * of covered and combined works: "Based on UG4 (www.ug4.org/license)".
 * 
 * (2) The following notice must be displayed at a prominent place in the
 * terminal output of covered works: "Based on UG4 (www.ug4.org/license)".
 * 
 * (3) The following bibliography is recommended for citation and must be
 * preserved in all covered files:
 * "Reiter, S., Vogel, A., Heppner, I., Rupp, M., and Wittum, G. A massively
 *   parallel geometric multigrid solver on hierarchically distributed grids.
 *   Computing and visualization in science 16, 4 (2013), 151-164"
 * "Vogel, A., Reiter, S., Rupp, M., Nägel, A., and Wittum, G. UG4 -- a novel
 *   flexible software system for simulating pde based models on high performance
 *   computers. Computing and visualization in science 16, 4 (2013), 165-179"
 * 
 * This program 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.
 */
 
#ifndef __H__UG_pyramid_rules_impl
#define __H__UG_pyramid_rules_impl
 
#include "pyramid_rules.h"
#include "grid_object_ids.h"
 
namespace ug{
namespace pyra_rules{
 
template <class TCmp>
int ConvertToTetrahedra(int* newIndsOut, TCmp cmp)
{
//  The idea and implementation follows:
//  Dompierre et al., "How to Subdivide Pyramids, Prisms and Hexahedra into Tetrahedra"
 
//  find the smallest index of the base quadrilateral
  int smallest = 0;
  for(int i = 1; i < 4; ++i){
    if(cmp(i, smallest))
      smallest = i;
  }
 
  if((smallest == 0) || (smallest == 2)){
    int i = 0;
    newIndsOut[i++] = GOID_TETRAHEDRON;
    newIndsOut[i++] = 0; newIndsOut[i++] = 1;
    newIndsOut[i++] = 2; newIndsOut[i++] = TOP_VERTEX;
 
    newIndsOut[i++] = GOID_TETRAHEDRON;
    newIndsOut[i++] = 0; newIndsOut[i++] = 2;
    newIndsOut[i++] = 3; newIndsOut[i++] = TOP_VERTEX;
    return i;
  }
  else{
    int i = 0;
    newIndsOut[i++] = GOID_TETRAHEDRON;
    newIndsOut[i++] = 0; newIndsOut[i++] = 1;
    newIndsOut[i++] = 3; newIndsOut[i++] = TOP_VERTEX;
 
    newIndsOut[i++] = GOID_TETRAHEDRON;
    newIndsOut[i++] = 1; newIndsOut[i++] = 2;
    newIndsOut[i++] = 3; newIndsOut[i++] = TOP_VERTEX;
    return i;
  }
}
 
}// end of namespace
}// end of namespace
 
#endif  //__H__UG_pyramid_rules_impl