Intrepid2_TensorTopologyMap.hpp

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// @HEADER
// *****************************************************************************
//                           Intrepid2 Package
//
// Copyright 2007 NTESS and the Intrepid2 contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#ifndef Intrepid2_TensorTopologyMap_h
#define Intrepid2_TensorTopologyMap_h

#include "Intrepid2_Utils.hpp"

#include "Shards_CellTopology.hpp"

#include <map>
#include <set>
#include <vector>

namespace Intrepid2
{
  class TensorTopologyMap
  {
    shards::CellTopology cellTopo1_;
    shards::CellTopology cellTopo2_;
    shards::CellTopology compositeCellTopo_;
    
    using Subcell     = std::pair<unsigned,unsigned>; // first: dimension, second: subcell ordinal
    using SubcellPair = std::pair<Subcell,Subcell>;   // first: subcell in cellTopo1_, second: subcell in cellTopo2_
    std::map<SubcellPair,Subcell> subcellMap_;        // values are the subcell in compositeCellTopo (the dimension of this subcell is the sum of the dimensions in the SubcellPair)
  public:
    TensorTopologyMap(shards::CellTopology cellTopo1, shards::CellTopology cellTopo2, shards::CellTopology compositeCellTopo,
                      std::vector< std::pair<unsigned,unsigned> > nodePairs = std::vector< std::pair<unsigned,unsigned> >())
    :
    cellTopo1_(cellTopo1),
    cellTopo2_(cellTopo2),
    compositeCellTopo_(compositeCellTopo)
    {
      if (nodePairs.size() == 0)
      {
        nodePairs = defaultNodePairs(cellTopo1, cellTopo2, compositeCellTopo);
      }
      
      auto spaceDim1 = cellTopo1.getDimension();
      auto spaceDim2 = cellTopo2.getDimension();
      auto spaceDim  = compositeCellTopo.getDimension();
      INTREPID2_TEST_FOR_EXCEPTION(spaceDim1 + spaceDim2 != spaceDim, std::invalid_argument, "incompatible spatial dimensions");
      std::map<std::pair<unsigned,unsigned>,unsigned> compositeNodeOrdinalMap;
      for (unsigned compositeNodeOrdinal=0; compositeNodeOrdinal<nodePairs.size(); compositeNodeOrdinal++)
      {
        compositeNodeOrdinalMap[nodePairs[compositeNodeOrdinal]] = compositeNodeOrdinal;
      }
      for (unsigned d1=0; d1<=spaceDim1; d1++)
      {
        unsigned subcellCount1 = cellTopo1.getSubcellCount(d1);
        for (unsigned subcellOrdinal1=0; subcellOrdinal1<subcellCount1; subcellOrdinal1++)
        {
          Subcell subcell1 = {d1, subcellOrdinal1};
          std::set<unsigned> subcell1Nodes; // set because we don't care about ordering
          unsigned nodeCount1 = cellTopo1_.getNodeCount(d1, subcellOrdinal1);
          // unfortunately, the node count for vertices is given as 0 by shards::CellTopology.  This seems like a bug.
          if (d1 == 0)
          {
            subcell1Nodes.insert(subcellOrdinal1);
          }
          else
          {
            for (unsigned nodeOrdinal1=0; nodeOrdinal1<nodeCount1; nodeOrdinal1++)
            {
              subcell1Nodes.insert(cellTopo1_.getNodeMap(d1, subcellOrdinal1, nodeOrdinal1));
            }
          }
          for (unsigned d2=0; d2<=spaceDim2; d2++)
          {
            unsigned subcellCount2 = cellTopo2.getSubcellCount(d2);
            for (unsigned subcellOrdinal2=0; subcellOrdinal2<subcellCount2; subcellOrdinal2++)
            {
              Subcell subcell2 = {d2, subcellOrdinal2};
              std::set<unsigned> subcell2Nodes; // set because we don't care about ordering
              unsigned nodeCount2 = cellTopo2_.getNodeCount(d2, subcellOrdinal2);
              // unfortunately, the node count for vertices is given as 0 by shards::CellTopology.  This seems like a bug.
              if (d2 == 0)
              {
                subcell2Nodes.insert(subcellOrdinal2);
              }
              else
              {
                for (unsigned nodeOrdinal2=0; nodeOrdinal2<nodeCount2; nodeOrdinal2++)
                {
                  subcell2Nodes.insert(cellTopo2_.getNodeMap(d2, subcellOrdinal2, nodeOrdinal2));
                }
              }
              
              std::set<unsigned> compositeNodes; // all the nodes from subcell1 times nodes from subcell2
              for (auto subcellNode1 : subcell1Nodes)
              {
                for (auto subcellNode2 : subcell2Nodes)
                {
                  INTREPID2_TEST_FOR_EXCEPTION(compositeNodeOrdinalMap.find({subcellNode1,subcellNode2}) == compositeNodeOrdinalMap.end(),
                                             std::invalid_argument, "Node combination not found in map");
                  compositeNodes.insert(compositeNodeOrdinalMap[{subcellNode1,subcellNode2}]);
                }
              }
              // now, search the composite topology for the unique subcell that involves all those nodes
              // we do a brute-force search; we'll never have very big topologies, so the cost is not an issue
              unsigned compositeSubcellDim = d1 + d2;
              unsigned compositeSubcellCount = compositeCellTopo.getSubcellCount(compositeSubcellDim);
              bool compositeSubcellFound = false;
              for (unsigned compositeSubcellOrdinal=0; compositeSubcellOrdinal<compositeSubcellCount; compositeSubcellOrdinal++)
              {
                unsigned compositeSubcellNodeCount = (compositeSubcellDim > 0) ? compositeCellTopo.getNodeCount(compositeSubcellDim, compositeSubcellOrdinal)
                                                                               : 1; // again, dealing with the fact that the node count for vertices is defined as 0, not 1
                if (compositeSubcellNodeCount != compositeNodes.size()) continue; // node counts don't match, so this is not the subcell we're looking for
                bool matches = true; // if we don't find a node that isn't contained in compositeNodes, then this is the subcell we're looking for
                for (unsigned compositeSubcellNode=0; compositeSubcellNode<compositeSubcellNodeCount; compositeSubcellNode++)
                {
                  unsigned nodeInCell = compositeCellTopo.getNodeMap(compositeSubcellDim, compositeSubcellOrdinal, compositeSubcellNode);
                  if (compositeNodes.find(nodeInCell) == compositeNodes.end())
                  {
                    matches = false;
                    break;
                  }
                }
                if (matches)
                {
                  compositeSubcellFound = true;
                  subcellMap_[{subcell1,subcell2}] = {compositeSubcellDim, compositeSubcellOrdinal};
                  break;
                }
              }
              INTREPID2_TEST_FOR_EXCEPTION(!compositeSubcellFound, std::invalid_argument, "Composite subcell not found");
            }
          }
        }
      }
    }
    TensorTopologyMap(shards::CellTopology cellTopo1, shards::CellTopology cellTopo2)
    :
    TensorTopologyMap(cellTopo1, cellTopo2, compositeCellTopology(cellTopo1,cellTopo2)) {}
    
    unsigned getCompositeSubcellOrdinal(unsigned subcell1Dim, unsigned subcell1Ordinal, unsigned subcell2Dim, unsigned subcell2Ordinal)
    {
      Subcell subcell1 = {subcell1Dim, subcell1Ordinal};
      Subcell subcell2 = {subcell2Dim, subcell2Ordinal};
      auto entry = subcellMap_.find({subcell1,subcell2});
      INTREPID2_TEST_FOR_EXCEPTION(entry == subcellMap_.end(), std::invalid_argument, "entry not found");
      auto subcell = entry->second;
      return subcell.second; // subcell ordinal
    }
    
    static std::vector< std::vector<int> > referenceCellGeometry(shards::CellTopology cellTopo)
    {
      std::vector< std::vector<int> > nodes(cellTopo.getVertexCount());
      auto key = cellTopo.getKey();
      switch (key)
      {
        case shards::Node::key:
          nodes.push_back({}); // node.getVertexCount() returns 0; we do want a single (empty) entry, though, even though there's no spatial variation
          break;
        case shards::Line<2>::key:
          nodes[0] = {0};
          nodes[1] = {1};
          break;
        case shards::Triangle<3>::key:
          nodes[0] = {0,0};
          nodes[1] = {1,0};
          nodes[2] = {0,1};
          break;
        case shards::Quadrilateral<4>::key:
          nodes[0] = {0,0};
          nodes[1] = {1,0};
          nodes[2] = {1,1};
          nodes[3] = {0,1};
          break;
        case shards::Hexahedron<8>::key:
          nodes[0] = {0,0,0};
          nodes[1] = {1,0,0};
          nodes[2] = {1,1,0};
          nodes[3] = {0,1,0};
          nodes[4] = {0,0,1};
          nodes[5] = {1,0,1};
          nodes[6] = {1,1,1};
          nodes[7] = {0,1,1};
          break;
        case shards::Wedge<6>::key: // wedge is triangle in (x,y) times line in z
          nodes[0] = {0,0,0};
          nodes[1] = {1,0,0};
          nodes[2] = {0,1,0};
          nodes[3] = {0,0,1};
          nodes[4] = {1,0,1};
          nodes[5] = {0,1,1};
          break;
        default:
          INTREPID2_TEST_FOR_EXCEPTION(true, std::invalid_argument, "Unsupported CellTopology");
      }
      return nodes;
    }
    
    static std::vector< std::pair<unsigned,unsigned> > defaultNodePairs(shards::CellTopology cellTopo1, shards::CellTopology cellTopo2, shards::CellTopology compositeCellTopo)
    {
      unsigned compositeNodeCount = compositeCellTopo.getVertexCount();
      unsigned nodeCount1 = cellTopo1.getVertexCount();
      unsigned nodeCount2 = cellTopo2.getVertexCount();
      INTREPID2_TEST_FOR_EXCEPTION(compositeNodeCount != nodeCount1 * nodeCount2, std::invalid_argument, "Incompatible topologies");
      std::vector< std::pair<unsigned,unsigned> > nodePairs(compositeNodeCount);
      auto nodes1 = referenceCellGeometry(cellTopo1);
      auto nodes2 = referenceCellGeometry(cellTopo2);
      auto compositeNodes = referenceCellGeometry(compositeCellTopo);
      std::map< std::vector<int>, unsigned > compositeNodeMap;
      for (unsigned compositeNodeOrdinal=0; compositeNodeOrdinal<compositeNodeCount; compositeNodeOrdinal++)
      {
        compositeNodeMap[compositeNodes[compositeNodeOrdinal]] = compositeNodeOrdinal;
      }
      for (unsigned nodeOrdinal1=0; nodeOrdinal1<nodeCount1; nodeOrdinal1++)
      {
        std::vector<int> node1 = nodes1[nodeOrdinal1];
        for (unsigned nodeOrdinal2=0; nodeOrdinal2<nodeCount2; nodeOrdinal2++)
        {
          std::vector<int> node2 = nodes2[nodeOrdinal2];
          std::vector<int> compositeNode(node1); // copy node1 into the first slots of compositeNode
          compositeNode.insert(compositeNode.end(), node2.begin(), node2.end());
          auto compositeNodeMapEntry = compositeNodeMap.find(compositeNode);
          INTREPID2_TEST_FOR_EXCEPTION(compositeNodeMapEntry == compositeNodeMap.end(), std::invalid_argument, "composite node not found in map");
          nodePairs[compositeNodeMapEntry->second] = {nodeOrdinal1,nodeOrdinal2};
        }
      }
      return nodePairs;
    }
    
    static shards::CellTopology compositeCellTopology(shards::CellTopology cellTopo1, shards::CellTopology cellTopo2)
    {
      if (cellTopo1.getBaseKey() == shards::Node::key)
      {
        return cellTopo2;
      }
      else if (cellTopo2.getBaseKey() == shards::Node::key)
      {
        return cellTopo1;
      }
      
      // if we get here, neither is a Node
      auto key1 = cellTopo1.getBaseKey();
      auto key2 = cellTopo2.getBaseKey();
      switch (key1)
      {
        case shards::Line<2>::key:
          switch (key2)
        {
          case shards::Line<2>::key:
            return shards::CellTopology(shards::getCellTopologyData<shards::Quadrilateral<> >() );
          case shards::Triangle<3>::key:
            // unsupported:
            INTREPID2_TEST_FOR_EXCEPTION(true,std::invalid_argument,"line x triangle is not supported at present.  Wedge is triangle x line.");
          case shards::Quadrilateral<4>::key:
            return shards::CellTopology(shards::getCellTopologyData<shards::Hexahedron<> >() );
          default:
            INTREPID2_TEST_FOR_EXCEPTION(true,std::invalid_argument,"Unsupported cell topology pair");
        }
        case shards::Triangle<3>::key:
          switch (key2)
        {
          case shards::Line<2>::key:
            return shards::CellTopology(shards::getCellTopologyData<shards::Wedge<> >() );
          default:
            INTREPID2_TEST_FOR_EXCEPTION(true,std::invalid_argument,"Unsupported cell topology pair");
        }
        case shards::Quadrilateral<4>::key:
          switch (key2)
        {
          case shards::Line<2>::key:
            return shards::CellTopology(shards::getCellTopologyData<shards::Hexahedron<> >() );
          default:
            INTREPID2_TEST_FOR_EXCEPTION(true,std::invalid_argument,"Unsupported cell topology pair");
        }
        default:
          INTREPID2_TEST_FOR_EXCEPTION(true,std::invalid_argument,"Unsupported cell topology pair");
      }
    }
  };
} // end namespace Intrepid2

#endif /* Intrepid2_TensorTopology_h */