modify.cpp

#include "inmost.h"
#include "incident_matrix.hpp"
#include <queue>
#if defined(USE_MESH)

//TODO:
// incident_matrix class should measure for minimal volume,
// possibly check and update from projects/OctreeCutcell/octgrid.cpp
#if defined(USE_PARALLEL_WRITE_TIME)
#define REPORT_MPI(x) {WriteTab(out_time) << "<MPI><![CDATA[" << #x << "]]></MPI>" << std::endl; x;}
#define REPORT_STR(x) {WriteTab(out_time) << "<TEXT><![CDATA[" << x << "]]></TEXT>" << std::endl;}
#define REPORT_VAL(str,x) {WriteTab(out_time) << "<VALUE name=\"" << str << "\"> <CONTENT><![CDATA[" << x << "]]></CONTENT> <CODE><![CDATA[" << #x << "]]></CODE></VALUE>" << std::endl;}
#define ENTER_FUNC() double all_time = Timer(); {WriteTab(out_time) << "<FUNCTION name=\"" << __FUNCTION__ << "\" id=\"func" << func_id++ << "\">" << std::endl; Enter();}
#define EXIT_FUNC() {WriteTab(out_time) << "<TIME>" << Timer() - all_time << "</TIME>" << std::endl; Exit(); WriteTab(out_time) << "</FUNCTION>" << std::endl;}
#define EXIT_FUNC_DIE() {WriteTab(out_time) << "<TIME>" << -1 << "</TIME>" << std::endl; Exit(); WriteTab(out_time) << "</FUNCTION>" << std::endl;}
#else
#define REPORT_MPI(x) x
#define REPORT_STR(x) {}
#define REPORT_VAL(str,x) {}
#define ENTER_FUNC() {}
#define EXIT_FUNC() {}
#define EXIT_FUNC_DIE()  {}
#endif


namespace INMOST
{

	


	
	
	void Element::Disconnect(bool del_upper) const
	{
		
		dynarray<adj_type::size_type,64> del;
		Mesh * m = GetMeshLink();
		//BEGIN NEW CODE - CHECK
		//Reorder face edges, so that they always apear in right direction
		if( GetElementType() == CELL ) //This is a cell
		{
			getAsCell()->SwapBackCell();
			/*
			MarkerType hm = m->HideMarker();
			adj_type & lc = m->LowConn(GetHandle());
			for( adj_type::size_type it = 0; it < lc.size(); it++) //if( !m->GetMarker(lc[it],hm) ) //iterator over unhidden faces
			{
				adj_type & hc = m->HighConn(lc[it]);
				if( !hc.empty() && m->Count(hc.data(),static_cast<enumerator>(hc.size()),hm) == 2 ) //there are two cells connected to face
				{
					enumerator k1 = ENUMUNDEF, k2;
					k1 = m->getNext(hc.data(),static_cast<enumerator>(hc.size()),k1,hm);
					if( hc[k1] == GetHandle() ) //the first cell is current
					{
						k2 = m->getNext(hc.data(),static_cast<enumerator>(hc.size()),k1,hm);
						hc[k1] = hc[k2];
						//hc[k2] = GetHandle(); //cannot use the cell because virtualization table is already destroyed and FixNormalOrientation will do bad things
						hc.resize(1); //just remove element, we will do this anyway later
						Face(m,lc[it])->FixNormalOrientation(); //restore orientation
					}
				}
			}
			*/
		}
		//END NEW CODE - CHECK
		adj_type & hc = m->HighConn(GetHandle());
		adj_type::size_type i = 0;
		for( adj_type::size_type it = 0; it < hc.size(); it++)
		{
			int flag = 0;
			adj_type & ilc = m->LowConn(hc[it]);
			adj_type::iterator jt = ilc.begin();
			while (jt != ilc.end())
			{
				if(*jt == GetHandle())
				{
					flag = 1;
					jt = ilc.erase(jt);
				}
				else ++jt;
			}
			if( flag ) del.push_back(i);
			i++;
		}
		if( del_upper )
		{
			if( GetElementType() < CELL ) 
			{
				if( Hidden() ) 
				{
					for(dynarray<adj_type::size_type,64>::iterator it = del.begin(); it != del.end(); it++)
						if( m->GetMarker(hc[*it],m->HideMarker()) ) m->Delete(hc[*it]);
				}
				else 
				{
					for(dynarray<adj_type::size_type,64>::iterator it = del.begin(); it != del.end(); it++)
						m->Delete(hc[*it]);
				}
			}
		}
		hc.clear();
		adj_type & lc = m->LowConn(GetHandle());
		for(adj_type::size_type it = 0; it < lc.size(); it++)
		{
			adj_type & ihc = m->HighConn(lc[it]);
			adj_type::iterator jt = ihc.begin();
			while (jt != ihc.end())
			{
				if(*jt == GetHandle()) jt = ihc.erase(jt);
				else ++jt;
			}
		}
		lc.clear();
	}
	
	Cell Cell::UniteCells(const ElementArray<Cell> & unite, MarkerType del_protect)
	{
		Mesh * m = unite.GetMeshLink();
		if( unite.empty() ) return Cell(m,InvalidHandle());
		tiny_map<HandleType, int, 64> face_visit; // we check all edges of faces, inner edges are visited several times, outer - once
		ElementArray<Face> faces(m); 
		dynarray<HandleType,64> inner_faces;
		bool doexit = false;
		MarkerType hm = m->HideMarker();
		//Compute which faces of the provided cells lay on boundary (1 visit) and
		//inside of the set of cells (2 visits)
		for(ElementArray<Cell>::size_type j = 0; j < unite.size(); j++)
		{
			if( unite[j]->GetMarker(del_protect) ) doexit = true;
			//access faces
			adj_type const & lc = m->LowConn(unite.at(j));
			for(adj_type::size_type it = 0; it < lc.size(); it++)
				if( !m->GetMarker(lc[it],hm) ) face_visit[lc[it]]++;
		}
		if( doexit ) return Cell(m,InvalidHandle());
		MarkerType visited = m->CreateMarker(), rem = m->CreateMarker();
		dynarray<HandleType,64> edges;
		dynarray<HandleType,64> nodes;
		//gather boundary faces into set that will be used to create new cell
		//mark internal faces to be deleted. For internal faces find out
		//all internal edges that should be deleted as well.
		for(tiny_map<HandleType,int,64>::iterator it = face_visit.begin(); it != face_visit.end(); it++)
		{
			if( it->second == 1 ) //boundary faces, use for new cell
				faces.push_back(it->first);
			else //internal faces
			{
				if( m->GetMarker(it->first,del_protect) ) doexit = true;
				//mark face to be deleted
				m->SetMarker(it->first,rem);
				//access edges of the face, gather into array
				adj_type const & lc = m->LowConn(it->first);
				for(adj_type::size_type jt = 0; jt < lc.size(); jt++) if( !m->GetMarker(lc[jt],hm) )
					if( !m->GetMarker(lc[jt],visited) )
					{
						m->SetMarker(lc[jt],visited);
						edges.push_back(lc[jt]);
					}
				//gather internal faces
				inner_faces.push_back(it->first);
			}
		}
		//for edges of internal faces gather their nodes,
		//for each edge check if all it's faces are to be deleted,
		//then the edge should be deleted, otherwise keep the edge
		for(dynarray<HandleType,64>::size_type i = 0; i < edges.size(); i++) 
		{
			m->RemMarker(edges[i],visited);
			//access nodes of the edge, gather into array
			adj_type const & lc = m->LowConn(edges[i]);
			for(adj_type::size_type jt = 0; jt < lc.size(); jt++) if( !m->GetMarker(lc[jt],hm) )
			{
				if( !m->GetMarker(lc[jt],visited) )
				{
					m->SetMarker(lc[jt],visited);
					nodes.push_back(lc[jt]);
				}
			}
			//access faces of the edge, check is there any
			//face that would not be deleted
			int nonzero = 0;
			adj_type const & hc = m->HighConn(edges[i]);
			for(adj_type::size_type jt = 0; jt < hc.size(); jt++) if( !m->GetMarker(hc[jt],hm) )//iterate over faces
				if( !m->GetMarker(hc[jt],rem) ) nonzero++; // check if it is not deleted
			if( nonzero == 0 ) //all faces should be deleted, edge to remove
			{
				//mark edge to be deleted
				m->SetMarker(edges[i],rem);
				if( m->GetMarker(edges[i],del_protect) ) doexit = true;
			}
		}
		//for nodes of internal faces check is there any edges
		//that should not be deleted
		for(dynarray<HandleType,64>::size_type i = 0; i < nodes.size(); i++) 
		{
			m->RemMarker(nodes[i],visited);
			int nonzero = 0;
			//acces edges of the node, check is there any
			//edge that would not be deleted
			adj_type const & hc = m->HighConn(nodes[i]);
			for(adj_type::size_type jt = 0; jt < hc.size(); jt++) if( !m->GetMarker(hc[jt],hm) )
				if( !m->GetMarker(hc[jt],rem) ) nonzero++;
			if( nonzero == 0 ) //all edges should be deleted, node to remove
			{
				//mark node to be deleted
				m->SetMarker(nodes[i],rem);
				if( m->GetMarker(nodes[i],del_protect) ) doexit = true;
			}
		}
		m->ReleaseMarker(visited);
		if( doexit )
		{
			m->RemMarkerArray(inner_faces.data(),(enumerator)inner_faces.size(),rem);
			m->RemMarkerArray(edges.data(), (enumerator)edges.size(), rem);
			m->RemMarkerArray(nodes.data(), (enumerator)nodes.size(), rem);
			m->ReleaseMarker(rem);
			return Cell(m,InvalidHandle());
		}
		//delete cells
		for(ElementArray<Cell>::size_type j = 0; j < unite.size(); j++)
		{
			if( m->GetMarker(unite.at(j),del_protect) )
				std::cout << __FUNCTION__ << " deleted protected cells, united " << unite.size() << " cells " << std::endl;
			if( m->HideMarker() )
				m->Hide(unite.at(j));
			else
				m->Delete(unite.at(j));
		}
		//delete inner faces
		for(dynarray<HandleType,64>::size_type j = 0; j < inner_faces.size(); j++)
		{
			//std::cout << "delete face " << GetHandleID(inner_faces[j]) << std::endl;
			if( m->GetMarker(inner_faces[j],rem) )
			{
				m->RemMarker(inner_faces[j],rem);
				if( m->GetMarker(inner_faces[j],del_protect) )
					std::cout << __FUNCTION__ << " deleted protected faces, united " << unite.size() << " cells " << std::endl;
				if( m->HideMarker() )
					m->Hide(inner_faces[j]);
				else
					m->Delete(inner_faces[j]);
			}
		}
		//delete unused edges
		for(dynarray<HandleType,64>::size_type j = 0; j < edges.size(); j++)
		{
			if( m->GetMarker(edges[j],rem) )
			{
				m->RemMarker(edges[j],rem);
				if( m->GetMarker(edges[j],del_protect) )
					std::cout << __FUNCTION__ << " deleted protected edge, united " << unite.size() << " cells " << std::endl;
				if( m->HideMarker() )
					m->Hide(edges[j]);
				else
					m->Delete(edges[j]);
			}
		}
		//delete unused nodes
		for(dynarray<HandleType,64>::size_type j = 0; j < nodes.size(); j++)
		{

			if( m->GetMarker(nodes[j],rem) ) //there are no edges that use this edge
			{
				m->RemMarker(nodes[j],rem);
				// there must be no cells that use this node
				assert( m->LowConn(nodes[j]).empty() || m->Count(m->LowConn(nodes[j]).data(),static_cast<integer>(m->LowConn(nodes[j]).size()),hm) == 0 );
				if( m->GetMarker(nodes[j],del_protect) )
					std::cout << __FUNCTION__ << " deleted protected node, united " << unite.size() << " cells " << std::endl;
				if( m->HideMarker() )
					m->Hide(nodes[j]);
				else
					m->Delete(nodes[j]);
				//disconnect node from cell
				//we don't need this algorithm, because all dependent cells should be deleted
				//if( !nodes[j]->Hide() )
				//{					
					//adj_iterator it = nodes[j]->LowConn().begin();
					//while(it != nodes[j]->LowConn().end()) if( !(*it)->GetMarker(hm) ) //iterate through cells of the node
					//{
					//	adj_iterator jt =(*it)->HighConn().begin();
					//	while(jt != (*it)->HighConn().end() ) if( !(*jt)->GetMarker(hm) ) // iterate through nodes of the cell
					//	{
					//		if( *jt == nodes[j] )
					//			jt = (*it)->HighConn().erase(jt); //erase link to node
					//		else ++jt;
					//	}
					//  ++it;
					//}
					//nodes[j]->Disconnect();
					//nodes[j]->Delete();
				//}
			}
		}
		m->ReleaseMarker(rem);
		//reconstruct cell by outer faces
		return m->CreateCell(faces).first;
	}
	
	
	bool Cell::TestUniteCells(const ElementArray<Cell> & unite, MarkerType del_protect)
	{
		if( unite.empty() ) return false;
		Mesh * m = unite.GetMeshLink();
		tiny_map<HandleType,int,64> face_visit; // we check all edges of faces, inner edges are visited several times, outer - once
		bool doexit = false;
		MarkerType hm = m->HideMarker();			
		for(ElementArray<Cell>::size_type j = 0; j < unite.size(); j++)
		{
			if( m->GetMarker(unite.at(j),del_protect) ) doexit = true; 
			adj_type const & lc = m->LowConn(unite.at(j));
			for(adj_type::size_type it = 0; it < lc.size(); it++) if( !m->GetMarker(lc[it],hm) )
				face_visit[lc[it]]++;
		}
		if( doexit ) return false;
		MarkerType rem = m->CreateMarker();
		dynarray<HandleType,64> edges;
		dynarray<HandleType,64> nodes;		
		for(tiny_map<HandleType,int,64>::iterator it = face_visit.begin(); it != face_visit.end(); it++)
		{
			if( it->second != 1 )
			{
				if( m->GetMarker(it->first,del_protect) ) doexit = true;
				m->SetMarker(it->first,rem);
				adj_type const & lc = m->LowConn(it->first);
				for(adj_type::size_type jt = 0; jt < lc.size(); jt++) if( !m->GetMarker(lc[jt],hm) )
					if( !m->GetMarker(lc[jt],rem) )
					{
						m->SetMarker(lc[jt],rem);
						edges.push_back(lc[jt]);
					}
			}
		}
		for(dynarray<HandleType,64>::size_type i = 0; i < edges.size(); i++) 
		{
			m->RemMarker(edges[i],rem);
			adj_type const & lc = m->LowConn(edges[i]);
			for(adj_type::size_type jt = 0; jt < lc.size(); jt++) if( !m->GetMarker(lc[jt],hm) )
			{
				if( !m->GetMarker(lc[jt],rem) )
				{
					m->SetMarker(lc[jt],rem);
					nodes.push_back(lc[jt]);
				}
			}
			int nonzero = 0;
			//access faces of the edge, check is there any
			//that would not be deleted
			adj_type const & hc = m->HighConn(edges[i]);
			for(adj_type::size_type jt = 0; jt < hc.size(); jt++) if( !m->GetMarker(hc[jt],hm) ) //iterate over faces
				if( !m->GetMarker(hc[jt],rem) ) nonzero++; // check if it is not deleted
			//all faces should be deleted, edge to remove
			if( nonzero == 0 && m->GetMarker(edges[i],del_protect) )
				doexit = true;
		}
		for(dynarray<HandleType,64>::size_type i = 0; i < nodes.size(); i++) 
		{
			int nonzero = 0;
			//access edges of the node, check is there
			//any that would not be deleted
			adj_type const & hc = m->HighConn(nodes[i]);
			for(adj_type::size_type jt = 0; jt < hc.size(); jt++) if( !m->GetMarker(hc[jt],hm) )
				if( !m->GetMarker(hc[jt],rem) ) nonzero++;
			//all edges should be deleted, node to remove
			if( nonzero == 0 && m->GetMarker(edges[i],del_protect) )
				doexit = true;
		}
		for(tiny_map<HandleType,int,64>::iterator it = face_visit.begin(); it != face_visit.end(); it++) m->RemMarker(it->first,rem);
		m->RemMarkerArray(edges.data(), (enumerator)edges.size(),rem);
		m->RemMarkerArray(nodes.data(), (enumerator)nodes.size(), rem);
		m->ReleaseMarker(rem);
		if( doexit ) return false;
		return true;
	}
	
	
	Face Face::UniteFaces(const ElementArray<Face> & unite, MarkerType del_protect)
	{
		Mesh * m = const_cast<Mesh *>(unite.GetMeshLink());
		assert(m != NULL);
		if( unite.empty() ) return Face(m,InvalidHandle());
		MarkerType hm = m->HideMarker();
		bool doexit = false, dothrow = false;
		for(ElementArray<Face>::size_type j = 0; j < unite.size(); j++)
			if( m->GetMarker(unite.at(j),del_protect) ) doexit = true;
		if( doexit ) return Face(m,InvalidHandle());
		dynarray<HandleType,64> cells;
		MarkerType edge_set = m->CreateMarker();
		MarkerType rem = m->CreateMarker();
		
		//gather cells adjacent to united faces
		for(ElementArray<Face>::size_type j = 0; j < unite.size(); j++)
		{
			adj_type const & hc = m->HighConn(unite.at(j));
			for(adj_type::size_type it = 0; it < hc.size(); it++) if( !m->GetMarker(hc[it],hm) )
			{
				if( !m->GetMarker(hc[it],edge_set) )
				{
					cells.push_back(hc[it]);
					m->SetMarker(hc[it],edge_set);
				}
			}
		}
		m->RemMarkerArray(cells.data(), (enumerator)cells.size(), edge_set);
		assert(cells.size() <= 2);
		//check is there a topological problem
		//new face should be adjacent to no more then two cells
		if( m->GetTopologyCheck(TRIPLE_SHARED_FACE) && cells.size() > 2 )
		{
			m->SetTopologyError(TRIPLE_SHARED_FACE);
			if( m->GetTopologyCheck(PRINT_NOTIFY) ) std::cerr << TopologyCheckNotifyString(TRIPLE_SHARED_FACE) << std::endl;
			if( m->GetTopologyCheck(THROW_EXCEPTION) ) throw TopologyCheckError;
		}
		
		dynarray<HandleType,64> nodes;
		tiny_map<HandleType, int,64> edge_visit;
		ElementArray<Edge> edges(m);
		//compute how many times each edge is visited
		for(ElementArray<Face>::size_type j = 0; j < unite.size(); j++)
		{
			//access edges of the face
			adj_type const & lc = m->LowConn(unite.at(j));
			for(adj_type::size_type it = 0; it < lc.size(); it++)
				if( !m->GetMarker(lc[it],hm) ) edge_visit[lc[it]]++;
		}
		HandleType first = InvalidHandle(); //first edge
		HandleType prev = InvalidHandle(); //prev node
		//Mark all the edges on boundary to recreate the face,
		//assemble set of nodes
		int expect_q = 0; //used to test for consistency of the loop of edges
		for(tiny_map<HandleType,int,64>::iterator it = edge_visit.begin(); it != edge_visit.end(); it++)
		{
			if( it->second == 1 )
			{
				expect_q++;
				m->SetMarker(it->first,edge_set);
				if( first == InvalidHandle() ) first = it->first;
			}
			else if( it->second == 2 )
			{
				//edge is protected
				if( m->GetMarker(it->first,del_protect) ) doexit = true;
				//mark edge to be deleted
				m->SetMarker(it->first,rem);
				//access nodes of the edge
				adj_type const & lc = m->LowConn(it->first);
				for(adj_type::size_type jt = 0; jt < lc.size(); jt++) if( !m->GetMarker(lc[jt],hm) )
				{
					if( !m->GetMarker(lc[jt],edge_set) )
					{
						m->SetMarker(lc[jt],edge_set);
						nodes.push_back(lc[jt]);
					}
				}
			}
			else 
			{
				doexit = true; //the faces we unite would not appear as one surface
				dothrow = true;
			}
		}
		//Find out set of nodes to be deleted
		for(dynarray<HandleType,64>::size_type j = 0; j < nodes.size(); j++) 
		{
			m->RemMarker(nodes[j],edge_set);
			int nonzero = 0;
			//access edges of the nodes, find out whether all
			//of them are deleted
			adj_type const & hc = m->HighConn(nodes[j]);
			for(adj_type::size_type it = 0; it < hc.size(); it++) if( !m->GetMarker(hc[it],hm) ) //iterate through edges of the node
				if( !m->GetMarker(hc[it],rem) ) nonzero++; // check if edge should not be deleted
			if( nonzero == 0 ) //all edges are deleted but the node is protected
			{
				m->SetMarker(nodes[j],rem);
				if( m->GetMarker(nodes[j],del_protect) ) doexit = true;
			}
		}
			
		if( doexit )
		{
			for(tiny_map<HandleType,int,64>::iterator it = edge_visit.begin(); it != edge_visit.end(); it++)
			{
				m->RemMarker(it->first,rem);
				m->RemMarker(it->first,edge_set);
			}
			m->RemMarkerArray(nodes.data(), (enumerator)nodes.size(), rem);
			m->ReleaseMarker(edge_set);
			m->ReleaseMarker(rem);
			assert( !dothrow ); //report the situation, because user need to debug the input
			return Face(m,InvalidHandle());
		}
		//Order edges on the boundary of united faces into loop
		edges.push_back(first);
		edges.back()->RemMarker(edge_set);
		bool done = false;
		int q = 1;
		while( !done )
		{
			enumerator k1 = ENUMUNDEF,k2;
			//access nodes of the last pushed edge
			adj_type const & lc = m->LowConn(edges.atback());
			//find out first node
			k1 = m->getNext(lc.data(),static_cast<enumerator>(lc.size()),k1,hm);
			//find out second node
			k2 = m->getNext(lc.data(),static_cast<enumerator>(lc.size()),k1,hm);
			//find out which of the nodes should connect to the next edge
			//at the begining we can select any of the two
			if( lc[k1] != prev ) 
				prev = lc[k1]; 
			else 
				prev = lc[k2];
			//find out the next edge connected to the privious node
			bool found = false; //detect that edge was found, otherwise there is no loop
			adj_type const & hc = m->HighConn(prev);
			for(adj_type::size_type it = 0; it < hc.size(); ++it) if( !m->GetMarker(hc[it],hm) )
			{
				//we came back to the first edge, the loop is closed
				if( hc[it] == first && q != 1)
				{
					found = done = true;
					break;
				}
				if( m->GetMarker(hc[it],edge_set) )
				{
					q++;
					found = true;
					edges.push_back(hc[it]);
					m->RemMarker(hc[it],edge_set);
					break;
				}
			}
			assert(found); //there is no loop
			//if( !found ) throw Failure;
		}
		m->ReleaseMarker(edge_set);
		
		//number of edges collected matches number of edges expected
		assert(expect_q == q);
		

		
		
		if( !m->HideMarker() ) //we can't hide elements
		{
			unite.SetMarker(rem);
			//untie every face from the cell
			for(dynarray<HandleType,64>::size_type it = 0; it < cells.size(); it++)
			{
				adj_type & lc = m->LowConn(cells[it]);
				adj_type::iterator jt = lc.begin();
				while( jt != lc.end()) //don't need to check is it hidden
					if( m->GetMarker(*jt,rem) )
						jt = lc.erase(jt);
					else jt++;
			}
			unite.RemMarker(rem);
		}
		
		//delete old faces
		if( m->HideMarker() )
			for(ElementArray<Face>::size_type j = 0; j < unite.size(); j++)
				m->Hide(unite.at(j));
		else
		{
			// delete all faces
			for(ElementArray<Face>::size_type j = 0; j < unite.size(); j++)
			{
				//untie cells from face
				m->HighConn(unite.at(j)).clear();
				if( m->GetMarker(unite.at(j),del_protect) )
					std::cout << __FUNCTION__ << " deleted protected face, united " << unite.size() << " faces " << std::endl;
				m->Delete(unite.at(j)); 
			}
		}

		for(tiny_map<HandleType,int,64>::iterator it = edge_visit.begin(); it != edge_visit.end(); it++)
			if( it->second != 1 )
			{
				m->RemMarker(it->first,rem);
				assert( m->HighConn(it->first).empty() || m->Count(m->HighConn(it->first).data(),static_cast<integer>(m->HighConn(it->first).size()),hm) == 0 ); //it's connected to face somewhere
				if( m->GetMarker(it->first,del_protect) )
					std::cout << __FUNCTION__ << " deleted protected edge, united " << unite.size() << " faces " << std::endl;
				if( m->HideMarker() )
					m->Hide(it->first);
				else
					m->Delete(it->first);
			}
			
		

		for(dynarray<HandleType,64>::size_type it = 0; it < nodes.size(); it++) //delete nodes inside the face
		{
			//adj_type const & hc = m->HighConn(nodes[it]);
			if( m->GetMarker(nodes[it],rem) )
			{
				assert( m->HighConn(nodes[it]).empty() || m->Count(m->HighConn(nodes[it]).data(),static_cast<integer>(m->HighConn(nodes[it]).size()),hm) == 0 );
				m->RemMarker(nodes[it],rem);
				if( !m->HideMarker() )
				{
					adj_type & lc = m->LowConn(nodes[it]);
					adj_type::iterator jt = lc.begin();
					while(jt != lc.end() ) // iterate through cells of the node
					{
						adj_type & ihc = m->HighConn(*jt);
						adj_type::iterator qt = ihc.begin(); //iterate through nodes of the cell
						while( qt != ihc.end() )
						{
							if( *qt == nodes[it] ) 
								qt = ihc.erase(qt); //remove links from the cell to the node
							else ++qt;
						}
						++jt;
					}
					lc.clear(); // remove links to cells
					if( m->GetMarker(nodes[it],del_protect) )
						std::cout << __FUNCTION__ << " deleted protected node, united " << unite.size() << " faces " << std::endl;
					m->Destroy(nodes[it]);
				}
				else m->Hide(nodes[it]);
			}
		}
		
		m->ReleaseMarker(rem);
				
		Face ret = m->CreateFace(edges).first;
		
		
		assert( ret->GetGeometricType() != MultiLine );
		
		
		adj_type & hc = m->HighConn(ret->GetHandle());
		for(dynarray<HandleType,64>::size_type it = 0; it < cells.size(); it++)  //tie new face to old cells
		{
			hc.push_back(cells[it]); // connect new face to cells
			m->LowConn(cells[it]).push_back(ret.GetHandle()); // connect cells to new face
			
		}
		
		
		for(dynarray<HandleType,64>::size_type it = 0; it < cells.size(); it++)  //tie new face to old cells
		{
			assert(m->Count(m->LowConn(cells[it]).data(),m->LowConn(cells[it]).size(),hm) >= 4);
			//compute geometric data
			m->ComputeGeometricType(cells[it]);
			assert(m->GetGeometricType(cells[it]) != MultiPolygon);
			//change nodes of the cell according to ordering
			ElementArray<Node> nodes(m);
			m->RestoreCellNodes(cells[it],nodes);
			adj_type & hc = m->HighConn(cells[it]);
			assert(nodes.size() == m->Count(hc.data(),hc.size(),hm));
			//should keep hidden nodes of the cell
			//todo: think about how we should order them
			for(adj_type::size_type k = 0; k < hc.size(); ++k)
				if( m->Hidden(hc[k]) ) nodes.push_back(hc[k]);
			hc.replace(hc.begin(),hc.end(),nodes.begin(),nodes.end());
			//recompute geometric data
			m->RecomputeGeometricData(cells[it]);
		}
		
		return ret;
	}
	
	
	bool Face::TestUniteFaces(const ElementArray<Face> & unite, MarkerType del_protect)
	{
		Mesh * m = const_cast<Mesh *>(unite.GetMeshLink());
		if( unite.size() == 0 ) return false;
		bool doexit = false, dothrow = false;
		for(ElementArray<Face>::size_type j = 0; j < unite.size(); j++)
			if( m->GetMarker(unite.at(j),del_protect) ) doexit = true;
		MarkerType hm = m->HideMarker();
		if( doexit ) return false;
		dynarray<HandleType,64> cells;
		MarkerType rem = m->CreateMarker();
		for(ElementArray<Face>::size_type j = 0; j < unite.size(); j++)
		{
			adj_type const & hc = m->HighConn(unite.at(j));
			for(adj_type::size_type it = 0; it < hc.size(); it++) if( !m->GetMarker(hc[it],hm) )
				if( !m->GetMarker(hc[it],rem) )
				{
					cells.push_back(hc[it]);
					m->SetMarker(hc[it],rem);
				}
		}
		m->RemMarkerArray(cells.data(), (enumerator)cells.size(), rem);
		dynarray<HandleType,64> nodes;
		tiny_map<HandleType, int,64> edge_visit;
		for(ElementArray<Face>::size_type j = 0; j < unite.size(); j++)
		{
			adj_type const & lc = m->LowConn(unite.at(j));
			for(adj_type::size_type it = 0; it < lc.size(); it++) if( !m->GetMarker(lc[it],hm) )
				edge_visit[lc[it]]++;
		}
		for(tiny_map<HandleType,int,64>::iterator it = edge_visit.begin(); it != edge_visit.end(); it++)
		{
			if( it->second == 2 )
			{
				if( m->GetMarker(it->first,del_protect) ) doexit = true; // edge is protected
				m->SetMarker(it->first,rem);
				adj_type const & lc = m->LowConn(it->first);
				for(adj_type::size_type jt = 0; jt < lc.size(); jt++) if( !m->GetMarker(lc[jt],hm) )
				{
					if( !m->GetMarker(lc[jt],rem) )
					{
						m->SetMarker(lc[jt],rem);
						nodes.push_back(lc[jt]);
					}
				}
			}
			else if( it->second != 1 )
			{
				doexit = true;
				dothrow = true;
			}
		}
		for(dynarray<HandleType,64>::size_type j = 0; j < nodes.size(); j++) 
		{
			m->RemMarker(nodes[j],rem);
			int nonzero = 0;
			adj_type const & hc = m->HighConn(nodes[j]);
			for(adj_type::size_type it = 0; it < hc.size(); it++) if( !m->GetMarker(hc[it],hm) )//iterate through edges of the node
				if( !m->GetMarker(hc[it],rem) ) nonzero++; // check if edge should not be deleted
			//all edges are deleted but the node is protected
			if( nonzero == 0 && m->GetMarker(nodes[j],del_protect)) doexit = true;
		}
		for(tiny_map<HandleType,int,64>::iterator it = edge_visit.begin(); it != edge_visit.end(); it++)
			if( it->second != 1 ) m->RemMarker(it->first,rem);
		m->ReleaseMarker(rem);
		if( doexit )
		{
			assert(!dothrow);
			//if( dothrow ) throw Impossible; //something went the way it shouldn't, possibly bad input
			return false;
		}
		return true;
	}

	Edge Edge::UniteEdges(const ElementArray<Edge> & edges, MarkerType del_protect)
	{
		Mesh * m = const_cast<Mesh *>(edges.GetMeshLink());
		if( edges.size() == 0 ) return Edge(m,InvalidHandle());
		
		bool doexit = false, dothrow = false;
		MarkerType hm = m->HideMarker();
		MarkerType rem = m->CreateMarker();
		dynarray<HandleType,64> cells;
		dynarray<HandleType,64> faces;
		tiny_map<HandleType,int,64> nodes;
		ElementArray<Node> build_nodes(m);
		for(ElementArray<Edge>::size_type it = 0; it < edges.size(); ++it)
		{
			if( m->GetMarker(edges.at(it),del_protect) )
				doexit = true;
			adj_type const & hc = m->HighConn(edges.at(it));
			for(adj_type::size_type jt = 0; jt != hc.size(); ++jt) if( !m->GetMarker(hc[jt],hm) )
			{
				if( !m->GetMarker(hc[jt],rem) )
				{
					faces.push_back(hc[jt]);
					m->SetMarker(hc[jt],rem);
				}
			}
			adj_type const & lc = m->LowConn(edges.at(it));
			for(adj_type::size_type jt = 0; jt < lc.size(); ++jt) if( !m->GetMarker(lc[jt],hm) )
				nodes[lc[jt]]++;
		}
		
		for(dynarray<HandleType,64>::size_type it = 0; it < faces.size(); ++it)
		{
			m->RemMarker(faces[it],rem);
			adj_type const & hc = m->HighConn(faces[it]);
			for(adj_type::size_type jt = 0; jt < hc.size(); ++jt)
			{
				if( !m->GetMarker(hc[jt],rem) )
				{
					m->SetMarker(hc[jt],rem);
					cells.push_back(hc[jt]);
				}
			}
		}
		
		m->RemMarkerArray(cells.data(), (enumerator)cells.size(), rem);
		
		

		if( doexit )
		{
			m->ReleaseMarker(rem);
			return Edge(m,InvalidHandle());
		}
		
		for(tiny_map<HandleType,int,64>::iterator it = nodes.begin(); it != nodes.end(); it++)
		{
			
			if( it->second == 1 )
				build_nodes.push_back(it->first);
			else if( it->second == 2 )
			{
				if( m->GetMarker(it->first,del_protect) )
					doexit = true;
			}
			else 
			{
				doexit = true; //edges have some loop
				dothrow = true;
			}
		}
		
		
		assert(build_nodes.size() == 2);

		if( doexit )
		{
			m->ReleaseMarker(rem);
			assert(!dothrow);
			//if( dothrow ) throw Impossible; // bad input
			return Edge(m,InvalidHandle());
		}


		dynarray<adj_type::size_type,64> insert_pos; //position where we insert new edge

		for(ElementArray<Edge>::size_type it = 0; it < edges.size(); ++it)
			m->SetMarker(edges.at(it),rem);

		for(dynarray<HandleType,64>::size_type it = 0; it < faces.size(); ++it)
		{
			adj_type const & lc = m->LowConn(faces[it]); //edges of face
			bool found_rem = false;
			for(adj_type::size_type k = 0; k < lc.size(); k++) //insert new edge to the first position where we delete old edge
			{
				if( m->GetMarker(lc[k],rem) )
				{
					//all united edges should appear in consecutive order in deleted face
					/*
					adj_type::size_type sum = 0, j = k;
					while( j < lc.size() && !m->GetMarker(lc[j],hm) && m->GetMarker(lc[j],rem) )
					{
						sum++; j++;
					}
					if( sum != static_cast<adj_type::size_type>(edges.size()) ) //not all edges belong to current face - face will be broken!
					{
						doexit = true;
						dothrow = true;
					}
					 */
					insert_pos.push_back(k);
					found_rem = true;
					break;
				}
			}
			if( !found_rem )
			{
				doexit = true;
				dothrow = true;
			}
		}

		if( doexit )
		{
			m->RemMarkerArray(edges.data(), (enumerator)edges.size(), rem);
			m->ReleaseMarker(rem);
			assert(!dothrow);
			//if( dothrow ) throw Impossible; // bad input
			return Edge(m,InvalidHandle());
		}

		if( !m->HideMarker() ) //disconnect if cannot hide
		{
			for(dynarray<HandleType,64>::size_type it = 0; it < faces.size(); ++it)
			{
				adj_type & lc = m->LowConn(faces[it]);
				adj_iterator jt = lc.begin(); //iterate over edges of faces
				while( jt != lc.end())
				{
					if( m->GetMarker(*jt,rem) )
						jt = lc.erase(jt);
					else ++jt;
				}
			}
		}


		for(ElementArray<Edge>::size_type it = 0; it < edges.size(); ++it)//delete edges
		{
			m->RemMarker(edges.at(it),rem);