ProperCycle::ProperCycle(const KeyEdgeSet & edgeSetConst)
{
// If no edge, then invalid
if(edgeSetConst.isEmpty())
return;
// if not all edges at same time, then invalid
KeyEdge * first = *edgeSetConst.begin();
Time t = first->time();
foreach(KeyEdge * iedge, edgeSetConst)
{
if(iedge->time() != t)
{
//QMessageBox::information(0, QObject::tr("operation aborted"),
// QObject::tr("not all edges are on same time"));
return;
}
}
// copy the set to be able to modify it
KeyEdgeSet edgeSet = edgeSetConst;
// insert first edge
halfedges_ << KeyHalfedge(first, true);
edgeSet.erase(edgeSet.begin());
// check case where it's a pure loop
if(first->isClosed())
{
if(!edgeSet.isEmpty())
{
//QMessageBox::information(0, QObject::tr("operation aborted"),
// QObject::tr("more than one edge and one of them is a pure loop"));
halfedges_.clear();
return;
}
// else: good!
}
else
{
// not a pure loop, let's find the chain
while(!edgeSet.isEmpty())
{
KeyHalfedge lastAddedHalfedge = halfedges_.last(); // we know it's not a loop, otherwise couldn't be here
KeyVertex * lastVertex = lastAddedHalfedge.endVertex(); // hence this is a valid vertex
// find next
KeyHalfedge nextHalfedge;
auto it = edgeSet.begin();
auto itEnd = edgeSet.end();
for(;it!=itEnd;++it)
{
if((*it)->startVertex() == lastVertex)
{
nextHalfedge = KeyHalfedge(*it, true);
break;
}
else if((*it)->endVertex() == lastVertex)
{
nextHalfedge = KeyHalfedge(*it, false);
break;
}
}
// if found: great, insert it!
if(nextHalfedge.isValid())
{
halfedges_ << nextHalfedge;
edgeSet.erase(it);
}
else
{
//QMessageBox::information(0, QObject::tr("operation aborted"),
// QObject::tr("not a valid loop: no valid next edge found"));
halfedges_.clear();
return;
}
}
// So far, we've inserted all N edges, and every edge i in [0,N-2]
// satisfies edges_[i]->endVertex() == edges_[i+1]->startVertex()
// Check that it's looping
if(halfedges_.last().endVertex() != halfedges_.first().startVertex())
{
//QMessageBox::information(0, QObject::tr("operation aborted"),
// QObject::tr("not a valid loop: last edge not compatible with first one"));
halfedges_.clear();
return;
}
// Check that it's simple
KeyVertexSet vertices;
foreach(KeyHalfedge he, halfedges_)
{
KeyVertex * vertex = he.startVertex();
if(vertices.contains(vertex))
{
//QMessageBox::information(0, QObject::tr("operation aborted"),
// QObject::tr("not a valid loop: not simple"));
halfedges_.clear();
return;
}
else
{
vertices << vertex;
}
}
// Done :-) If you're here you have a valid simple loop
}
