/*
PolygonPartition::sweep
Determines if two polygons are neighbors. The host is assumed to be
partitioned.
Uses two criteria to establish neighborhood:
is_queen == true then: common point, else: common boundary
*/
int PolygonPartition::sweep(PolygonPartition & guest, bool is_queen,
double precision_threshold)
{
int host, dot, cly, cell;
double yStart= GetMinY(), yStop= GetMaxY();
Shapefile::Point* pt;
guest.MakeSmallPartition(pX.Cells(), GetMinX(), GetMaxX());
for (cell= 0; cell < pX.Cells(); ++cell) {
for (host= pX.first(cell); host != GdaConst::EMPTY; host= pX.tail(host))
pY.include(host);
for (dot=guest.pX.first(cell); dot != GdaConst::EMPTY; dot=guest.pX.tail(dot))
{
pt= guest.GetPoint(dot);
cly= pY.inTheRange(pt->y - yStart);
if (cly != -1) {
for (host= pY.first(cly); host != GdaConst::EMPTY;
host= pY.tail(host))
{
if (pt->equals( GetPoint(host), precision_threshold) )
{
if (is_queen || edge(guest, host, dot, precision_threshold)) {
pY.cleanup(pX, cell);
return 1;
}
}
}
}
}
pY.cleanup(pX, cell);
}
return 0;
}
GalElement* MakeContiguity(Shapefile::Main& main, const int crit,
double precision_threshold=0.0)
{
using namespace Shapefile;
int curr;
GalElement * gl= new GalElement [ gRecords ];
if (!gl) return NULL;
GeoDaSet Neighbors(gRecords), Related(gRecords);
// cout << "total steps= " << gMinX.Cells() << endl;
for (int step= 0; step < gMinX.Cells(); ++step) {
// include all elements from xmin[step]
for (curr= gMinX.first(step); curr != GdaConst::EMPTY;
curr= gMinX.tail(curr)) gY->include(curr);
// test each element in xmax[step]
for (curr= gMaxX.first(step); curr != GdaConst::EMPTY;
curr= gMaxX.tail(curr)) {
PolygonContents* ply = dynamic_cast<PolygonContents*> (
main.records[curr].contents_p);
PolygonPartition testPoly(ply);
testPoly.MakePartition();
// form a list of neighbors
for (int cell=gY->lowest(curr); cell <= gY->upmost(curr); ++cell) {
int potential = gY->first( cell );
while (potential != GdaConst::EMPTY) {
if (potential != curr) Neighbors.Push( potential );
potential = gY->tail(potential, cell);
}
}
// test each potential neighbor
for (int nbr = Neighbors.Pop(); nbr != GdaConst::EMPTY;
nbr = Neighbors.Pop()) {
PolygonContents* nbr_ply = dynamic_cast<PolygonContents*> (
main.records[nbr].contents_p);
if (ply->intersect(nbr_ply)) {
PolygonPartition nbrPoly(nbr_ply);
//shp.seekg(gOffset[nbr]+12, ios::beg);
//nbrPoly.ReadShape(shp);
if (curr == 0 && nbr == 0) {
}
// run sweep with testPoly as a host and nbrPoly as a guest
int related = testPoly.sweep(nbrPoly, crit,
precision_threshold);
if (related) Related.Push(nbr);
}
}
if (Related.Size() && gl[curr].alloc(Related.Size())) {
while (Related.Size()) gl[curr].Push(Related.Pop());
}
gY->remove(curr); // remove from the partition
}
}
return gl;
}
void cleanup(const BasePartition &p, const int cl) {
for (int cnt= p.first(cl); cnt != GdaConst::EMPTY; cnt= p.tail(cnt))
remove(cnt);
}
