/*private*/
void
ConvexHull::cleanRing(const Coordinate::ConstVect &original,
Coordinate::ConstVect &cleaned)
{
size_t npts=original.size();
const Coordinate *last = original[npts-1];
//util::Assert::equals(*(original[0]), *last);
assert(last);
assert(original[0]->equals2D(*last));
const Coordinate *prev = NULL;
for (size_t i=0; i<npts-1; ++i)
{
const Coordinate *curr = original[i];
const Coordinate *next = original[i+1];
// skip consecutive equal coordinates
if (curr->equals2D(*next)) continue;
if ( prev != NULL && isBetween(*prev, *curr, *next) )
{
continue;
}
cleaned.push_back(curr);
prev=curr;
}
cleaned.push_back(last);
}
/* private */
void
ConvexHull::reduce(Coordinate::ConstVect &pts)
{
Coordinate::ConstVect polyPts;
if ( ! computeOctRing(pts, polyPts) ) {
// unable to compute interior polygon for some reason
return;
}
// add points defining polygon
Coordinate::ConstSet reducedSet;
reducedSet.insert(polyPts.begin(), polyPts.end());
/**
* Add all unique points not in the interior poly.
* CGAlgorithms.isPointInRing is not defined for points
* actually on the ring, but this doesn't matter since
* the points of the interior polygon are forced to be
* in the reduced set.
*
* @@TIP: there should be a std::algo for this
*/
for (size_t i=0, n=pts.size(); i<n; ++i)
{
if ( !CGAlgorithms::isPointInRing(*(pts[i]), polyPts) )
{
reducedSet.insert(pts[i]);
}
}
inputPts.assign(reducedSet.begin(), reducedSet.end());
if ( inputPts.size() < 3 ) padArray3(inputPts);
}
void object::test<1>()
{
using geos::geom::Coordinate;
// Create geometry from WKT
const Coordinate::ConstVect::size_type size5 = 5;
const std::string wkt("MULTIPOINT(10 10, 20 20, 30 30, 20 20, 10 10)");
GeometryPtr geo(reader_.read(wkt));
ensure_equals( geo->getGeometryTypeId(), geos::geom::GEOS_MULTIPOINT );
std::auto_ptr<geos::geom::CoordinateSequence> cs;
cs.reset(geo->getCoordinates());
ensure_equals(cs->getSize(), size5 );
// Create collection buffer for filtered coordinates
const Coordinate::ConstVect::size_type size0 = 0;
Coordinate::ConstVect coords;
// Create filtering object
geos::util::UniqueCoordinateArrayFilter filter(coords);
ensure_equals( coords.size(), size0 );
// Apply filter
const Coordinate::ConstVect::size_type size3 = 3;
geo->apply_ro(&filter);
cs.reset(geo->getCoordinates());
ensure_equals( cs->getSize(), size5 );
ensure_equals( coords.size(), size3 );
ensure_equals( coords.at(0)->x, 10 );
ensure_equals( coords.at(0)->y, 10 );
ensure_equals( coords.at(1)->x, 20 );
ensure_equals( coords.at(1)->y, 20 );
ensure_equals( coords.at(2)->x, 30 );
ensure_equals( coords.at(2)->y, 30 );
}
/* private */
Geometry*
ConvexHull::lineOrPolygon(const Coordinate::ConstVect &input)
{
Coordinate::ConstVect cleaned;
cleanRing(input, cleaned);
if (cleaned.size()==3) { // shouldn't this be 2 ??
cleaned.resize(2);
CoordinateSequence *cl1=toCoordinateSequence(cleaned);
LineString *ret = geomFactory->createLineString(cl1);
return ret;
}
CoordinateSequence *cl2=toCoordinateSequence(cleaned);
LinearRing *linearRing=geomFactory->createLinearRing(cl2);
return geomFactory->createPolygon(linearRing,NULL);
}
/* private */
bool
ConvexHull::computeOctRing(const Coordinate::ConstVect &inputPts,
Coordinate::ConstVect &dest)
{
computeOctPts(inputPts, dest);
// Remove consecutive equal Coordinates
// unique() returns an iterator to the end of the resulting
// sequence, we erase from there to the end.
dest.erase( std::unique(dest.begin(),dest.end()), dest.end() );
// points must all lie in a line
if ( dest.size() < 3 ) return false;
// close ring
dest.push_back(dest[0]);
return true;
}
/* private */
void
ConvexHull::preSort(Coordinate::ConstVect &pts)
{
// find the lowest point in the set. If two or more points have
// the same minimum y coordinate choose the one with the minimum x.
// This focal point is put in array location pts[0].
for(size_t i=1, n=pts.size(); i<n; ++i)
{
const Coordinate *p0=pts[0]; // this will change
const Coordinate *pi=pts[i];
if ( (pi->y<p0->y) || ((pi->y==p0->y) && (pi->x<p0->x)) )
{
const Coordinate *t=p0;
pts[0]=pi;
pts[i]=t;
}
}
// sort the points radially around the focal point.
std::sort(pts.begin(), pts.end(), RadiallyLessThen(pts[0]));
}
/*private*/
void
ConvexHull::grahamScan(const Coordinate::ConstVect &c,
Coordinate::ConstVect &ps)
{
ps.push_back(c[0]);
ps.push_back(c[1]);
ps.push_back(c[2]);
for(size_t i=3, n=c.size(); i<n; ++i)
{
const Coordinate *p = ps.back(); ps.pop_back();
while (!ps.empty() &&
CGAlgorithms::computeOrientation(
*(ps.back()), *p, *(c[i])) > 0)
{
p = ps.back(); ps.pop_back();
}
ps.push_back(p);
ps.push_back(c[i]);
}
ps.push_back(c[0]);
}
/* private */
void
ConvexHull::computeOctPts(const Coordinate::ConstVect &inputPts,
Coordinate::ConstVect &pts)
{
// Initialize all slots with first input coordinate
pts = Coordinate::ConstVect(8, inputPts[0]);
for (size_t i=1, n=inputPts.size(); i<n; ++i)
{
if (inputPts[i]->x < pts[0]->x) {
pts[0] = inputPts[i];
}
if (inputPts[i]->x - inputPts[i]->y < pts[1]->x - pts[1]->y) {
pts[1] = inputPts[i];
}
if (inputPts[i]->y > pts[2]->y) {
pts[2] = inputPts[i];
}
if (inputPts[i]->x + inputPts[i]->y > pts[3]->x + pts[3]->y) {
pts[3] = inputPts[i];
}
if (inputPts[i]->x > pts[4]->x) {
pts[4] = inputPts[i];
}
if (inputPts[i]->x - inputPts[i]->y > pts[5]->x - pts[5]->y) {
pts[5] = inputPts[i];
}
if (inputPts[i]->y < pts[6]->y) {
pts[6] = inputPts[i];
}
if (inputPts[i]->x + inputPts[i]->y < pts[7]->x + pts[7]->y) {
pts[7] = inputPts[i];
}
}
}