Hi all,
I am having trouble with boost::polygon: when get_trapezoids is called on a polygon_set_data containing a polygon_with_holes_data, it returns trapezoids covering the outer loop but that cover the hole (i.e., the hole is being ignored). A small example is below to demonstrate. I've tried with boost 1.60, 1.55, and 1.50. Am I doing something wrong?
Thanks,
David
#include "boost/polygon/polygon.hpp"
#include <vector>
namespace poly = boost::polygon;
typedef long long Coord;
typedef poly::point_data<Coord> Point;
Coord outerPts[] = {
-37205784000000LL, -22528321200000LL,
-20252740200000LL, -40391736000000LL,
19228717200000LL, -39708900000000LL,
37774737000000LL, 32882157000000LL,
-37205784000000LL, -22528321200000LL,
};
Coord innerPts[] = {
-8808676800000LL, -4351000500000LL,
29799924000000LL, 21288613500000LL,
8185023000000LL, -10611816600000LL,
-8808676800000LL, -4351000500000LL,
};
template<typename T>
void liftPt(double x[2], const T& pt, double sf)
{
x[0] = sf * pt.x();
x[1] = sf * pt.y();
}
template<typename T>
void print_polyarray(const std::string& msg, T& parr, double scale, double iscale)
{
std::cout << msg << " has " << parr.size() << " polygons\n";
std::vector::const_iterator pit;
int pp = 0;
for (pit = parr.begin(); pit != parr.end(); ++pit, ++pp)
{
poly::polygon_data<Coord>::iterator_type pcit;
std::cout << " Polygon " << pp << " has " << pit->size() << " points\n";
double p0[2];
for (pcit = poly::begin_points(*pit); pcit != poly::end_points(*pit); ++pcit)
{
liftPt(p0, *pcit, iscale);
std::cout << " " << p0[0] << " " << p0[1] << "\n";
}
std::cout << "--\n";
}
}
int main()
{
const double scale = 2.31e13;
const double iscale = 1./2.31e13;
poly::polygon_with_holes_data<Coord> pface;
std::vector holes;
poly::polygon_data<Coord> loop;
std::vector<Point> polypts1;
for (unsigned ii = 0; ii < sizeof(outerPts)/sizeof(outerPts[0])/2; ++ii)
{
polypts1.push_back(Point(outerPts[2*ii], outerPts[2*ii + 1]));
}
pface.set(polypts1.begin(), polypts1.end());
std::vector<Point> polypts2;
for (unsigned ii = 0; ii < sizeof(innerPts)/sizeof(innerPts[0])/2; ++ii)
{
polypts2.push_back(Point(innerPts[2*ii], innerPts[2*ii + 1]));
}
loop.set(polypts2.rbegin(), polypts2.rend());
holes.push_back(loop);
pface.set_holes(holes.begin(), holes.end());
Point holecenter( 9725423400000LL, 2108598800000LL);
Point nonholepnt(37774730000000LL, 32882150000000LL);
// ^^ Compare to 37774737000000LL, 32882157000000LL, which is a vertex in outerPts.
std::cout << "Polygon has " << pface.size() << " vertices and " << pface.size_holes() << " holes\n";
std::cout << "Winding is " << (poly::winding(pface) == poly::CLOCKWISE ? "cw" : "ccw") << "\n";
std::cout << "Contains hole center? " << (poly::contains(pface, holecenter) ? "Y" : "N") << "\n";
std::cout << "Contains point it should? " << (poly::contains(pface, nonholepnt) ? "Y" : "N") << "\n";
// The above demonstrates that pface appears to be a valid polygon with a hole.
// However, now when we ask for trapezoids, no hole is provided:
// Add pface to polys so we can get trapezoids:
poly::polygon_set_data<Coord> polys;
std::vector parr;
polys.insert(pface);
polys.get(parr);
// This prints that parr (and thus polys) contains 0 polygons, which seems wrong:
print_polyarray("Original polygon set", parr, scale, iscale);
polys.get_trapezoids(parr);
// This prints 2 polygons that form only the outer boundary, which seems wrong:
print_polyarray("Tessellation ", parr, scale, iscale);
return 0;
}
