boost1.81.0
Visual Studio 2019. x64 debug
void Test()
{
namespace bg = boost::geometry;
using point = bg::model::point<double, 2, bg::cs::cartesian>;
using ring = bg::model::ring<point>;
using multi_polygon = bg::model::multi_polygon<bg::model::polygon<point>>;
multi_polygon input0;
ring input1;
constexpr double ng_y = -115.4;
//constexpr double ng_y = -115.5;
input0.resize(2);
// green
input0[0].outer().assign({
{-63,-88},
{0,ng_y},
{0,-124},
{-63,-124},
{-63,-88}
});
// blue
input0[1].outer().assign({
{0,-150},
{0,-124},
{13,-124},
{13,-121},
{0,ng_y},
{0,-88},
{40,-88},
{40,-150},
{0,-150}
});
// red
input1.assign({
{0,-88},
{0,ng_y},
{-10,-88},
{0,-88}
});
assert(bg::is_valid(input0));
assert(bg::is_valid(input1));
multi_polygon output;
bg::union_(input0, input1, output);
for (size_t i = 0; i < output.size(); ++i) {
std::cout << "====polygon " << i << std::endl;
for (auto& point : output[i].outer()) {
std::cout << point.get<0>() << "," << point.get<1>() << std::endl;
}
}
auto area_in = bg::area(input0) + bg::area(input1);
auto area_out = bg::area(output);
assert(area_in >= area_out);
}
result
====polygon 0
0,-115.4
0,-124
-63,-124
-63,-88
-4.35207e-13,-115.4
0,-115.4
0,-124
-63,-124
-63,-88
0,-115.4
====polygon 1
0,-115.4
-10,-88
0,-88
40,-88
40,-150
0,-150
0,-124
13,-124
13,-121
-4.35207e-13,-115.4
0,-115.4
0,-88
40,-88
40,-150
0,-150
0,-124
13,-124
13,-121
0,-115.4
If ng_y is not -111.4 but -111.5, it works well.
boost1.81.0
Visual Studio 2019. x64 debug
result
If ng_y is not -111.4 but -111.5, it works well.