Hi all,

I am using boost/polygon to do unions of multiple polygons, and I lose holes that were in the input after the assign() operation. Here is code that demonstrates the issue:

// Create outer contour

Point outer[] = {gtl::construct<Point>(0, 0),

gtl::construct<Point>(0, 10),

gtl::construct<Point>(10, 10),

gtl::construct<Point>(10, 0)};

// Create inner contour

Point inner[] = {gtl::construct<Point>(2, 2),

gtl::construct<Point>(8, 2),

gtl::construct<Point>(8, 8),

gtl::construct<Point>(2, 8)};

// Define inner contour as a polygon

polygon_with_holes_data<long> input_poly_inner;

gtl::set_points(input_poly_inner, inner, inner+4);

// Put inner polygon in a list

vector<polygon_with_holes_data<long> > inners;

inners.push_back(input_poly_inner);

// Create input polygon as outer contour + inner polygon list

polygon_with_holes_data<long> input_poly;

gtl::set_points(input_poly, outer, outer+4);

gtl::set_holes(input_poly, inners.begin(), inners.end());

// Create input polygon set, insert input polygon

polygon_set_data<long> input_poly_set;

input_poly_set.insert(input_poly);

// Create output polygon set, assign input polygon set

vector<polygon_with_holes_data<long> > output_poly_set;

assign(output_poly_set, input_poly_set);

// Print result

std::cout << output_poly_set.size() << " polys" << std::endl;

std::cout << output_poly_set[0].size_holes() << " holes" << std::endl;

This prints:

1 polys

0 holes

Any idea what I am doing wrong ?

Kind regards,

Julien Nicoulaud