Function angle_between_dirs_deg

src/svgfill/src/arrange_polygons.cpp:1003–1011

}

double angle_between_dirs_deg(const DDir& a, const DDir& b) {
    auto u = unit(a);
    auto v = unit(b);
    auto c = std::abs(u * v);
    if (c > 1.) {
        c = 1.;
    }
    return std::acos(c) * 180. / 3.14159265358979323846;
}

std::array<DPoint, 4> rectangle_corners(const DPoint& start, const DPoint& end, double width) {
    auto u = unit(end - start);