PerturbPolygon.h

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#pragma once
 
#ifdef OGDF_INCLUDE_CGAL
 
#   include <ogdf/geometric/cr_min/geometry/objects/Polygon.h>
 
namespace ogdf {
namespace internal {
namespace gcm {
namespace geometry {
 
template<typename Kernel>
Polygon_t<Kernel> peturb(const Polygon_t<Kernel>& polygon, double eps = 1e-5) {
    using Segment = LineSegment_t<Kernel>;
 
    auto bisector = [&](const Segment& s1, const Segment& s2) {
        const auto& v_in = s1.to_vector();
        const auto& v_out = s2.to_vector();
        auto bisected = bisect(-v_in, v_out);
        if (geometry::right_turn(v_in, bisected)) {
            bisected = -bisected;
        }
 
        return bisected;
    };
 
    Polygon_t<Kernel> perturbed;
    auto itr = polygon.edges_circulator();
    for (unsigned int i = 0; i < polygon.size(); ++i) {
        perturbed.push_back(polygon[i] + bisector(*(itr - 1), *itr) * eps);
        ++itr;
    }
    return perturbed;
}
 
}
}
}
}
 
#endif