geometry/is-contained.hpp

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• Last update: 2026-08-30 15:33:14+09:00
• Include: #include "geometry/is-contained.hpp"

Depends on

• geometry/base.hpp
• geometry/cross.hpp
• geometry/dot.hpp

Required by

• 幾何ライブラリ (geometry/geometry.hpp)

Verified with

• test/mytest/geometry/geometry.test.cpp

Code

#pragma once

#include <vector>

#include "cross.hpp"
#include "dot.hpp"

namespace geometry {
    // 多角形gに点pが含まれているか?
    // 含まれる:2, 辺上にある:1, 含まれない:0
    inline int isContained(const std::vector<Point> &g, const Point &p) {
        bool in = false;
        int n = (int)g.size();
        for(int i = 0; i < n; i++) {
            Point a = g[i] - p, b = g[(i + 1) % n] - p;
            if(imag(a) > imag(b)) swap(a, b);
            if(imag(a) <= EPS && EPS < imag(b) && cross(a, b) < -EPS) in = !in;
            if(cross(a, b) == 0 && dot(a, b) <= 0) return 1;
        }
        return (in ? 2 : 0);
    }
} // namespace geometry

#line 2 "geometry/is-contained.hpp"

#include <vector>

#line 2 "geometry/cross.hpp"

#line 2 "geometry/base.hpp"

#include <cmath>
#include <complex>

namespace geometry {
    // Point : 複素数型を位置ベクトルとして扱う
    // 実軸(real)をx軸、挙軸(imag)をy軸として見る
    using D = long double;
    using Point = std::complex<D>;
    const D EPS = 1e-7;
    const D PI = std::acos(D(-1));

    inline bool equal(const D &a, const D &b) { return std::fabs(a - b) < EPS; }
} // namespace geometry
#line 4 "geometry/cross.hpp"

namespace geometry {
    // 外積(cross product) : a×b = |a||b|sinΘ
    inline D cross(const Point &a, const Point &b) {
        return (a.real() * b.imag() - a.imag() * b.real());
    }
} // namespace geometry
#line 2 "geometry/dot.hpp"

#line 4 "geometry/dot.hpp"

namespace geometry {
    // 内積(dot product) : a・b = |a||b|cosΘ
    inline D dot(const Point &a, const Point &b) {
        return (a.real() * b.real() + a.imag() * b.imag());
    }
} // namespace geometry
#line 7 "geometry/is-contained.hpp"

namespace geometry {
    // 多角形gに点pが含まれているか?
    // 含まれる:2, 辺上にある:1, 含まれない:0
    inline int isContained(const std::vector<Point> &g, const Point &p) {
        bool in = false;
        int n = (int)g.size();
        for(int i = 0; i < n; i++) {
            Point a = g[i] - p, b = g[(i + 1) % n] - p;
            if(imag(a) > imag(b)) swap(a, b);
            if(imag(a) <= EPS && EPS < imag(b) && cross(a, b) < -EPS) in = !in;
            if(cross(a, b) == 0 && dot(a, b) <= 0) return 1;
        }
        return (in ? 2 : 0);
    }
} // namespace geometry

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