test/geometry/Projection.test.cpp

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Last update: 2023-06-08 15:34:10+09:00
Problem: https://onlinejudge.u-aizu.ac.jp/courses/library/4/CGL/1/CGL_1_A

Depends on

Code

#define PROBLEM \
    "https://onlinejudge.u-aizu.ac.jp/courses/library/4/CGL/1/CGL_1_A"
#define ERROR 0.0000001

#include "../../geometry/line.hpp"
#include "../../template/template.hpp"

using namespace lib;

int main() {
    std::cout << std::fixed << std::setprecision(15);
    line l;
    {
        ld x1, y1, x2, y2;
        std::cin >> x1 >> y1 >> x2 >> y2;
        l.a = {x1, y1};
        l.b = {x2, y2};
    }
    int q;
    std::cin >> q;
    while (q--) {
        ld x, y;
        std::cin >> x >> y;
        vec p = proj(l, {x, y});
        std::cout << p.real() << " " << p.imag() << '\n';
    }
}

#line 1 "test/geometry/Projection.test.cpp"
#define PROBLEM \
    "https://onlinejudge.u-aizu.ac.jp/courses/library/4/CGL/1/CGL_1_A"
#define ERROR 0.0000001

#line 2 "geometry/line.hpp"

#line 2 "geometry/base_ld.hpp"

#line 2 "template/template.hpp"

#include <bits/stdc++.h>

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)
#define all(v) v.begin(), v.end()

using ll = long long;
using ld = long double;
using ull = unsigned long long;

template <typename T> bool chmin(T &a, const T &b) {
    if (a <= b) return false;
    a = b;
    return true;
}
template <typename T> bool chmax(T &a, const T &b) {
    if (a >= b) return false;
    a = b;
    return true;
}

namespace lib {

using namespace std;

}  // namespace lib

// using namespace lib;
#line 4 "geometry/base_ld.hpp"

namespace lib {

using vec = complex<ld>;

const ld PI = acos(-1);

void ldout(int len = 20) {
    cout << fixed << setprecision(len);
}

int sgn(ld a, const ld eps = 1e-7) {
    return (a < -eps) ? -1 : (a > eps) ? 1 : 0;
}

bool same_vec(vec a, vec b) {
    a -= b;
    return sgn(a.real()) == 0 && sgn(a.imag()) == 0;
}

ld dot(const vec &a, const vec &b) {
    return (conj(a) * b).real();
}

ld cross(const vec &a, const vec &b) {
    return (conj(a) * b).imag();
}

int isp(const vec &a, const vec &b, const vec &c) {
    int cross_sgn = sgn(cross(b - a, c - a));
    if (cross_sgn == 0) {
        if (sgn(dot(b - a, c - a)) < 0) return -2;
        if (sgn(dot(a - b, c - b)) < 0) return 2;
    }
    return cross_sgn;
}

vec rot90(const vec &a) {
    return {-a.imag(), a.real()};
}

vec rot(const vec &a, ld rad) {
    return a * vec(cosl(rad), sinl(rad));
}

bool comp_for_argument_sort(const vec &lhs, const vec &rhs) {
    // if (abs(arg(lhs)-arg(rhs)) < eps) return false; // need ?
    return arg(lhs) < arg(rhs);
}

}  // namespace lib
#line 4 "geometry/line.hpp"

namespace lib {

struct line {
    vec a, b;
};

vec proj(const line &l, const vec &p) {
    vec ab = l.b - l.a;
    return l.a + ab * (dot(ab, p - l.a) / norm(ab));
}

vec refl(const line &l, const vec &p) {
    return proj(l, p) * ld(2) - p;
}

int intersection(const line &a, const line &b) {
    if (sgn(cross(a.b - a.a, b.a - b.b)) != 0) {
        if (sgn(dot(a.b - a.a, b.a - b.b)) == 0) {
            return 1;
        }
        return 0;
    } else if (sgn(cross(a.b - a.a, b.a - a.a)) != 0) {
        return 2;
    } else {
        return 3;
    }
}

ld dist(const line &a, const vec &p) {
    return abs(cross(p - a.a, a.b - a.a) / abs(a.b - a.a));
}

vec cross_point(const line &a, const line &b) {
    assert(intersection(a, b) < 2);
    return a.a + (a.b - a.a) * cross(b.a - a.a, b.b - b.a) /
                     cross(a.b - a.a, b.b - b.a);
}

}  // namespace lib
#line 7 "test/geometry/Projection.test.cpp"

using namespace lib;

int main() {
    std::cout << std::fixed << std::setprecision(15);
    line l;
    {
        ld x1, y1, x2, y2;
        std::cin >> x1 >> y1 >> x2 >> y2;
        l.a = {x1, y1};
        l.b = {x2, y2};
    }
    int q;
    std::cin >> q;
    while (q--) {
        ld x, y;
        std::cin >> x >> y;
        vec p = proj(l, {x, y});
        std::cout << p.real() << " " << p.imag() << '\n';
    }
}