c++ 三维 2线段最小距离 源代码

以下是C++的三维两线段最小距离的源代码：

#include <bits/stdc++.h>
using namespace std;

double DotProduct(double x1, double y1, double z1, double x2, double y2, double z2) {
    return x1 * x2 + y1 * y2 + z1 * z2;
}

double CrossProduct(double x1, double y1, double z1, double x2, double y2, double z2, double& x, double& y, double& z) {
    x = y1 * z2 - y2 * z1;
    y = z1 * x2 - z2 * x1;
    z = x1 * y2 - x2 * y1;
    return sqrt(x * x + y * y + z * z);
}

double Distance(double x1, double y1, double z1, double x2, double y2, double z2) {
    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2) + (z1 - z2) * (z1 - z2));
}

double SegmentAndSegment(double x1, double y1, double z1, double x2, double y2, double z2, double x3, double y3, double z3, double x4, double y4, double z4) {
    double x, y, z;
    double a1 = x2 - x1;
    double b1 = y2 - y1;
    double c1 = z2 - z1;
    double a2 = x4 - x3;
    double b2 = y4 - y3;
    double c2 = z4 - z3;
    double a3 = x1 - x3;
    double b3 = y1 - y3;
    double c3 = z1 - z3;
    double d1 = DotProduct(a1, b1, c1, a2, b2, c2);
    double d2 = DotProduct(a1, b1, c1, a1, b1, c1);
    double d3 = DotProduct(a2, b2, c2, a2, b2, c2);
    double d4 = DotProduct(a1, b1, c1, a3, b3, c3);
    double d5 = DotProduct(a2, b2, c2, a3, b3, c3);
    double d = d2 * d3 - d1 * d1;
    double t1, t2;
    if (d == 0) {
        t1 = 0;
        t2 = (d1 > d3 ? d1 / d2 : d3 / d2);
    } else {
        t1 = (d1 * d5 - d2 * d4) / d;
        t2 = (d1 * t1 + d5) / d3;
    }
    t1 = max(0.0, min(t1, 1.0));
    t2 = max(0.0, min(t2, 1.0));
    double u1 = x1 + t1 * a1;
    double v1 = y1 + t1 * b1;
    double w1 = z1 + t1 * c1;
    double u2 = x3 + t2 * a2;
    double v2 = y3 + t2 * b2;
    double w2 = z3 + t2 * c2;
    return Distance(u1, v1, w1, u2, v2, w2);
}

int main() {
    double x1, y1, z1, x2, y2, z2, x3, y3, z3, x4, y4, z4;
    cin >> x1 >> y1 >> z1 >> x2 >> y2 >> z2 >> x3 >> y3 >> z3 >> x4 >> y4 >> z4;
    cout << SegmentAndSegment(x1, y1, z1, x2, y2, z2, x3, y3, z3, x4, y4, z4) << endl;
    return 0;
}

其中，`DotProduct`函数计算向量的点积，`CrossProduct`函数计算向量的叉积，`Distance`函数计算两点之间的距离，`SegmentAndSegment`函数计算两条线段之间的最小距离。