多边形外的点到多边形边界最近点的坐标

多边形外的点到多边形边界最近点的坐标

package com.ruoyi.system.utils;

import cn.hutool.core.collection.CollUtil;
import com.alibaba.fastjson.JSON;
import com.ruoyi.common.core.text.Convert;
import com.ruoyi.system.domain.TbRail;
import com.ruoyi.system.domain.TbRailPoint;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.annotations.Param;

import java.awt.geom.Point2D;
import java.math.BigDecimal;
import java.util.*;
import java.util.stream.Collectors;

@Slf4j
public class RailUtil {

/**
 * 找到多边形边界上一个点，使得这个点与多边形外面的指定点距离最短
 * @param railPointList
 * @param point
 * @return
 */
public static TbRailPoint findClosestPointOnPolygonBoundary(List railPointList, TbRailPoint point){
    TbRailPoint rtn = new TbRailPoint();
    rtn.setLongitude(BigDecimal.ZERO);
    rtn.setLatitude(BigDecimal.ZERO);
    Point2D.Double closestPointOnPolygonBoundary = findClosestPointOnPolygonBoundary(railPointList, new Point2D.Double(point.getLongitude().doubleValue(), point.getLatitude().doubleValue()));
    if (Objects.isNull(closestPointOnPolygonBoundary)){
        return rtn;
    }
    rtn.setLongitude(BigDecimal.valueOf(closestPointOnPolygonBoundary.x));
    rtn.setLatitude(BigDecimal.valueOf(closestPointOnPolygonBoundary.y));
    return rtn;
}

public static Point2D.Double findClosestPointOnPolygonBoundary(List polygonVertices, Point2D.Double externalPoint) {
    double minDistance = Double.MAX_VALUE;
    Point2D.Double closestPoint = null;

    // 遍历多边形的每条边
    for (int i = 0; i < polygonVertices.size(); i++) {
        Point2D.Double p1 = polygonVertices.get(i);
        Point2D.Double p2 = polygonVertices.get((i + 1) % polygonVertices.size()); // 循环到下一个顶点

        // 计算边与externalPoint的最近点
        Point2D.Double nearestOnEdge = findNearestPointOnLineSegment(p1, p2, externalPoint);

        // 计算距离
        double distance = distance(externalPoint, nearestOnEdge);

        // 更新最小距离和对应的点
        if (distance < minDistance) {
            minDistance = distance;
            closestPoint = nearestOnEdge;
        }
    }

    return closestPoint;
}

// 计算两点之间的距离
public static double distance(Point2D.Double p1, Point2D.Double p2) {
    return Math.sqrt(Math.pow(p2.x - p1.x, 2) + Math.pow(p2.y - p1.y, 2));
}

// 找到线段上与点P最近的点
public static Point2D.Double findNearestPointOnLineSegment(Point2D.Double p, Point2D.Double q, Point2D.Double r) {
    double l2 = distance(p, q) * distance(p, q);

    if (l2 == 0.0) return p;

    double t = ((r.x - p.x) * (q.x - p.x) + (r.y - p.y) * (q.y - p.y)) / l2;

    t = Math.max(0, Math.min(1, t));

    Point2D.Double projection = new Point2D.Double();
    projection.x = p.x + t * (q.x - p.x);
    projection.y = p.y + t * (q.y - p.y);

    return projection;
}


/**
 * 点 p（我们要找到它到线段 ab 的最近点的点），以及线段的两个端点 a 和 end。它首先计算点 p 到线段 ab 的垂足位置，然后根据这个位置是否在线段上来确定最近的点。如果垂足不在线段上，则最近的点将是线段的起点或终点，具体取决于哪个点距离 point 更近。
 * @param point
 * @return
 */
public static Point2D.Double perpendicularIntersection(Point2D.Double point, Point2D.Double lineStart, Point2D.Double lineEnd) {
    // 计算点到线段两个端点的向量
    double dx1 = lineEnd.x - lineStart.x;
    double dy1 = lineEnd.y - lineStart.y;
    double dx2 = point.x - lineStart.x;
    double dy2 = point.y - lineStart.y;

    // 计算点到线段垂直向量的点积
    double dotProduct = dx1 * dx2 + dy1 * dy2;

    // 如果点积为0，则点垂直于线段，即点在线段上或其延长线上
    if (dotProduct <= 0) {
        return lineStart; // 最近点就是线段的起点
    }

    // 计算线段长度
    double lineLengthSquared = dx1 * dx1 + dy1 * dy1;

    // 如果点积大于线段长度的平方，则点垂直于线段延长线，最近点是线段的终点
    if (dotProduct >= lineLengthSquared) {
        return lineEnd; // 最近点就是线段的终点
    }

    // 计算投影长度
    double projLength = dotProduct / lineLengthSquared;

    // 计算最近点的坐标
    double closestX = lineStart.x + dx1 * projLength;
    double closestY = lineStart.y + dy1 * projLength;

    // 返回最近点
    return new Point2D.Double(closestX,closestY);
}

public static TbRailPoint findClosestPointOnPolygonBoundary2(List polygonVertices, TbRailPoint point) {
    TbRailPoint rtn = new TbRailPoint();
    rtn.setLongitude(BigDecimal.ZERO);
    rtn.setLatitude(BigDecimal.ZERO);
    Point2D.Double externalPoint = new Point2D.Double(point.getLongitude().doubleValue(), point.getLatitude().doubleValue());
    if (CollUtil.isEmpty(polygonVertices) || polygonVertices.size()!=4){
        log.info("【3D围栏维护】边界异常 {} ", JSON.toJSONString(polygonVertices));
        return rtn;
    }
    // 界外的点，对每一条边界做垂线，找到最近的点
    Point2D.Double p1 = perpendicularIntersection(externalPoint, polygonVertices.get(0), polygonVertices.get(1));
    Point2D.Double p2 = perpendicularIntersection(externalPoint, polygonVertices.get(1), polygonVertices.get(2));
    Point2D.Double p3 = perpendicularIntersection(externalPoint, polygonVertices.get(2), polygonVertices.get(3));
    Point2D.Double p4 = perpendicularIntersection(externalPoint, polygonVertices.get(3), polygonVertices.get(0));
    ArrayList nearPts = CollUtil.newArrayList(p1, p2, p3, p4);
    nearPts.addAll(polygonVertices);
    double minDis = distance(externalPoint, p1);
    Point2D.Double nearest = p1;
    for (Point2D.Double nearPt : nearPts) {
        double distance = distance(externalPoint, p2);
        if (distance