Polygon计算每一个角的角度

Polygon计算每一个角的角度

主要算法

• Polygon 拆解 (孔型)
• 两条线段之间求角度值

测试数据

• 面数据

POLYGON ((350 100, 450 450, 150 400, 100 200, 350 100), (200 300, 350 350, 300 200, 200 300))

流程注解

• JTS org.locationtech.jts.geom.Geometry 类

 Coordinate[] coordinates = geometry.getCoordinates();

获取的结果为

[(350.0, 100.0, NaN), (450.0, 450.0, NaN), (150.0, 400.0, NaN), (100.0, 200.0, NaN), (350.0, 100.0, NaN)]

顺序为 节点0 , 节点1 , 节点2 , 节点3 , 节点0 最终回到 节点0

那么每一个角的角度构造的直线为

• 0,1 - 1,2
• 1,2 - 2,3
• 2,3 - 3,4
• 4/0,3 - 4/0,1

根据以上的直线计算流程即可获得每个角度

代码实现

• 数据结果

package com.huifer.planar.aset.entity;

import com.huifer.planar.aset.algo.impl.PolygonAngleCore.PointF;
import java.util.HashMap;
import java.util.List;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.locationtech.jts.geom.Polygon;

/**
 * 
Title : PolygonAngleResult 
 * 
Description : polygon 角度计算结果
 *
 * @author huifer
 * @date 2019-01-28
 */
@Data
@NoArgsConstructor
@AllArgsConstructor
public class PolygonAngleResult {

    private List<HashMap<PointF, Double>> polygonAngles;
    private Polygon polygon;
}

• 主要实现流程

package com.huifer.planar.aset.algo.impl;

import com.huifer.planar.aset.algo.PolygonAngleInterface;
import com.huifer.planar.aset.entity.PolygonAngleResult;
import com.huifer.planar.aset.utils.shptools.overlay.Operation;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import lombok.Data;
import lombok.EqualsAndHashCode;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.GeometryFactory;
import org.locationtech.jts.geom.LineString;
import org.locationtech.jts.geom.Polygon;
import org.locationtech.jts.io.ParseException;

/**
 * 
Title : PolygonAngleCore 
 * 
Description : polygon 计算角度 
 *
 * @author huifer
 * @date 2019-01-28
 */
public class PolygonAngleCore implements PolygonAngleInterface {

    /**
     * 计算夹角
     *
     * @param o 基准点 两条直线共有点
     * @param s 起点
     * @param e 终点
     * @return 角度
     */
    public static double angle(PointF o, PointF s,
            PointF e) {
        double cosfi = 0, fi = 0, norm = 0;
        double dsx = s.x - o.x;
        double dsy = s.y - o.y;
        double dex = e.x - o.x;
        double dey = e.y - o.y;

        cosfi = dsx * dex + dsy * dey;
        norm = (dsx * dsx + dsy * dsy) * (dex * dex + dey * dey);
        cosfi /= Math.sqrt(norm);

        if (cosfi >= 1.0) {
            return 0;
        }
        if (cosfi <= -1.0) {
            return Math.PI;
        }
        fi = Math.acos(cosfi);
        if (180 * fi / Math.PI < 180) {
            return 180 * fi / Math.PI;
        } else {
            return 360 - 180 * fi / Math.PI;
        }
    }

    /**
     * 节点 1，2 | 2，3  节点 2，3 | 3，4  节点 4，1 | 1,2 计算角度
     *
     * @param coordinates 节点坐标值
     * @return 角度列表
     */
    private static HashMap<PointF, Double> calcAngle(Coordinate[] coordinates) {
        List<Double> angles = new ArrayList<>();
        HashMap<PointF, Double> rs = new HashMap<>();
        for (int i = 0; i < coordinates.length; i++) {
            if (i + 2 < coordinates.length) {
                // 基准点
                PointF o = new PointF(coordinates[i + 1].x, coordinates[i + 1].y);
                // 起点
                PointF s = new PointF(coordinates[i].x, coordinates[i].y);
                // 终点
                PointF e = new PointF(coordinates[i + 2].x, coordinates[i + 2].y);
                double angle = angle(o, s, e);
                angles.add(angle);
                rs.put(o, angle);
            }
            if (i == coordinates.length - 1) {
                PointF o = new PointF(coordinates[0].x, coordinates[0].y);
                PointF s = new PointF(coordinates[coordinates.length - 2].x,
                        coordinates[coordinates.length - 2].y);
                PointF e = new PointF(coordinates[1].x, coordinates[1].y);
                double angle = angle(o, s, e);
                angles.add(angle);
                rs.put(o, angle);
            }
        }
        return rs;
    }

    /**
     * polygon计算角度核心
     *
     * @param wkt polygonWKT描述
     * @return {@link PolygonAngleResult}
     * @throws ParseException wkt格式化异常
     */
    private static PolygonAngleResult polygonWktAngleCore(String wkt)
            throws ParseException {
        Operation op = new Operation();
        GeometryFactory gFactory = new GeometryFactory();
        Polygon polygon = op.createPolygonByWKT(wkt);
        List<HashMap<PointF, Double>> polygonAngles = new ArrayList<>();
        List<LineString> ls = new ArrayList<>();
        PolygonAngleResult polygonAngleResult = new PolygonAngleResult();
        Geometry geometry = null;
        // 是否有环形
        if (polygon.getNumInteriorRing() == 0) {
            LineString exteriorRing = polygon.getExteriorRing();
            geometry = gFactory.createMultiLineString(new LineString[]{exteriorRing});
            Coordinate[] coordinates = geometry.getCoordinates();
            HashMap<PointF, Double> doubles = calcAngle(coordinates);
            polygonAngles.add(doubles);
            polygonAngleResult.setPolygon(polygon);
            polygonAngleResult.setPolygonAngles(polygonAngles);

        } else {
            geometry = polygon.getBoundary();
            // geometry 数量
            int dimension = geometry.getDimension();

            for (int i = 0; i <= dimension; i++) {
                Geometry line = geometry.getGeometryN(i);
                ls.add((LineString) line);
                Coordinate[] coordinates = line.getCoordinates();
                HashMap<PointF, Double> doubles = calcAngle(coordinates);
                polygonAngles.add(doubles);
            }

            polygonAngleResult.setPolygon(polygon);
            polygonAngleResult.setPolygonAngles(polygonAngles);
        }

        return polygonAngleResult;
    }


    @Override
    public PolygonAngleResult polygonWktAngle(String wkt) throws ParseException {
        PolygonAngleResult polygonAngleResult = polygonWktAngleCore(wkt);
        return polygonAngleResult;
    }

    /**
     * 计算两条直线之间夹角的点类
     */
    @EqualsAndHashCode
    @Data
    public static class PointF {

        double x;
        double y;

        public PointF() {
        }

        public PointF(double x, double y) {
            this.x = x;
            this.y = y;
        }

        @Override
        public String toString() {
            final StringBuilder sb = new StringBuilder("{");
            sb.append("\"x\":")
                    .append(x);
            sb.append(",\"y\":")
                    .append(y);
            sb.append('}');
            return sb.toString();
        }

    }
}

• 可视化

package com.huifer.planar.aset.view;

import com.huifer.planar.aset.algo.PolygonAngleInterface;
import com.huifer.planar.aset.algo.impl.PolygonAngleCore;
import com.huifer.planar.aset.algo.impl.PolygonAngleCore.PointF;
import com.huifer.planar.aset.entity.PolygonAngleResult;
import com.huifer.planar.aset.view.base.BaseFrame;
import com.huifer.planar.aset.view.base.FrameContext;
import com.huifer.planar.aset.view.base.ViewHelper;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.util.HashMap;
import java.util.List;
import org.locationtech.jts.awt.ShapeWriter;
import org.locationtech.jts.geom.Polygon;
import org.locationtech.jts.io.ParseException;

/**
 * 
Title : PolygonAngleView 
 * 
Description :PolygonAngleView 
 *
 * @author huifer
 * @date 2019-01-28
 */
public class PolygonAngleView extends FrameContext {

    public static void main(String[] args) {
        PolygonAngleView polygonAngleView = new PolygonAngleView();
        BaseFrame frame = new BaseFrame(polygonAngleView);
        frame.run();
    }

    @Override
    public void drawing(Graphics g) throws ParseException {
//        String wkt = "POLYGON ((350 100, 450 450, 150 400, 100 200, 350 100), (200 300, 350 350, 300 200, 200 300))";
        String wkt = "POLYGON ((350 100, 450 450, 150 400, 100 200, 350 100))";

        ShapeWriter sw = new ShapeWriter();
        PolygonAngleInterface polygonAngleInterface = new PolygonAngleCore();
        PolygonAngleResult polygonAngleResult = polygonAngleInterface.polygonWktAngle(wkt);
        Graphics2D g2d = (Graphics2D) g;
        Polygon polygon = polygonAngleResult.getPolygon();
        List<HashMap<PointF, Double>> polygonAngles = polygonAngleResult.getPolygonAngles();

        // 绘图流程
        ViewHelper.setStrokeWidth(g2d, 2);
        ViewHelper.setColor(g2d, ViewHelper.BLUE);
        Shape polyShape = sw.toShape(polygon);
        g2d.draw(polyShape);

        ViewHelper.setColor(g2d, ViewHelper.GREEN);
        for (HashMap<PointF, Double> angle : polygonAngles) {
            angle.forEach(
                    (k, v) -> {
                        ViewHelper.drawText(g2d, v.toString(), (int) k.getX(), (int) k.getY());
                    }
            );
        }
    }

    @Override
    public void paintComponent(Graphics g) {
        try {
            drawing(g);
        } catch (ParseException e) {
            e.printStackTrace();
        }
    }
}

AWT 中左上角为原点(0,0) 所以旋转

源码

本文代码及可视化代码均放在 gitee 码云上 欢迎star & fork