计算点到多线段最短间距的点(nearestPointOnLine)

> npm install @turf/nearest-point-on-line

Takes a Point and a LineString and calculates the closest Point on the (Multi)LineString. 获取一个点(Point)和一个线(LineString)，计算并返回该点在改线上最近的点要素。

参数

参数	类型	描述
lines	Geometry | Feature<LineString | MultiLineString>	参照物的线要素
pt	Geometry | Feature<Point>	需计算的点要素
options	Object	可配置项

options 选项

属性	类型	默认值	描述
units	string	kilometers	单位，可选的有 degrees、radians、miles、kilometers

返回

Feature <Point> - closest point on the line to point. The properties object will contain three values: index : closest point was found on nth line part, dist : distance between pt and the closest point, location : distance along the line between start and the closest point.

Feature <Point> - 距离线段最近的点. properties 对象将包含三个值：index：在第 n 行部分找到最近的点，dist：pt 和最近点之间的距离，location：起点和最近点沿着直线的距离

示例

var line = turf.lineString([
  [-77.031669, 38.878605],
  [-77.029609, 38.881946],
  [-77.020339, 38.884084],
  [-77.025661, 38.885821],
  [-77.021884, 38.889563],
  [-77.019824, 38.892368],
]);
var pt = turf.point([-77.037076, 38.884017]);

var snapped = turf.nearestPointOnLine(line, pt, { units: "miles" }); // [-77.02996941477018, 38.881361463229524]的点要素

基础用法

打开 线几何： 点几何： 单位(units)：

<template>
  <base-map>
    <a-button
      type="primary"
      @click="
        () => {
          visible = true;
        }
      "
      >打开</a-button
    >
    <drawer :visible.sync="visible" :code="code">
      <a-row
        ><a-space
          >线几何：<geojson-obj :value.sync="turfObj1"></geojson-obj
        ></a-space>
      </a-row>
      <a-row
        ><a-space
          >点几何：<geojson-obj :value.sync="turfObj2"></geojson-obj
        ></a-space>
      </a-row>
      <a-row
        >单位(units)：<length-units :value.sync="units"></length-units
      ></a-row>

      <a-row> <json :data="result"></json> </a-row>
    </drawer>

    <vue2ol-layer-vector key="1">
      <vue2ol-source-vector :features="features1"> </vue2ol-source-vector>
    </vue2ol-layer-vector>
    <vue2ol-layer-vector :style-obj="styleRed" key="2">
      <vue2ol-source-vector :features="features"> </vue2ol-source-vector>
    </vue2ol-layer-vector>
  </base-map>
</template>
<script>
import * as turf from "@turf/turf";
import { getFeaturesFromTurf, styleRed } from "../../utils/index.js";
export default {
  data() {
    return {
      features: [],
      result: null,
      visible: true,
      styleRed,
      turfObj1: turf.lineString([
        [119.7307062149048, 28.1473069190979],
        [119.68401432037355, 27.9880051612854],
        [119.94219303131105, 27.934446811676025],
        [120.1646661758423, 27.948179721832275],
        [120.13033390045167, 28.10610818862915],
      ]),
      turfObj2: turf.point([119.98401432037355, 27.9880051612854]),
      units: "kilometers",
    };
  },
  computed: {
    code() {
      return `let result = turf.nearestPointOnLine(${JSON.stringify(
        this.turfObj1
      )},${JSON.stringify(this.turfObj2)},
{
  units:'${this.units}'
});`;
    },
    features1() {
      return getFeaturesFromTurf(this.turfObj1).concat(
        getFeaturesFromTurf(this.turfObj2)
      );
    },
  },
  watch: {
    turfObj1() {
      this.init();
    },
    turfObj2() {
      this.init();
    },
    units() {
      this.init();
    },
  },
  methods: {
    init() {
      if (!this.turfObj1 || !this.turfObj2) {
        return;
      }
      try {
        this.features = [];
        this.result = null;
        this.result = turf.nearestPointOnLine(this.turfObj1, this.turfObj2, {
          units: this.units,
        });

        this.features = getFeaturesFromTurf(this.result);
      } catch (e) {
        this.result = {
          error: e.toString(),
        };
      }
    },
  },
};
</script>

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动态绘制

打开 线几何: 点几何:

<template>
  <base-map>
    <a-button
      type="primary"
      @click="
        () => {                                                 
          visible = true;
        }
      "
      >打开</a-button
    >
    <drawer :visible.sync="visible" :code="code">
      <a-row>
        线几何:<draw :type.sync="type1" @draw-end="handleDrawEnd1"></draw>
      </a-row>
      <a-row>
        点几何:<draw :type.sync="type2" @draw-end="handleDrawEnd2"></draw>
      </a-row>
      <a-row> <json :data="result"></json> </a-row>
    </drawer>
    <vue2ol-layer-vector :style-obj="styleRed" key="2">
      <vue2ol-source-vector :features="features"> </vue2ol-source-vector>
    </vue2ol-layer-vector>
  </base-map>
</template>
<script>
import * as turf from "@turf/turf";
import { GeoJSON } from "ol/format";
import { getFeaturesFromTurf, styleRed } from "../../utils/index.js";
export default {
  data() {
    return {
      type1: "",
      type2: "",
      features: [],
      feature1: null,
      feature2: null,

      result: null,
      visible: true,
      styleRed,
    };
  },
  mounted() {},
  watch: {
    feature1() {
      this.init();
    },
    feature2() {
      this.init();
    },
    type1() {
      if (this.type1) {
        this.type2 = "";
      }
    },
    type2() {
      if (this.type2) {
        this.type1 = "";
      }
    },
  },
  computed: {
    code() {
      if (!this.turfObj1 || !this.turfObj2) {
        return;
      }
      return `let result = turf.nearestPointOnLine(${JSON.stringify(
        this.turfObj1
      )},${JSON.stringify(this.turfObj2)},
{
  units:'${this.units}'
});`;
    },
    turfObj1() {
      if (this.feature1) {
        return JSON.parse(new GeoJSON().writeFeature(this.feature1));
      }
    },
    turfObj2() {
      if (this.feature2) {
        return JSON.parse(new GeoJSON().writeFeature(this.feature2));
      }
    },
  },
  methods: {
    handleDrawEnd1(feature) {
      this.feature1 = feature;
    },
    handleDrawEnd2(feature) {
      this.feature2 = feature;
    },
    init() {
      if (!this.turfObj1 || !this.turfObj2) {
        return;
      }

      try {
        this.features = [];
        this.result = null;
        this.result = turf.nearestPointOnLine(this.turfObj1, this.turfObj2, {
          units: this.units,
        });

        this.features = getFeaturesFromTurf(this.result);
      } catch (e) {
        this.result = {
          error: e.toString(),
        };
      }
    },
  },
};
</script>

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