标签：多边形 Polygon geometry webgis coordinates return var turf LineString

完整代码类如下：

import * as turf from '@turf/turf'

/**
 * geoJson数据处理模块
 * (需要引入turf.js)
 * 输入输出数据均为标准geoJson格式
 */
const geoClipUtil = {
    /**
     * 合并多边形
     */
    unionPolygon: function (polygons) {
        var polygon = polygons[0];
        for (var i = 0; i < polygons.length; i++) {
            polygon = turf.union(polygon, polygons[i]);
        };
        return polygon;
    },

    /**
     * 线分割面
     * 面类型只能是polygon或是环
     * 线与多边形必须有两个交点
     */
    polygonClipByLine: function (polygon, clipLine) {
        if (polygon.geometry.type === 'Polygon') {
            var polyLine = turf.polygonToLine(polygon)
            if (polyLine.geometry.type === 'LineString') { // 切割普通多边形
                return this.singlePolygonClip(polyLine, clipLine);
            } else if (polyLine.geometry.type === 'MultiLineString') { //切割环
                return this.multiPolygonClip(polyLine, clipLine);
            }
        } else if (polygon.geometry.type === 'MultiPolygon') {
            // 若输入的多边形类型为Multipolygon则拆分成多个Polygon
            var polygons = this.multiPolygon2polygons(polygon)
            var clipPolygon = null;
            var clipPolygonIndex = -1
            // 获取MultiPolygon中与切割线相交的多边形（有且只能有一个多边形相交2个交点）
            polygons.forEach(function (polygon, index) {
                var polyLine = turf.polygonToLine(polygon)
                if (turf.lineIntersect(polyLine, clipLine).features.length === 2) {
                    if (!clipPolygon) {
                        clipPolygon = polygon
                        clipPolygonIndex = index
                    } else {
                        return { state: 'error', message: 'MultiPolygon只能有一个多边形与切割线存在交点' };
                    }
                }
            })
            if (clipPolygonIndex !== -1) {
                polygons.splice(clipPolygonIndex, 1)
                return turf.featureCollection(polygons.concat(this.polygonClipByLine(clipPolygon, clipLine).features));
            } else {
                return { state: 'error', message: 'MultiPolygon与切割线无交点' };
            }

        } else {
            return { state: 'error', message: '输入的多边形类型为错误' };
        }
    },


    /**
     * 线分割面
     * 切割普通多边形
    */
    singlePolygonClip: function (polyLine, clipLine) {
        // 获得裁切点
        var intersects = turf.lineIntersect(polyLine, clipLine);
        if (intersects.features.length !== 2) {
            return { state: 'error', message: '切割线与多边形交点应该为2个,当前交点个数为' + intersects.features.length };
        }
        // 检查切割线与多边形的位置关系 （切割线的起点和终点不能落在多边形内部）
        var clipLineLength = clipLine.geometry.coordinates.length;
        var clipLineStartPoint = turf.point(clipLine.geometry.coordinates[0])
        var clipLineEndPoint = turf.point(clipLine.geometry.coordinates[clipLineLength - 1])
        var polygon = turf.polygon([polyLine.geometry.coordinates])
        if (turf.booleanPointInPolygon(clipLineStartPoint, polygon) || turf.booleanPointInPolygon(clipLineEndPoint, polygon)) {
            return { state: 'error', message: '切割线起点或终点不能在 裁剪多边形内部' };
        }
        // 通过裁切点 分割多边形（只能获得多边形的一部分）
        var slicedPolyLine = turf.lineSlice(intersects.features[0], intersects.features[1], polyLine);
        // 裁剪线分割 保留多边形内部部分
        var slicedClipLine = turf.lineSlice(intersects.features[0], intersects.features[1], clipLine);
        // 重新拼接多边形 存在 对接的问题 所以先进行判断 如何对接裁剪的多边形和裁剪线
        var resultPolyline1 = this.connectLine(slicedPolyLine, slicedClipLine)
        resultPolyline1.properties.clipName = 'clip_01'
        // 闭合线 来构造多边形
        resultPolyline1.geometry.coordinates.push(resultPolyline1.geometry.coordinates[0])
        var resultPolygon1 = turf.lineToPolygon(resultPolyline1);
        // 构造切割的另一面多边形
        var firstPointOnLine = this.isOnLine(turf.point(polyLine.geometry.coordinates[0]), slicedPolyLine);
        var pointList = [];
        if (firstPointOnLine) {
            for (var i = 0; i < polyLine.geometry.coordinates.length; i++) {
                var coordinate = polyLine.geometry.coordinates[i];
                if (!this.isOnLine(turf.point(coordinate), slicedPolyLine)) {
                    pointList.push(coordinate)
                }
            };
        } else {
            var skipNum = 0; // 记录前面被跳过的点的个数
            var isStartPush = false;
            for (var i = 0; i < polyLine.geometry.coordinates.length; i++) {
                var coordinate = polyLine.geometry.coordinates[i];
                if (!this.isOnLine(turf.point(coordinate), slicedPolyLine)) {
                    if (isStartPush) {
                        pointList.push(coordinate)
                    } else {
                        skipNum++
                    }

                } else {
                    isStartPush = true;
                }
            };
            // 将前面跳过的点补充到 点数组中
            for (var i = 0; i < skipNum; i++) {
                pointList.push(polyLine.geometry.coordinates[i])
            }
        }
        var slicedPolyLine_2 = turf.lineString(pointList, slicedPolyLine.properties);
        var resultPolyline2 = this.connectLine(slicedPolyLine_2, slicedClipLine)
        resultPolyline2.properties.clipName = 'clip_02'
        // 闭合线 来构造多边形
        resultPolyline2.geometry.coordinates.push(resultPolyline2.geometry.coordinates[0])
        var resultPolygon2 = turf.lineToPolygon(resultPolyline2);
        // 返回面要素集
        return {
            features: turf.featureCollection([
                resultPolygon1,
                resultPolygon2
            ]), state: 'success'
        };

    },

    /**
     * 线分割面
     * 切割环
    */
    multiPolygonClip: function (polyLine, clipLine) {
        // 将环 多边形分割成 内部逆时针多边形+外部多边形
        var outPolyline, insidePolylineList = [];
        for (var i = 0; i < polyLine.geometry.coordinates.length; i++) {
            var splitPolyline = turf.lineString(polyLine.geometry.coordinates[i]);
            if (turf.booleanClockwise(splitPolyline)) {
                if (outPolyline) {
                    return { state: 'error', message: '出现了两个外部多边形无法处理' };
                } else {
                    outPolyline = splitPolyline
                }
            } else {
                var intersects = turf.lineIntersect(splitPolyline, clipLine);
                if (intersects.features.length > 0) {
                    return { state: 'error', message: '切割线不能与内环有交点' };
                }
                insidePolylineList.push(splitPolyline)
            }
        }
        var resultCollection = this.singlePolygonClip(outPolyline, clipLine)

        for (var i = 0; i < resultCollection.features.length; i++) {
            for (var j = 0; j < insidePolylineList.length; j++) {
                var startPoint = turf.point(insidePolylineList[j].geometry.coordinates[0]);
                if (turf.booleanPointInPolygon(startPoint, resultCollection.features[i])) {
                    resultCollection.features[i] = turf.mask(resultCollection.features[i], turf.lineToPolygon(insidePolylineList[j]));
                }
            }
        }
        return resultCollection
    },

    /**
     * 连接两条线
     * 方法会将两条线段最近的一段直接连接
     */
    connectLine: function (line1, line2) {
        var line2_length = line2.geometry.coordinates.length;
        var line1_startPoint = line1.geometry.coordinates[0]
        var line2_startPoint = line2.geometry.coordinates[0]
        var line2_endPoint = line2.geometry.coordinates[line2_length - 1]
        var pointList = [];
        // 获取line1 所有点坐标
        for (var i = 0; i < line1.geometry.coordinates.length; i++) {
            var coordinate = line1.geometry.coordinates[i];
            pointList.push(coordinate)
        };

        // 判断两条线的 起点是否接近，如果接近 逆转line2线 进行连接
        if (turf.distance(line1_startPoint, line2_startPoint) < turf.distance(line1_startPoint, line2_endPoint)) {
            line2.geometry.coordinates = line2.geometry.coordinates.reverse();
        }
        for (var i = 0; i < line2.geometry.coordinates.length; i++) {
            var coordinate = line2.geometry.coordinates[i];
            pointList.push(coordinate)
        };
        return turf.lineString(pointList, line1.properties);
    },

    /**
     * 判断点是否在线里面
     * 注：线组成的坐标对比
     */
    isOnLine: function (point, line) {
        for (var i = 0; i < line.geometry.coordinates.length; i++) {
            var coordinate = line.geometry.coordinates[i];
            if (point.geometry.coordinates[0] === coordinate[0] && point.geometry.coordinates[1] === coordinate[1]) {
                return true;
            }
        };
        return false;
    },

    /**
     * 获得两条线交点
     */
    getIntersectPoints: function (line1, line2) {
        return turf.lineIntersect(line1, line2);
    },

    /**
     * multiPolygon转polygons
     */
    multiPolygon2polygons: function (multiPolygon) {
        if (multiPolygon.geometry.type !== 'MultiPolygon') {
            return
        }
        var polygons = [];
        multiPolygon.geometry.coordinates.forEach((item) => {
            var polygon = {
                type: 'Feature',
                properties: {},
                geometry: {
                    type: 'Polygon',
                    coordinates: []
                }
            };
            polygon.geometry.coordinates = item;
            polygons.push(polygon)
        });
        return polygons;
    },

    /**
    * polygons转multiPolygon
    * 考虑polygons中就存在多面的情况
    */
    polygons2MultiPolygon: function (geoJson) {
        var newGeoJson = {
            type: "FeatureCollection",
            features: [{ geometry: { coordinates: [], type: "MultiPolygon" }, type: "Feature", properties: {} }]
        };
        geoJson.features.forEach((item) => {
            if (item.geometry.type === "Polygon") {
                newGeoJson.features[0].geometry.coordinates.push(item.geometry.coordinates);
            } else {
                item.geometry.coordinates.forEach((item) => {
                    newGeoJson.features[0].geometry.coordinates.push(item);
                })
            }
        })
        return newGeoJson;
    },
}

export default geoClipUtil

基于turf的相关api链接：GET START | Turf.js中文网

示例：多边形切割demo

标签：多边形,Polygon,geometry,webgis,coordinates,return,var,turf,LineString
来源： https://blog.csdn.net/u013869554/article/details/120516495

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