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- // index.js
- import { flattenEach } from "@turf/meta";
- import { getCoords, getType } from "@turf/invariant";
- import {
- isObject,
- lineString,
- multiLineString,
- lengthToDegrees
- } from "@turf/helpers";
- // lib/intersection.js
- function ab(segment) {
- var start = segment[0];
- var end = segment[1];
- return [end[0] - start[0], end[1] - start[1]];
- }
- function crossProduct(v1, v2) {
- return v1[0] * v2[1] - v2[0] * v1[1];
- }
- function add(v1, v2) {
- return [v1[0] + v2[0], v1[1] + v2[1]];
- }
- function sub(v1, v2) {
- return [v1[0] - v2[0], v1[1] - v2[1]];
- }
- function scalarMult(s, v) {
- return [s * v[0], s * v[1]];
- }
- function intersectSegments(a, b) {
- var p = a[0];
- var r = ab(a);
- var q = b[0];
- var s = ab(b);
- var cross = crossProduct(r, s);
- var qmp = sub(q, p);
- var numerator = crossProduct(qmp, s);
- var t = numerator / cross;
- var intersection2 = add(p, scalarMult(t, r));
- return intersection2;
- }
- function isParallel(a, b) {
- var r = ab(a);
- var s = ab(b);
- return crossProduct(r, s) === 0;
- }
- function intersection(a, b) {
- if (isParallel(a, b)) return false;
- return intersectSegments(a, b);
- }
- // index.js
- function lineOffset(geojson, distance, options) {
- options = options || {};
- if (!isObject(options)) throw new Error("options is invalid");
- var units = options.units;
- if (!geojson) throw new Error("geojson is required");
- if (distance === void 0 || distance === null || isNaN(distance))
- throw new Error("distance is required");
- var type = getType(geojson);
- var properties = geojson.properties;
- switch (type) {
- case "LineString":
- return lineOffsetFeature(geojson, distance, units);
- case "MultiLineString":
- var coords = [];
- flattenEach(geojson, function(feature) {
- coords.push(
- lineOffsetFeature(feature, distance, units).geometry.coordinates
- );
- });
- return multiLineString(coords, properties);
- default:
- throw new Error("geometry " + type + " is not supported");
- }
- }
- function lineOffsetFeature(line, distance, units) {
- var segments = [];
- var offsetDegrees = lengthToDegrees(distance, units);
- var coords = getCoords(line);
- var finalCoords = [];
- coords.forEach(function(currentCoords, index) {
- if (index !== coords.length - 1) {
- var segment = processSegment(
- currentCoords,
- coords[index + 1],
- offsetDegrees
- );
- segments.push(segment);
- if (index > 0) {
- var seg2Coords = segments[index - 1];
- var intersects = intersection(segment, seg2Coords);
- if (intersects !== false) {
- seg2Coords[1] = intersects;
- segment[0] = intersects;
- }
- finalCoords.push(seg2Coords[0]);
- if (index === coords.length - 2) {
- finalCoords.push(segment[0]);
- finalCoords.push(segment[1]);
- }
- }
- if (coords.length === 2) {
- finalCoords.push(segment[0]);
- finalCoords.push(segment[1]);
- }
- }
- });
- return lineString(finalCoords, line.properties);
- }
- function processSegment(point1, point2, offset) {
- var L = Math.sqrt(
- (point1[0] - point2[0]) * (point1[0] - point2[0]) + (point1[1] - point2[1]) * (point1[1] - point2[1])
- );
- var out1x = point1[0] + offset * (point2[1] - point1[1]) / L;
- var out2x = point2[0] + offset * (point2[1] - point1[1]) / L;
- var out1y = point1[1] + offset * (point1[0] - point2[0]) / L;
- var out2y = point2[1] + offset * (point1[0] - point2[0]) / L;
- return [
- [out1x, out1y],
- [out2x, out2y]
- ];
- }
- var turf_line_offset_default = lineOffset;
- export {
- turf_line_offset_default as default,
- lineOffset
- };
- //# sourceMappingURL=index.js.map
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