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- import bearing from "@turf/bearing";
- import destination from "@turf/destination";
- import measureDistance from "@turf/distance";
- import { point } from "@turf/helpers";
- import { getGeom } from "@turf/invariant";
- /**
- * Takes a {@link LineString} and returns a {@link Point} at a specified distance along the line.
- *
- * @name along
- * @param {Feature<LineString>} line input line
- * @param {number} distance distance along the line
- * @param {Object} [options] Optional parameters
- * @param {string} [options.units="kilometers"] can be degrees, radians, miles, or kilometers
- * @returns {Feature<Point>} Point `distance` `units` along the line
- * @example
- * var line = turf.lineString([[-83, 30], [-84, 36], [-78, 41]]);
- * var options = {units: 'miles'};
- *
- * var along = turf.along(line, 200, options);
- *
- * //addToMap
- * var addToMap = [along, line]
- */
- export default function along(line, distance, options) {
- if (options === void 0) { options = {}; }
- // Get Coords
- var geom = getGeom(line);
- var coords = geom.coordinates;
- var travelled = 0;
- for (var i = 0; i < coords.length; i++) {
- if (distance >= travelled && i === coords.length - 1) {
- break;
- }
- else if (travelled >= distance) {
- var overshot = distance - travelled;
- if (!overshot) {
- return point(coords[i]);
- }
- else {
- var direction = bearing(coords[i], coords[i - 1]) - 180;
- var interpolated = destination(coords[i], overshot, direction, options);
- return interpolated;
- }
- }
- else {
- travelled += measureDistance(coords[i], coords[i + 1], options);
- }
- }
- return point(coords[coords.length - 1]);
- }
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