103 lines
3.8 KiB
JavaScript
Executable File
103 lines
3.8 KiB
JavaScript
Executable File
import { getCoord, getCoords } from "@turf/invariant";
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/**
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* Returns true if a point is on a line. Accepts a optional parameter to ignore the
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* start and end vertices of the linestring.
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*
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* @name booleanPointOnLine
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* @param {Coord} pt GeoJSON Point
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* @param {Feature<LineString>} line GeoJSON LineString
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* @param {Object} [options={}] Optional parameters
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* @param {boolean} [options.ignoreEndVertices=false] whether to ignore the start and end vertices.
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* @param {number} [options.epsilon] Fractional number to compare with the cross product result. Useful for dealing with floating points such as lng/lat points
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* @returns {boolean} true/false
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* @example
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* var pt = turf.point([0, 0]);
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* var line = turf.lineString([[-1, -1],[1, 1],[1.5, 2.2]]);
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* var isPointOnLine = turf.booleanPointOnLine(pt, line);
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* //=true
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*/
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function booleanPointOnLine(pt, line, options) {
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if (options === void 0) { options = {}; }
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// Normalize inputs
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var ptCoords = getCoord(pt);
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var lineCoords = getCoords(line);
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// Main
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for (var i = 0; i < lineCoords.length - 1; i++) {
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var ignoreBoundary = false;
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if (options.ignoreEndVertices) {
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if (i === 0) {
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ignoreBoundary = "start";
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}
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if (i === lineCoords.length - 2) {
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ignoreBoundary = "end";
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}
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if (i === 0 && i + 1 === lineCoords.length - 1) {
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ignoreBoundary = "both";
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}
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}
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if (isPointOnLineSegment(lineCoords[i], lineCoords[i + 1], ptCoords, ignoreBoundary, typeof options.epsilon === "undefined" ? null : options.epsilon)) {
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return true;
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}
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}
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return false;
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}
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// See http://stackoverflow.com/a/4833823/1979085
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// See https://stackoverflow.com/a/328122/1048847
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/**
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* @private
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* @param {Position} lineSegmentStart coord pair of start of line
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* @param {Position} lineSegmentEnd coord pair of end of line
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* @param {Position} pt coord pair of point to check
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* @param {boolean|string} excludeBoundary whether the point is allowed to fall on the line ends.
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* @param {number} epsilon Fractional number to compare with the cross product result. Useful for dealing with floating points such as lng/lat points
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* If true which end to ignore.
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* @returns {boolean} true/false
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*/
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function isPointOnLineSegment(lineSegmentStart, lineSegmentEnd, pt, excludeBoundary, epsilon) {
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var x = pt[0];
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var y = pt[1];
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var x1 = lineSegmentStart[0];
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var y1 = lineSegmentStart[1];
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var x2 = lineSegmentEnd[0];
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var y2 = lineSegmentEnd[1];
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var dxc = pt[0] - x1;
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var dyc = pt[1] - y1;
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var dxl = x2 - x1;
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var dyl = y2 - y1;
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var cross = dxc * dyl - dyc * dxl;
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if (epsilon !== null) {
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if (Math.abs(cross) > epsilon) {
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return false;
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}
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}
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else if (cross !== 0) {
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return false;
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}
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if (!excludeBoundary) {
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if (Math.abs(dxl) >= Math.abs(dyl)) {
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return dxl > 0 ? x1 <= x && x <= x2 : x2 <= x && x <= x1;
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}
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return dyl > 0 ? y1 <= y && y <= y2 : y2 <= y && y <= y1;
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}
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else if (excludeBoundary === "start") {
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if (Math.abs(dxl) >= Math.abs(dyl)) {
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return dxl > 0 ? x1 < x && x <= x2 : x2 <= x && x < x1;
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}
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return dyl > 0 ? y1 < y && y <= y2 : y2 <= y && y < y1;
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}
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else if (excludeBoundary === "end") {
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if (Math.abs(dxl) >= Math.abs(dyl)) {
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return dxl > 0 ? x1 <= x && x < x2 : x2 < x && x <= x1;
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}
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return dyl > 0 ? y1 <= y && y < y2 : y2 < y && y <= y1;
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}
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else if (excludeBoundary === "both") {
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if (Math.abs(dxl) >= Math.abs(dyl)) {
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return dxl > 0 ? x1 < x && x < x2 : x2 < x && x < x1;
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}
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return dyl > 0 ? y1 < y && y < y2 : y2 < y && y < y1;
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}
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return false;
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}
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export default booleanPointOnLine;
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