51 lines
1.9 KiB
JavaScript
Executable File
51 lines
1.9 KiB
JavaScript
Executable File
import bearing from "@turf/bearing";
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import { bearingToAzimuth, isObject } from "@turf/helpers";
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import rhumbBearing from "@turf/rhumb-bearing";
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/**
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* Finds the angle formed by two adjacent segments defined by 3 points. The result will be the (positive clockwise)
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* angle with origin on the `startPoint-midPoint` segment, or its explementary angle if required.
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*
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* @name angle
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* @param {Coord} startPoint Start Point Coordinates
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* @param {Coord} midPoint Mid Point Coordinates
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* @param {Coord} endPoint End Point Coordinates
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* @param {Object} [options={}] Optional parameters
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* @param {boolean} [options.explementary=false] Returns the explementary angle instead (360 - angle)
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* @param {boolean} [options.mercator=false] if calculations should be performed over Mercator or WGS84 projection
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* @returns {number} Angle between the provided points, or its explementary.
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* @example
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* turf.angle([5, 5], [5, 6], [3, 4]);
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* //=45
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*/
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function angle(startPoint, midPoint, endPoint, options) {
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if (options === void 0) { options = {}; }
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// Optional Parameters
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if (!isObject(options)) {
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throw new Error("options is invalid");
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}
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// Validation
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if (!startPoint) {
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throw new Error("startPoint is required");
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}
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if (!midPoint) {
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throw new Error("midPoint is required");
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}
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if (!endPoint) {
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throw new Error("endPoint is required");
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}
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// Rename to shorter variables
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var A = startPoint;
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var O = midPoint;
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var B = endPoint;
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// Main
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var azimuthAO = bearingToAzimuth(options.mercator !== true ? bearing(A, O) : rhumbBearing(A, O));
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var azimuthBO = bearingToAzimuth(options.mercator !== true ? bearing(B, O) : rhumbBearing(B, O));
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var angleAO = Math.abs(azimuthAO - azimuthBO);
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// Explementary angle
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if (options.explementary === true) {
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return 360 - angleAO;
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}
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return angleAO;
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}
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export default angle;
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