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Compares two points' latitude and longitude and returns true if within provided metres
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| const {asin, cos, sin, sqrt, PI} = Math | |
| const EARTH_RADIUS_KM = 6371 | |
| const METERS_IN_KM = 1000 | |
| // const deg2rad = n => Math.tan(n * (Math.PI / 180)) | |
| const convertDegToRad = degries => degries * (PI / 180) | |
| /** | |
| * is One Point within Another | |
| * @param point {Object} {latitude: Number, longitude: Number} | |
| * @param interest {Object} {latitude: Number, longitude: Number} | |
| * @param kms {Number} | |
| * @returns {boolean} | |
| */ | |
| function isWithinRadius( | |
| { latitude, longitude }, | |
| { referenceLatitude, referenceLongitude }, | |
| radiusMetres | |
| ) { | |
| const virtualApexLatitude = convertDegToRad(referenceLatitude - latitude) | |
| const virtualApexLongitude = convertDegToRad(referenceLongitude - longitude) | |
| // TODO Work out a meaningul name for a and c... | |
| const a = | |
| sin(virtualApexLatitude / 2) * sin(virtualApexLatitude / 2) + | |
| cos(convertDegToRad(latitude)) * | |
| cos(convertDegToRad(referenceLatitude)) * | |
| sin(virtualApexLongitude / 2) * | |
| sin(virtualApexLongitude / 2) | |
| const c = 2 * Math.asin(sqrt(a)) | |
| const distance = EARTH_RADIUS_KM * c | |
| return distance <= radiusMetres * METERS_IN_KM | |
| } |
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