in packages/geofire-common/src/index.ts [288:307]
export function boundingBoxCoordinates(center: Geopoint, radius: number):
[Geopoint, Geopoint,Geopoint,Geopoint,Geopoint,Geopoint,Geopoint,Geopoint,Geopoint] {
const latDegrees = radius / METERS_PER_DEGREE_LATITUDE;
const latitudeNorth = Math.min(90, center[0] + latDegrees);
const latitudeSouth = Math.max(-90, center[0] - latDegrees);
const longDegsNorth = metersToLongitudeDegrees(radius, latitudeNorth);
const longDegsSouth = metersToLongitudeDegrees(radius, latitudeSouth);
const longDegs = Math.max(longDegsNorth, longDegsSouth);
return [
[center[0], center[1]],
[center[0], wrapLongitude(center[1] - longDegs)],
[center[0], wrapLongitude(center[1] + longDegs)],
[latitudeNorth, center[1]],
[latitudeNorth, wrapLongitude(center[1] - longDegs)],
[latitudeNorth, wrapLongitude(center[1] + longDegs)],
[latitudeSouth, center[1]],
[latitudeSouth, wrapLongitude(center[1] - longDegs)],
[latitudeSouth, wrapLongitude(center[1] + longDegs)]
];
}