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fix: respect an explicit zero observer/timestamp in getSatelliteInfo #61

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fix: respect an explicit zero observer/timestamp in getSatelliteInfo #61

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14 changes: 14 additions & 0 deletions __tests__/sgp4.js
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Original file line number Diff line number Diff line change
Expand Up @@ -473,3 +473,17 @@ describe('getVisibleSatellites', () => {
expect(allVisible.length).toEqual(1);
});
});

describe('getSatelliteInfo observer defaults', () => {
test('respects an explicit observer at (0, 0, 0)', () => {
// A falsy check (`observerLat || default`) previously replaced an
// explicit 0 (equator / prime meridian / sea level) with the default
// observer, so an explicit origin observer must match a near-origin one.
const timestamp = 1501039265000;
const atOrigin = getSatelliteInfo(tleStr, timestamp, 0, 0, 0);
const nearOrigin = getSatelliteInfo(tleStr, timestamp, 1e-7, 1e-7, 1e-7);
expect(atOrigin.azimuth).toBeCloseTo(nearOrigin.azimuth, 4);
expect(atOrigin.elevation).toBeCloseTo(nearOrigin.elevation, 4);
expect(atOrigin.range).toBeCloseTo(nearOrigin.range, 2);
});
});
8 changes: 4 additions & 4 deletions src/sgp4.js
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Expand Up @@ -84,7 +84,7 @@ export function clearCache() {
* TODO: return error instead of throwing?
*/
export function getSatelliteInfo(rawTLE, rawTimestamp, observerLat, observerLng, observerHeight) {
const timestamp = rawTimestamp || Date.now();
const timestamp = rawTimestamp ?? Date.now();

const { tle, error: parseError } = parseTLE(rawTLE);

Expand All @@ -98,9 +98,9 @@ export function getSatelliteInfo(rawTLE, rawTimestamp, observerLat, observerLng,
height: 0.37,
};

const obsLat = observerLat || defaultObserverPosition.lat;
const obsLng = observerLng || defaultObserverPosition.lng;
const obsHeight = observerHeight || defaultObserverPosition.height;
const obsLat = observerLat ?? defaultObserverPosition.lat;
const obsLng = observerLng ?? defaultObserverPosition.lng;
const obsHeight = observerHeight ?? defaultObserverPosition.height;

// Memoization
const cacheKey = `${tle[0]}-${timestamp}-${observerLat}-${observerLng}
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