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Documentation Index

Fetch the complete documentation index at: https://mintlify.com/V3RNE42/helios/llms.txt

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trigo.js contains the spherical mathematics that allow Helios to find the geographic position of the vehicle at any fraction of its journey. It is a pure module with no external dependencies.

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Exports

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getNewCoords(startCoords, endCoords, fraction)

Returns the interpolated geographic position at a given progress fraction along the great-circle path between two coordinates.
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startCoords
{ lat, lon }
required
Origin coordinates.
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endCoords
{ lat, lon }
required
Destination coordinates.
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fraction
number
required
Progress fraction between 0 (origin) and 1 (destination).
Returns { lat, lon } — the interpolated geographic position. Returns startCoords immediately if fraction === 0, and endCoords immediately if fraction === 1. Otherwise it delegates to getAngularDistance, getBearing, and getDestinationCoords for full great-circle interpolation. 
function getNewCoords(startCoords, endCoords, fraction) {
    if (fraction == 0) return startCoords;
    if (fraction == 1) return endCoords;
    const distance = getAngularDistance(startCoords, endCoords);
    const fractionDistance = fraction * distance;
    const bearing = getBearing(startCoords, endCoords);
    const newCoords = getDestinationCoords(startCoords, fractionDistance, bearing);
    return newCoords;
}

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getAngularDistance(startCoords, endCoords)

Returns the great-circle distance between two geographic coordinates in kilometres.
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startCoords
{ lat, lon }
required
Origin coordinates.
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endCoords
{ lat, lon }
required
Destination coordinates.
Returns number — distance in kilometres, computed using the haversine formula with Earth radius 6371 km.

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getAbsoluteDiff(num1, num2)

Returns the absolute difference between two numbers.
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num1
number
required
First number.
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num2
number
required
Second number.
Returns number — |num1 - num2|. Used by computeRouteSections in routeSolar.js to measure the convergence error (diff) of the iterative solar event search: once diff falls below MAX_DIFF (2500 ms), the inner loop exits.

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Internal helpers

These functions are not exported and are used only within trigo.js:
HelperPurpose
getBearing(startCoords, endCoords)Computes the initial compass bearing (in radians, normalised to 0–2π) between two coordinates using the forward azimuth formula.
getDestinationCoords(startCoords, distance, bearing)Calculates the destination point given an origin, a distance in kilometres, and a bearing, using the spherical law of cosines with Earth radius 6371 km.
toRadians(degrees)Converts decimal degrees to radians (degrees × π / 180).
toDegrees(radians)Converts radians to decimal degrees (radians × 180 / π).

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