isOnSegmentGC static method

bool isOnSegmentGC(num lat1, num lng1, num lat2, num lng2, num lat3, num lng3, num havTolerance,)

Implementation

static bool isOnSegmentGC(num lat1, num lng1, num lat2, num lng2,
    num lat3, num lng3, num havTolerance) {
  num havDist13 = havDistance(lat1, lat3, lng1 - lng3);
  if (havDist13 <= havTolerance) {
    return true;
  }
  num havDist23 = havDistance(lat2, lat3, lng2 - lng3);
  if (havDist23 <= havTolerance) {
    return true;
  }
  double sinBearing = sinDeltaBearing(lat1, lng1, lat2, lng2, lat3, lng3);
  num sinDist13 = MathUtil.sinFromHav(havDist13);
  num havCrossTrack = MathUtil.havFromSin(sinDist13 * sinBearing);
  if (havCrossTrack > havTolerance) {
    return false;
  }
  num havDist12 = havDistance(lat1, lat2, lng1 - lng2);
  num term = havDist12 + havCrossTrack * (1 - 2 * havDist12);
  if (havDist13 > term || havDist23 > term) {
    return false;
  }
  if (havDist12 < 0.74) {
    return true;
  }
  num cosCrossTrack = 1 - 2 * havCrossTrack;
  double havAlongTrack13 = (havDist13 - havCrossTrack) / cosCrossTrack;
  double havAlongTrack23 = (havDist23 - havCrossTrack) / cosCrossTrack;
  num sinSumAlongTrack = MathUtil.sinSumFromHav(havAlongTrack13, havAlongTrack23);
  return sinSumAlongTrack > 0;  // Compare with half-circle == PI using sign of sin().
}