intersectionOfTwoGeoPointsByPaths static method

LatLng? intersectionOfTwoGeoPointsByPaths(LatLng l1, LatLng l2, num b1, num b2,)

Calculate the geo point of intersection of two given paths

Implementation

static LatLng? intersectionOfTwoGeoPointsByPaths(
    LatLng l1, LatLng l2, num b1, num b2) {
  final num l1LatRadians = degToRadian(l1.latitude);
  final num l1LngRadians = degToRadian(l1.longitude);
  final num l2LatRadians = degToRadian(l2.latitude);
  final num l2LngRadians = degToRadian(l2.longitude);
  final num b1Radians = degToRadian(b1 as double);
  final num b2Radians = degToRadian(b2 as double);

  final latRadiansDiff = l2LatRadians - l1LatRadians;
  final lngRadiansDiff = l2LngRadians - l1LngRadians;

  final num angularDistance = 2 *
      asin(sqrt(sin(latRadiansDiff / 2) * sin(latRadiansDiff / 2) +
          cos(l1LatRadians) *
              cos(l2LatRadians) *
              sin(lngRadiansDiff / 2) *
              sin(lngRadiansDiff / 2)));

  if (angularDistance == 0) return null;

  num initBearingX = acos(
      (sin(l2LatRadians) - sin(l1LatRadians) * cos(angularDistance)) /
          (sin(angularDistance) * cos(l1LatRadians)));
  if (initBearingX.isNaN) initBearingX = 0;

  num initBearingY = acos(
      (sin(l1LatRadians) - sin(l2LatRadians) * cos(angularDistance)) /
          (sin(angularDistance) * cos(l2LatRadians)));

  final finalBearingX = sin(l2LngRadians - l1LngRadians) > 0
      ? initBearingX
      : 2 * pi - initBearingX;
  final finalBearingY = sin(l2LngRadians - l1LngRadians) > 0
      ? 2 * pi - initBearingY
      : initBearingY;

  final angle1 = b1Radians - finalBearingX;
  final angle2 = finalBearingY - b2Radians;

  if (sin(angle1) == 0 && sin(angle2) == 0) return null;
  if (sin(angle1) * sin(angle2) < 0) return null;

  final num angle3 = acos(-cos(angle1) * cos(angle2) +
      sin(angle1) * sin(angle2) * cos(angularDistance));
  final num dst13 = atan2(sin(angularDistance) * sin(angle1) * sin(angle2),
      cos(angle2) + cos(angle1) * cos(angle3));

  final num lat3 = asin(sin(l1LatRadians) * cos(dst13) +
      cos(l1LatRadians) * sin(dst13) * cos(b1Radians));

  final num lngRadiansDiff13 = atan2(
      sin(b1Radians) * sin(dst13) * cos(l1LatRadians),
      cos(dst13) - sin(l1LatRadians) * sin(lat3));

  final l3LngRadians = l1LngRadians + lngRadiansDiff13;

  return LatLng(radianToDeg(lat3 as double),
      (radianToDeg(l3LngRadians as double) + 540) % 360 - 180);
}