/// <summary>
/// Does the ship's heading put it on course to enter Duluth Canal?
/// Ships report numerous false destinations. Therefore, we use this method
/// to check a ship's actual heading against the bearing to the two nearest ports
/// and make a determination whether or not the ship will actually use Duluth Canal
/// </summary>
/// <param name="shipTest">shipTest object</param>
/// <returns>true or false</returns>
public static bool IsHeadingTowardDuluth(this ShipTest shipTest)
{
var twoNearestPortsAndBearing = Ports.All.Select(p => {
var bearing = GeoHelper.GetBearing(shipTest.Position, p);
var adjustment = Math.Abs(bearing - shipTest.Heading);
if (adjustment > 180)
{
adjustment = 360 - adjustment;
}
return(new {
Position = p,
Bearing = bearing,
Adjustment = adjustment
});
}).OrderBy(
p => p.Adjustment
).Take(2).ToArray();
var firstPort = twoNearestPortsAndBearing[0];
var secondPort = twoNearestPortsAndBearing[1];
var portBearingDiff = Math.Abs(firstPort.Bearing - secondPort.Bearing);
var weight = 1 / 2D;
if (shipTest.Destination == firstPort.Position)
{
weight = 2 / 3D;
}
else if (shipTest.Destination == secondPort.Position)
{
weight = 1 / 3D;
}
var threshold = weight * portBearingDiff;
Position nearestPort = null;
if (firstPort.Adjustment <= threshold)
{
nearestPort = firstPort.Position;
}
else if (secondPort.Adjustment <= threshold)
{
nearestPort = secondPort.Position;
}
else if (shipTest.IsMovingToward(firstPort.Position))
{
nearestPort = firstPort.Position;
}
return(nearestPort == Ports.Duluth);
}
/// <summary>
/// If the a ship's bearing to a given position is less than 90 degrees away from exact heading needed to get to the port,
/// Then we says that a ship is moving toward that port
/// </summary>
/// <param name="shipTest">shipTest object</param>
/// <returns>true or false</returns>
public static bool IsMovingTowardDuluth(this ShipTest shipTest)
{
return(shipTest.IsMovingToward(Ports.Duluth));
}