/// <summary>
/// Gets a new instance of <see cref="SurfaceRegion"/>.
/// </summary>
/// <param name="planet">The planet on which this region is found.</param>
/// <param name="northLatitude">The latitude of the northwest corner of the region.</param>
/// <param name="westLongitude">The longitude of the northwest corner of the region.</param>
/// <param name="southLatitude">The latitude of the southeast corner of the region.</param>
/// <param name="eastLongitude">The longitude of the southeast corner of the region.</param>
/// <remarks>
/// The region's actual size will be adjusted to ensure that the boundaries indicated would
/// be fully displayed on both an equirectangular and a cylindrical equal-area projection of
/// the region, which might result in a larger distance in one dimension than indicated by
/// the given dimensions.
/// </remarks>
public static SurfaceRegion FromBounds(Planetoid planet, double northLatitude, double westLongitude, double southLatitude, double eastLongitude)
{
var latitudeRange = Math.Abs(southLatitude - northLatitude);
var centerLat = northLatitude + (latitudeRange / 2);
var longitudeRange = Math.Abs(eastLongitude - westLongitude);
var halfLongitudeRange = longitudeRange / 2;
var position = planet.LatitudeAndLongitudeToVector(
centerLat,
westLongitude + halfLongitudeRange);
latitudeRange = Math.Max(
latitudeRange,
halfLongitudeRange);
var equalAreaAspectRatio = Math.PI * Math.Cos(centerLat).Square();
latitudeRange = Math.Max(
latitudeRange,
longitudeRange / equalAreaAspectRatio);
latitudeRange = Math.Min(
latitudeRange,
Math.PI);
return(new SurfaceRegion(
planet,
position,
latitudeRange));
}
/// <summary>
/// Initializes a new instance of <see cref="SurfaceRegion"/>.
/// </summary>
/// <param name="planet">The planet on which this region is found.</param>
/// <param name="latitude">The latitude of the center of the region.</param>
/// <param name="longitude">The longitude of the center of the region.</param>
/// <param name="latitudeRange">
/// <para>
/// The range of latitudes encompassed by this region, as an angle (in radians).
/// </para>
/// <para>
/// Maximum value is π (a full hemisphere, which produces the full globe).
/// </para>
/// </param>
public SurfaceRegion(Planetoid planet, double latitude, double longitude, HugeNumber latitudeRange)
: base(planet.Id, new Frustum <HugeNumber>(2, planet.LatitudeAndLongitudeToVector(latitude, longitude) * (planet.Shape.ContainingRadius + planet.Atmosphere.AtmosphericHeight), HugeNumber.Min(latitudeRange, HugeNumber.Pi), 0))
{
}