/// <summary>
/// Partitions a polygon by triangles.
/// </summary>
public void Compute()
{
this.result = new List <Coordinate[]>();
List <Coordinate> shell = new List <Coordinate>(this.Source);
List <Coordinate> nextShell = new List <Coordinate>(this.Source);
Coordinate[] triangle;
Int32 coordinateCount = shell.Count - 1;
Int32 coordinateIndex = 1;
while (shell.Count != 4)
{
Coordinate centroid = LineAlgorithms.Centroid(shell[(shell.Count + coordinateIndex - 1) % coordinateCount], shell[(shell.Count + coordinateIndex + 1) % coordinateCount], this.PrecisionModel);
nextShell.Remove(nextShell[coordinateIndex]);
if (!WindingNumberAlgorithm.InExterior(shell, centroid, this.PrecisionModel) && !ShamosHoeyAlgorithm.Intersects(nextShell, this.PrecisionModel))
{
triangle = new Coordinate[3]
{
shell[(coordinateCount + coordinateIndex - 1) % coordinateCount],
shell[coordinateIndex],
shell[(coordinateCount + coordinateIndex + 1) % coordinateCount]
};
this.result.Add(triangle);
shell.Remove(shell[coordinateIndex]);
coordinateIndex = 1;
coordinateCount--;
}
else
{
coordinateIndex = (coordinateIndex + 1) % (shell.Count - 1);
nextShell = new List <Coordinate>(shell);
}
}
triangle = new Coordinate[3] {
shell[0], shell[1], shell[2]
};
this.result.Add(triangle);
this.hasResult = true;
}
/// <summary>
/// Computes the distance between the specified geometries.
/// </summary>
/// <param name="lineString">The line string.</param>
/// <param name="polygon">The polygon.</param>
/// <param name="precisionModel">The precision model.</param>
/// <returns>The distance between the specified geometries.</returns>
/// <exception cref="System.ArgumentNullException">
/// The line string is null.
/// or
/// The polygon is null.
/// </exception>
public static Double Distance(IBasicLineString lineString, IBasicPolygon polygon, PrecisionModel precisionModel)
{
if (lineString == null)
{
throw new ArgumentNullException(nameof(lineString));
}
if (polygon == null)
{
throw new ArgumentNullException(nameof(polygon));
}
if (WindingNumberAlgorithm.InExterior(polygon, lineString[0]))
{
return(0);
}
if (polygon.HoleCount == 0)
{
return(Distance(lineString, polygon.Shell, precisionModel));
}
return(Math.Min(Distance(lineString, polygon.Shell, precisionModel), polygon.Holes.Min(hole => Distance(lineString, hole, precisionModel))));
}
/// <summary>
/// Computes the distance between the specified geometries.
/// </summary>
/// <param name="first">The line string.</param>
/// <param name="second">The polygon.</param>
/// <param name="precisionModel">The precision model.</param>
/// <returns>The distance between the specified geometries.</returns>
/// <exception cref="System.ArgumentNullException">
/// The first polygon is null.
/// or
/// The second polygon is null.
/// </exception>
public static Double Distance(IBasicPolygon first, IBasicPolygon second, PrecisionModel precisionModel)
{
if (first == null)
{
throw new ArgumentNullException(nameof(first));
}
if (second == null)
{
throw new ArgumentNullException(nameof(second));
}
if (WindingNumberAlgorithm.InExterior(first, second.Shell[0]))
{
return(0);
}
if (first.HoleCount == 0)
{
return(Distance(first.Shell, second, precisionModel));
}
return(Math.Min(Distance(first.Shell, second, precisionModel), first.Holes.Min(hole => Distance(hole, second, precisionModel))));
}
/// <summary>
/// Computes the distance between the specified geometries.
/// </summary>
/// <param name="point">The point.</param>
/// <param name="polygon">The polygon.</param>
/// <param name="precisionModel">The precision model.</param>
/// <returns>The distance between the specified geometries.</returns>
/// <exception cref="System.ArgumentNullException">
/// The point is null.
/// or
/// The polygon is null.
/// </exception>
public static Double Distance(IBasicPoint point, IBasicPolygon polygon, PrecisionModel precisionModel)
{
if (point == null)
{
throw new ArgumentNullException(nameof(point));
}
if (polygon == null)
{
throw new ArgumentNullException(nameof(polygon));
}
if (!WindingNumberAlgorithm.InExterior(polygon, point.Coordinate))
{
return(0);
}
if (polygon.HoleCount == 0)
{
return(Distance(point, polygon.Shell, precisionModel));
}
return(Math.Min(Distance(point, polygon.Shell, precisionModel), polygon.Holes.Min(hole => Distance(point, hole, precisionModel))));
}
/// <summary>
/// Computes the location of the specified coordinate within a polygon.
/// </summary>
/// <param name="shell">The shell of the polygon.</param>
/// <param name="holes">The holes of the polygon.</param>
/// <param name="coordinate">The examined coordinate.</param>
/// <param name="precisionModel">The precision model.</param>
/// <returns>The location of the coordinate.</returns>
private static RelativeLocation ComputeLocation(IEnumerable <Coordinate> shell, IEnumerable <IEnumerable <Coordinate> > holes, Coordinate coordinate, PrecisionModel precisionModel)
{
if (!coordinate.IsValid)
{
return(RelativeLocation.Undefined);
}
if (shell.Any(coord => coord == null || !coord.IsValid))
{
return(RelativeLocation.Undefined);
}
if (!Envelope.Contains(shell, coordinate))
{
return(RelativeLocation.Exterior);
}
WindingNumberAlgorithm algorithm = new WindingNumberAlgorithm(shell, coordinate, precisionModel);
algorithm.Compute();
// probably the Winding Number algorithm already detected that the coordinate is on the boundary of the polygon shell
if (algorithm.isCoordinateOnEdge)
{
return(RelativeLocation.Boundary);
}
// additionally check the boundary
if (ComputeOnBoundary(shell, coordinate, precisionModel))
{
return(RelativeLocation.Boundary);
}
if (algorithm.Result == 0)
{
return(RelativeLocation.Exterior);
}
// if the coordinate is not outside, the holes are also required to be checked
if (holes != null)
{
foreach (IEnumerable <Coordinate> hole in holes)
{
if (hole == null)
{
continue;
}
if (hole.Any(coord => coord == null || !coord.IsValid))
{
return(RelativeLocation.Undefined);
}
algorithm = new WindingNumberAlgorithm(hole, coordinate, precisionModel);
algorithm.Compute();
if (algorithm.isCoordinateOnEdge)
{
return(RelativeLocation.Boundary);
}
// additionally check the boundary
if (ComputeOnBoundary(hole, coordinate, precisionModel))
{
return(RelativeLocation.Boundary);
}
if (algorithm.Result != 0)
{
return(RelativeLocation.Exterior);
}
}
}
return(RelativeLocation.Interior);
}
