/// <summary>
/// Tests if the supplied Polygon and this Polygon are coincident in any way when compared on a shared plane.
/// </summary>
/// <param name="polygon">The Polygon to compare to this Polygon.</param>
/// <returns>
/// Returns true if the supplied Polygon do not intersect or touch this Polygon when compared on a shared plane or if the supplied Polygon is null.
/// </returns>
public bool Disjoint(Polygon polygon)
{
if (polygon == null)
{
return(true);
}
var thisPath = this.ToClipperPath();
var polyPath = polygon.ToClipperPath();
foreach (IntPoint vertex in thisPath)
{
if (Clipper.PointInPolygon(vertex, polyPath) != 0)
{
return(false);
}
}
foreach (IntPoint vertex in polyPath)
{
if (Clipper.PointInPolygon(vertex, thisPath) != 0)
{
return(false);
}
}
return(true);
}
/// <summary>
/// Tests if the supplied Polygon is within this Polygon with or without edge coincident vertices when compared on a shared plane.
/// </summary>
/// <param name="polygon">The Polygon to compare to this Polygon.</param>
/// <returns>
/// Returns true if every vertex of the supplied Polygon is within this Polygon or coincident with an edge when compared on a shared plane. Returns false if any vertex of the supplied Polygon is outside this Polygon, or if the supplied Polygon is null.
/// </returns>
public bool Covers(Polygon polygon)
{
if (polygon == null)
{
return(false);
}
var clipper = new Clipper();
var solution = new List <List <IntPoint> >();
clipper.AddPath(this.ToClipperPath(), PolyType.ptSubject, true);
clipper.AddPath(polygon.ToClipperPath(), PolyType.ptClip, true);
clipper.Execute(ClipType.ctIntersection, solution);
if (solution.Count != 1)
{
return(false);
}
return(solution.First().ToPolygon().Area == polygon.ToClipperPath().ToPolygon().Area);
}
/// <summary>
/// Constructs the geometric union between this Polygon and the supplied Polygon.
/// </summary>
/// <param name="polygon">The Polygon to be combined with this Polygon.</param>
/// <returns>
/// Returns a single Polygon from a successful union.
/// Returns null if a union cannot be performed on the two Polygons.
/// </returns>
public Polygon Union(Polygon polygon)
{
var thisPath = this.ToClipperPath();
var polyPath = polygon.ToClipperPath();
Clipper clipper = new Clipper();
clipper.AddPath(thisPath, PolyType.ptSubject, true);
clipper.AddPath(polyPath, PolyType.ptClip, true);
var solution = new List <List <IntPoint> >();
clipper.Execute(ClipType.ctUnion, solution);
if (solution.Count > 1)
{
return(null);
}
return(solution.First().ToPolygon());
}
/// <summary>
/// Tests if at least one point of an edge of the supplied Polygon is shared with an edge of this Polygon without the Polygons interesecting when compared on a shared plane.
/// </summary>
/// <param name="polygon">The Polygon to compare to this Polygon.</param>
/// <returns>
/// Returns true if the supplied Polygon shares at least one edge point with this Polygon without the Polygons intersecting when compared on a shared plane. Returns false if the Polygons intersect, are disjoint, or if the supplied Polygon is null.
/// </returns>
public bool Touches(Polygon polygon)
{
if (polygon == null || this.Intersects(polygon))
{
return(false);
}
var thisPath = this.ToClipperPath();
var polyPath = polygon.ToClipperPath();
foreach (IntPoint vertex in thisPath)
{
if (Clipper.PointInPolygon(vertex, polyPath) == -1)
{
return(true);
}
}
return(false);
}
/// <summary>
/// Returns Polygons representing the symmetric difference between this Polygon and the supplied Polygon.
/// </summary>
/// <param name="polygon">The intersecting polygon.</param>
/// <returns>
/// Returns a list of Polygons representing the symmetric difference of this Polygon and the supplied Polygon.
/// Returns a representation of this Polygon and the supplied Polygon if the Polygons do not intersect.
/// </returns>
public IList <Polygon> XOR(Polygon polygon)
{
var thisPath = this.ToClipperPath();
var polyPath = polygon.ToClipperPath();
Clipper clipper = new Clipper();
clipper.AddPath(thisPath, PolyType.ptSubject, true);
clipper.AddPath(polyPath, PolyType.ptClip, true);
var solution = new List <List <IntPoint> >();
clipper.Execute(ClipType.ctUnion, solution);
var polygons = new List <Polygon>();
foreach (List <IntPoint> path in solution)
{
polygons.Add(PolygonExtensions.ToPolygon(path));
}
return(polygons);
}
