/// <summary>
/// Constructs the Polygon intersections between this Polygon and the supplied Polygon.
/// </summary>
/// <param name="polygon">The intersecting Polygon.</param>
/// <returns>
/// Returns a list of Polygons representing the intersection of this Polygon with the supplied Polygon.
/// Returns null if the two Polygons do not intersect.
/// </returns>
public IList <Polygon> Intersection(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.ctIntersection, solution);
if (solution.Count == 0)
{
return(null);
}
var polygons = new List <Polygon>();
foreach (List <IntPoint> path in solution)
{
polygons.Add(PolygonExtensions.ToPolygon(path));
}
return(polygons);
}
/// <summary>
/// Constructs the geometric difference between this Polygon and the supplied Polygon.
/// </summary>
/// <param name="polygon">The intersecting Polygon.</param>
/// <param name="tolerance">An optional tolerance value.</param>
/// <returns>
/// Returns a list of Polygons representing the subtraction of the supplied Polygon from this Polygon.
/// Returns null if the area of this Polygon is entirely subtracted.
/// Returns a list containing a representation of the perimeter of this Polygon if the two Polygons do not intersect.
/// </returns>
public IList <Polygon> Difference(Polygon polygon, double tolerance = Vector3.EPSILON)
{
var thisPath = this.ToClipperPath(tolerance);
var polyPath = polygon.ToClipperPath(tolerance);
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.ctDifference, solution, PolyFillType.pftNonZero);
if (solution.Count == 0)
{
return(null);
}
var polygons = new List <Polygon>();
foreach (List <IntPoint> path in solution)
{
polygons.Add(PolygonExtensions.ToPolygon(path, tolerance));
}
return(polygons);
}