public static MultiPolycurve CreateEmpty()
{
var result = new MultiPolycurve(new List <Linestring>(0));
result.SetEmpty();
return(result);
}
public override MultiLinestring Clone()
{
var result = new MultiPolycurve(Linestrings)
{
//Id = Id
};
return(result);
}
/// <summary>
/// Cuts the source ring using the target and returns separate lists
/// of result rings on the left/right side of the cut line.
/// </summary>
/// <param name="leftPolys">Result polygons on the left side of the cut line.</param>
/// <param name="rightPolys">Result polygons on the right side of the cut line.</param>
/// <param name="clipPolys"></param>
/// <param name="undefinedSidePolys"></param>
/// <param name="unCutParts"></param>
/// <returns>Whether the cut operation was successful or not.</returns>
public bool CutXY([NotNull] out IList <RingGroup> leftPolys,
[NotNull] out IList <RingGroup> rightPolys,
[NotNull] out IList <RingGroup> clipPolys,
[NotNull] out IList <MultiLinestring> undefinedSidePolys,
[NotNull] out MultiLinestring unCutParts)
{
Assert.ArgumentCondition(_subcurveNavigator.Source.IsClosed, "source must be closed.");
// Based on Weiler–Atherton clipping algorithm, added specific logic for
// linear intersections, un-closed target lines and multi-parts.
// Potential enhancements: Do not insert phantom points!
IList <Linestring> rightRings = GetRightSideRings();
IList <Linestring> leftRings = GetLeftSideRings();
IList <Linestring> duplicates = new List <Linestring>();
if (!_subcurveNavigator.Target.IsClosed &&
_subcurveNavigator.AreIntersectionPointsNonSequential())
{
// Cut backs result in duplicates which are both on the left and the right!
duplicates = RemoveDuplicateRings(leftRings, rightRings);
}
// Assign the cut inner rings (anti-clockwise) to un-cut outer rings...
var unCutOuterRings = _subcurveNavigator.GetNonIntersectedSourceRings()
.Where(r => r.ClockwiseOriented != false)
.ToList();
rightPolys = AssignToResultRingGroups(rightRings, unCutOuterRings);
leftPolys = AssignToResultRingGroups(leftRings, unCutOuterRings);
IList <RingGroup> bothSidePolys = AssignToResultRingGroups(duplicates, unCutOuterRings);
unCutParts =
unCutOuterRings.Count == 1
? (MultiLinestring) new RingGroup(unCutOuterRings[0])
: new MultiPolycurve(unCutOuterRings);
// Assign the remaining interior rings;
AssignInteriorRings(rightRings, leftPolys, rightPolys, bothSidePolys, unCutParts,
_subcurveNavigator.Tolerance);
AssignInteriorRings(leftRings, leftPolys, rightPolys, bothSidePolys, unCutParts,
_subcurveNavigator.Tolerance);
AssignInteriorRings(duplicates, leftPolys, rightPolys, bothSidePolys, unCutParts,
_subcurveNavigator.Tolerance);
// Assign the inner rings from the original
var unCutIslands = _subcurveNavigator.GetNonIntersectedSourceRings()
.Where(r => r.ClockwiseOriented == false);
AssignInteriorRings(unCutIslands, leftPolys, rightPolys, bothSidePolys, unCutParts,
_subcurveNavigator.Tolerance);
// Assign closed cut lines completely contained by an outer ring (and not by an inner ring)
var unusedCutRings =
_subcurveNavigator.GetNonIntersectedTargets().Where(t => t.IsClosed);
undefinedSidePolys = bothSidePolys.Cast <MultiLinestring>().ToList();
clipPolys = new List <RingGroup>();
foreach (Linestring unusedCutRing in unusedCutRings)
{
MultiLinestring updatedUnCut;
RingGroup cookie;
if (!unCutParts.IsEmpty &&
TryCutCookie(unusedCutRing, unCutParts, out updatedUnCut, out cookie))
{
unCutParts = MultiPolycurve.CreateEmpty();
undefinedSidePolys.Add(updatedUnCut);
clipPolys.Add(cookie);
continue;
}
RingGroup updatedCut;
if (TryCutCookie(unusedCutRing, leftPolys, out updatedCut, out cookie))
{
clipPolys.Add(cookie);
continue;
}
if (TryCutCookie(unusedCutRing, rightPolys, out updatedCut, out cookie))
{
clipPolys.Add(cookie);
continue;
}
if (TryCutCookie(unusedCutRing, bothSidePolys, out updatedCut, out cookie))
{
clipPolys.Add(cookie);
}
}
return((rightPolys.Count > 0 && leftPolys.Count > 0) ||
undefinedSidePolys.Count > 1 || clipPolys.Count > 0);
}