public static bool ValidPolygon(Ring2 <double> outer, RingSet2 <double> inner)
{
if (outer == null || inner == null)
{
return(false);
}
HashSet <Ring2 <double> > ringHash = new HashSet <Ring2 <double> >(); //check for the silly condition of multiple references to the same ring
ringHash.Add(outer);
Envelope2 <double> outerEnv = outer.Envelope;
PlanarChainGraph <double> gr = new PlanarChainGraph <double>();
foreach (Ring2 <double> r in inner.Rings)
{
if (!ringHash.Add(r))
{
return(false); //oops, duplicate reference
}
if (!Envelope2 <double> .EnvelopeContain(outerEnv, r.Envelope)) //all inner rings must be contained by outer ring, so the envelopes must overlap
{
return(false);
}
gr.Add(r);
}
ringHash.Clear();
ringHash = null;
gr.Add(outer);
SegmentGroup <double> activeEdges = new SegmentGroup <double>();
IEnumerator <Node <double> > points = gr.GetEnumerator(); //walk through the points in xy sorted order
Node <double> nd;
LeakyResizableArray <Edge <double> > localEdges;
int localCt;
int activeCt = 0;
Edge <double> localEdge;
LineSegment2IntersectionResult <double> intersects;
Point2 <double> localStart;
Point2 <double> localEnd;
Point2 <double> activeStart;
Point2 <double> activeEnd;
Point2 <double> intPoint;
SimpleGraph <object> touchingRings = new SimpleGraph <object>();
HashSet <object> outerRingTouching = new HashSet <object>();
//new point event in the moving front
while (points.MoveNext())
{
nd = points.Current;
localEdges = nd.Edges; //edges connected to this point
localCt = (int)localEdges.Count;
//compute intersections with other edges in the scan area
for (int i = 0; i < localCt; i++)
{
localEdge = localEdges.Data[i];
localStart = localEdge.Start.Point;
localEnd = localEdge.End.Point;
activeCt = activeEdges.Edges.Count;
foreach (Edge <double> activeEdge in activeEdges.Edges)
{
if (object.ReferenceEquals(localEdge, activeEdge) || object.ReferenceEquals(localEdge.Start.ParentShape, activeEdge.Start.ParentShape))
{
continue; //exiting edge || 2 edges on same ring
}
activeStart = activeEdge.Start.Point;
activeEnd = activeEdge.End.Point;
intersects = SegmentUtils.ComputeIntersection(localStart, localEnd, activeStart, activeEnd);
if (intersects.IntersectionType != LineIntersectionType.NoIntersection)
{
if (intersects.IntersectionType == LineIntersectionType.CollinearIntersection)
{
return(false); // there's a full segment of intersection - must be between outer ring and an inner ring
}
//ok, we have an intersection that is a point between 2 different rings
intPoint = intersects.BasePoint;
if (object.ReferenceEquals(localEdge.Start.ParentShape, outer)) //localEdge is on the shell
{
if (PointUtilsDouble.PointsEqual(intPoint, activeStart))
{
//only add the shell touching for segment intersection at segment start point - prevents recounting point
if (!PointUtilsDouble.PointsEqual(intPoint, localEnd))
{
if (!outerRingTouching.Add(activeEdge.Start.ParentShape))
{
return(false); //same ring touches outer ring at multiple non-adjacent points
}
}
if (!RingUtils.PointInteriorToRing(outer, activeEnd))
{
return(false); //ring is outside of shell or crosses shell at a vertex
}
}
else if (PointUtilsDouble.PointsEqual(intPoint, activeEnd))
{
//only add the shell touching for segment intersection at segment start point - prevents recounting point
if (!PointUtilsDouble.PointsEqual(intPoint, localEnd))
{
if (!outerRingTouching.Add(activeEdge.Start.ParentShape))
{
return(false); //same ring touches outer ring at multiple non-adjacent points
}
}
if (!RingUtils.PointInteriorToRing(outer, activeStart))
{
return(false); //ring is outside of shell or crosses shell at a vertex
}
}
else
{
return(false); //we have a mid-segment intersection between the outer ring and an inner ring
}
}
else if (object.ReferenceEquals(activeEdge.Start.ParentShape, outer)) //activeEdge is on the shell
{
if (PointUtilsDouble.PointsEqual(intPoint, localStart))
{
//only add the shell touching for segment intersection at segment start point - prevents recounting point
if (!PointUtilsDouble.PointsEqual(intPoint, activeEnd))
{
if (!outerRingTouching.Add(localEdge.Start.ParentShape))
{
return(false); //same ring touches outer ring at multiple non-adjacent points
}
}
if (!RingUtils.PointInteriorToRing(outer, localEnd))
{
return(false); //ring is outside of shell or crosses shell at a vertex
}
}
else if (PointUtilsDouble.PointsEqual(intPoint, localEnd))
{
//only add the shell touching for segment intersection at segment start point - prevents recounting point
if (!PointUtilsDouble.PointsEqual(intPoint, activeEnd))
{
if (!outerRingTouching.Add(localEdge.Start.ParentShape))
{
return(false); //same ring touches outer ring at multiple non-adjacent points
}
}
if (!RingUtils.PointInteriorToRing(outer, localStart))
{
return(false); //ring is outside of shell or crosses shell at a vertex
}
}
else
{
return(false); //we have a mid-segment intersection between the outer ring and an inner ring
}
}
else //both are on inner rings
{
//since the ringset is valid, we just need to map the connectivity of rings
if (!touchingRings.Contains(localEdge.Start.ParentShape))
{
touchingRings.AddNode(localEdge.Start.ParentShape);
}
if (!touchingRings.Contains(activeEdge.Start.ParentShape))
{
touchingRings.AddNode(activeEdge.Start.ParentShape);
}
touchingRings.AddEdge(localEdge.Start.ParentShape, activeEdge.Start.ParentShape);
}
} //end !nointersection
} //end foreach
} //end for
//remove all exiting segments and add all starting segments
//Action gets called exactly twice per edge -- once to add it, once to remove it
for (int i = 0; i < localCt; i++)
{
activeEdges.Action(localEdges.Data[i]);
}
}
//we now know all the rings of the ringset are "legally" connected wrt the shell -- but --
//inner rings may be adjacent to both the shell and other inner rings to form a "path" cutting the shell
//any ring COULD be outside the shell -- we did already do the quick envelope check, so just do singular point-in-ring checks
//shell cutting test (quick)
object[] shellTouchers = outerRingTouching.ToArray();
for (int i = shellTouchers.Length - 1; i > 0; i--)
{
object adjacentRingA = shellTouchers[i];
if (touchingRings.Contains(adjacentRingA))
{
for (int j = 0; j < i; j++)
{
object adjacentRingB = shellTouchers[j];
if (touchingRings.Contains(adjacentRingB))
{
if (HasPath(adjacentRingA, adjacentRingB, touchingRings))
{
return(false); //path exists between shell touching inner rings
}
}
}
}
}
//ring inside shell testing
foreach (Ring2 <double> innerR in inner.Rings)
{
if (!(RingUtils.PointInteriorToRing(outer, innerR.Points[0]) || RingUtils.PointInteriorToRing(outer, innerR.Points[1]))) //at least one of 2 adjacent points must be interior
{
return(false);
}
}
return(true);
}