protected override bool ValidStartingIntersection(SegmentIntersection intersectionData, out PolygonEdge currentEdge,
out bool startAgain)
{
startAgain = false;
if (intersectionData.Relationship == SegmentRelationship.NoOverlap)
{
if (intersectionData.CollinearityType == CollinearityTypes.ABeforeBAfter && !intersectionData.VisitedA && !intersectionData.VisitedB)
{
currentEdge = intersectionData.EdgeB;
return(true);
}
if (intersectionData.CollinearityType == CollinearityTypes.AAfterBBefore && !intersectionData.VisitedB && !intersectionData.VisitedA)
{
currentEdge = intersectionData.EdgeA;
return(true);
}
if (intersectionData.CollinearityType == CollinearityTypes.None)
{
startAgain = !(intersectionData.VisitedB || intersectionData.VisitedA);
if (!intersectionData.VisitedA)
{
currentEdge = intersectionData.EdgeA;
return(true);
}
if (!intersectionData.VisitedB)
{
currentEdge = intersectionData.EdgeB;
return(true);
}
}
}
if (intersectionData.VisitedB || intersectionData.VisitedA)
{
currentEdge = null;
return(false);
}
if (intersectionData.Relationship == SegmentRelationship.AEnclosesB && !intersectionData.VisitedB && !intersectionData.VisitedA)
{
currentEdge = intersectionData.EdgeA;
return(true);
}
if (intersectionData.Relationship == SegmentRelationship.BEnclosesA && !intersectionData.VisitedB && !intersectionData.VisitedA)
{
currentEdge = intersectionData.EdgeB;
return(true);
}
if (intersectionData.Relationship == SegmentRelationship.CrossOver_AOutsideAfter && !intersectionData.VisitedB)
{
currentEdge = intersectionData.EdgeB;
return(true);
}
if (intersectionData.Relationship == SegmentRelationship.CrossOver_BOutsideAfter && !intersectionData.VisitedA)
{
currentEdge = intersectionData.EdgeA;
return(true);
}
currentEdge = null;
return(false);
}
protected override bool PolygonCompleted(SegmentIntersection currentIntersection, SegmentIntersection startingIntersection, PolygonEdge currentEdge, PolygonEdge startingEdge)
{
if (startingIntersection != currentIntersection)
{
return(false);
}
if (startingIntersection.Relationship == SegmentRelationship.DoubleOverlap &&
startingIntersection.CollinearityType == CollinearityTypes.None)
{
return(currentEdge == startingEdge);
}
return(true);
}
protected override bool SwitchAtThisIntersection(SegmentIntersection intersectionData, bool currentEdgeIsFromPolygonA)
{
if (intersectionData.Relationship == SegmentRelationship.DoubleOverlap)
{
return(true);
}
if (!currentEdgeIsFromPolygonA)
{
return
(intersectionData.Relationship == SegmentRelationship.CrossOver_BOutsideAfter ||
intersectionData.Relationship == SegmentRelationship.BEnclosesA);
}
return(intersectionData.Relationship == SegmentRelationship.CrossOver_AOutsideAfter ||
intersectionData.Relationship == SegmentRelationship.AEnclosesB);
}
