/// <summary>
/// Initializes a new instance of the <see cref="SegmentIntersection"/> class.
/// </summary>
/// <param name="edgeA">The edge a.</param>
/// <param name="edgeB">The edge b.</param>
/// <param name="intersectionPoint">The intersection point.</param>
/// <param name="relationship">The relationship.</param>
internal SegmentIntersection(PolygonEdge edgeA, PolygonEdge edgeB, Vector2 intersectionPoint, SegmentRelationship relationship,
WhereIsIntersection whereIsIntersection, CollinearityTypes collinearity)
{
this.EdgeA = edgeA;
this.EdgeB = edgeB;
this.IntersectCoordinates = intersectionPoint;
this.Relationship = relationship;
this.WhereIntersection = whereIsIntersection;
this.CollinearityType = collinearity;
VisitedA = false;
VisitedB = false;
}
private void MakeThisPolygonsEdges()
{
var numPoints = Vertices.Count;
_edges = new PolygonEdge[numPoints];
for (int i = 0, j = numPoints - 1; i < numPoints; j = i++)
// note this compact approach to setting i and j.
{
var fromNode = Vertices[j];
var toNode = Vertices[i];
var polySegment = new PolygonEdge(fromNode, toNode);
fromNode.StartLine = polySegment;
toNode.EndLine = polySegment;
_edges[i] = polySegment;
}
}
/// <summary>
/// Determines whether [is adjacent to] [the specified other]. That is, do they share an endpoint or not.
/// </summary>
/// <param name="other">The other.</param>
/// <returns><c>true</c> if [is adjacent to] [the specified other]; otherwise, <c>false</c>.</returns>
public bool IsAdjacentTo(PolygonEdge other)
{
return(FromPoint == other.ToPoint ||
ToPoint == other.FromPoint);
}
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 ValidStartingIntersection(SegmentIntersection intersectionData,
out PolygonEdge currentEdge,
out bool startAgain)
{
startAgain = false;
if (intersectionData.Relationship == SegmentRelationship.DoubleOverlap)
{
if (intersectionData.CollinearityType == CollinearityTypes.ABeforeBAfter && !intersectionData.VisitedA && !intersectionData.VisitedB)
{
currentEdge = intersectionData.EdgeB;
return(true);
}
if (intersectionData.CollinearityType == CollinearityTypes.AAfterBBefore && !intersectionData.VisitedA && !intersectionData.VisitedB)
{
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)
{
currentEdge = intersectionData.EdgeB;
return(true);
}
if (intersectionData.Relationship == SegmentRelationship.BEnclosesA && !intersectionData.VisitedA)
{
currentEdge = intersectionData.EdgeA;
return(true);
}
if (intersectionData.Relationship == SegmentRelationship.CrossOver_AOutsideAfter && !intersectionData.VisitedA)
{
currentEdge = intersectionData.EdgeA;
return(true);
}
if (intersectionData.Relationship == SegmentRelationship.CrossOver_BOutsideAfter && !intersectionData.VisitedB)
{
currentEdge = intersectionData.EdgeB;
return(true);
}
currentEdge = null;
return(false);
}
