private static VisibilityVertex GetCrossingInteriorVertex(VisibilityGraph vg, VisibilityVertex crossingVertex,
GroupBoundaryCrossing crossing) {
Point interiorPoint = crossing.GetInteriorVertexPoint(crossingVertex.Point);
return vg.FindVertex(interiorPoint) ?? vg.AddVertex(interiorPoint);
}
private bool AppendGroupCrossingsThroughPoint(VisibilityGraph vg, Point lastPoint) {
if (null == GroupBoundaryPointAndCrossingsList) {
return false;
}
bool found = false;
while (GroupBoundaryPointAndCrossingsList.CurrentIsBeforeOrAt(lastPoint)) {
// We will only create crossing Edges that the segment actually crosses, not those it ends before crossing.
// For those terminal crossings, the adjacent segment creates the interior vertex and crossing edge.
PointAndCrossings pac = GroupBoundaryPointAndCrossingsList.Pop();
GroupBoundaryCrossing[] lowDirCrossings = null;
GroupBoundaryCrossing[] highDirCrossings = null;
if (PointComparer.Compare(pac.Location, Start) > 0) {
lowDirCrossings = PointAndCrossingsList.ToCrossingArray(pac.Crossings,
ScanDirection.OppositeDirection);
}
if (PointComparer.Compare(pac.Location, End) < 0) {
highDirCrossings = PointAndCrossingsList.ToCrossingArray(pac.Crossings, ScanDirection.Direction);
}
found = true;
VisibilityVertex crossingVertex = vg.FindVertex(pac.Location) ?? vg.AddVertex(pac.Location);
if ((null != lowDirCrossings) || (null != highDirCrossings)) {
AddLowCrossings(vg, crossingVertex, lowDirCrossings);
AddHighCrossings(vg, crossingVertex, highDirCrossings);
} else {
// This is at this.Start with only lower-direction toward group interior(s), or at this.End with only
// higher-direction toward group interior(s). Therefore an adjacent ScanSegment will create the crossing
// edge, so create the crossing vertex here and we'll link to it.
if (null == LowestVisibilityVertex) {
SetInitialVisibilityVertex(crossingVertex);
} else {
Debug.Assert(PointComparer.Equal(End, crossingVertex.Point), "Expected this.End crossingVertex");
AppendHighestVisibilityVertex(crossingVertex);
}
}
}
return found;
}
private void LoadEndOverlapVertexIfNeeded(VisibilityGraph vg) {
// See comments in LoadStartOverlapVertexIfNeeded.
if (NeedEndOverlapVertex) {
VisibilityVertex vertex = vg.FindVertex(End);
AppendVisibilityVertex(vg, vertex ?? vg.AddVertex(End));
}
}
internal void CreateSparseVerticesAndEdges(VisibilityGraph vg) {
if (this.sparsePerpendicularCoords == null) {
return;
}
AppendGroupCrossingsThroughPoint(vg, Start);
foreach (var perpCoord in this.sparsePerpendicularCoords.OrderBy(d => d)) {
var vertexLocation = this.CreatePointFromPerpCoord(perpCoord);
Debug.Assert(this.ContainsPoint(vertexLocation), "vertexLocation is not on Segment");
this.AppendVisibilityVertex(vg, vg.FindVertex(vertexLocation) ?? vg.AddVertex(vertexLocation));
}
AppendGroupCrossingsThroughPoint(vg, End);
GroupBoundaryPointAndCrossingsList = null;
this.sparsePerpendicularCoords.Clear();
this.sparsePerpendicularCoords = null;
}
private void LoadStartOverlapVertexIfNeeded(VisibilityGraph vg) {
// For adjacent segments with different IsOverlapped, we need a vertex that
// joins the two so a path may be run. This is paired with the other segment's
// LoadEndOverlapVertexIfNeeded.
if (NeedStartOverlapVertex) {
VisibilityVertex vertex = vg.FindVertex(Start);
AppendVisibilityVertex(vg, vertex ?? vg.AddVertex(Start));
}
}