public FortuneArc SplitArc(FortuneArc splittingArc, FortuneArc splitter)
{
FortuneArc left = new FortuneArc();
left.Site = splittingArc.Site;
FortuneArc right = new FortuneArc();
right.Site = splittingArc.Site;
// create a new edge
VoronoiEdge edge = new VoronoiEdge(splittingArc.Site.Cell, splitter.Site.Cell);
// both nodes of the edge are initially points at infinity,
// but can become final after the event range
double x = splitter.Site.Cell.DataPoint.X;
double y = splitter.Site.Cell.DataPoint.Y;
double distance = getDistanceToArc(splittingArc.Site.Cell.DataPoint, y, x);
edge.Node1 = new VoronoiNode(x, y - distance);
edge.Node1.IsInfinit = true;
edge.Node2 = new VoronoiNode(x, y - distance);
edge.Node2.IsInfinit = true;
// add this edge in both cell diagram
splitter.Site.Cell.AddEdge(edge);
splittingArc.Site.Cell.AddEdge(edge);
//add nodes to the arcs of the ribs
splitter.LeftNode = edge.Node1;
splitter.RightNode = edge.Node2;
left.LeftNode = splittingArc.LeftNode;
left.RightNode = edge.Node1;
right.LeftNode = edge.Node2;
right.RightNode = splittingArc.RightNode;
left.Left = splittingArc.Left;
right.Right = splittingArc.Right;
splitter.Left = left;
splitter.Right = right;
if (splittingArc.Parent != null)
{
if (splittingArc.Parent.Left == splittingArc)
{
splittingArc.Parent.Left = splitter;
}
else if (splittingArc.Parent.Right == splittingArc)
{
splittingArc.Parent.Right = splitter;
}
}
else
{
Root = splitter;
}
return(splitter);
}
/// <summary>
/// Sets the directions of dangles for infinite edges.
/// </summary>
/// <param name="rectangle">Bounding rectangle of the tessellation nodes</param>
/// <param name="startVerticalNodes">The initial nodes of the infinit vertical edges,
/// formed by points with the maximum Y coordinate</param>
internal void Finish(BoundingRectangle rectangle, List <VoronoiNode> startVerticalNodes)
{
double l = rectangle.MinY - rectangle.Width - rectangle.Height;
FortuneArc arc = Root;
while (arc.Left != null)
{
arc = arc.Left;
}
while (arc != null)
{
FortuneArc rn = arc.RightNeighbor;
if (rn != null)
{
ICoordinate[] points =
getArcIntersections(arc.Site.Cell.DataPoint, rn.Site.Cell.DataPoint, 2 * l);
if (points.Length == 2)
{
ICoordinate p1 = points[0].X < points[1].X ? points[0] : points[1];
ICoordinate p2 = points[0].X < points[1].X ? points[1] : points[0];
if (arc.RightNode != null && arc.RightNode.IsInfinit)
{
if (arc.Site.Cell.DataPoint.Y > rn.Site.Cell.DataPoint.Y)
{
arc.RightNode.Point = p1;
}
else
{
arc.RightNode.Point = p2;
}
}
}
if (points.Length == 1)
{
if (arc.RightNode != null && arc.RightNode.IsInfinit)
{
arc.RightNode.Point = points[0];
}
}
}
arc = rn;
}
foreach (VoronoiNode node in startVerticalNodes)
{
node.Point = PlanimetryEnvironment.NewCoordinate(node.Point.X, rectangle.MaxY + rectangle.Height);
}
}
private FortuneEvent getCircleEvent(FortuneArc arc1,
FortuneArc arc2,
FortuneArc arc3,
double y)
{
ICoordinate a = arc1.Site.Cell.DataPoint;
ICoordinate b = arc2.Site.Cell.DataPoint;
ICoordinate c = arc3.Site.Cell.DataPoint;
//bc should turn to the right with respect to ab
if ((b.X - a.X) * (c.Y - a.Y) - (c.X - a.X) * (b.Y - a.Y) > 0)
{
return(null);
}
ICoordinate point = getCircleCenter(a, b, c);
if (point != null)
{
FortuneCircleEvent newEvent = new FortuneCircleEvent();
newEvent.CircleCenter = point;
double distance = PlanimetryAlgorithms.Distance(point, a);
point = PlanimetryEnvironment.NewCoordinate(point.X, point.Y - distance);
newEvent.Point = point;
newEvent.Arc = arc2;
if (_buildTriangles)
{
newEvent.Triangle = new Triangle(arc1.Site.Cell, arc2.Site.Cell, arc3.Site.Cell);
}
return(newEvent);
}
return(null);
}
/// <summary>
/// Removes an arc from the shoreline.
/// </summary>
/// <param name="arc">An arc to remove</param>
public void RemoveArc(FortuneArc arc)
{
removeArcRecursive(Root, arc);
}
private bool removeArcRecursive(FortuneArc root, FortuneArc arc)
{
if (root == null)
{
return(false);
}
if (root == arc)
{
// no children
if (arc.Left == null && arc.Right == null)
{
if (arc.Parent != null)
{
if (arc.Parent.Left == arc)
{
arc.Parent.Left = null;
}
else if (arc.Parent.Right == arc)
{
arc.Parent.Right = null;
}
}
if (Root == arc)
{
Root = null;
}
return(true);
}
// one child
if (arc.Left != null ^ arc.Right != null)
{
FortuneArc child = arc.Left != null ? arc.Left : arc.Right;
if (arc.Parent != null)
{
if (arc.Parent.Left == arc)
{
arc.Parent.Left = child;
}
else if (arc.Parent.Right == arc)
{
arc.Parent.Right = child;
}
}
else
{
Root = child;
Root.Parent = null;
}
return(true);
}
// have both child
FortuneArc rightLeft = root.Right;
while (rightLeft.Left != null)
{
rightLeft = rightLeft.Left;
}
rightLeft.Left = arc.Left;
if (arc.Parent != null)
{
if (arc.Parent.Left == arc)
{
arc.Parent.Left = arc.Right;
}
else if (arc.Parent.Right == arc)
{
arc.Parent.Right = arc.Right;
}
}
if (Root == arc)
{
Root = arc.Right;
Root.Parent = null;
}
return(true);
}
else
{
if (removeArcRecursive(root.Left, arc))
{
return(true);
}
return(removeArcRecursive(root.Right, arc));
}
}
/// <summary>
/// Finds the arc of the shoreline, under which arose a point event.
/// </summary>
/// <param name="eventX">An X coordinate of event</param>
/// <param name="ly">A Y coordinate of the sweepline</param>
/// <returns>The arc finded or null</returns>
public FortuneArc FindArc(double eventX, double ly)
{
if (Root == null)
{
return(null);
}
FortuneArc currentArc = Root;
while (true)
{
if (currentArc.Left == null && currentArc.Right == null)
{
return(currentArc);
}
if (currentArc.Site.Cell.DataPoint.Y == ly)
{
currentArc = currentArc.Site.Cell.DataPoint.X < eventX ? currentArc.Right : currentArc.Left;
continue;
}
//find the boundaries of the left and right subtrees
FortuneArc leftNeighbor = currentArc.LeftSubtreeBound;
FortuneArc rightNeighbor = currentArc.RightSubtreeBound;
ICoordinate[] pointsPrev = null;
ICoordinate[] pointsNext = null;
if (leftNeighbor != null)
{
pointsPrev = getArcIntersections(leftNeighbor.Site.Cell.DataPoint, currentArc.Site.Cell.DataPoint, ly);
if (pointsPrev.Length == 2)
{
if ((pointsPrev[1].X < pointsPrev[0].X ^ leftNeighbor.Site.Cell.DataPoint.Y < currentArc.Site.Cell.DataPoint.Y))
{
pointsPrev[0] = pointsPrev[1];
}
}
}
if (rightNeighbor != null)
{
pointsNext = getArcIntersections(rightNeighbor.Site.Cell.DataPoint, currentArc.Site.Cell.DataPoint, ly);
if (pointsNext.Length == 2)
{
if ((pointsNext[1].X <pointsNext[0].X ^ rightNeighbor.Site.Cell.DataPoint.Y> currentArc.Site.Cell.DataPoint.Y))
{
pointsNext[0] = pointsNext[1];
}
}
}
if ((currentArc.Left == null || pointsPrev[0].X <= eventX) &&
(currentArc.Right == null || pointsNext[0].X >= eventX))
{
return(currentArc);
}
if (leftNeighbor != null && pointsPrev[0].X > eventX)
{
currentArc = currentArc.Left;
continue;
}
if (rightNeighbor != null && pointsNext[0].X < eventX)
{
currentArc = currentArc.Right;
continue;
}
}
}
/// <summary>
/// Initializes a new instance of MapAround.Geometry.Tessellations.FortuneArc
/// </summary>
internal FortuneArc(FortuneArc left, FortuneArc right)
{
_left = left;
_right = right;
}
private void init(List <VoronoiCell> cells, int lastMaxYIndex)
{
_rectangle = new BoundingRectangle();
_eventList = new LinkedList <FortuneEvent>();
_startVerticalNodes = new List <VoronoiNode>();
// Where several points have the minimum ordinate requires a separate pre-treatment
int skipEventCount = 0;
if (lastMaxYIndex > 0)
{
VoronoiNode previousNode = null;
FortuneArc currentArc = null;
skipEventCount = lastMaxYIndex + 1;
for (int i = 0; i <= lastMaxYIndex; i++)
{
// add an arc of coastline
FortuneArc arc = new FortuneArc();
FortuneSite site = new FortuneSite();
site.Cell = cells[i];
arc.Site = site;
if (currentArc != null)
{
currentArc.Right = arc;
}
currentArc = arc;
if (_shoreLine.Root == null)
{
_shoreLine.Root = arc;
}
if (previousNode != null)
{
arc.LeftNode = previousNode;
}
// add the vertical edges of the Voronoi diagram
if (i < lastMaxYIndex)
{
VoronoiEdge edge = new VoronoiEdge(cells[i], cells[i + 1]);
double middleX = (cells[i].DataPoint.X + cells[i + 1].DataPoint.X) / 2;
double middleY = cells[i].DataPoint.Y;
edge.Node1 = new VoronoiNode(middleX, middleY);
edge.Node1.IsInfinit = true;
_startVerticalNodes.Add(edge.Node1);
edge.Node2 = new VoronoiNode(middleX, middleY);
edge.Node2.IsInfinit = true;
previousNode = edge.Node2;
arc.RightNode = edge.Node2;
cells[i].AddEdge(edge);
cells[i + 1].AddEdge(edge);
}
}
}
// fill all point events
int j = 0;
foreach (VoronoiCell cell in cells)
{
if (skipEventCount > j++)
{
continue;
}
FortunePointEvent ev = new FortunePointEvent();
ev.Point = cell.DataPoint;
ev.Cell = cell;
_eventList.AddLast(ev);
}
}
private void handleCircleEvent(FortuneCircleEvent ev)
{
FortuneArc ln = ev.Arc.LeftNeighbor;
FortuneArc rn = ev.Arc.RightNeighbor;
// remove events range associated with this arc
if (ln.CircleEvent != null)
{
_eventList.Remove(ln.CircleEvent);
}
if (rn.CircleEvent != null)
{
_eventList.Remove(rn.CircleEvent);
}
// remove the arc of coastline
_shoreLine.RemoveArc(ev.Arc);
//fix slave nodes arc ribs
if (ev.Arc.LeftNode != null)
{
ev.Arc.LeftNode.Point = ev.CircleCenter;
ev.Arc.LeftNode.IsInfinit = false;
}
if (ev.Arc.RightNode != null)
{
ev.Arc.RightNode.Point = ev.CircleCenter;
ev.Arc.RightNode.IsInfinit = false;
}
// add a new edge
VoronoiEdge edge = new VoronoiEdge(ln.Site.Cell, rn.Site.Cell);
edge.Node1 = new VoronoiNode(ev.CircleCenter.X, ev.CircleCenter.Y);
edge.Node2 = new VoronoiNode((ln.Site.Cell.DataPoint.X + rn.Site.Cell.DataPoint.X) / 2,
(ln.Site.Cell.DataPoint.Y + rn.Site.Cell.DataPoint.Y) / 2);
//expand the bounding rectangle of the chart
_rectangle.Join(ev.CircleCenter);
// one node of the new edge is fixed, the second - no
edge.Node1.IsInfinit = false;
edge.Node2.IsInfinit = true;
// dobavleyaem edge to cells
ln.Site.Cell.AddEdge(edge);
rn.Site.Cell.AddEdge(edge);
//add a triangle in the Delaunay triangulation, if necessary
if (_buildTriangles)
{
_triangles.Add(ev.Triangle);
}
// not a fixed node is a new edge now vanished neighbors arc
ln.RightNode = edge.Node2;
rn.LeftNode = edge.Node2;
FortuneArc lnln = ln.LeftNeighbor;
FortuneArc lnrn = ln.RightNeighbor;
FortuneArc rnln = rn.LeftNeighbor;
FortuneArc rnrn = rn.RightNeighbor;
// add events to the newly formed circle arcs triples
if (lnln != null)
{
if (lnrn != null)
{
FortuneEvent eventToAdd = getCircleEvent(lnln, ln, lnrn, ev.Point.Y);
if (eventToAdd != null)
{
addCircleEvent(eventToAdd);
}
ln.CircleEvent = eventToAdd;
}
}
if (rnln != null)
{
if (rnrn != null)
{
FortuneEvent eventToAdd = getCircleEvent(rnln, rn, rnrn, ev.Point.Y);
if (eventToAdd != null)
{
addCircleEvent(eventToAdd);
}
rn.CircleEvent = eventToAdd;
}
}
}
private void handlePointEvent(FortunePointEvent ev)
{
if (_shoreLine.Root == null)
{
FortuneArc arc = new FortuneArc();
FortuneSite site = new FortuneSite();
site.Cell = ev.Cell;
arc.Site = site;
_shoreLine.Root = arc;
return;
}
FortuneArc arcAbove = _shoreLine.FindArc(ev.Point.X, ev.Point.Y);
// remove events range from the queue
if (arcAbove.CircleEvent != null)
{
_eventList.Remove(arcAbove.CircleEvent);
}
// create an arc
FortuneArc splitter = new FortuneArc();
splitter.Site = new FortuneSite();
splitter.Site.Cell = ev.Cell;
FortuneArc newArc = _shoreLine.SplitArc(arcAbove, splitter);
FortuneArc ln = newArc.LeftNeighbor;
FortuneArc lnln = null;
if (ln != null)
{
lnln = ln.LeftNeighbor;
}
FortuneArc rn = newArc.RightNeighbor;
FortuneArc rnrn = null;
if (rn != null)
{
rnrn = rn.RightNeighbor;
}
if (ln != null)
{
if (lnln != null)
{
FortuneEvent eventToAdd = getCircleEvent(lnln, ln, newArc, ev.Point.Y);
if (eventToAdd != null)
{
addCircleEvent(eventToAdd);
}
ln.CircleEvent = eventToAdd;
}
}
if (rn != null)
{
if (rnrn != null)
{
FortuneEvent eventToAdd = getCircleEvent(newArc, rn, rnrn, ev.Point.Y);
if (eventToAdd != null)
{
addCircleEvent(eventToAdd);
}
rn.CircleEvent = eventToAdd;
}
}
}