private void ProcessSiteEvent(FortunesAlgorithmState state, SiteEvent e)
{
var sweepY = e.Y;
var newParabolaFocus = e.Point;
if (state.Root == null)
{
state.Root = new Node(new ParabolaData(newParabolaFocus));
return;
}
var cutNode = state.Root.FindDeepestNodeAtX(newParabolaFocus.X, newParabolaFocus.Y);
if (!cutNode.IsLeaf())
{
throw new NotSupportedException("Cutting edge node not supported.");
}
var cutParabolaFocus = ((ParabolaData)cutNode.Data).Focus;
Node leftParabola, centerParabola, rightParabola;
Node newNode = BeachlineNodeOperations.ComputeThreeParabolasFromDifferentYParabolaNodeCut(
cutParabolaFocus, newParabolaFocus,
out leftParabola, out centerParabola, out rightParabola);
NodeOperations.ReplaceNode(cutNode, newNode, ref state.Root);
state.DelanayEdges.Add(new VoronoiEdge(newParabolaFocus, true, cutParabolaFocus, true));
Node leftLeftParabola;
if (leftParabola.TryGetLeftLeaf(out leftLeftParabola))
{
HandleAddCircleEvent(state, leftLeftParabola, leftParabola, centerParabola, sweepY);
}
Node rightRightParabola;
if (rightParabola.TryGetRightLeaf(out rightRightParabola))
{
HandleAddCircleEvent(state, centerParabola, rightParabola, rightRightParabola, sweepY);
}
}
void ProcessCircleEvent(FortunesAlgorithmState state, CircleEvent e)
{
var sweepY = e.Y;
var swallowedParabolaNode = e.SwallowedParabolaNode;
if (swallowedParabolaNode.Parent == null)
{
return;
}
Node leftAncestor, rightAncestor;
swallowedParabolaNode.FindDirectionalAncestors(out leftAncestor, out rightAncestor);
var leftAncestorEdgeRayData = (EdgeRayData)leftAncestor.Data;
var rightAncestorEdgeRayData = (EdgeRayData)rightAncestor.Data;
state.VoronoiEdges.Add(new VoronoiEdge(
leftAncestorEdgeRayData.Origin, leftAncestorEdgeRayData.IsOriginBounded, e.Circumcenter, true));
state.VoronoiEdges.Add(new VoronoiEdge(
rightAncestorEdgeRayData.Origin, leftAncestorEdgeRayData.IsOriginBounded, e.Circumcenter, true));
var leftParabolaNode = leftAncestor.Left.GetRightmost();
var leftParabolaFocus = ((ParabolaData)leftParabolaNode.Data).Focus;
var rightParabolaNode = rightAncestor.Right.GetLeftmost();
var rightParabolaFocus = ((ParabolaData)rightParabolaNode.Data).Focus;
state.DelanayEdges.Add(new VoronoiEdge(leftParabolaFocus, true, rightParabolaFocus, true));
// One ancestor will become the edge shared by the left/right parabolas,
// the other will be deleted. It's guranteed our parent is one of these
// ancestors and that the other ancestor is above it (that is, it has a
// parent) so opt to delete our parent.
var nodeParent = swallowedParabolaNode.Parent;
var nodeSibling = nodeParent.Left == swallowedParabolaNode ? nodeParent.Right : nodeParent.Left;
NodeOperations.ReplaceNode(nodeParent, nodeSibling, ref state.Root);
nodeParent.Left = nodeParent.Right = null;
var olderAncestor = nodeParent == leftAncestor ? rightAncestor : leftAncestor;
var leftFocusRightFocus = rightParabolaFocus - leftParabolaFocus; // x is positive
var edgeDirection = new TVector2(-leftFocusRightFocus.Y, leftFocusRightFocus.X);
var leftRightFocusCenter = new TVector2(
MathUtil.Average(leftParabolaFocus.X, rightParabolaFocus.X),
MathUtil.Average(leftParabolaFocus.Y, rightParabolaFocus.Y));
var dy = sweepY - leftRightFocusCenter.Y;
var edgeStart = e.Circumcenter;
olderAncestor.Data = new EdgeRayData(true, edgeStart, edgeDirection);
// add new potential circle events
Node leftLeftLeaf;
if (leftParabolaNode.TryGetLeftLeaf(out leftLeftLeaf))
{
HandleAddCircleEvent(state, leftLeftLeaf, leftParabolaNode, rightParabolaNode, sweepY);
}
Node rightRightLeaf;
if (rightParabolaNode.TryGetRightLeaf(out rightRightLeaf))
{
HandleAddCircleEvent(state, leftParabolaNode, rightParabolaNode, rightRightLeaf, sweepY);
}
}