public Int32 CompareTo(CircleEvent other)
{
if (this.vertex.x < other.vertex.x)
{
return(-1);
}
if (this.vertex.x > other.vertex.x)
{
return(1);
}
return(0);
}
void ProcessEvent(CircleEvent circleEvent)
{
//Debug.Log("ProcessEvent: " + circleEvent);
// if event has been marked as invalid, skip
if (!circleEvent.valid)
{
return;
}
// FIXME: remove
vertexList.Add(circleEvent.center);
// circle event is associated with arc which is disappearing from beachline
// that arc has two breakpoints which are converging, so update those edges associated with
// those breakpoints with event vertex. this is a vertex in the voronoi diagram
circleEvent.arc.upperBreakpoint.edge.AssignVertex(
circleEvent.center,
circleEvent.arc.upperBreakpoint.intersectionIndex);
if (circleEvent.arc.upperBreakpoint.edge.done)
{
AddFinishedEdge(circleEvent.arc.upperBreakpoint.edge);
}
circleEvent.arc.lowerBreakpoint.edge.AssignVertex(
circleEvent.center,
circleEvent.arc.lowerBreakpoint.intersectionIndex);
if (circleEvent.arc.lowerBreakpoint.edge.done)
{
AddFinishedEdge(circleEvent.arc.lowerBreakpoint.edge);
}
// convergence of edge means that arc associated w/ circle event also converged to a point and
// needs to be removed from beachline
// a new edge and associated breakpoints are added instead
// edge starts w/ circle event vertex
var arcNode = beachline.GetNode(circleEvent.arc);
var lowerNode = beachline.GetPredecessor(arcNode);
var upperNode = beachline.GetSuccessor(arcNode);
beachline.Delete(circleEvent.arc);
// update vertex of new edge between lower/upper nodes
var lowerArc = beachline.GetNodeData(lowerNode);
var upperArc = beachline.GetNodeData(upperNode);
lowerArc.upperBreakpoint.edge.AssignVertex(circleEvent.center,
(upperArc.site.x > lowerArc.site.x) ? 1 : 0);
// check for new circle events for each side of arc that has been removed
CreateCircleEvent(lowerNode, circleEvent.vertex.x);
CreateCircleEvent(upperNode, circleEvent.vertex.x);
//beachline.Dump();
}
public Int32 CompareTo(object otherObj)
{
CircleEvent other = (CircleEvent)otherObj;
if (this.vertex.x < other.vertex.x)
{
return(-1);
}
if (this.vertex.x > other.vertex.x)
{
return(1);
}
return(0);
}
public void CreateCircleEvent(object arcNode, float directrix)
{
if (arcNode == null)
{
return;
}
// invalidate any circle event already associated with arc
// this is cheaper than removing the entry from the Q
var middleArc = beachline.GetNodeData(arcNode);
if (middleArc.circleEvent != null)
{
middleArc.circleEvent.valid = false;
middleArc.circleEvent = null;
}
//beachline.Dump();
var lowerNode = beachline.GetPredecessor(arcNode);
var upperNode = beachline.GetSuccessor(arcNode);
if (lowerNode == null || upperNode == null)
{
return;
}
var lowerArc = beachline.GetNodeData(lowerNode);
var upperArc = beachline.GetNodeData(upperNode);
// find determinant for three sites
// order of comparison is important here, this assumes bottom to top
// determinant < 0 => converging edges, consider intersection
// = 0 => colinear, ignore
// > 0 => diverging edges, ignore
var ba = middleArc.site - lowerArc.site;
var cb = upperArc.site - middleArc.site;
var determinant = ba.x * cb.y - ba.y * cb.x;
if (determinant >= 0)
{
/*
* Debug.Log(String.Format(
* "ignoring invalid circle event: larc: {0}\nmarc: {1}\nuarc: {2}\ndx: {3} determinant:{4}",
* lowerArc, middleArc, upperArc, directrix, determinant));
*/
return;
}
// find center of circle
Vector2 center;
float radius;
var circleExists = Geometry.FindCircle(
lowerArc.site,
middleArc.site,
upperArc.site,
out center,
out radius
);
if (circleExists && (center.x + radius) > directrix)
{
var point = new Vector2(center.x + radius, center.y);
var circleEvent = new CircleEvent(middleArc, center, point);
/*
* Debug.Log(String.Format(
* "new circle event: larc: {0}\nmarc: {1}\nuarc: {2}\ndx: {3} determinant:{4}\ncenter: {5} point: {6}\nevent: {7}",
* lowerArc, middleArc, upperArc, directrix, determinant, center, point, circleEvent));
*/
middleArc.circleEvent = circleEvent;
// add to event q
eventQ.Insert(circleEvent);
}
}
