public void SplitBeachSection(Point site)
{
BeachSection containingBeachSection = BeachSectionContainingPoint(site);
BeachSection newBeachSectionLeft = new BeachSection(containingBeachSection.focus, containingBeachSection.leftBoundary, site);
BeachSection newBeachSectionCentre = new BeachSection(site, containingBeachSection.focus, containingBeachSection.focus);
BeachSection newBeachSectionRight = new BeachSection(containingBeachSection.focus, site, containingBeachSection.rightBoundary);
beachSections.Remove(containingBeachSection);
beachSections.Add(newBeachSectionLeft);
beachSections.Add(newBeachSectionCentre);
beachSections.Add(newBeachSectionRight);
foreach (IntersectEventPoint iep in IntersectEventPoint.FromBeachSections(new List <BeachSection> {
newBeachSectionLeft, newBeachSectionRight
}))
{
if (iep.Point().y <= site.y)
{
eventQueue.Add(iep);
}
}
foreach (IntersectEventPoint iep in IntersectEventPoint.FromBeachSections(new List <BeachSection> {
containingBeachSection
}))
{
if (iep.Point().y <= site.y)
{
eventQueue.Remove(iep);
}
}
}
public override bool Equals(object obj)
{
if (obj == null || GetType() != obj.GetType())
{
return(false);
}
IntersectEventPoint that = (IntersectEventPoint)obj;
List <Point> thisPoints = new List <Point> {
a, b, c
};
return(thisPoints.Contains(that.a) && thisPoints.Contains(that.b) && thisPoints.Contains(that.c));
}
public static HashSet <IntersectEventPoint> FromBeachSections(IEnumerable <BeachSection> beachSections)
{
HashSet <IntersectEventPoint> set = new HashSet <IntersectEventPoint>();
foreach (BeachSection bs in beachSections)
{
if (!bs.IsLeftmost() &&
!bs.IsRightmost() &&
bs.leftBoundary != bs.rightBoundary
)
{
Line lineA = bs.leftBoundary.LineWith(bs.rightBoundary);
Line lineB = bs.leftBoundary.LineWith(bs.focus);
if (!lineA.Equals(lineB) && bs.Closed())
{
IntersectEventPoint iep = new IntersectEventPoint(bs);
set.Add(iep);
}
}
}
return(set);
}
public void ConsumeBeachSection(IntersectEventPoint intersectEventPoint)
{
BeachSection consumedBeachSection = intersectEventPoint.consumedBeachSection;
BeachSection leftBeachSection = beachSections.Predecessor(consumedBeachSection);
BeachSection rightBeachSection = beachSections.Successor(consumedBeachSection);
BeachSection newLeftBeachSection = new BeachSection(leftBeachSection.focus, leftBeachSection.leftBoundary, rightBeachSection.focus);
BeachSection newRightBeachSection = new BeachSection(rightBeachSection.focus, leftBeachSection.focus, rightBeachSection.rightBoundary);
beachSections.Remove(consumedBeachSection);
beachSections.Remove(leftBeachSection);
beachSections.Remove(rightBeachSection);
beachSections.Add(newLeftBeachSection);
beachSections.Add(newRightBeachSection);
foreach (IntersectEventPoint iep in IntersectEventPoint.FromBeachSections(new List <BeachSection> {
leftBeachSection, rightBeachSection
}))
{
if (iep.Point().y <= intersectEventPoint.Point().y)
{
eventQueue.Remove(iep);
}
}
foreach (IntersectEventPoint iep in IntersectEventPoint.FromBeachSections(new List <BeachSection> {
newLeftBeachSection, newRightBeachSection
}))
{
if (iep.Point().y <= intersectEventPoint.Point().y)
{
if (!iep.Equals(intersectEventPoint))
{
eventQueue.Add(iep);
}
}
}
}
internal Dictionary <Point, VoronoiCellUnorganised> WithPoints(IEnumerable <Point> points)
{
if (points.Count() == 0)
{
throw new System.ArgumentException("No points provided");
}
cells = new Dictionary <Point, VoronoiCellUnorganised>();
// We'll start at the top of the field and work down.
// Initialise the beachline with all points having most Y coordinate.
// There'll often be only one of these, but calculating their interactions
// with no background beachline is more difficult so it helps to include them all at once.
HashSet <Point> distinctPoints = new HashSet <Point>(points);
List <Point> highestPoints = FindHighestPoints(distinctPoints).OrderBy(p => p.x).ToList();
float mostY = highestPoints.First().y;
IEnumerable <Point> otherPoints = distinctPoints.Where(p => p.y < mostY);
List <BeachSection> initialBeachSections = new List <BeachSection>();
for (int i = 0; i < highestPoints.Count; i++)
{
Point left = null;
Point right = null;
Point focus = highestPoints[i];
cells[focus] = new VoronoiCellUnorganised(focus);
if (i > 0)
{
left = highestPoints[i - 1];
cells[focus].AddBorder(left);
}
if (i + 1 < highestPoints.Count)
{
right = highestPoints[i + 1];
cells[focus].AddBorder(right);
}
BeachSection bs = new BeachSection(focus, left, right);
initialBeachSections.Add(bs);
}
BeachLine beachLine = new BeachLine(initialBeachSections, otherPoints);
// For the remaining points that don't lie on the initial beachline, handle them in descending order
// of their y coordinate.
while (beachLine.HasMoreEvents())
{
IEventPoint eventPoint = beachLine.PopEvent();
if (eventPoint.EventType() == "Site")
{
Point site = eventPoint.Point();
BeachSection containingBeachSection = beachLine.BeachSectionContainingPoint(site);
VoronoiCellUnorganised cell = new VoronoiCellUnorganised(site);
cells[site] = cell;
AddBorderBetweenCells(site, containingBeachSection.focus);
beachLine.SplitBeachSection(site);
}
else // EventType = "Intersect"
{
IntersectEventPoint intersectEventPoint = (IntersectEventPoint)eventPoint;
BeachSection consumedBeachSection = intersectEventPoint.consumedBeachSection;
AddBorderBetweenCells(consumedBeachSection.leftBoundary, consumedBeachSection.rightBoundary);
beachLine.ConsumeBeachSection(intersectEventPoint);
}
}
return(cells);
}