public void Add(Point2Int point)
{
if (!BoundingBox.ContainsPoint(point))
{
throw new ArgumentOutOfRangeException($"point:{point} is not inside bounding box:{BoundingBox}");
}
// invariant: if points == null then the children are active
if (Points == null)
{
AddPointToChildren(point);
return;
}
var nextIndex = Points.Length;
if (nextIndex + 1 > MaxItems)
{
SpawnChildrenAndSubdivide(point);
return;
}
var newPoints = new Point2Int[Points.Length + 1];
Points.CopyTo(newPoints, 0);
Points = newPoints;
Points[Points.Length - 1] = point;
}
/// <summary>
/// Checks to see if the actual point is in the quad tree as opposed to being bounded by it
/// </summary>
/// <param name="point"></param>
/// <returns></returns>
public bool Contains(Point2Int point)
{
if (!BoundingBox.ContainsPoint(point))
{
return(false);
}
if (Points != null)
{
return(Points.Contains(point));
}
var center = BoundingBox.CenterPoint();
if (point.X < center.X)
{
if (point.Y < center.Y)
{
// bottom left
return(SouthWest.Contains(point));
}
//top left
return(NorthWest.Contains(point));
}
if (point.Y < center.Y)
{
// bottom right
return(SouthEast.Contains(point));
}
//top right
return(NorthEast.Contains(point));
}
/// <summary>
/// Returns whether a given point lies inside the bounding box
/// </summary>
/// <param name="point"></param>
/// <returns></returns>
public bool ContainsPoint(Point2Int point)
{
return(point.X < UpperRight.X &&
point.X >= LowerLeft.X &&
point.Y < UpperRight.Y &&
point.Y >= LowerLeft.Y);
}
public Bounding2DBox(Point2Int lowerLeft, Point2Int upperRight)
{
if (lowerLeft.X > upperRight.X ||
lowerLeft.Y > upperRight.Y)
{
throw new ArgumentOutOfRangeException($"Bottom Left is not bottom left of top right, bottomLeft:{lowerLeft}, topRight:{upperRight}");
}
LowerLeft = lowerLeft;
UpperRight = upperRight;
}
public QuadTree(Bounding2DBox boundingBox, int maxItems, IQuadTreeDivisionStrategy divisionStrategy)
{
if (divisionStrategy == null)
{
throw new ArgumentNullException(nameof(divisionStrategy));
}
MaxItems = maxItems;
DivisionStrategy = divisionStrategy;
BoundingBox = boundingBox;
Points = new Point2Int[0];
}
private void SpawnChildrenAndSubdivide(Point2Int point)
{
QuadTree northWest;
QuadTree northEast;
QuadTree southWest;
QuadTree southEast;
DivisionStrategy.SubDivide(Points, point, BoundingBox, out northWest, out northEast, out southWest, out southEast);
NorthWest = northWest;
NorthEast = northEast;
SouthWest = southWest;
SouthEast = southEast;
Points = null;
}
private void AddPointToChildren(Point2Int point)
{
var center = BoundingBox.CenterPoint();
if (point.X < center.X)
{
if (point.Y < center.Y)
{
SouthWest.Add(point);
return;
}
NorthWest.Add(point);
return;
}
if (point.Y < center.Y)
{
SouthEast.Add(point);
return;
}
NorthEast.Add(point);
}
