/// <summary>
/// Query the index for nodes with a rectangle.
/// Points that lie exactly on the edge of the rectangle are
/// considered to be within the rectangle and will be returned
/// </summary>
/// <param name="x1">min x</param>
/// <param name="y1">min y</param>
/// <param name="x2">max x</param>
/// <param name="y2">max y</param>
public List <Point <T> > Query(double x1, double y1, double x2, double y2)
{
List <Point <T> > hitPoints = new List <Point <T> >();
Stack <SearchState> stack = new Stack <SearchState>();
stack.Push(new SearchState(0, points.Count - 1, SearchAxis.XAxis));
double x;
double y;
while (stack.Count > 0)
{
SearchState state = stack.Pop();
if (state.End - state.Start <= nodeSize)
{
for (var i = state.Start; i <= state.End; i++)
{
x = points[i].X;
y = points[i].Y;
if (x >= x1 && x <= x2 && y >= y1 && y <= y2)
{
hitPoints.Add(points[i]);
}
}
continue;
}
int m = (state.Start + state.End) / 2;
x = points[m].X;
y = points[m].Y;
if (x >= x1 && x <= x2 && y >= y1 && y <= y2)
{
hitPoints.Add(points[m]);
}
SearchAxis nextAxis = (state.Axis == SearchAxis.XAxis) ? SearchAxis.YAxis : SearchAxis.XAxis;
if ((state.Axis == SearchAxis.XAxis) ? x1 <= x : y1 <= y)
{
stack.Push(new SearchState(state.Start, m - 1, nextAxis));
}
if ((state.Axis == SearchAxis.XAxis) ? x2 >= x : y2 >= y)
{
stack.Push(new SearchState(m + 1, state.End, nextAxis));
}
}
return(hitPoints);
}
/// <summary>
/// Query the index for nodes with a circle.
/// Points that lie exactly on the edge of the circle are
/// considered to be within the circle and will be returned
/// </summary>
/// <param name="x">center X of the circle</param>
/// <param name="y">center Y of the circle</param>
/// <param name="radius">radius of the circle</param>
public List <Point <T> > Query(double x, double y, double radius)
{
List <Point <T> > hitPoints = new List <Point <T> >();
Stack <SearchState> stack = new Stack <SearchState>();
stack.Push(new SearchState(0, points.Count - 1, SearchAxis.XAxis));
double r2 = radius * radius;
while (stack.Count > 0)
{
SearchState state = stack.Pop();
if ((state.End - state.Start) <= nodeSize)
{
for (var i = state.Start; i <= state.End; i++)
{
if (SquareDistance(points[i].X, points[i].Y, x, y) <= r2)
{
hitPoints.Add(points[i]);
}
}
continue;
}
int m = (state.Start + state.End) / 2;
double px = points[m].X;
double py = points[m].Y;
if (SquareDistance(px, py, x, y) <= r2)
{
hitPoints.Add(points[m]);
}
SearchAxis nextAxis = (state.Axis == SearchAxis.XAxis) ? SearchAxis.YAxis : SearchAxis.XAxis;
if ((state.Axis == SearchAxis.XAxis) ? x - radius <= px : y - radius <= py)
{
stack.Push(new SearchState(state.Start, m - 1, nextAxis));
}
if ((state.Axis == SearchAxis.XAxis) ? x + radius >= px : y + radius >= py)
{
stack.Push(new SearchState(m + 1, state.End, nextAxis));
}
}
return(hitPoints);
}
public SearchState(int start, int end, SearchAxis axis)
{
Axis = axis;
Start = start;
End = end;
}
