public Point GeneratePointWithin(Boundary boundary)
{
var x = boundary.Center.X + (2 * (_random.NextDouble() - 0.5) * boundary.HalfWidth);
var y = boundary.Center.Y + (2 * (_random.NextDouble() - 0.5) * boundary.HalfHeight);
return new Point(x, y);
}
public Boundary GenerateIntersectingBoundary(Boundary boundary)
{
var center = GeneratePointWithin(boundary);
var halfWidth = boundary.HalfWidth * 0.05 * (_random.NextDouble() + 0.0001);
var halfHeight = boundary.HalfWidth * 0.05 * (_random.NextDouble() + 0.0001);
return new Boundary(center, halfWidth, halfHeight);
}
public List<Point> GeneratePointsWithin(Boundary boundary, int quantity)
{
var points = new List<Point>(quantity);
for (var i = 0; i < quantity; i++)
points.Add(GeneratePointWithin(boundary));
return points;
}
public List<Boundary> GenerateIntersectingBoundaries(Boundary boundary, int quantity)
{
var boundaries = new List<Boundary>();
for (var i = 0; i < quantity; i++)
boundaries.Add(GenerateIntersectingBoundary(boundary));
return boundaries;
}
public ISpatialIndex BuildIndex(IQueryable<ISpatialDocument> documents)
{
if (!documents.Any()) return new EmptySpatialIndex();
var mercator = new Boundary(new Point(0, 0), 180, 90);
var quadTree = new QuadTree<SpatialDocument>(mercator);
foreach (var doc in documents)
{
quadTree.Insert(new SpatialDocument(doc));
}
var index = new SpatialIndex(quadTree);
return index;
}
private Boundary GetSearchArea(KnnQuery query)
{
var top = query.Coordinate.Add(query.MaxDistance, 0);
var bottom = query.Coordinate.Add(-query.MaxDistance, 0);
var right = query.Coordinate.Add(0, query.MaxDistance);
var left = query.Coordinate.Add(0, -query.MaxDistance);
var halfLatitude = (top.Latitude - bottom.Latitude) / 2;
var halfLongitude = (right.Longitude - left.Longitude) / 2;
var center = new Point(left.Longitude + halfLongitude, bottom.Latitude + halfLatitude);
var searchArea = new Boundary(center, halfLongitude, halfLatitude);
// TODO: consider borders. search might need to be split into two.
return searchArea;
}
public bool Intersects(Boundary other)
{
return this.Left <= other.Right && this.Right >= other.Left &&
this.Bottom <= other.Top && this.Top >= other.Bottom;
}