private void nearest(KDTreeNode <T> current, double[] position, KDTreeNodeCollection <T> list)
{
// Compute distance from this node to the point
double d = distance(position, current.Position);
if (current.IsLeaf)
{
// Base: node is leaf
list.Add(current, d);
}
else
{
// Check for leafs on the opposite sides of
// the subtrees to nearest possible neighbors.
// Prepare for recursion. The following null checks
// will be used to avoid function calls if possible
double value = position[current.Axis];
double median = current.Position[current.Axis];
double u = (value - median);
if (u < 0)
{
if (current.Left != null)
{
nearest(current.Left, position, list);
}
list.Add(current, d);
if (current.Right != null)
{
if ((u * u) < list.Distance.Max)
{
nearest(current.Right, position, list);
}
}
}
else
{
if (current.Right != null)
{
nearest(current.Right, position, list);
}
list.Add(current, d);
if (current.Left != null)
{
if ((u * u) < list.Distance.Max)
{
nearest(current.Left, position, list);
}
}
}
}
}
private bool approximate(KDTreeNode <T> current, double[] position,
KDTreeNodeCollection <T> list, int maxLeaves, ref int visited)
{
// Compute distance from this node to the point
double d = distance(position, current.Position);
list.Add(current, d);
if (++visited > maxLeaves)
{
return(true);
}
// Check for leafs on the opposite sides of
// the subtrees to nearest possible neighbors.
// Prepare for recursion. The following null checks
// will be used to avoid function calls if possible
double value = position[current.Axis];
double median = current.Position[current.Axis];
double u = value - median;
if (u <= 0)
{
if (current.Left != null)
{
if (approximate(current.Left, position, list, maxLeaves, ref visited))
{
return(true);
}
}
if (current.Right != null && Math.Abs(u) <= list.Maximum)
{
if (approximate(current.Right, position, list, maxLeaves, ref visited))
{
return(true);
}
}
}
else
{
if (current.Right != null)
{
approximate(current.Right, position, list, maxLeaves, ref visited);
}
if (current.Left != null && Math.Abs(u) <= list.Maximum)
{
if (approximate(current.Left, position, list, maxLeaves, ref visited))
{
return(true);
}
}
}
return(false);
}