KdTreeNode getNearestNeighbour(Vector3 find, KdTreeNode searchNode, KdTreeNode best)
{
if (searchNode == null)
return best;
if (best == null)
best = searchNode;
bool isNearLeft = isLeftOfAxis(searchNode.axis, searchNode.value.position, find);
var nearChild = isNearLeft ? searchNode.left : searchNode.right;
var farChild = isNearLeft ? searchNode.right : searchNode.left;
//consider currenet node
if (distance(find, searchNode.value) < distance(find, best.value))
best = searchNode;
//search the near branch
best = getNearestNeighbour(find, nearChild, best);
//search away branch maybe
if(distance_axis(find,searchNode)<distance(find,best.value))
best = getNearestNeighbour(find, farChild, best);
return best;
}
KdTreeNode buildTree(List<MapPoint> points, int depth)
{
if (points.Count > 0)
{
int axis = depth % 3;
List<MapPoint> leftList = new List<MapPoint>();
List<MapPoint> rightList = new List<MapPoint>();
KdTreeNode node = new KdTreeNode();
MapPoint selected = points[0];
for (int i = 1; i < points.Count; i++)
{
if (isLeftOfAxis(axis, selected.position, points[i].position))
leftList.Add(points[i]);
else
rightList.Add(points[i]);
}
node.value = selected;
node.left = buildTree(leftList, depth + 1);
node.right = buildTree(rightList, depth + 1);
node.axis = axis;
return node;
}
else return null;
}
KdTreeNode buildTree(List <MapPoint> points, int depth)
{
if (points.Count > 0)
{
int axis = depth % 3;
List <MapPoint> leftList = new List <MapPoint>();
List <MapPoint> rightList = new List <MapPoint>();
KdTreeNode node = new KdTreeNode();
MapPoint selected = points[0];
for (int i = 1; i < points.Count; i++)
{
if (isLeftOfAxis(axis, selected.position, points[i].position))
{
leftList.Add(points[i]);
}
else
{
rightList.Add(points[i]);
}
}
node.value = selected;
node.left = buildTree(leftList, depth + 1);
node.right = buildTree(rightList, depth + 1);
node.axis = axis;
return(node);
}
else
{
return(null);
}
}
KdTreeNode getNearestNeighbour(Vector3 find, KdTreeNode searchNode, KdTreeNode best)
{
if (searchNode == null)
{
return(best);
}
if (best == null)
{
best = searchNode;
}
bool isNearLeft = isLeftOfAxis(searchNode.axis, searchNode.value.position, find);
var nearChild = isNearLeft ? searchNode.left : searchNode.right;
var farChild = isNearLeft ? searchNode.right : searchNode.left;
//consider currenet node
if (distance(find, searchNode.value) < distance(find, best.value))
{
best = searchNode;
}
//search the near branch
best = getNearestNeighbour(find, nearChild, best);
//search away branch maybe
if (distance_axis(find, searchNode) < distance(find, best.value))
{
best = getNearestNeighbour(find, farChild, best);
}
return(best);
}
float distance_axis(Vector3 queryPoint, KdTreeNode axisSpliter)
{
switch (axisSpliter.axis)
{
case 0:
return Math.Abs(axisSpliter.value.position.X - queryPoint.X);
//break;
case 1:
return Math.Abs(axisSpliter.value.position.Y - queryPoint.Y);
//break;
case 2:
return Math.Abs(axisSpliter.value.position.Z - queryPoint.Z);
default:
throw new Exception();
}
}
float distance_axis(Vector3 queryPoint, KdTreeNode axisSpliter)
{
switch (axisSpliter.axis)
{
case 0:
return(Math.Abs(axisSpliter.value.position.X - queryPoint.X));
//break;
case 1:
return(Math.Abs(axisSpliter.value.position.Y - queryPoint.Y));
//break;
case 2:
return(Math.Abs(axisSpliter.value.position.Z - queryPoint.Z));
default:
throw new Exception();
}
}
public KdTree3(List<MapPoint> input)
{
Random r = new Random(242);
root = buildTree(input.OrderBy((m) => r.Next()).ToList(), 0);//build tree after randomizing input order
}
public KdTree3(List <MapPoint> input)
{
Random r = new Random(242);
root = buildTree(input.OrderBy((m) => r.Next()).ToList(), 0);//build tree after randomizing input order
}
