private HSTNode BuildTreeParallel(int bit, int left, int right, int level = 0)
{
if (bit < 0 || right - left <= 1)
{
return(null);
}
int[] dids = new int[(1 << D) + 1];
dids[0] = left;
dids[1 << D] = right;
SortAndDivide(dids, bit, 0, 1 << D);
HSTNode[] children = new HSTNode[1 << D];
if (level < 3 && right - left > 2048)
{
Parallel.For(0, 1 << D, i => children[i] = BuildTreeParallel(bit - D, dids[i], dids[i + 1], level + 1));
}
else
{
for (int i = (1 << D) - 1; i >= 0; i--)
{
children[i] = BuildTreeSequential(bit - D, dids[i], dids[i + 1]);
}
}
return(new HSTNode(this, dids, children));
}
private HSTNode BuildTreePresorted(int bit, int left, int right)
{
if (bit < 0 || right - left <= 1)
{
return(null);
}
int[] dids = new int[(1 << D) + 1];
dids[0] = left;
dids[1 << D] = right;
dids = FindDivision(dids, bit, 0, 1 << D);
HSTNode[] children = new HSTNode[1 << D];
for (int i = (1 << D) - 1; i >= 0; i--)
{
children[i] = BuildTreePresorted(bit - D, dids[i], dids[i + 1]);
}
return(new HSTNode(this, dids, children));
}
public void RebuildTree(bool presort)
{
size = 2 * AbsoluteMax();
Parallel.For(0, N, i =>
{
ids[i] = i;
ulong hash = 0;
for (int j = 0; j < D; j++)
{
ulong bin = (ulong)(maxv * (points[j + i * D] / size + 0.5)); //normalization should be <0, 1)
if (bin == maxv)
{
bin--; //fix normalization
}
for (int k = j; bin != 0; k += 8 * D)
{
hash += morton[bin & 0xFF] << k;
bin >>= 8;
}
}
hashes[i] = hash;
});
if (presort)
{
Array.Sort(hashes, ids);
root = BuildTreePresorted(bit4dim * D - 1, 0, hashes.Length);
}
else
{
root = BuildTreeParallel(bit4dim * D - 1, 0, hashes.Length);
}
root.Fill(size / 2.0);
}
