public static DbvtNode TopDown(Dbvt pdbvt, ObjectArray <DbvtNode> leaves, int bu_treshold)
{
if (leaves.Count > 1)
{
if (leaves.Count > bu_treshold)
{
DbvtAabbMm vol = Bounds(leaves);
IndexedVector3 org = vol.Center();
ObjectArray <DbvtNode>[] sets = { new ObjectArray <DbvtNode>(), new ObjectArray <DbvtNode>() };
int bestaxis = -1;
int bestmidp = leaves.Count;
int[] a1 = new int[] { 0, 0 };
int[] a2 = new int[] { 0, 0 };
int[] a3 = new int[] { 0, 0 };
int[][] splitcount = new int[][] { a1, a2, a3 };
int i;
for (i = 0; i < leaves.Count; ++i)
{
IndexedVector3 x = leaves[i].volume.Center() - org;
for (int j = 0; j < 3; ++j)
{
++splitcount[j][IndexedVector3.Dot(x, axis[j]) > 0 ? 1 : 0];
}
}
for (i = 0; i < 3; ++i)
{
if ((splitcount[i][0] > 0) && (splitcount[i][1] > 0))
{
int midp = (int)Math.Abs((splitcount[i][0] - splitcount[i][1]));
if (midp < bestmidp)
{
bestaxis = i;
bestmidp = midp;
}
}
}
if (bestaxis >= 0)
{
sets[0].EnsureCapacity(splitcount[bestaxis][0]);
sets[1].EnsureCapacity(splitcount[bestaxis][1]);
Split(leaves, sets[0], sets[1], ref org, ref axis[bestaxis]);
}
else
{
sets[0].EnsureCapacity(leaves.Count / 2 + 1);
sets[1].EnsureCapacity(leaves.Count / 2);
for (int i2 = 0, ni = leaves.Count; i2 < ni; ++i2)
{
sets[i2 & 1].Add(leaves[i2]);
}
}
DbvtNode node = CreateNode(pdbvt, null, ref vol, null);
node._children[0] = TopDown(pdbvt, sets[0], bu_treshold);
node._children[1] = TopDown(pdbvt, sets[1], bu_treshold);
node._children[0].parent = node;
node._children[1].parent = node;
return(node);
}
else
{
BottomUp(pdbvt, leaves);
return(leaves[0]);
}
}
return(leaves[0]);
}