/**
* Enlarge cubical "box", salvaging existing tree structure.
*
* @param tree the root of the tree.
* @param nsteps the current time step
*/
public void expandBox(BTree tree, int nsteps)
{
MathVector rmid = MathVector.makeMathVector();
int k;
bool inbox = icTest(tree);
while (!inbox)
{
double rsize = tree.rsize;
rmid.addScalar(tree.rmin, 0.5 * rsize);
for (k = 0; k < MathVector.NDIM; k++)
{
if (pos.value(k) < rmid.value(k))
{
double rmin = tree.rmin.value(k);
tree.rmin.setValue(k, rmin - rsize);
}
}
tree.rsize = 2.0 * rsize;
if (tree.root != null)
{
MathVector ic = tree.intcoord(rmid);
k = Node.oldSubindex(ic, Node.IMAX >> 1);
Cell newt = Cell.makeCell();
newt.subp [k] = tree.root;
tree.root = newt;
inbox = icTest(tree);
}
}
}
/**
* Descend Tree and insert particle. We're at a body so we need to
* create a cell and attach this body to the cell.
*
* @param p the body to insert
* @param xpic
* @param l
* @param tree the root of the data structure
* @return the subtree with the new body inserted
*/
public override Cell loadTree(Body p, MathVector xpic, int l, BTree tree)
{
// create a Cell
Cell retval = Cell.makeCell();
int si = subindex(tree, l);
// attach this Body node to the cell
retval.subp [si] = this;
// move down one level
si = Node.oldSubindex(xpic, l);
Node rt = retval.subp [si];
if (rt != null)
{
retval.subp [si] = rt.loadTree(p, xpic, l >> 1, tree);
}
else
{
retval.subp [si] = p;
}
return(retval);
}