ANNbd_tree::ANNbd_tree( // construct from point array
ES_INFO* es_info,
ANNpointArray pa, // point array (with at least n pts)
int n, // number of points
int dd, // dimension
int bs, // bucket size
ANNsplitRule split, // splitting rule
ANNshrinkRule shrink) // shrinking rule
: ANNkd_tree(n, dd, bs) // build skeleton base tree
{
pts = pa; // where the points are
if (n == 0) return; // no points--no sweat
ANNorthRect bnd_box(dd); // bounding box for points
// construct bounding rectangle
annEnclRect(es_info, pa, pidx, n, dd, bnd_box);
// copy to tree structure
bnd_box_lo = annCopyPt(dd, bnd_box.lo);
bnd_box_hi = annCopyPt(dd, bnd_box.hi);
switch (split) { // build by rule
case ANN_KD_STD: // standard kd-splitting rule
root = rbd_tree(es_info, pa, pidx, n, dd, bs, bnd_box, kd_split, shrink);
break;
case ANN_KD_MIDPT: // midpoint split
root = rbd_tree(es_info, pa, pidx, n, dd, bs, bnd_box, midpt_split, shrink);
break;
case ANN_KD_SUGGEST: // best (in our opinion)
case ANN_KD_SL_MIDPT: // sliding midpoint split
root = rbd_tree(es_info, pa, pidx, n, dd, bs, bnd_box, sl_midpt_split, shrink);
break;
case ANN_KD_FAIR: // fair split
root = rbd_tree(es_info, pa, pidx, n, dd, bs, bnd_box, fair_split, shrink);
break;
case ANN_KD_SL_FAIR: // sliding fair split
root = rbd_tree(es_info, pa, pidx, n, dd, bs,
bnd_box, sl_fair_split, shrink);
break;
default:
annError("Illegal splitting method", ANNabort);
}
}
ANNkd_ptr rbd_tree( // recursive construction of bd-tree
ANNpointArray pa, // point array
ANNidxArray pidx, // point indices to store in subtree
int n, // number of points
int dim, // dimension of space
int bsp, // bucket space
ANNorthRect &bnd_box, // bounding box for current node
ANNkd_splitter splitter, // splitting routine
ANNshrinkRule shrink) // shrinking rule
{
ANNdecomp decomp; // decomposition method
ANNorthRect inner_box(dim); // inner box (if shrinking)
if (n <= bsp) { // n small, make a leaf node
if (n == 0) // empty leaf node
return KD_TRIVIAL; // return (canonical) empty leaf
else // construct the node and return
return new ANNkd_leaf(n, pidx);
}
decomp = selectDecomp( // select decomposition method
pa, pidx, // points and indices
n, dim, // number of points and dimension
bnd_box, // current bounding box
splitter, shrink, // splitting/shrinking methods
inner_box); // inner box if shrinking (returned)
if (decomp == SPLIT) { // split selected
int cd; // cutting dimension
ANNcoord cv; // cutting value
int n_lo; // number on low side of cut
// invoke splitting procedure
(*splitter)(pa, pidx, bnd_box, n, dim, cd, cv, n_lo);
ANNcoord lv = bnd_box.lo[cd]; // save bounds for cutting dimension
ANNcoord hv = bnd_box.hi[cd];
bnd_box.hi[cd] = cv; // modify bounds for left subtree
ANNkd_ptr lo = rbd_tree( // build left subtree
pa, pidx, n_lo, // ...from pidx[0..n_lo-1]
dim, bsp, bnd_box, splitter, shrink);
bnd_box.hi[cd] = hv; // restore bounds
bnd_box.lo[cd] = cv; // modify bounds for right subtree
ANNkd_ptr hi = rbd_tree( // build right subtree
pa, pidx + n_lo, n-n_lo,// ...from pidx[n_lo..n-1]
dim, bsp, bnd_box, splitter, shrink);
bnd_box.lo[cd] = lv; // restore bounds
// create the splitting node
return new ANNkd_split(cd, cv, lv, hv, lo, hi);
}
else { // shrink selected
int n_in; // number of points in box
int n_bnds; // number of bounding sides
annBoxSplit( // split points around inner box
pa, // points to split
pidx, // point indices
n, // number of points
dim, // dimension
inner_box, // inner box
n_in); // number of points inside (returned)
ANNkd_ptr in = rbd_tree( // build inner subtree pidx[0..n_in-1]
pa, pidx, n_in, dim, bsp, inner_box, splitter, shrink);
ANNkd_ptr out = rbd_tree( // build outer subtree pidx[n_in..n]
pa, pidx+n_in, n - n_in, dim, bsp, bnd_box, splitter, shrink);
ANNorthHSArray bnds = NULL; // bounds (alloc in Box2Bnds and
// ...freed in bd_shrink destroyer)
annBox2Bnds( // convert inner box to bounds
inner_box, // inner box
bnd_box, // enclosing box
dim, // dimension
n_bnds, // number of bounds (returned)
bnds); // bounds array (modified)
// return shrinking node
return new ANNbd_shrink(n_bnds, bnds, in, out);
}
}
