static kdnode *
build(kdtree *tree, int depth, double bx0, double bx1, double by0, double by1,
int l, int u, double *x, double *y)
{
int m, i;
kdnode *p = MALLOC(1, kdnode);
p->empty = false;
depth++;
if (u-l+1 <= BUCKET_CUTOFF) {
p->bnds_available = false;
p->bucket = 1;
p->lopt = l;
p->hipt = u;
for (i = l; i <= u; i++) {
tree->bucket_ptr[tree->perm[i]] = p;
}
} else {
if (depth % BNDSLEVEL) {
p->bnds_available = false;
} else {
p->bnds_available = true;
p->bnds_x[0] = bx0; p->bnds_x[1] = bx1;
p->bnds_y[0] = by0; p->bnds_y[1] = by1;
}
p->bucket = 0;
p->cutdim = findmaxspread(tree, l, u, x, y);
m = (l + u) / 2;
assert(p->cutdim == 0 || p->cutdim == 1);
if (p->cutdim == 0) {
select_rs(tree->perm, x, l, u, m);
p->cutval = x[tree->perm[m]];
p->loson = build(tree, depth, bx0, p->cutval, by0, by1,
l, m, x, y);
p->hison = build(tree, depth, p->cutval, bx0, by0, by1,
m + 1, u, x, y);
} else {
select_rs(tree->perm, y, l, u, m);
p->cutval = y[tree->perm[m]];
p->loson = build(tree, depth, bx0, bx1, by0, p->cutval,
l, m, x, y);
p->hison = build(tree, depth, bx0, bx1, p->cutval, by1,
m + 1, u, x, y);
}
p->loson->father = p;
p->hison->father = p;
}
return p;
}
struct kdnode *build_kd(struct perm_pt *p_pts, int l, int u)
{
int cutoff = 20;
int m;
struct kdnode *p;
p = (struct kdnode *) ckalloc(sizeof(struct kdnode));
if( u-l+1 <= cutoff )
{
p->bucket = 1;
p->lopt = l;
p->hipt = u;
p->loson = NULL;
p->hison = NULL;
}
else
{
p->bucket = 0;
p->cutdim = findmaxspread(p_pts, l, u);
if( p->cutdim == 1 ) quick_sort_plist_x(p_pts, l, u);
else if( p->cutdim == 2 ) quick_sort_plist_y(p_pts, l, u);
m = (l + u) / 2;
m = adjust_m(p_pts, l, u, m, p->cutdim);
p->cutval = px(p_pts, m, p->cutdim);
if( p->cutdim == 1 )
{
p->loson = build_kd(p_pts, l, m-1);
p->hison = build_kd(p_pts, m+1, u);
}
else
{
p->loson = build_kd(p_pts, l, m-1);
p->hison = build_kd(p_pts, m+1, u);
}
}
return p;
}
