// Recursive Delaunay Triangulation Procedure
// Contains modifications for axis-switching division.
void CDelaunay::build(int lo, int hi, EdgePointer *le, EdgePointer *re, int rows)
{
EdgePointer a, b, c, ldo, rdi, ldi, rdo, maxx, minx;
int split, lowrows;
int low, high;
SitePointer s1, s2, s3;
low = lo;
high = hi;
if ( low < (high-2) ) {
// more than three elements; do recursion
minx = sp[low];
maxx = sp[high];
if (rows == 1) { // time to switch axis of division
spsorty( sp, low, high);
rows = 65536;
}
lowrows = rows/2;
split = low - 1 + (int)
(0.5 + ((double)(high-low+1) * ((double)lowrows / (double)rows)));
build( low, split, &ldo, &ldi, lowrows );
build( split+1, high, &rdi, &rdo, (rows-lowrows) );
doMerge(&ldo, ldi, rdi, &rdo);
while (orig(ldo) != minx) {
ldo = rprev(ldo);
}
while (orig(rdo) != maxx) {
rdo = (SitePointer) lprev(rdo);
}
*le = ldo;
*re = rdo;
}
else if (low >= (high - 1)) { // two or one points
a = makeEdge(sp[low], sp[high]);
*le = a;
*re = (EdgePointer) sym(a);
} else { // three points
// 3 cases: triangles of 2 orientations, and 3 points on a line
a = makeEdge((s1 = sp[low]), (s2 = sp[low+1]));
b = makeEdge(s2, (s3 = sp[high]));
splice((EdgePointer) sym(a), b);
if (ccw(s1, s3, s2)) {
c = connectLeft(b, a);
*le = (EdgePointer) sym(c);
*re = c;
} else {
*le = a;
*re = (EdgePointer) sym(b);
if (ccw(s1, s2, s3)) {
// not colinear
c = connectLeft(b, a);
}
}
}
}
void dwg :: connectLeft(dwg_node *l) {
connectLeft(l,0);
}
