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Compare segments to the current pool as they come into scope

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Erica Fischer
2023-11-13 13:08:46 -08:00
parent 1238711571
commit c05ae1bbff
1 changed files with 18 additions and 22 deletions
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polygon.cpp
+18 -22
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@@ -372,36 +372,31 @@ void snap_round(std::vector<segment> &segs) {
// do the scan // do the scan
std::set<size_t> active; std::set<size_t> active;
std::set<std::pair<size_t, size_t>> already;
size_t bottom = 0; size_t bottom = 0;
for (size_t i = 0; i < tops.size(); i++) { for (size_t i = 0; i < tops.size(); i++) {
// activate anything that is coming into view // activate anything that is coming into view.
active.insert(tops[i].segment); active.insert(tops[i].segment);
if (i + 1 < tops.size() && tops[i + 1].y == tops[i].y) { // fprintf(stderr, "into scope: %zu at %lld\n", tops[i].segment, tops[i].y);
continue;
}
// look at the active segments // compare anything coming into view with the other
// currently-active segments
for (size_t s1 : active) { for (size_t s2 : active) {
for (size_t s2 : active) { size_t s1 = tops[i].segment;
if (s1 < s2) {
if (previously_affected.size() == 0 || // first time
previously_affected.count(segs[s1]) > 0 ||
previously_affected.count(segs[s2]) > 0) {
if (already.find(std::make_pair(s1, s2)) == already.end()) {
if (intersect(segs, s1, s2, affected)) {
// if the segments intersected,
// we need to do another scan,
// because introducing a new node
// may have caused new intersections
again = true;
}
already.insert(std::make_pair(s1, s2)); if (s1 != s2) {
} if (previously_affected.size() == 0 || // first time
previously_affected.count(segs[s1]) > 0 ||
previously_affected.count(segs[s2]) > 0) {
// fprintf(stderr, "check %zu vs %zu\n", s1, s2);
if (intersect(segs, s1, s2, affected)) {
// if the segments intersected,
// we need to do another scan,
// because introducing a new node
// may have caused new intersections
again = true;
} }
} }
} }
@@ -413,6 +408,7 @@ void snap_round(std::vector<segment> &segs) {
while (bottom < bottoms.size() && bottoms[bottom].y < tops[i + 1].y) { while (bottom < bottoms.size() && bottoms[bottom].y < tops[i + 1].y) {
auto found = active.find(bottoms[bottom].segment); auto found = active.find(bottoms[bottom].segment);
active.erase(found); active.erase(found);
// fprintf(stderr, "out of scope: %zu at %lld\n", bottoms[bottom].segment, bottoms[bottom].y);
bottom++; bottom++;
} }
} }