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A sorted list is smaller and faster than a map of sets

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This commit is contained in:
Eric Fischer 2016-09-29 14:58:38 -07:00
parent 4c1b135848
commit 7258643d5a
1 changed files with 57 additions and 23 deletions
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80
tile.cpp
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@ -581,8 +581,54 @@ static drawvec reverse_subring(drawvec const &dv) {
return out;
}
struct edge {
unsigned x1;
unsigned y1;
unsigned x2;
unsigned y2;
unsigned ring;
edge(unsigned _x1, unsigned _y1, unsigned _x2, unsigned _y2, unsigned _ring) {
x1 = _x1;
y1 = _y1;
x2 = _x2;
y2 = _y2;
ring = _ring;
}
bool operator<(const edge &s) const {
long long cmp = (long long) y1 - s.y1;
if (cmp == 0) {
cmp = (long long) x1 - s.x1;
}
if (cmp == 0) {
cmp = (long long) y2 - s.y2;
}
if (cmp == 0) {
cmp = (long long) x2 - s.x2;
}
return cmp < 0;
}
};
bool edges_same(std::pair<std::vector<edge>::iterator, std::vector<edge>::iterator> e1, std::pair<std::vector<edge>::iterator, std::vector<edge>::iterator> e2) {
if ((e2.second - e2.first) != (e1.second - e1.first)) {
return false;
}
while (e1.first != e1.second) {
if (e1.first->ring != e2.first->ring) {
return false;
}
++e1.first;
++e2.first;
}
return true;
}
void find_common_edges(std::vector<partial> &partials, int z, int line_detail, double simplification, int maxzoom) {
std::map<drawvec, std::set<size_t>> edges;
#ifdef PERF
clock_t then = clock();
#endif
@ -631,6 +677,7 @@ void find_common_edges(std::vector<partial> &partials, int z, int line_detail, d
// that each edge appears in. (The ring number is across all polygons;
// we don't need to look it back up, just to tell where it changes.)
std::vector<edge> edges;
size_t ring = 0;
for (size_t i = 0; i < partials.size(); i++) {
if (partials[i].t == VT_POLYGON) {
@ -650,20 +697,15 @@ void find_common_edges(std::vector<partial> &partials, int z, int line_detail, d
dv.push_back(partials[i].geoms[j][k]);
}
auto e = edges.find(dv);
if (e != edges.end()) {
e->second.insert(ring);
} else {
std::set<size_t> s;
s.insert(ring);
edges.insert(std::pair<drawvec, std::set<size_t>>(dv, s));
}
edges.push_back(edge(dv[0].x, dv[0].y, dv[1].x, dv[1].y, ring));
}
}
}
}
}
std::sort(edges.begin(), edges.end());
#ifdef PERF
now = clock();
printf("2: %lld\n", (long long) (now - then));
@ -710,7 +752,7 @@ void find_common_edges(std::vector<partial> &partials, int z, int line_detail, d
if (left[1] < left[0]) {
fprintf(stderr, "left misordered\n");
}
std::map<drawvec, std::set<size_t>>::iterator e1 = edges.find(left);
std::pair<std::vector<edge>::iterator, std::vector<edge>::iterator> e1 = std::equal_range(edges.begin(), edges.end(), edge(left[0].x, left[0].y, left[1].x, left[1].y, 0));
for (size_t k = 0; k < s; k++) {
drawvec right;
@ -723,28 +765,18 @@ void find_common_edges(std::vector<partial> &partials, int z, int line_detail, d
right.push_back(g[a + k]);
}
auto e2 = edges.find(right);
std::pair<std::vector<edge>::iterator, std::vector<edge>::iterator> e2 = std::equal_range(edges.begin(), edges.end(), edge(right[0].x, right[0].y, right[1].x, right[1].y, 0));
if (right[1] < right[0]) {
fprintf(stderr, "left misordered\n");
}
if (e1 == edges.end() || e2 == edges.end()) {
if (e1.first == e1.second || e2.first == e2.second) {
fprintf(stderr, "Internal error: polygon edge lookup failed for %lld,%lld to %lld,%lld or %lld,%lld to %lld,%lld\n", left[0].x, left[0].y, left[1].x, left[1].y, right[0].x, right[0].y, right[1].x, right[1].y);
for (auto ei = edges.begin(); ei != edges.end(); ++ei) {
if (ei->first[1] < ei->first[0]) {
fprintf(stderr, "%lld,%lld to %lld,%lld %lu\n",
ei->first[0].x, ei->first[0].y,
ei->first[1].x, ei->first[1].y,
ei->second.size());
}
}
exit(EXIT_FAILURE);
}
if (e1->second != e2->second) {
if (!edges_same(e1, e2)) {
g[a + k].necessary = 1;
necessaries.insert(g[a + k]);
}
@ -760,6 +792,8 @@ void find_common_edges(std::vector<partial> &partials, int z, int line_detail, d
}
}
edges.clear();
#ifdef PERF
now = clock();
printf("3: %lld\n", (long long) (now - then));