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Only let --preserve-point-density-threshold shift density around

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Erica Fischer
2024-10-16 15:08:50 -07:00
parent afb89edf6f
commit ecf01f2231
3 changed files with 45 additions and 774 deletions
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main.cpp
+38 -22
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@@ -288,6 +288,7 @@ struct drop_state {
unsigned long long previndex;
double interval;
double seq; // floating point because interval is
std::vector<int> debt;
};
struct drop_densest {
@@ -306,47 +307,62 @@ int calc_feature_minzoom(struct index *ix, struct drop_state *ds, int maxzoom, d
if (gamma >= 0 && (ix->t == VT_POINT ||
(additional[A_LINE_DROP] && ix->t == VT_LINE) ||
(additional[A_POLYGON_DROP] && ix->t == VT_POLYGON))) {
// increment all the counters
for (ssize_t i = maxzoom; i >= 0; i--) {
ds[i].seq++;
}
// find the highest zoom that is due for a new feature
for (ssize_t i = maxzoom; i >= 0; i--) {
if (ds[i].seq < 0) {
feature_minzoom = i + 1;
// The feature we are pushing out
// appears in zooms i + 1 through maxzoom,
// so track where that was so we can make sure
// not to cluster something else that is *too*
// far away into it.
for (ssize_t j = i + 1; j <= maxzoom; j++) {
ds[j].previndex = ix->ix;
}
break;
} else {
ds[i].seq -= ds[i].interval;
}
}
int chosen = feature_minzoom;
// if that zoom is overdrawn, find the zoom that lent it a feature
// and give that zoom a feature instead
while (ds[feature_minzoom].debt.size() > 0) {
int lender = ds[feature_minzoom].debt.back();
ds[feature_minzoom].debt.pop_back();
feature_minzoom = lender;
}
// If this feature has been chosen only for a high zoom level,
// check whether at a low zoom level it is nevertheless too far
// from the last feature chosen for that low zoom, in which case
// we will go ahead and push it out.
if (preserve_point_density_threshold > 0) {
for (ssize_t i = 0; i < feature_minzoom && i < maxzoom; i++) {
if (ix->ix - ds[i].previndex > ((1LL << (32 - i)) / preserve_point_density_threshold) * ((1LL << (32 - i)) / preserve_point_density_threshold)) {
feature_minzoom = i;
for (ssize_t j = i; j <= maxzoom; j++) {
ds[j].previndex = ix->ix;
if (std::find(ds[i].debt.begin(), ds[i].debt.end(), feature_minzoom) == ds[i].debt.end()) {
ds[i].debt.push_back(feature_minzoom);
feature_minzoom = i;
break;
}
break;
}
}
}
// credit all the zooms that the feature was intended to appear in
// with a feature increment. (Don't credit the one that it actually
// appeared in, or z0 will never be chosen again and will never
// pay off any of its debt)
for (ssize_t i = maxzoom; i >= chosen; i--) {
ds[i].seq -= ds[i].interval;
}
// The feature we are pushing out
// appears in zooms i + 1 through maxzoom,
// so track where that was so we can make sure
// not to cluster something else that is *too*
// far away into it.
for (ssize_t j = feature_minzoom; j <= maxzoom; j++) {
ds[j].previndex = ix->ix;
}
// XXX manage_gap
}
@@ -1056,7 +1072,7 @@ void radix1(int *geomfds_in, int *indexfds_in, int inputs, int prefix, int split
void prep_drop_states(struct drop_state *ds, int maxzoom, int basezoom, double droprate) {
// Needs to be signed for interval calculation
for (ssize_t i = 0; i <= maxzoom; i++) {
for (ssize_t i = 0; i <= std::max(maxzoom, basezoom); i++) {
ds[i].gap = 0;
ds[i].previndex = 0;
ds[i].interval = 0;
@@ -1139,7 +1155,7 @@ void radix(std::vector<struct reader> &readers, int nreaders, FILE *geomfile, FI
geom_total += geomst.st_size;
}
struct drop_state ds[maxzoom + 1];
struct drop_state ds[std::max(maxzoom, basezoom) + 1];
prep_drop_states(ds, maxzoom, basezoom, droprate);
long long progress = 0, progress_max = geom_total, progress_reported = -1;
@@ -2698,7 +2714,7 @@ std::pair<int, metadata> read_input(std::vector<source> &sources, char *fname, i
madvise(geom, indexpos, MADV_SEQUENTIAL);
madvise(geom, indexpos, MADV_WILLNEED);
struct drop_state ds[maxzoom + 1];
struct drop_state ds[std::max(basezoom, maxzoom) + 1];
prep_drop_states(ds, maxzoom, basezoom, droprate);
if (drop_denser > 0) {