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Don't coalesce features that cross tile boundaries

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This commit is contained in:
Erica Fischer
2023-08-11 14:38:55 -07:00
parent c2895dacaa
commit 149ae6f8f2
7 changed files with 7556 additions and 13128 deletions
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tile.cpp
+37 -3
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@@ -1906,6 +1906,24 @@ void add_sample_to(std::vector<T> &vals, T val, size_t &increment, size_t seq) {
}
}
// do not allow coalescing geometries that cross tile boundaries
bool coalescable(drawvec const &geom, int z) {
long long tile_extent = (1LL << 32) >> z;
for (size_t i = 1; i < geom.size(); i++) {
if (geom[i].op == VT_LINETO) {
if ((geom[i - 1].x < 0) != (geom[i].x < 0) ||
(geom[i - 1].x > tile_extent) != (geom[i].x > tile_extent) ||
(geom[i - 1].y < 0) != (geom[i].y < 0) ||
(geom[i - 1].y > tile_extent) != (geom[i].y > tile_extent)) {
return false;
}
}
}
return true;
}
long long write_tile(decompressor *geoms, std::atomic<long long> *geompos_in, char *stringpool, int z, const unsigned tx, const unsigned ty, const int detail, int min_detail, sqlite3 *outdb, const char *outdir, int buffer, const char *fname, compressor **geomfile, int minzoom, int maxzoom, double todo, std::atomic<long long> *along, long long alongminus, double gamma, int child_shards, long long *pool_off, unsigned *initial_x, unsigned *initial_y, std::atomic<int> *running, double simplification, std::vector<std::map<std::string, layermap_entry>> *layermaps, std::vector<std::vector<std::string>> *layer_unmaps, size_t tiling_seg, size_t pass, unsigned long long mingap, long long minextent, double fraction, const char *prefilter, const char *postfilter, struct json_object *filter, write_tile_args *arg, atomic_strategy *strategy, bool compressed_input) {
double merge_fraction = 1;
double mingap_fraction = 1;
@@ -2137,7 +2155,8 @@ long long write_tile(decompressor *geoms, std::atomic<long long> *geompos_in, ch
if (indices.size() < MAX_INDICES) {
indices.push_back(sf.index);
}
if (sf.gap < (long long) mingap && find_partial(partials, sf, which_partial, layer_unmaps, LLONG_MAX)) {
if (sf.gap < (long long) mingap && find_partial(partials, sf, which_partial, layer_unmaps, LLONG_MAX) &&
coalescable(sf.geometry, z) && coalescable(partials[which_partial].geoms[0], z)) {
partials[which_partial].geoms.push_back(sf.geometry);
partials[which_partial].coalesced = true;
coalesced_area += sf.extent;
@@ -2156,7 +2175,8 @@ long long write_tile(decompressor *geoms, std::atomic<long long> *geompos_in, ch
}
} else if (additional[A_COALESCE_SMALLEST_AS_NEEDED]) {
add_sample_to(extents, sf.extent, extents_increment, seq);
if (sf.extent + coalesced_area <= minextent && find_partial(partials, sf, which_partial, layer_unmaps, minextent)) {
if (sf.extent + coalesced_area <= minextent && find_partial(partials, sf, which_partial, layer_unmaps, minextent) &&
coalescable(sf.geometry, z) && coalescable(partials[which_partial].geoms[0], z)) {
partials[which_partial].geoms.push_back(sf.geometry);
partials[which_partial].coalesced = true;
coalesced_area += sf.extent;
@@ -2178,8 +2198,22 @@ long long write_tile(decompressor *geoms, std::atomic<long long> *geompos_in, ch
}
}
// Even though this only explicitly refers to A_COALESCE_FRACTION_AS_NEEDED, it also
// applies to A_DROP_FRACTION_AS_NEEDED and P_DYNAMIC_DROP, which are now also
// constrained against dropping features that cross tile boundaries, because
// the same fraction_accum logic drives all of them.
//
// A_DROP_DENSEST_AS_NEEDED and A_DROP_SMALLEST_AS_NEEDED don't need this check,
// because the features' density and size are calculated globally, so each feature
// is either included or excluded the same way in all the tiles that it appears in,
// unlike the feature fraction, which counts features independently in each tile.
//
// This is probably an argument for doing the fraction globally too, but I'm not
// sure where to drive it from. A global sequence number?
fraction_accum += fraction;
if (fraction_accum < 1 && find_partial(partials, sf, which_partial, layer_unmaps, LLONG_MAX)) {
if (fraction_accum < 1 && find_partial(partials, sf, which_partial, layer_unmaps, LLONG_MAX) &&
coalescable(sf.geometry, z) && coalescable(partials[which_partial].geoms[0], z)) {
if (additional[A_COALESCE_FRACTION_AS_NEEDED]) {
partials[which_partial].geoms.push_back(sf.geometry);
partials[which_partial].coalesced = true;