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Drop more points at each lower zoom level

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This commit is contained in:
Eric Fischer
2014-09-23 14:42:17 -07:00
parent 7fc1c0cd24
commit 91eefcbd16
3 changed files with 24 additions and 4 deletions
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tile.cc
+19 -1
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@@ -6,6 +6,7 @@
#include <zlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <math.h>
#include "vector_tile.pb.h"
extern "C" {
@@ -121,7 +122,7 @@ int draw(char **meta, mapnik::vector::tile_feature *feature, int z, unsigned tx,
}
void write_tile(struct index *start, struct index *end, char *metabase, unsigned *file_bbox, int z, unsigned tx, unsigned ty, int detail) {
void write_tile(struct index *start, struct index *end, char *metabase, unsigned *file_bbox, int z, unsigned tx, unsigned ty, int detail, int basezoom) {
GOOGLE_PROTOBUF_VERIFY_VERSION;
mapnik::vector::tile tile;
@@ -144,6 +145,13 @@ void write_tile(struct index *start, struct index *end, char *metabase, unsigned
values.head = NULL;
values.tail = NULL;
double interval = 1;
double seq = 0;
if (z < basezoom) {
interval = exp(log(2.5) * (basezoom - z));
}
struct index *i;
for (i = start; i < end; i++) {
int t;
@@ -151,6 +159,16 @@ void write_tile(struct index *start, struct index *end, char *metabase, unsigned
char *meta = metabase + i->fpos;
deserialize_int(&meta, &t);
if (t == VT_POINT) {
seq++;
if (seq >= 0) {
seq -= interval;
} else {
continue;
}
}
if (t == VT_POINT || draw(&meta, NULL, z, tx, ty, detail)) {
meta = metabase + i->fpos;
deserialize_int(&meta, &t);