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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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6
geojson.c
View File

@ -14,6 +14,8 @@
#include "jsonpull.h"
#include "tile.h"
#define BASE_ZOOM 14
#define GEOM_POINT 0 /* array of positions */
#define GEOM_MULTIPOINT 1 /* array of arrays of positions */
#define GEOM_LINESTRING 2 /* array of arrays of positions */
@ -303,7 +305,7 @@ void check(struct index *ix, long long n, char *metabase, unsigned *file_bbox) {
fprintf(stderr, "\n");
int z;
for (z = 14; z >= 0; z--) {
for (z = BASE_ZOOM; z >= 0; z--) {
struct index *i, *j = NULL;
for (i = ix; i < ix + n && i != NULL; i = j) {
unsigned wx, wy;
@ -334,7 +336,7 @@ void check(struct index *ix, long long n, char *metabase, unsigned *file_bbox) {
printf("%d/%u/%u %x %x %lld to %lld\n", z, tx, ty, wx, wy, (long long)(i - ix), (long long)(j - ix));
write_tile(i, j, metabase, file_bbox, z, tx, ty, z == 14 ? 12 : 10);
write_tile(i, j, metabase, file_bbox, z, tx, ty, z == BASE_ZOOM ? 12 : 10, BASE_ZOOM);
}
}
}

20
tile.cc
View File

@ -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);

2
tile.h
View File

@ -47,4 +47,4 @@ struct index {
};
void write_tile(struct index *start, struct index *end, char *metabase, unsigned *file_bbox, int z, unsigned x, unsigned y, int detail);
void write_tile(struct index *start, struct index *end, char *metabase, unsigned *file_bbox, int z, unsigned x, unsigned y, int detail, int basezoom);