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Better handling of features that cross the antimeridian

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This commit is contained in:
Eric Fischer 2015-12-03 13:12:34 -08:00
parent 53471521f3
commit c832b34160
4 changed files with 25 additions and 25 deletions
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2
geojson.c
View File

@ -160,7 +160,7 @@ void parse_geometry(int t, json_object *j, unsigned *bbox, long long *fpos, FILE
}
} else {
if (j->length >= 2 && j->array[0]->type == JSON_NUMBER && j->array[1]->type == JSON_NUMBER) {
unsigned x, y;
long long x, y;
double lon = j->array[0]->number;
double lat = j->array[1]->number;
latlon2tile(lat, lon, 32, &x, &y);

24
projection.c
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@ -2,39 +2,19 @@
#include "projection.h"
// http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
void latlon2tile(double lat, double lon, int zoom, unsigned int *x, unsigned int *y) {
void latlon2tile(double lat, double lon, int zoom, long long *x, long long *y) {
double lat_rad = lat * M_PI / 180;
unsigned long long n = 1LL << zoom;
long long llx = n * ((lon + 180) / 360);
long long lly = n * (1 - (log(tan(lat_rad) + 1 / cos(lat_rad)) / M_PI)) / 2;
if (lat >= 85.0511) {
lly = 0;
}
if (lat <= -85.0511) {
lly = n - 1;
}
if (llx < 0) {
llx = 0;
}
if (lly < 0) {
lly = 0;
}
if (llx >= n) {
llx = n - 1;
}
if (lly >= n) {
lly = n - 1;
}
*x = llx;
*y = lly;
}
// http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
void tile2latlon(unsigned int x, unsigned int y, int zoom, double *lat, double *lon) {
void tile2latlon(long long x, long long y, int zoom, double *lat, double *lon) {
unsigned long long n = 1LL << zoom;
*lon = 360.0 * x / n - 180.0;
*lat = atan(sinh(M_PI * (1 - 2.0 * y / n))) * 180.0 / M_PI;

4
projection.h
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@ -1,4 +1,4 @@
void latlon2tile(double lat, double lon, int zoom, unsigned int *x, unsigned int *y);
void tile2latlon(unsigned int x, unsigned int y, int zoom, double *lat, double *lon);
void latlon2tile(double lat, double lon, int zoom, long long *x, long long *y);
void tile2latlon(long long x, long long y, int zoom, double *lat, double *lon);
unsigned long long encode(unsigned int wx, unsigned int wy);
void decode(unsigned long long index, unsigned *wx, unsigned *wy);

20
tile.cc
View File

@ -544,6 +544,26 @@ long long write_tile(char **geoms, char *metabase, char *stringpool, int z, unsi
continue;
}
if (z == 0) {
if (bbox[0] < 0 || bbox[2] > 1LL << 32) {
// If the geometry extends off the edge of the world, concatenate on another copy
// shifted by 360 degrees, and then make sure both copies get clipped down to size.
unsigned n = geom.size();
for (unsigned i = 0; i < n; i++) {
geom.push_back(draw(geom[i].op, geom[i].x - (1LL << 32), geom[i].y));
}
for (unsigned i = 0; i < n; i++) {
geom.push_back(draw(geom[i].op, geom[i].x + (1LL << 32), geom[i].y));
}
bbox[0] = 0;
bbox[2] = 1LL << 32;
quick = -1;
}
}
if (quick != 1) {
if (t == VT_LINE) {
geom = clip_lines(geom, z, line_detail, buffer);