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Add minimal support for alternate input projections

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This commit is contained in:
Eric Fischer
2016-06-01 15:49:41 -07:00
parent 5da636ba23
commit af412e2038
11 changed files with 1838 additions and 12 deletions
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projection.cpp
+13 -2
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@@ -1,8 +1,9 @@
#include <stdio.h>
#include <math.h>
#include "projection.hpp"
// http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
void latlon2tile(double lat, double lon, int zoom, long long *x, long long *y) {
void lonlat2tile(double lon, double lat, int zoom, long long *x, long long *y) {
// Must limit latitude somewhere to prevent overflow.
// 89.9 degrees latitude is 0.621 worlds beyond the edge of the flat earth,
// hopefully far enough out that there are few expectations about the shape.
@@ -31,12 +32,22 @@ void latlon2tile(double lat, double lon, int zoom, long long *x, long long *y) {
}
// http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
void tile2latlon(long long x, long long y, int zoom, double *lat, double *lon) {
void tile2lonlat(long long x, long long y, int zoom, double *lon, double *lat) {
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;
}
void epsg3857totile(double ix, double iy, int zoom, long long *x, long long *y) {
*x = ix * (1LL << 31) / 6378137.0 / M_PI + (1LL << 31);
*y = ((1LL << 32) - 1) - (iy * (1LL << 31) / 6378137.0 / M_PI + (1LL << 31));
if (zoom != 0) {
*x >>= (32 - zoom);
*y >>= (32 - zoom);
}
}
unsigned long long encode(unsigned int wx, unsigned int wy) {
unsigned long long out = 0;