tippecanoe/projection.hpp

void lonlat2tile(double lon, double lat, int zoom, long long *x, long long *y);
void epsg3857totile(double ix, double iy, int zoom, long long *x, long long *y);
void tile2lonlat(long long x, long long y, int zoom, double *lon, double *lat);
unsigned long long encode(unsigned int wx, unsigned int wy);
void decode(unsigned long long index, unsigned *wx, unsigned *wy);

struct projection {
	const char *name;
	void (*project)(double ix, double iy, int zoom, long long *ox, long long *oy);
	const char *alias;
};

extern struct projection *projection;